Drought Resistance

Anastatica hierochuntica is a monocarpic desert annual whose dry skeletons, enclosing mature fruits, often persist for a number of years. The aerial seed bank in these hygrochas-tic 'resurrection plants' therefore persists too. Life tables and fecundity schedules were constructed for A. hierochuntica populations raised under four water treatments, equivalent to 100, 200, 500 and 1000 mm rainfall. Seedling survivorship showed a Deevey type III curve for 100 mm, and a type II curve for 200 mm, while 500 and 1000 mm treat-ments produced Deevey type I curves. Fewer seeds germinated and seedling survivorship was lower in the low water treatments. The stage-specific mor-tality rate reached 0.75 under the 100 mm treat-ment in the seed germination stage, compared to 0.08 under the 1000 mm treatment. Increased water availability resulted in greater plant growth and reproductive output, in terms of both number of seeds per individual and reproductive value. In field studies, aerial se...

Introduction

About 70% of the total freshwater withdrawal from resources is used in the agricultural sector. Water and soil salinity is one of the most important problems in the agricultural sector in arid and semi-arid regions. In such areas that are facing water shortages, saline water is commonly used in irrigated lands and it will be of great help in preserving freshwater resources. Crop modeling in combination with field measurements is an efficient method to improve water productivity in the field and investigate the crop's biological response to different field conditions. Several crop models have been developed for crop growth simulation. Among these models, AquaCrop software has been widely studied in recent years. AquaCrop software is able to simulate the growth process under different conditions with few input data that can be easily measured in the field. Few studies have been conducted on saffron crop modeling with AquaCrop software, but this model has not yet been calibrated to simulate salinity during the growing season. This research was carried out to calibrate the AquaCrop software for simulating the variations of soil salinity in the root zone of two-year-old saffron. In addition, in the present study, the effect of different levels of salinity and the application of different levels of organic mulch and their mutual effect on the yield of daughter corms, biomass, and water productivity were investigated.

Material and Methods

To calibrate the AquaCrop software for two-year saffron during the growing season in the research farm of the Ferdowsi University of Mashhad (FUM), growth parameters of saffron crop such as the soil moisture and salinity, the dry weight of daughter corms and the crop canopy cover were continuously measured during the growing season. Soil moisture and salinity were measured at least once a week, and the dry weight of daughter corms was measured biweekly. After model calibration, the accuracy of the model for simulating soil salinity during the growing season was evaluated by comparing the measured and simulated values. Statistical indicators of Pearson correlation coefficient, root mean square error, and Nash Sutcliffe model efficiency coefficient, were used to evaluate the accuracy of crop model simulation. The model was subsequently run for different initial conditions of soil salinity and irrigation water salinity. The dry weight of daughter corm, biomass, and ET water productivity were monitored for different conditions. Then, the model was run in the same conditions of water and soil salinity under the application of organic mulch, and the effect of mulch on the yield of daughter corms and evapotranspiration water productivity under salinity stress was investigated.

Results and Discussion

The statistical indicators between the measured and simulated values of soil moisture, canopy cover, and biomass approved the capability of AquaCrop for simulating saffron growth. Then, according to the measured salinity values of the root zone using the TDR sensor, AquaCrop was recalibrated to simulate soil salinity. Afterward, the changes in the measured salinity values of the root zone during the growing season were compared with the values simulated by AquaCrop. The Pearson correlation coefficient for measured and simulated soil salinity by software was 0.9 and the root mean square error was 0.086 dS m-1. Nash–Sutcliffe efficiency was 0.66, showing the high accuracy of AquaCrop for simulating soil salinity. The results of the crop growth simulation in saline conditions show the sensitivity of saffron to salinity. The results showed that under no initial salinity (0.5 dS m-1) in the soil, increasing the salinity of irrigation water from 1 dS m-1 to 4 dS m-1 caused a decrease of 3.7 % in the daughter corms weight. In addition, considering the initial salinity of 2 dS m-1, increasing the salinity of the irrigation water has a significant effect on reducing the daughter corm weight. In the presence of high-quality irrigation water (0.5 dS m-1), increasing the initial salinity of the soil from no salinity (0.5 dS m-1) to 4 dS m-1 caused a 38% decrease in the weight of daughter corms. The effect of organic mulch was also evaluated under saline water irrigation conditions. The results showed that the use of organic mulch with 100% coverage in water and soil salinity conditions equal to 4 dS m-1 can mitigate the effect of salinity stress by increasing 51% of daughter corm weight.

Conclusion

Water and soil salinity and its related problems are limiting factors in agricultural production in arid and semi-arid regions. The expansion of irrigation methods with saline water without proper management can lead to the risk of soil quality loss and in turn the loss of agricultural lands in the long term. In this research, the AquaCrop model was calibrated to simulate soil salinity during the saffron growing season, and the effect of organic mulch on soil and water salinity conditions was evaluated on the yield of daughter corms. The findings of this research will be of great help to farmers and water experts in improving the performance of saffron in saline soil and irrigation water.

The influence of arbuscular mycorrhizal fungi (AMF) on “chococitos” white maize plants subjected to waterlogging and drought stress was evaluated. The trial consisted of evaluating, under controlled conditions, the effect of three levels of soil moisture: severe drought (20% of the pot's field capacity), normal conditions (100% of field capacity), and waterlogging (permanent presence of a water film on the pot surface). Two AMF inoculation conditions (-AMF sterilized inoculum and +AMF live inoculum) on the growth of white chococitos maize plants grown in plastic pots, with eight replicates per treatment for a total of 48 plants. After 90 days, the variables height, number of leaves, dry weight, leaf area, and percentage of root colonization were measured. The results show that, in general, plants colonized by AMF showed greater tolerance to the negative effects caused by both types of abiotic stress. These results support the idea of ​​disseminating the use of mycorrhizae among farmers in the Pacific region as a strategy to improve crop performance in the face of abiotic stress.

Drought is an important abiotic factor where maize is grown under rainfall conditions. In order to identify drought resistant lines, 77 S5 maize lines from the breeding program at Cotaxtla, Veracruz and four CML maize lines from CIMMYTwere evaluated under irrigation  (So) and drought stress (S1). Five indexes were applied to select drought tolerant lines. Four indexes use the grain yield as criteria for selection, these are, the drought index (DI), the arithmetic mean (AM), the geometric mean (GM), and the stress tolerance index (STI). The last index, (G+GxS), takes into consideration all the traits evaluated in the trial. In general, all measured characteristics were affected by the drought treatment. The DI the other indexes. DI selects germplasm with the lowest yields, while, AM, GM, STI and G+Gxs indexes selected the same lines and all of these displayed a superior mean yield in comparison to those that were selected by the DI index. Among the best 10%, five lines and the checks...

Plants are subjected to unregulated water loss from their surface by cuticular transpiration. Therefore, specific morphophysiological changes may occur during leaf development to eliminate water loss. This study aimed to examine the cuticular transpiration of 23 winter wheat genotypes and their wild-growing predecessors of the genus Aegilops, which were divided into three groups to demonstrate their diversity. The genotypes were sown in autumn and grown in regular field trials at the Research Institute of Plant Production in Piešťany, Slovakia. Cuticular transpiration and growth parameters were analyzed in the postanthesis growth stage. Gravimetric measurement of residual water loss was performed on detached leaves with a precisely measured leaf area. The lowest nonproductive transpiration values were observed in modern wheat genotypes, while higher cuticular transpiration was observed in a group of landraces. Aegilops species generally showed the highest cuticular transpiration wit...

