Seed longevity

The question of human immortality has long fascinated philosophy, science, and speculative thought. Despite tremendous advances in medicine and biotechnology, death remains the inevitable endpoint of biological life. This paper sets forth my own theoretical perspective on a radical possibility: replacing human blood with a synthetic, life-sustaining liquid that could maintain physiological function without food, oxygen, or conventional metabolism. Drawing on established biological knowledge of postmortem decay, hematology, and cellular function, I argue that such a medium could fundamentally alter human existence. I believe the first step toward this vision requires controlled experimentation in animals, followed by eventual human application if feasibility is demonstrated. The most pressing challenge is to discover the true source of energy or the elemental basis that could sustain cells indefinitely without reliance on oxygen or nutrients. I argue that scientists and governments must dedicate far greater resources to this pursuit, including space exploration, because the key to eternal life may lie in unknown elements or compounds beyond Earth. This work is written from my perspective and conviction that immortality is not only possible but essential for the future of humanity. While speculative, I propose a roadmap grounded in scientific curiosity, philosophical reflection, and the drive to transcend mortality. References from contemporary biology, regenerative medicine, and philosophy support this argument, but the framework itself is original and represents my own expectation of how humanity might one day achieve infinite life.

Seed longevity and viability are fundamental to sustainable crop production, especially in the era of climate change. In the context of climate-smart agriculture (CSA), which aims to increase productivity, enhance resilience, and reduce greenhouse gas emissions, maintaining
the physiological and biochemical integrity of seeds becomes crucial. Seed longevity refers to the duration a seed can remain viable during storage, while viability indicates the seed’s ability to germinate and develop into a healthy seedling under favorable conditions

Using flow cytometry, we determined relative DNA amounts expressed as C-values, of large numbers of nuclei isolated from embryo root tips in three seed lots of pepper (Capsicum annuum) and tomato (Lycopersicon esculentum). The nuclei in embryos of fully matured dry pepper and tomato seeds predominantly revealed 2C signals, which indicates that the cells of maturing seeds have arrested at G1 phase of the cell cycle. Priming of pepper and tomato seeds in −1.1, −1.3 or −1.5 MPa polyethylene glycol (PEG) for 14 days reduced the mean time to germination. In all seed lots an induction of 4C signals was found after priming, indicating that during priming the cells of the embryonic root tip had replicated their DNA and arrested at the G2 phase of the cell cycle. For both tomato and pepper, the frequency of 4C signals was highest at the lowest PEG concentration (osmotic potential of −1.1 MPa). A significant inverse correlation was found between the frequency of root tip cells expressing 4C D...

The ability to produce highly dense and persistent seedbanks is a major contributor to the successful widespread establishment of invasive plants. This study seeks to identify seed persistence and seedbank longevity for the invasive tussock grass Nassella trichotoma (Nees.) Hack. ex Arechav in order to recommend management strategies for preventing re-emergence from the seedbank. To determine the seedbank longevity and persistence, two experiments were conducted: (i) seeds were buried at four depths (0, 1, 2, and 4 cm) and collected and assessed for viability, seed decay, and in-field germination after 6, 9, 12, 15, and 18 months of field burial; and (ii) seeds were exposed to artificial ageing conditions (60% RH and 45 • C) for 1, 2, 5, 9, 20, 30, 50, 75, 100, and 120 days, and viability was determined through germination tests and tetrazolium tests. Less than 10% of the seeds collected after 12 months of in-field burial were viable. The artificial ageing treatment found germination declined to 50% after 5.8 days, further suggesting that N. trichotoma seeds are short lived. The results from both experiments indicate that N. trichotoma has a transient seedbank, with less than 10% of the seeds demonstrating short-term persistence. It is likely the persistent seeds beyond 12 months were exhibiting secondary dormancy as viable seeds did not germinate under optimal germination conditions. The "Best Practice Guidelines" recommend monitoring for seedbank recruitment for at least three years after treating N. trichotoma infestations. The results of this study support this recommendation as a small proportion of the seeds demonstrated short-term persistence.