The present investigation consists of 45 upland rice germplasm provided during 2010 and 2011 at Sam Higginbottom Institute of Agricultural Technology and Sciences, Allahabad, U.P. The experiment was conducted in RBD having three replications. The data were recorded on 12 characters to study the analysis of variance, heritability, genetic advance, coefficient of variation, correlation coefficient and path analysis. Based on the mean performance table IR 82589-B-B-149-4 and IR 82589-B-B-36-2 were identified as best genotype for grain yield. Highly significant variation was obtained for number of spikelets per panicle, plant height, harvest index, biological yield, days to 50% flowering and days to maturity. Seed yield per plant, number of spikelets per panicle, biological yield, flag leaf length and number of tiller per plant showed relatively high GCV and PCV estimates. High heritability was obtained for number of spikelets per panicle (100%), flag leaf width (96%), plant height (93%...

Drought is a major abiotic factor that limits plant growth and productivity. Tomato is an important vegetable crop and area under production is limited by irrigation water scarcity. Effort was made to screen tomato germplasm under in vitro condition using polyethylene glycol (PEG) at four concentrations (0, 20, 40 and 60 g/l) with two replications in factorial CRD. Important seedling characters like root length and weight; shoot length and weight were recorded. Drought resistant mutant derivatives and hybrid produced using mutant derivative as female parent performed significantly superior for root characters. Decrease in seedling growth was worth notice with increasing concentration of PEG indicating precise nature of the in vitro screening. Mutant hybrid and its derivatives were observed with outstanding ability to continue root growth under in vitro stress conditions indicating there ability to fight with sever water stress situation. These results were further confirmed for earl...

Rooting characteristics significantly affect the water-use patterns and acquirement of nutrient for any plant species. Plant growth promoting rhizobacteria improve the plant growth by a variety of ways like the production of phytohormones, nitrogen fixation, phosphate solubilization and improvement in root morphology etc, and are also useful in cutting down the cost of chemical fertilizers. The present investigation was carried out to determine the comparative effect of plant growth promoting rhizobacteria (PGPR), Azospirillum brasilense, Azotobacter vinelandii and Pseudomonas stutzeri, either alone or in combination with different doses of chemical fertilizers [full dose (Urea at 60 kg ha -1 and DAP at 30 kg ha -1 ), half dose (Urea 30 kg ha -1 and DAP 15 kg ha -1 ) and quarter dose (Urea 15 kg ha -1 and DAP 7.5 kg ha -1 )] on root morphology and root distribution pattern of safflower (Carthamus tinctorius L.) viz. cvv. Thori and Saif-32 in the soil. The PGPR were applied as seed inoculation at 10 6 cells/ml prior to sowing. P. stutzeri either alone or in combination with full dose of chemical fertilizers, was highly effective in increasing the root area in cv. Saif-32, whereas, the percent increase due to A. brasilense was comparable to that of treatment with full dose of chemical fertilizers. P. stutzeri inoculation resulted in significantly higher root length in both the cultivars. Significantly, higher root width (54%) of cv. Thori was observed in treatment receiving inoculation with A. vinelandii and supplemented with half dose of chemical fertilizers, whereas maximum root width of cv. Saif-32 was recorded in treatment supplemented with half dose of chemical fertilizers. It is inferred that PGPR inoculation especially those of A. brasilense and P. stutzeri either alone and more so in combination with half dose of chemical fertilizers, are highly effective in improving root morphology and growth in safflower.

Plant microRNAs (miRNAs) play important roles in plant development and responses to biotic and abiotic stress. Recently, there is clear evidence that miRNAs are involved in host-virus interactions. By using stem-loop RT-PCR, an expression levels change of thirteen miRNA belonging to six miRNA families targeting leaf development and morphogenesis were analyzed upon Tobacco Mosaic Virus (TMV)-tomato infection. Compared to mock plants, significant changes in relative expression levels of nine miRNAs were observed. The miR319c-5p showed the highest statistically significant increase in accumulation at 15 days post-inoculation. At all time points tested, miR159, miR164a-3p, miR164a-5p, miR166c-5p and miR319c-5p were up-regulated while miR160, miR319a, miR319b, miR319c-3p were down-regulated in most cases. Our data could provide new insights into the role of miRNAs in tomato-TMV interaction and in developing efficient strategies for improving tomato resistance against viral infection.

• An assumption still in debate nowadays: ~85% of terrestrial plant invaders would not shift their climatic niche (Petitpierre et al. 2012, Sciences). • Gorse is a particularly interesting model species as it is among the 30 most noxious weed species worldwide (UICN).

Arabidopsis microRNA expression regulation was studied in a wide array of abiotic stresses such as drought, heat, salinity, copper excess/deficiency, cadmium excess, and sulfur deficiency. A home-built RT-qPCR mirEX platform for the amplification of 289 Arabidopsis microRNA transcripts was used to study their response to abiotic stresses. Small RNA sequencing, Northern hybridization, and TaqMan ® microRNA assays were performed to study the abundance of mature microRNAs. A broad response on the level of primary miRNAs (pri-miRNAs) was observed. However, stress response at the level of mature microRNAs was rather confined. The data presented show that in most instances, the level of a particular mature miRNA could not be predicted based on the level of its pri-miRNA. This points to an essential role of posttranscriptional regulation of microRNA expression. New Arabidopsis microRNAs responsive to abiotic stresses were discovered. Four microRNAs: miR319a/b, miR319b.2, and miR400 have been found to be responsive to several abiotic stresses and thus can be regarded as general stress-responsive microRNA species.

Although Jatropha curcas, an important tropical biofuel crop, is reputed for its drought resistance, its ability to perform under dry conditions has hardly been investigated. In a greenhouse experiment we investigated the plant-water relationships of Jatropha seedlings from different accessions under different levels of drought stress. There was little difference in plant water relations between accessions. Drought significantly reduced leaf area, biomass and relative growth rate, but had no effect on specific leaf area, daily range in leaf water potential, leaf water content, transpiration efficiency or aboveground biomass water productivity, corrected for atmospheric conditions. Stem wood density was equally low (0.26 gÂFP -3 ) for all treatments. Stem water content was lowest for dry treatment seedlings. Based on these results, Jatropha could be characterized as a stem succulent tree. In contrast to other stem-succulent deciduous trees, leaves were not shed immediately after the seedlings were confronted with drought. Instead, at the onset of drought, leaves with a higher adaxial stomatal density were formed, after which leaves were only gradually shed. The role of the succulent stem in the water economy of Jatropha was confined to balancing the small water losses of the leaves during drought.

The services that urban trees provide to human society and the natural environment are widely recognized, but urban trees are in jeopardy due to climate change and urban stressors. With drought as a major threat in many areas, it is important for the future of urban forestry to select species composition based upon performance under water stress. Certain leaf functional traits can help horticulturalists more accurately predict water usage of urban trees. Comprehension through rigorous experimentation is lacking, partly due to the thousands of mostly exotic species. Previous studies suggest that species whose leaves have a denser arrangement of smaller stomata and a higher leaf mass per area (LMA) are better adapted to low water availability. We sampled 70 urban tree species California and analyzed their stomatal length, stomatal density, and LMA. We compared the traits with water use data from the Water Use Classification of Landscape Species to assess possible correlations. All pairwise trait comparisons show significant correlation (P < 0.05), and LMA is significantly higher in low water use species compared to medium water use species (P= 0.0045). After using independent contrasts to incorporate phylogenetic relationships, significance was lost, implying that basal divergences are responsible for observed trends. Other potential explanations for differences in species water usage are foliar longevity (deciduous vs. evergreen) and stomatal distribution (amphistomatous vs. hypostomatous). Low water use species are more likely to be evergreen and amphistomatous compared to medium water use species. Consideration of all these traits in combination with good management practices can help ensure future success of urban forests.

This brief summarizes detailed analysis of the determinants of household crop income in rural Mozambique from 2002 to 2005. Increased crop income is associated with increases in household land area, use of animal traction, crop diversification into tobacco or cotton, access to market price information, and access to extension agents (for tobacco/cotton growers). Decreases in crop income are associated with drought. Results demonstrate that there are both public and private investments that can enhance farmers&#39; ability to increase crop income and avoid losses. Priority investments include: development and dissemination of drought-resistant varieties for maize and cassava, conservation farming, animal traction, market information, access to high-value crops and small-scale irrigation.

The formation of hybrid varieties by self-crossing the F2 population has been carried out, thus obtaining the first generation selfing line (S1). This research aims to determine the level of drought stress resistance of S1 lines of corn plants and the correlation between their characters and stress sensitivity index (SSI) value for each stress. The method used is an experimental method with field experiments. The experiment was carried out from March to June 2023 in Gumantar Village, Kayangan District, North Lombok Regency. The experimental design used was a randomized block design (RBD) in a split plot design with the main plot consisting of stress and normal treatments, while the sub plots were the S1 lines and the F2 population. The results showed that there were different levels of resistance in the S1 line. G27 has resistance with tolerant criteria, 13 lines are moderately tolerant, and 16 other lines are susceptible; Correlation criteria between characters vary with the SSI value in each stress and normal condition. Characters that are strongly correlated with the SSI value are chlorophyll A, total chlorophyll, harvest dry cob weight, and dry grain weight. The formation of S2 lines can be done using tolerant and moderately tolerant lines.

Background: Common bean is an important legume crop with only a moderate number of short expressed sequence tags (ESTs) made with traditional methods. The goal of this research was to use full-length cDNA technology to develop ESTs that would overlap with the beginning of open reading frames and therefore be useful for gene annotation of genomic sequences. The library was also constructed to represent genes expressed under drought, low soil phosphorus and high soil aluminum toxicity. We also undertook comparisons of the fulllength cDNA library to two previous non-full clone EST sets for common bean. Results: Two full-length cDNA libraries were constructed: one for the drought tolerant Mesoamerican genotype BAT477 and the other one for the acid-soil tolerant Andean genotype G19833 which has been selected for genome sequencing. Plants were grown in three soil types using deep rooting cylinders subjected to drought and non-drought stress and tissues were collected from both roots and above ground parts. A total of 20,000 clones were selected robotically, half from each library. Then, nearly 10,000 clones from the G19833 library were sequenced with an average read length of 850 nucleotides. A total of 4,219 unigenes were identified consisting of 2,981 contigs and 1,238 singletons. These were functionally annotated with gene ontology terms and placed into KEGG pathways. Compared to other EST sequencing efforts in common bean, about half of the sequences were novel or represented the 5' ends of known genes. The present full-length cDNA libraries add to the technological toolbox available for common bean and our sequencing of these clones substantially increases the number of unique EST sequences available for the common bean genome. All of this should be useful for both functional gene annotation, analysis of splice site variants and intron/exon boundary determination by comparison to soybean genes or with common bean wholegenome sequences. In addition the library has a large number of transcription factors and will be interesting for discovery and validation of drought or abiotic stress related genes in common bean.

The effect of drying on color changes of St. John’s wort (Hypericum perforatum L.) leaves was investigated. The samples were dried at drying air temperatures of 40, 50, 60, and 70°C, air velocities of 0.3, 0.7, and 1 m/s and bed depths of 1, 2, and 3cm with factorial experimental design based on completely randomized design. All treatments were tested in three replications. The total color difference (ΔE) and saturation index or chroma (SI) was evaluated as the important quality parameters. The Duncan’s multiple range tests was used to compare the treatment means. Regarding to SI and ΔE indices the most suitable quality was found for the samples dried at temperature of 40°C, air velocity of 0.3 m/s and bed depth of 3 cm.

Roots and tubers such as potatoes and cassava rank within the top six among the world's most important food crops, yet the extent to which their global production has been adversely affected by drought remains unclear. Greater uncertainties exist on how drought effects co-vary with: 1) root and tuber species, 2) soil texture, 3) agro-ecological region, and 4) drought timing. It is often assumed that potato is drought-sensitive whereas cassava and sweet potato are resistant to drought. To address these uncertainties, we collected literature data between 1980 and 2015 that reported monoculture root and tuber yield responses to drought under field conditions, and analyzed this large data set using meta-analysis techniques. Our results showed that the amount of water reduction was positively related with yield reduction, but the extent of the impact varied with root or tuber species and the phenological phase during which drought occurred. In contrast to common assumptions regarding drought resistance of certain root and tuber crops, we found that yield reduction was similar between potato and species thought to be drought-resistant such as cassava and sweet potato. Here we suggest that drought-resistance in cassava and sweet potato could be more related to survival rather than yield. All roots or tubers crops, however, experienced greater yield reduction when drought struck during the tuberization period compared to during their vegetative phase. The effect of soil texture on yield reduction was less obvious, and similarly we did not find any significant effects of region (and related climatic factors) on neither yield reduction nor drought sensitivity. Our study provides useful information that could inform agricultural planning, and influence the direction of research for improving the productivity and the resilience of these under-utilized crops in the drought-prone regions of the world.

Diurnal courses of net CO 2 uptake rate, stomatal conductance (g S ), maximum photochemical efficiency of PSII (Fv/Fm) and apparent photosynthetic electron transport rate (ETR) were measured in Quercus ilex and Phillyrea latifolia in a holm oak forest throughout the seasons of the year. These measurements were complemented with response curves of photosynthetic rates to PPFD and CO 2 concentrations. P. latifolia was better adapted to drought and warm conditions and showed higher net CO 2 uptake, g S and Fv/Fm values than Q. ilex in summer. But in autumn and specially in winter P. latifolia was more sensitive to low temperatures and experienced lower net CO 2 uptake, g S , ETR and Fv/Fm values than Q. ilex. The maximum net CO 2 uptake values for P. latifolia occurred under summer high temperatures whereas maximum net CO 2 uptake values for Q. ilex occurred under winter low temperatures. However, in summer during midday, both species presented null or slightly negative net CO 2 uptake rates. Since in the summer season both species experienced similar ETR values, the lower net CO 2 uptake values of Q. ilex suggest that Q. ilex presented greater photorespiration rates. During winter, very low Fv/Fm values were found especially for P. latifolia, indicating that maximal photochemical efficiency of PSII is very sensitive to low temperatures. However, they were not accompanied by low net CO 2 uptake rates showing that cold photoinhibition determined a potential but not an actual decrease in photosynthetic performance. Under well watered conditions and with high CO 2 concentration and saturated PPFD, Q. ilex was able to increase its photosynthetic rates whereas P. latifolia had lower plasticity to make a profit of optimal environmental conditions. These results show different strategies between these two dominant co-occurring species. They also indicate that the warmer and drier conditions expected for the Mediterranean region in the near decades as a result of climate change will favour drought resistant species with lower photosynthetic rates such as P. latifolia in detriment of more mesic species such as Q. ilex.