Unlike orthodox seeds, mature seeds of some species do not survive desiccation and are often referred to as "recalcitrant" (Hong et al. 1998). Approximately 10-20% of angiosperm species produce seeds that acquire some, but not full, tolerance of desiccation during maturation (Dickie and Pritchard 2002). Incidence of recalcitrance does not distribute along phylogenetic clades, though some plant families include many species producing recalcitrant seeds (e.g., Fagaceae, Lauraceae, Sapindaceae, Meliaceae) while other families apparently lack species exhibiting this trait (e.g., Solanaceae, Asteraceae, Amaranthaceae). Life history traits of the plant, such as a long lived, perennial nature, and its habitat, such as aquatic or rainforest, are associated with seed recalcitrance, but not all plants with these characteristics produce recalcitrant seeds. The term "recalcitrant" is also used to describe seeds that are particularly difficult to germinate because they have deep dormancy or an unknown dormancy release mechanism. Though frustrating to work with, seeds with this dormancy physiology are amenable to B.M. Reed (ed.

SYNOPSIS. Persistence of anhydrous organisms in nature may depend on how long they remain viable in dry environments. Longevity is determined by interactions of humidity, temperature, and unknown cellular factors that affect the propensity for damaging reactions. Here we describe our research to elucidate those cellular factors and to ultimately predict how long a population can survive under extreme conditions. Loss of viability typically follows a sigmoidal pattern, where a period of small changes precedes a cataclysmic decline. The time for viability to decrease to 50% (P50) varied among seed species and among 10 phylogenetically diverse organisms. When stored at elevated temperatures of 35؇C and 32% relative humidity (RH), P50 ranged from about a week for spores of Serratia marcescens to several years for fronds of Selaginella lepidophylla. Most of the species studied survived longest at low humidity (10-20% RH), but suffered under complete dryness. Temperature dependencies of aging kinetics appeared similar among diverse organisms despite the disparate longevities. The effect of temperature on seed aging rates was consistent with the temperature dependency of molecular mobility of aqueous glasses, with both showing a reduction by several orders of magnitude when seeds were cooled from 60؇C to 0؇C. Longevity is an inherited trait in seeds, but its complex expression among widely divergent taxa suggests that it developed through multiple pathways.

SYNOPSIS. Persistence of anhydrous organisms in nature may depend on how long they remain viable in dry environments. Longevity is determined by interactions of humidity, temperature, and unknown cellular factors that affect the propensity for damaging reactions. Here we describe our research to elucidate those cellular factors and to ultimately predict how long a population can survive under extreme conditions. Loss of viability typically follows a sigmoidal pattern, where a period of small changes precedes a cataclysmic decline. The time for viability to decrease to 50% (P50) varied among seed species and among 10 phylogenetically diverse organisms. When stored at elevated temperatures of 35؇C and 32% relative humidity (RH), P50 ranged from about a week for spores of Serratia marcescens to several years for fronds of Selaginella lepidophylla. Most of the species studied survived longest at low humidity (10-20% RH), but suffered under complete dryness. Temperature dependencies of aging kinetics appeared similar among diverse organisms despite the disparate longevities. The effect of temperature on seed aging rates was consistent with the temperature dependency of molecular mobility of aqueous glasses, with both showing a reduction by several orders of magnitude when seeds were cooled from 60؇C to 0؇C. Longevity is an inherited trait in seeds, but its complex expression among widely divergent taxa suggests that it developed through multiple pathways.

Though cryogenic storage is presumed to provide nearly infinite longevity to cells, the actual shelf life achieved under ultra-cold temperatures has not been addressed theoretically or empirically. Here, we report measurable changes in germination of dried seeds stored under liquid nitrogen conditions for >10 years. There was considerable variability in the extent of deterioration among species and accessions within a species. Aging time courses for lettuce seeds stored at temperatures between 50 and )196 °C were fit to a form of the Avrami equation to determine rate coefficients and predict half-life of accessions. A reduction in the temperature dependency on aging rate, determined as a break in the Arrhenius plot, occurred at about )15 °C, and this resulted in faster deterioration than anticipated from extrapolation of kinetics measured at higher temperatures. The break in Arrhenius behavior occurred at temperatures in between the glass transition temperature (28 °C) and the Kauzmann temperature ()42 °C) and also coincided with a major triacylglycerol phase change ()40 to )7 °C). In spite of the faster than anticipated deterioration, cryogenic storage clearly prolonged shelf life of lettuce seeds with half-lives projected as $500 and $3400 years for fresh lettuce seeds stored in the vapor and liquid phases of liquid nitrogen, respectively. The benefit of low temperature storage ()18 or )135 °C) on seed longevity was progressively lost if seeds were first stored at 5 °C. Collectively, these results demonstrate that lowering storage temperature progressively increases longevity of seeds. However, cryogenic temperatures were not sufficient to stop deterioration, especially if initial stages of aging were allowed to progress at higher storage temperatures. This work contributes to reliable assessments of the potential benefit and cost of different genebanking strategies.