Haflhafl ülkemizin önemli kültür bitkilerinden birisidir. Hem kapsüllerinde bulunan alkaloitlerinden, hem de ya¤›ndan yararlan›lmaktad›r. Kapsül kabu¤unda bulunan, özellikle morfin baflta olmak üzere, papaverin, tebain ve kodein gibi alkaloitleri önemli ilaç hammaddesidir. Ayr›ca morfin ve bundan elde edilen eroin -yasak olmas›na ra¤men-dünyada uyuflturucu olarak yayg›n bir flekilde kullan›lmaktad›r. Hitit'ler döneminden beri haflhafl›n tar›m› yap›lmaktad›r. Ilk defa 1933 y›l›nda bitkinin tar›m› devlet kontrolü alt›na al›nm›fl ve zaman zaman ç›kar›lan kanun ve yönetmeliklerle 1971 y›l›na kadar üretim devam etmifltir. 1971 y›l›nda 2654 say›l› hükümet kararnamesiyle haflhafl tar›m› Türkiye de yasaklanm›flt›r. Üretime 1974 y›l›nda tekrar izin verilmifl, ancak kapsül çizimi yasaklanm›flt›r. Kuru kapsüllerden alkaloitlerin elde edilmesi için Afyon'un Bolvadin ilçesinde 1976 y›l›nda bir

Selección de las líneas de maíz por resistencia a sequía. La sequía es un factor abiótico importante en ambientes donde el cultivo de maíz es de temporal. Se evaluaron en condiciones de riego (S o ) y sequía (S 1 ) a 77 líneas S5 del programa de maíz del Campo Experimental Cotaxtla (CE-COT) y cuatro CML's tolerantes a sequía del Centro Internacional de Mejoramiento de Maíz y Trigo (CIMMYT). Se utilizaron cinco índices de clasificación para seleccionar a las líneas tolerantes a sequía,. Cuatro de los índices basan la selección en el rendimiento de grano, éstos son, IS (índice de sequía), MA (media aritmética), MG (Media geométrica) e ITS (índice de tolerancia a sequía). El último índice, G+GxS (índice de tolerancia a sequía), involucra en su construcción a todos los caracteres evaluados. En general, todas las características evaluadas se vieron afectadas por el efecto de la sequía impuesta. El IS difirió del resto de índices en las líneas seleccionadas, éste índice selecciona germoplasma de menor promedio de rendimiento, mientras que los índices MA, MG, ITS y G+GxS, mostraron similitud al seleccionar a las mismas líneas y con rendimiento promedio superior a aquellas que seleccionó el IS. Del 10% de líneas seleccionadas por cada índice, cinco de ellas y los testigos CML 273 y CML 274 (tolerantes a sequía) fueron seleccionados con mayor frecuencia. En base a los resultados, seleccionar utilizando el índice G+GxS es mejor opción para mejorar por resistencia a sequía.

FR)* Anne-sophie sergent Institut national de recherche agronomique (INRA), Orléans (FR) Guillermina Dalla-salda Instituto nacional de technologia agropecuaria, Bariloche (AR) Alejandro Martinez-Meier Instituto nacional de technologia agropecuaria, Bariloche (AR) sara Marin Institut national de recherche agronomique (INRA), Orléans (FR) Manuela Ruiz-Diaz Institut national de recherche agronomique (INRA), Orléans (FR) Jean-Charles Bastien Institut national de recherche agronomique (INRA), Orléans (FR) Leopoldo sanchez Institut national de recherche agronomique (INRA), Orléans (FR) nathalie Bréda Institut national de recherche agronomique (INRA), Nancy (FR) For a number of years in certain regions of France the Douglas-fir trees (Pseudotsuga menziesii [Mirb.] Franco) have presented symptoms of withering which have been attributed to drought. Our results show that the hydraulic function of the wood plays a part in the resistance of the Douglas-fir to dry conditions. Narrower cellular conduits, and therefore a greater wood density, contribute to the survival of trees confronted with a period of a marked water deficit. This idea is confirmed by the existence of significant relationships between wood density and hydraulic properties of wood in which the raw sap circulates, and also by the relationships found between the ecological preferences of specimens in their area of origin and the density of their wood in regions of France where they have been introduced. Those coming from dry regions have a tendency to develop wood with characteristics similar to that of trees which have survived drought. While the relationship between wood density and survival has been demonstrated, the differences in the nature of this relationship between different sites show that the mechanisms involved are complex and to a large extent still not understood.

Attempts to identify individual traits to use as an indirect measure for grain yield have shown some degree of success in environments where crop yields are affected by no stress or only by predictable stresses. However, analytical breeding has been largely unsuccessful in the case of a) stressful environments characterized by low yields due to high variability in the frequency, timing, duration and severity of a number of climatic stresses, and b) breeding programs where the major objective is greater yield stability defined as a reduction in the frequency of crop failures. Experimental evidence suggests that, when environmental variability is high due to unpredictable differences in frequency, timing and severity of various climatic stresses, each time different combinations of several traits are likely to confer 'drought resistance'. Interaction among traits in determining overall crop response to variable stresses is expected to occasionally enhance the importance of a specific trait in a specific stress situation. In this context it becomes difficult to consider 'drought resistance' as a character with its own identity in terms of inheritance. Assessment and verification of traits based on the use of isogenic lines tends to oversimplify the interactions between traits, as the approach provides information on the effect of a specific trait only in a specific genetic background. At the population level of organisation, the dilemma between selection for individual traits and specific combinations of traits can be translated into the dilemma between selection for individual genotypes and specific combinations of genotypes. The evidence that natural selection under stress conditions has not been able to identify either a single trait or a single genotype with a given 'adapted' architecture of traits, is discussed in relation to germplasm development philosophies to stabilize yield in unpredictably stressed environments.

To improve feed availability for smallholder farmers in East Africa, we investigated the biomass production, drought resistance and nitrogen fixation of five forage legumes (Lablab purpureus, Desmodium uncinatum cv Silverleaf, Desmanthus virgatus, Macroptilium bracteatum cv Burgundy bean, and Canavalia brasiliensis) in a field trial in Uganda. The crops were grown under rain-fed conditions (control) and with additional irrigation (irrigated) and harvested five times at two-monthly intervals (first harvest in the wet season, two following in the dry season, last two in the wet season again). On average, the soil water content of the control plots was about 14 % lower than in the irrigated ones (measured at five occasions throughout the season). Before herbage harvests, the youngest leaves of the forage crops were sampled for stable carbon (C) and nitrogen (N) isotope analysis for an indication of intrinsic water-use efficiency and N fixation, respectively. The total herbage dry matte...

Uganda as a country is experiencing the effects of climate change, in terms of drought spells, high
temperatures, erratic rainfall and changes in wind patterns. It has worsened the occurrence of
landslides, drought occurrences, hailstones, flooding, and water logging around low-lying areas across
the country. This has caused a lot of suffering and sometimes reversing development achievements
already registered, through food insecurity, low yields, loss of assets, high cost of pest control and high
incidences of animal and crop diseases. The goal was to examine resilience of smallholder farmers to
effects of climate change, the objectives were  i)  establish evidence of climate change,  ii)  determine
effects of climate change on agroecosystems and iii)  determine the adaptation and mitigation
strategies employed by small holder farmers to climate change.  Several books,  articles,  and journals 
on  smallholder farmers resilience to climate change, Climate-smart agriculture, agroecology, and
effects of climate change on food security and livelihoods. A diagnostic research study was conducted
to determine the effects of i) climate change on agricultural production, ii) adaptation and iii)
mitigation measures smallholder farmers are employing. Results show that high temperatures are
occurring due to climate change (p=0.000) resulting in low agricultural production, high incidence of
invasive weeds, pests, and difficulty in rearing animals. There is a high incidence of invasive crop
pests (p=0.000). There is traditional indigenous knowledge that older farmers use to predict what can
happen in a particular season in terms of the amount of rain that can be received. This is grounded with
the old folk and lacking among young people. The appearance of particular birds  signal an abundance
of rainfall and drought prevalence in the area. The farmers use granaries to store food and undertake
water harvesting for production. The farmers practice polyculture (p=0.046) and grow cover crops in
their gardens (p=0.031) and harvest water for production (p=0.022). The climate seriously affects
smallholder farmers' means of livelihood with agriculture and there is a need to build farmers'
resilience capacity to effects without which, famine and poverty will be very dire among rural
smallholder farmers in Uganda. There is also a need to equip extension staff with climate-smart
practices and/or agroecology approaches to enable them to facilitate the farmers with context-specific
approaches to enable them to produce enough food in this challenging and variable climate.

Western Cape. Sorghum bicolor (L.) Moench is an important cereal crop currently explored as a potential bio-energy crop due to its stress tolerance and ability to ferment soluble sugars. Physiological studies on sorghum varieties have demonstrated that part of drought tolerance is attributed to sugar accumulation in the sorghum stems. Despite the agronomic advantages of sorghum as a bio-energy crop, more research efforts towards the molecular elucidation of sorghum traits that confer drought tolerance are necessary. Particular focus on traits, which could potentially contribute to an efficient bioenergy production under environmental constraints, would be an added advantage. This study examined the role of sugar biosynthesis proteins in conferring tolerance to drought-induced hyperosmotic stress, and ultimately osmotic adjustment in sorghum varieties. Sorghum bicolor (L.) Moench varieties (ICSB338, ICSB73, ICSV213 and S35) with different levels of drought tolerance, were grown under watered conditions until early anthesis after which, a 10-day water deficit period was introduced. iv Control (well-watered) and stressed plants were harvested and used to evaluate plant growth, water retention, chlorophyll content, metabolic profiles, and enzymatic activity of sucrose biosynthesis enzymes. GC-MS based metabolic profiling approach was used to determine the changes in the stem metabolome with stress induction. HPLC analysis was carried out to determine the total soluble sugar content in the stems in all four varieties. Q-PCR was used to determine the levels of mRNA expression of sucrose biosynthesis genes in control and stressed plants. Furthermore, twodimensional gel electrophoresis (2DE) coupled with mass spectrometry was used to identify stress responsive proteins in sorghum plants. A significant reduction in soil water content was observed. As a consequence leaf water content, total chlorophyll content and plant biomass was also reduced. Metabolite analysis revealed a higher abundance of soluble sugars compared to the free amino acid pool, which suggested that osmotic adjustment under stressed conditions was more attributed to sugar content. From a detailed soluble sugar analysis, an increase in total soluble sugars (brix) and hexose concentrations (glucose and fructose) was observed followed by a decrease in sucrose and starch levels in all four sorghum varieties. Gene (mRNA) expression analysis showed an up regulation of sucrose-biosynthesis genes as a consequence of drought stress. However, a direct correlation between the soluble sugar levels and mRNA expression was only evident in ICSV213, indicating that only this variety was responsive to hyperosmotic stress. throughout the course of this study. I am also grateful for the financial support received from the Agricultural Research Council and the Department of Science and Technology.  To Dr Sandile Ndimande, thank you for being a beacon of hope when I was at my lowest point and was ready to throw in the towel. To Dr Omodele Ibraheem, thank you for your guidance, support and friendship throughout this journey. To Dr Ashwil Klein and Dr Hannibal Musarurwa, thank you for your invaluable input during the most challenging period of compiling this document. To Dr Abram Madiehe, thank you for your mentorship.  To the Proteomics Group, thank you for the good and challenging times we have endured together during this learning phase of my life.  To my parents, siblings and extended family, thank you for your encouragement and constant belief in my abilities. My family, Akona and Yakhani Nakani, you've been my true inspiration and motivation in keeping the faith and finishing this race. Thank you. xv Table of Contents KEYWORDS .

Drought is a major abiotic stress that severely affects food production worldwide. Agronomic and physiological traits associated with drought tolerance are suitable indicators for selection of drought tolerance genotypes to reduce the impact of water deficit on crop yield in breeding program. The objective of this study was to identify indicators related to drought tolerance through analysis of photosynthetic traits in barley (Hordeurn vulgare L.). These traits included chlorophyll content, initial fluorescence (F,), maximum primary yield of photochemistry of photosystem 11 (F, / F,) and maximum quantum yield of photosystem I1 (Fv/Fm). Four genotypes (Tadmor, Arta, Morocco9-75 and WI2291) variable in drought tolerance were used to investigate the correlation between these traits and drought tolerance. The results reflected that all of these traits were affected negatively in the four genotypes at different levels of post-anthesis drought stress, but the decrease in drought tolerant genotypes was much less than that of drought sensitive genotypes. The results further revealed that the components of the photosynthetic apparatus could be damaged significantly in drought sensitive genotypes, while drought tolerant genotypes were relatively less affected. On the other hand, the values of chlorophyll content, F,, F,/F, and F,/F, in drought tolerance genotypes were significantly higher than those in drought sensitive genotypes under drought stress. It was concluded that chlorophyll content, F,, F,/F, and F,/F, could be considered as reliable indicators in screening barley germplasm for drought tolerance.