Under West Bengal conditions, maintenance of vigour and viability of green gram seed (Vigna radiata Wilczek L) is a serious problem from harvest to next sowing. To over come this problem, experiments were conducted under ambient laboratory conditions to slow down the ageing process of the seeds during storage. High vigorous seeds of 2-3 months old were taken and subjected to Hydration dehydration (H-D), Moisture-equilibration & drying (ME -D) and drydressings with powdered plant materials of Ashwagandha root (200 mg kg -1 ), Zinger rhizome (100 mg kg -1 ), Turmeric rhizome (100 mg kg -1 ), Trigonella seeds (200 mg kg -1 ), jute leaf (100 mg kg -1 ) and pharmaceutical preparations of vit C (celin tablet) and salicylic acid (Disprin tablet) were done. Among the treatments plain H -D with water for 3 hours and slow imbibition for 48 hours with ME -D showed significantly good effect over untreated control in respect of germination percentage and seedling growth. The treatment effect were magnified under accelerated (40 0 C + 98 0 % R.H.) and natural ageing (27  5 0 C and 73  7% R.H.) conditions where as in dry dressing with powered plant materials had significant beneficial effect in maintaining seed vigour and viability over control. Among the treatments with powdered plant material such as Turmeric rhizome and jute leaf as well as pharmaceutical preparation vit C (celin tablet) had highly beneficial effect under accelerated and natural ageing conditions. Peroxidase enzyme assay study showed betterment effect in all the treatments indicating that free-radical formation due to ageing quenched by the treatments over control.

  The fate of seeds during secondary dispersal is largely unknown for most species in most ecosystems. This paper deals with sources of seed output of Prosopis flexuosa D.C. (Fabaceae, Mimosoideae) from the surface soil seed‐bank. Prosopis flexuosa is the main tree species in the central Monte Desert, Argentina. In spite of occasional high fruit production, P. flexuosa seeds are not usually found in the soil, suggesting that this species does not form a persistent soil seed‐bank. The magnitude of removal by animals and germination of P. flexuosa seeds was experimentally analysed during the first stage of secondary dispersal (early autumn). The proportion of seeds removed by granivores was assessed by offering different types of diaspores: free seeds, seeds inside intact endocarps, pod segments consisting of 2–3 seeds, and seeds from faeces of one herbivorous hystricognath rodent, the mara (Dolichotis patagonum). The proportion of seeds lost through germination was measured for seeds...

Terrestrial orchids typically produce numerous small seeds that contain very small nutrient reserves. The seeds are structurally adapted for wind dispersal but little is known about their fate after dispersal. Some studies of seed viability in situ indicate survival for up to two years in temperate orchid species. Seeds stored in the laboratory may last much longer. We investigated seed viability of seven North American orchid species with seed packets buried in a range of soil and wood substrates within their natural habitats. In Goodyera pubescens most seeds germinated within one year. Four other species continued to germinate sparsely during the observation period, but after almost seven years many seeds were still viable. In one species, Liparis liliifolia, seeds that had been in situ for four years had germination rates as high as 68% when sown in vitro with a compatible fungus. The remaining two species did not germinate during the observation period but the seeds were judged to be intact and tested positively for viability after four years in the ground. These observations are interpreted as different species-specific strategies for in situ germination and their seed bank potential is discussed.

Calden (Prosopis caldenia) seeds not dispersed by animals sometimes constitute a considerable number of seeds to the seed bank which may contribute to the species' dissemination. The monthly change in the number of viable non-animal dispersed seeds was evaluated over a one-year period. We determined the percentage germination of seeds and the amount of predation by bruchid beetles to learn how these factors iniluence seed longevity. Forty eight bags containing 10 fruits were placed in 4 sites below calden tree canopies at the time of shedding (March). To monitor seed losses we randomly removed 1 bag per site every 25-35 days during a year. At the time of shedding, fruits contained 29 seeds, 73 + 5.0% which were viable and 9 + 2.2% attacked by bruchids. Viability decreased to 33 + 22.3 % one year later. Loss of viability was described by a polynomial quadratic & = 70.12 + 0.0238 t-0.0004 t2 (?= 0.62)). Bags with germinated seeds were observed beginning in November. Percentage germinated seed increased 4.8 rf: 3.7% in the last month of sampling. Consumption of seeds by bruchids also increased in November, but the effect was highly variable. In the last month of sampling (March in the following year), 35 + 18.0% of seeds were affected by bruchids. A predictive seed longevity model was developed considering climatic variables, but data were well described only until January (y = 81.50-0.097 time-3.94 precipitation (rr = 0.66)). Undispersed seeds had a high rate of decay and low germination. Longevity was strongly affected by bruchid attack.