The antioxidative protection in leaves of four winter wheat (Triticum aestivum L.) varieties with different field drought resistance was studied under severe recoverable soil drought at seedling stage by withholding irrigation for 7 days (57–59% leaf water deficit) followed by rewatering. A 3-fold raise in electrolyte leakage and a sharp increase in proline accumulation corresponded to drought severity. Hydrogen peroxide content and catalase (CAT) activity were maintained low under stress. Peroxidase (GPX) activity increased, whereas superoxide dismutase (SOD) activity only slightly changed. The content of ascorbate and low-molecular thiols diminished under severe drought and was restored in recovery. Malondialdehyde level was not changed significantly in drought-treated plants but raised after re-watering. In recovery CAT activity became significantly higher whereas GPX activity diminished. Three isoforms of SOD, one of catalase and three of GPX were revealed. Proline accumulation ...

The aim of the experimental work was to determine the sorption isotherms of wheat extrudates enriched with cocoa bean shells at different temperatures (10 °C, 25 °C, 40 °C) and water activities (0.11 to 0.85) using the static gravimetric method. Five three parameter models (Chung-Pfost, Halsey, Oswin, Henderson, GAB) were applied to survey the experimental data. It was established that the isotherms demonstrate Types II, according to the Brunauer's classification and the Oswin and Chung-Pfost models were suitable for describing the relationship between the equilibrium moisture content and the water activity. The monolayer moisture content was established using the Brunauer-Emmett-Teller equation and ranged within 5.08 % d.b. and 7.80 % d.b., respectively. The increase of temperature decreases the sorption characheristics of the examined extrudates. The specific surface area of sorption for wheat extrudates enriched with cocoa bean shells varies between 181.59 (m 2 /g) and 278.82 (m 2 /g). It was found that the increase of temperature of the matrix in the range of 10 °C to 40 °C decreases the values of monolayer moisture content and the specific surface area of sorption.

Genetic diversity is prerequisite for any crop improvement program as it helps in the development of superior recombinants. Fifty Malaysian upland rice accessions were evaluated for 12 growth traits, yield and yield components. All of the traits were significant and highly significant among the accessions. The higher magnitudes of genotypic and phenotypic coefficients of variation were recorded for flag leaf length-to-width ratio, spikelet fertility, and days to flowering. High heritability along with high genetic advance was registered for yield of plant, days to flowering, and flag leaf length-to-width ratio suggesting preponderance of additive gene action in the gene expression of these characters. Plant height showed highly significant positive correlation with most of the traits. According to UPGMA cluster analysis all accessions were clustered into six groups. Twelve morphological traits provided around 77% of total variation among the accessions.

Moghaddam, A., J. Vollmann, W. Wanek, M. R. Ardakani, A. Raza, G. Pietsch, and J. K. Friedel. 2012. Suitability of drought tolerance indices for selecting alfalfa (Medicago sativa L.) genotypes under organic farming in Austria. Crop Breeding Journal 2(2): 79-89. In eastern Austria, alfalfa is usually grown as a rainfed crop in crop rotations in organic farming systems, where yearto-year rainfall fluctuations cause different levels of drought stress. To identify the suitability of different alfalfa genotypes and drought tolerance indices, 18 contrasting alfalfa genotypes were evaluated under irrigated and rainfed conditions at the research station of the University of Natural Resources and Life Sciences (BOKU), Vienna, Austria, during 2006-08. The first study year (2006) was considered as the establishment year. Five drought tolerance selection indices were estimated based on shoot dry matter, total biomass yield and biological nitrogen fixation (BNF) data. The correlation between ir...

Resumen: El clavel tiene gran importancia para la floricultura colombiana, siendo Dianthus barbatus, en sus variedades Kiwi Mellow y Green Ball, una alternativa de crecimiento del sector, debido a la belleza que aporta a los arreglos florales. No obstante, las empresas colombianas necesitan innovar y optimizar recursos para llevar un manejo adecuado del espacio de siembra y así mejorar su productividad. Por lo anterior, se evaluaron diferentes densidades de siembra y contenedores en las variedades mencionadas, para lo que se empleó un diseño completamente aleatorizado con cuatro tratamientos por variedad (23 plantas/m 2 , dos contenedores por cama; 46 plantas/m 2 , dos contenedores por cama; 27 plantas/m 2 , un contenedor por cama; 54 plantas/m 2 , un contenedor por cama), con cuatro repeticiones por tratamiento. La densidad de siembra de 54 plantas/m 2 en un contenedor por cama, para las variedades Kiwi Mellow y Green Ball, tuvo un efecto significativo sobre la productividad, incrementando los rendimientos en 30 % y 20 %, respectivamente, en comparación al tratamiento común de la zona (densidad de siembra de 23 plantas/m 2 ). El aumento de las densidades de siembra no afectó los parámetros de calidad de la flor, ni aumentó las pérdidas por calidad nacional. La variedad Kiwi Mellow tiene un 3,16 % más de unidades Soil Plant Analysis Development (spad) en promedio que Green Ball. La mejor rentabilidad en el cultivo de D. barbatus para las dos variedades evaluadas fue obtenida con la densidad de siembra de 54 plantas/m 2 , superando respectivamente en un 34 % y 15 % al tratamiento de la zona.

The surge in global efforts to understand the causes and consequences of drought on forest ecosystems has tended to focus on specific impacts such as mortality. We propose an eco-climatic framework that takes a broader view of the ecological relevance of water deficits, linking elements of exposure and resilience to cumulative impacts on a range of ecosystem processes. This eco-climatic framework is underpinned by two hypotheses: 1) exposure to water deficit can be represented probabilistically and used to estimate exposure thresholds across different vegetation types or ecosystems; and 2) the cumulative impact of a series of water deficit events is defined by attributes governing the resistance and recovery of the affected processes. We present case studies comprising Pinus edulis and Eucalyptus globulus, tree species with contrasting ecological strategies, which demonstrate how links between exposure and resilience can be examined within our proposed framework. These examples reve...

The productivity of durum wheat [Triticum turgidum subsp. durum (Desf.) van Slageren] is affected by drought and/or high temperatures, challenges to be amplified by climate change. Pre‐breeding using wild relatives can supply useful traits for durum wheat improvement to adapt to major abiotic and biotic stresses. Sixty‐seven lines issued from backcrosses of Cham5 and Haurani durum wheat varieties with accessions of Triticum aegilopoides (Link) Bal. ex Koern., T. dicoccoides Koern. ex Schweinf., T. urartu Thumanian ex Gandilyan, and Aegilops speltoides Tausch were evaluated for drought and heat tolerance. The trials were conducted during two seasons (2016−2017 and 2017–2018) at Tessaout, Morocco, under full irrigation (optimal conditions) and rainfed conditions (drought stressed) and at Wed Medani, Sudan, under full irrigation combined with heat stress. The recurrent parents, along with eight best cultivars and elite breeding lines, were used as checks. Drought reduced the grain yiel...

The productivity of durum wheat [Triticum turgidum subsp. durum (Desf.) van Slageren] is affected by drought and/or high temperatures, challenges to be amplified by climate change. Pre‐breeding using wild relatives can supply useful traits for durum wheat improvement to adapt to major abiotic and biotic stresses. Sixty‐seven lines issued from backcrosses of Cham5 and Haurani durum wheat varieties with accessions of Triticum aegilopoides (Link) Bal. ex Koern., T. dicoccoides Koern. ex Schweinf., T. urartu Thumanian ex Gandilyan, and Aegilops speltoides Tausch were evaluated for drought and heat tolerance. The trials were conducted during two seasons (2016−2017 and 2017–2018) at Tessaout, Morocco, under full irrigation (optimal conditions) and rainfed conditions (drought stressed) and at Wed Medani, Sudan, under full irrigation combined with heat stress. The recurrent parents, along with eight best cultivars and elite breeding lines, were used as checks. Drought reduced the grain yiel...