Seed longevity (storability) is an important seed quality trait. High seed quality is important in agriculture, for the industry, and for safeguarding biodiversity as many species are stored as seeds in genebanks. To ensure exsitu seed survival, seeds are mostly stored at low relative humidity and low temperature. Oxidation is the main cause of seed deterioration in these dry storage conditions. The molecular mechanisms underlying dry seed survival remain poorly understood. Research on seed longevity is hampered by the lack of an experimental ageing method that mimics dry ageing well. Here, we propose the Elevated Partial Pressure of Oxygen (EPPO) method as the best available method to mimic and accelerate dry seed ageing. We have tested seed germination in Arabidopsis thaliana after EPPO storage at two different relative humidity (RH) conditions and confirm the large effect of oxygen and the seed moisture content on ageing during dry storage. Comparative Quantitative trait locus (QTL) analysis shows that EPPO at 55 % RH mimics dry ageing better than the commonly used Artificial Ageing and Controlled Deterioration tests at higher moisture levels.

Seed dormancy determines the timing of seed germination and may be released by dry storage, also referred to as after-ripening. Studies on dormancy-release mechanisms are often hampered by the long after-ripening requirements of seeds. After-ripening is thought to be mainly caused by oxidative processes during seed dry storage. These processes are also the main cause of seed ageing. Increasing partial oxygen pressure through the elevated partial pressure of oxygen (EPPO) system has been shown to mimic and accelerate dry seed ageing. In this study, we investigated whether the EPPO system may also release primary seed dormancy in Arabidopsis thaliana. EPPO mimics dry after-ripening at the genetic level, as quantitative trait locus (QTL) analysis after EPPO treatment identified the DELAY OF GERMINATION loci DOG1, DOG2, and DOG6 that were first described in a study using dry after-ripening to release seed dormancy. QTL analysis also showed that dormancy release by cold stratification (another common method to break seed dormancy) partly overlaps with release by after-ripening and EPPO treatment. We conclude that EPPO is an appropriate method to mimic and accelerate dormancy release and, as such, may have applications in both research and industry.

The simplified equation Vt = Vi-tg-.p is to predict the percentage of viability of any corn (Zea mays L.) seed lot after any period of time under open storage conditions. Based upon that equation, the objective of this work was to set a practical seed longevity chart to predict viability of corn seed lot during storage. From data of five corn seed lots stored at Sete Lagoas, MG, the value of the storage index (8) was calculated. This value (8 = 120 days) corresponded exactly to the time taken in days for the initial germination of corn seeds stored to fall to a certain germination value observed in the accelerated aging test. Once the storage index (8) is estimated, the viability chart which illustrates the relationship between initial germination, seed deterioration rate and storage condition over time can be constructed. The chart can be used by any seed producer once the value of storage index (8) in situ is determined. The application of the seed viability chart to short-term seed storage seems to be promising for seed growers. This predictive model is the first attempt of incorporating the effect of seed quality, the deterioration rate and the storage environmental conditions (temperature and relative humidity) into a seed longevity chart of an open storage.

Seed storability in rice (Oryza sativa L.) is an important agronomic trait. Two segregating populations with N22 (indica) as a common parent, viz. a set of 122 backcross-inbred lines (BILs) derived from the backcross Nanjing35 (japonica)/N22//Nanjing35 and another population comprising 189 recombinant inbred lines (RILs) from the cross of USSR5 (japonica) and N22, were studied to detect quantitative trait loci (QTL) controlling seed storability. Germination percentage (GP) was used to evaluate seed storability after aging treated under three different conditions, viz. natural, artificial and combined aging treatments. A total of seven QTLs were identified on chromosomes 1, 2, 5, 6 and 9. Among them, a major QTL, qSSn-9, was common in the two populations. In contrast, four QTLs (qSSnj-2-1, qSSn-2-2, qSSn-5 and qSSn-6) were detected in BILs and the QTL qSSn-1 was identified in RILs, which was a new QTL for seed storability. The N22-derived alleles increased the seed storability at all the loci except qSSnj-2-1. We also investigated the effect of QTLs using five selected lines with high storability from BILs and verified qSSn-5 with a near-isogenic line (NIL). These results provide an opportunity for pyramiding or map-based cloning major QTLs for seed storability in rice.