The objective of the InterDrought conferences is to be a platform for debating key issues that are relevant for increasing the yield and yield stability of crops under drought via integrated approaches. InterDrought-IV, held in Perth, Australia, in September 2013, followed previous InterDrought conferences in bringing together researchers in agronomy, soil science, modelling, physiology, biochemistry, molecular biology, genetics and plant breeding. Key themes were (i) maximising water productivity; (ii) maximising dryland crop production; (iii) adaptation to water-limited environments; (iv) plant productivity under drought through effective water capture, improved transpiration efficiency, and growth and yield; and (v) breeding for water-limited environments through variety development, and trait-based genomics-assisted and transgenic approaches. This paper highlights some key issues and presents recommendations for future action. Improved agronomic interventions were recognised as ...

• Cities have everything at their disposal: -Engines of economic growth -Better quality of life -Better infrastructure and communication facilities -Diversified livelihoods: You can be what you want to be! -Immense skill base -Better governance (well, most of the time) -Immediate response to address issues But there are a whole lot of things we ignore and these bring vulnerability to climate change

Background: Bottle gourd, a popular winter vegetable in Bangladesh, is experiencing a year-round increase in demand. High temperature stress disrupts physiological structure, fruit quality and crop yields, limiting the year-round cultivation of bottle gourd. The research aimed to identify heat stress-tolerant genotypes to extend growing seasons and increase production among varieties and breeding materials. The study conducted at Vegetable Research Center, Dinajpur of BRAC Seed and Agro Enterprise, Bangladesh consisting 58 bottle gourd genotypes under normal and heat stress conditions using augmented block design. Meteorological data showed heat stress resulted 5-7  C higher air temperatures than normal sowing environments. Result: Heat stress tolerance indices indicated that the genotypes with a combination of greater values of MP, GMP, HM, YI and STI and lower values of SSI and TOL are high performed and productive breeding material. Yield based stress indices SSI and TOL had a negative association with fruit yield under heat stress (Ys), while strong positive correlations with STI, MP, GMP, HM and YI. The cluster analysis classified bottle gourd genotypes as tolerant, medium tolerant and susceptible to heat stress. Heat stress tolerance indices could be effective tools for identifying heat tolerant bottle gourd genotypes in field. The genotypes BG-45, BG-02, BG-57, BG-39 and BG-43 determined as high performing and stable breeding material under both normal and heat stress environments and might potentially be employed in future breeding programs.

Early angiosperms are hypothesized as constrained to wet environments where many of their defining characteristics evolved. A functional capability potentially enforcing the wet habitation of early angiosperms was possession of xylem with low hydraulic capability and drought intolerance. Recent studies indicate that a structural hallmark of these performances is long, steeply angled scalariform perforation plates in extant basal angiosperms. However, Canella winterana (Canellaceae), a magnoliid, appears to have radiated into much drier tropical dry forest habitats despite possessing a wood vasculature structurally similar to hypothesized ancestral wet-adapted system for angiosperms as a whole. Based on a field study of Canella wood hydraulic function, we present ecophysiological data that basal vessels do not necessarily mark low resistance to drought. We found that Canella wood was resistant to drought-induced cavitation. Leaf hydraulic capacity as well as leaf pressurevolume relations and leaf water potential minima found for Canella were comparable to some of the most drought-tolerant tropical dry forest angiosperms. Thus, our results suggest that vessels of an ancestral design can be exported to dry environments. We found that scalariform-plated vessels in Canella were associated with low hydraulic capacities at the xylem and whole shoot-scales as well as limited plasticity of the xylem to varying hydrodynamic demand. Consequently, our results support the hypothesis that evolution of simple perforation plates, not vessels per se, represented a critical adaptation for producing large hydraulic gains during angiosperm evolution across a broader range of environments.

Roots and tubers such as potatoes and cassava rank within the top six among the world's most important food crops, yet the extent to which their global production has been adversely affected by drought remains unclear. Greater uncertainties exist on how drought effects co-vary with: 1) root and tuber species, 2) soil texture, 3) agro-ecological region, and 4) drought timing. It is often assumed that potato is drought-sensitive whereas cassava and sweet potato are resistant to drought. To address these uncertainties, we collected literature data between 1980 and 2015 that reported monoculture root and tuber yield responses to drought under field conditions, and analyzed this large data set using meta-analysis techniques. Our results showed that the amount of water reduction was positively related with yield reduction, but the extent of the impact varied with root or tuber species and the phenological phase during which drought occurred. In contrast to common assumptions regarding drought resistance of certain root and tuber crops, we found that yield reduction was similar between potato and species thought to be drought-resistant such as cassava and sweet potato. Here we suggest that drought-resistance in cassava and sweet potato could be more related to survival rather than yield. All roots or tubers crops, however, experienced greater yield reduction when drought struck during the tuberization period compared to during their vegetative phase. The effect of soil texture on yield reduction was less obvious, and similarly we did not find any significant effects of region (and related climatic factors) on neither yield reduction nor drought sensitivity. Our study provides useful information that could inform agricultural planning, and influence the direction of research for improving the productivity and the resilience of these under-utilized crops in the drought-prone regions of the world.

Potato is the most important non-grain crop worldwide with a production of 330 million tonnes globally in 2010 . Potato production has increased dramatically during the last decade in the developing world, surpassing the production levels of the developed world . Potato constitutes the main source of food security and income in the developing world , and will become increasingly important as the population is growing more rapidly in the developing world than developed regions KC, 2010Lutz and. A growing population, along with climate change and increasing climate variability, will put additional pressure on potato food systems. Assessing the implications of these trends requires integrating crop models when evaluating the impact of new technologies and strategies for adapting to climate change. Atmospheric concentration of carbon dioxide (CO 2 ) is expected to increase from 400 ppm in 2010 to -550 ppm by 2050 . Potato, a C3 crop, will respond with higher photosynthesis rate and water use efficiency under elevated atmospheric CO 2 concentrations (De Temmerman et al., 2002b;. But high levels of atmospheric CO 2 are the main driver of climate change and will increase global temperature and higher rainfall variability, leading to heat waves and more droughts in some regions . Studies in controlled experiment chambers suggest that elevated atmospheric CO 2 concentrations can mitigate stresses due to water shortage, but high temperatures can also negate the positive effects of increased atmospheric CO 2 concentrations on crop production . Crop models are powerful tools that describe crop development and growth as a function of crop management, weather, and soil conditions . More than 30 crop models have been developed for potato, and many of them have been used to study the impacts of climate change on potato production . Overall, these studies highlight that despite the positive effect of atmospheric CO 2 concentrations, potato production will decline across many regions in the world by 2100 ). However, Stockle et al. (2010) indicated that, taking into account the effect of CO 2 , adaptation strategies on crop production might guarantee the current production levels under future climate change conditions in the state of Washington in the United States. Others have used potato crop models to assess the impact of climate change on regional and global potato production . Nevertheless, models have been developed for specific cultivars and geographic domains (Griffin et al., 1993; ;. Global simulations require taking into account the crop variability across the globe and testing the model functionality with a standard cultivar across latitudes. In most of the climate change studies, potato models were used with cultivars and species from the developed world , neglecting the cultivar diversity of other cultivated species, as well as traditional and modern cultivars. Cultivars of the species Solanum tuberosum are most widely grown, whereas seven cultivated potato species, including Solanum andigenum (floury potato), and Solanum juzepzukii (bitter potato), coexist in the tropical Andes . Also, several hybrids of various species are grown in the developing world , where the use of potato models is limited.

Rice is economically very important in Ghana and West Africa. The lack of improved rice varieties, particularly upland varieties, is recognised as a constraint. The purpose of the project was: to analyse rainfall patterns and drought-spells in Ghana; to characterise the photothermal flowering responses of diverse varieties in order to understand adaptation; to understand farmers' indigenous technical knowledge of rice farming and varietal selection; to test and evaluate new droughtand weed-tolerant rice varieties with farmers using participatory techniques and formal replicated yield trials; and to disseminate participatory approaches to crop improvement in Ghana and West Africa. Long-term (30 years) daily rainfall data were analysed for selected locations in each of the forest, transition and moist and dry savanna zones. Rainfall patterns (start, end and duration of the growing season) and drought-spells were calculated. A Crop Performance Index (CPI) was used to examine the effect of toposequence on drought patterns. Photothermal flowering responses of 83 varieties were quantified from sowing date experiments in the field and a controlled environment experiment in the UK. PRA techniques were used to describe indigenous technical knowledge at two locations, Hohoe in the forest zone and Aframso in the transition zone. A Participatory Varietal Selection (PVS) programme with 60-100 varieties was initiated at Hohoe, Aframso and at Nyankpala in the moist savanna. Replicated yield trials with High Input (fertiliser + weeding) and Low Input (low fertiliser + no weeding) treatments were planted at four locations in 1998 and 1999. Rainfall patterns covering the major upland rice zones have been analysed. This analysis has shown that the savanna zone (i.e. Northern, Upper East and West Regions) and forest zone (Volta, Western Region) is favourable for rice production, with a minimum of a 100d growing season even in very shallow upland soils. In contrast, rice production is much riskier in the transition zone (Ashanti, Brong Ahafo Regions) because of the bi-modal rainfall pattern and the consequent break in the rains in August. There was considerable variation in photothermal flowering responses and hence adaptation to different rice ecosystems among varieties. Photothermal characteristics were clearly defined in terms of a basic vegetative phase (BVP) and a photoperiodsensitive phase (PSP). The participatory process has shown that farmers have a considerable knowledge of varieties and their characteristics. Traits which contribute to weed competition and drought-tolerance are important, as are post-harvest traits. A PVS programme was successfully implemented with male and female farmers, traders and consumers. Male and female farmers made many similar varietal choices, the most notable difference being for grain characteristics; women selected grain types suitable for home consumption while men preferred grain types with a high market value. The market prefers long, white grains which are similar to those of imported grains. At Hohoe, almost all farmers selected the same variety, IDSA85, both in the PVS trials and from paired-comparisons on-farm. At Aframso a larger number of varieties was chosen, including interspecifics and improved upland japonicas. At Nyankpala, improved japonicas, interspecifics and local glaberrimas were selected. A Regional Workshop has helped disseminate project findings and promote the participatory approach throughout the West African region

Rice is economically very important in Ghana and West Africa. The lack of improved rice varieties, particularly upland varieties, is recognised as a constraint. The purpose of the project was: to analyse rainfall patterns and drought-spells in Ghana; to characterise the photothermal flowering responses of diverse varieties in order to understand adaptation; to understand farmers' indigenous technical knowledge of rice farming and varietal selection; to test and evaluate new droughtand weed-tolerant rice varieties with farmers using participatory techniques and formal replicated yield trials; and to disseminate participatory approaches to crop improvement in Ghana and West Africa. Long-term (30 years) daily rainfall data were analysed for selected locations in each of the forest, transition and moist and dry savanna zones. Rainfall patterns (start, end and duration of the growing season) and drought-spells were calculated. A Crop Performance Index (CPI) was used to examine the effect of toposequence on drought patterns. Photothermal flowering responses of 83 varieties were quantified from sowing date experiments in the field and a controlled environment experiment in the UK. PRA techniques were used to describe indigenous technical knowledge at two locations, Hohoe in the forest zone and Aframso in the transition zone. A Participatory Varietal Selection (PVS) programme with 60-100 varieties was initiated at Hohoe, Aframso and at Nyankpala in the moist savanna. Replicated yield trials with High Input (fertiliser + weeding) and Low Input (low fertiliser + no weeding) treatments were planted at four locations in 1998 and 1999. Rainfall patterns covering the major upland rice zones have been analysed. This analysis has shown that the savanna zone (i.e. Northern, Upper East and West Regions) and forest zone (Volta, Western Region) is favourable for rice production, with a minimum of a 100d growing season even in very shallow upland soils. In contrast, rice production is much riskier in the transition zone (Ashanti, Brong Ahafo Regions) because of the bi-modal rainfall pattern and the consequent break in the rains in August. There was considerable variation in photothermal flowering responses and hence adaptation to different rice ecosystems among varieties. Photothermal characteristics were clearly defined in terms of a basic vegetative phase (BVP) and a photoperiodsensitive phase (PSP). The participatory process has shown that farmers have a considerable knowledge of varieties and their characteristics. Traits which contribute to weed competition and drought-tolerance are important, as are post-harvest traits. A PVS programme was successfully implemented with male and female farmers, traders and consumers. Male and female farmers made many similar varietal choices, the most notable difference being for grain characteristics; women selected grain types suitable for home consumption while men preferred grain types with a high market value. The market prefers long, white grains which are similar to those of imported grains. At Hohoe, almost all farmers selected the same variety, IDSA85, both in the PVS trials and from paired-comparisons on-farm. At Aframso a larger number of varieties was chosen, including interspecifics and improved upland japonicas. At Nyankpala, improved japonicas, interspecifics and local glaberrimas were selected. A Regional Workshop has helped disseminate project findings and promote the participatory approach throughout the West African region

El objetivo de este trabajo fue evaluar la productividad de nuevos cultivares y materiales experimentales INTA de Cenchrus ciliaris L., en comparación con los cultivares comerciales más difundidos.EEA Ingeniero JuárezFil: Cavallero, María Inés. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Ingeniero Juárez; ArgentinaFil: Pinto, Juan José. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Ingeniero Juárez; ArgentinaFil: Sanz, Patricio Hugo. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Ingeniero Juárez; ArgentinaFil: Bono, Gonzalo Raul. Instituto Nacional de Tecnología Agropecuaria (INTA). Estación Experimental Agropecuaria Ingeniero Juárez; ArgentinaFil: Griffa, Sabrina Mariana. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Fisiología y Recursos Genéticos Vegetales; ArgentinaFil: Tommasino, Exequiel Arturo. Instituto Nacional de Tecnología...