Burial and removal techniques with seed bags were used to examine the viability and longevity of Melaleuca quinquen- ervia seeds at four field sites representing different soil types and hydrological conditions in South Florida. Seed viability was determined over different burial durations in the soil through a combination of germination tests and 2,3,5-triphe- nyl-tetrazolium chloride (TTC) treatments. Control seeds kept

The control of two exotic grasses, Andropogon gayanus Kunth. (gamba grass) and Pennisetum polystachion L. Schult. (mission grass) represent a major management challenge in Australia's tropical savannas. Understanding the size and longevity of the soil seed bank can assist in understanding the management requirements for these species, such as ongoing control requirements. This study assessed the seed longevity of mission and gamba grasses, and the seed bank in sites densely invaded by either gamba or by mission grass, and compared them with uninvaded sites. The germinable seed bank of the exotic grasses declines markedly from the dry season to the early wet season, whereas the germinable native seed bank increases during this time. Longevity trials suggest that the proportion of exotic seeds carried over is low, approximately 2.3% and 0.1% for gamba and mission grass respectively. The carryover of the exotic seedbank demonstrates the importance of ongoing control. The seed bank of native species in the invaded sites was higher than the exotic seedbank, and it represents a natural source of seed for rehabilitation following control.

Lithospermum arvense is an increasing annual weed in winter crops of the semiarid region of southern Argentina under low impact tillage systems, an agricultural practice that has become popular in recent years. Seed distribution in the soil profile under conventional tillage will change when reduced tillage is implemented, thus affecting the germination microenvironment. The effect of seed burial depth and soil water regime on field germination, enforced dormancy, innate dormancy and seed decay was studied in relation to burial time in a field experiment. In addition, the effect of burial depth on seed germination and seedling emergence was examined under laboratory controlled conditions. Field germination of buried seed ranged from 55% to 65% for shallow (2 cm) and from 5% to 30% for greater depths (20 cm). Enforced dormancy levels were significantly higher among deeper seeds. The amount of innate dormant seeds was reduced to <10% after a year of burial. Lithospermum arvense seedbanks can be classified as short-term persistent. Germination in the laboratory was unaffected by burial depth, while seedling emergence reduction was adequately described by a sigmoidal model. Results indicate that agricultural practices that accumulate L. arvense seeds near the soil surface enhance seedling recruitment.

Propositions (Stellingen) 1) Chlorophyll in seed is required during seed development, but undesirable during maturation (this thesis). 2) Both the maternal genotype and light conditions play a critical role in determining the chlorophyll content of tomato seeds (this thesis). 3) Chlorophyll fluorescence of dry tomato seeds is a sensitive indicator of the physiological maturity of tomato seed (this thesis). 4) Seed quality is a complex concept, consisting of a number of components that each represent different physiological principles, e.g. germinability, viability, vigour and storability. 5) The most powerful method to study life processes in seeds is non-destructive and instantaneous. 6) A thesis which is written in English should be defended in English. 7) If the doctor makes a mistake, the patient will go to the soil. But, if the 'seed doctor' makes a mistake, the effect can only be seen when the seedlings emerge from the soil. Therefore, can we use a "stethoscope " to detect seed quality? 8) The best human being is somebody who always gives a valuable contribution to nature (Muhammad SAW).

Damage to non-dicamba resistant (non-DR) soybean [Glycine max (L.) Merr.] has been frequent in geographies where dicamba-resistant (DR) soybean and cotton (Gossypium hirsutum L.) have been grown and sprayed with the herbicide in recent years. Off-target movement field trials were conducted in northwest Arkansas to determine the relationship between dicamba concentration in the air and the extent of symptomology on non-DR soybean. Additionally, the frequency and concentration of dicamba in air samples at two locations in eastern Arkansas and environmental conditions that impacted the detection of the herbicide in air samples were evaluated. Treatment applications included dicamba at 560 g ae ha −1 (1X rate), glyphosate at 860 g ae ha −1 , and particle drift retardant at 1% v/v applied to 0.37-ha fields with varying degrees of vegetation. The relationship between dicamba concentration in air samples and non-DR soybean response to the herbicide was more predictive with visible injury (generalized R 2 = 0.82) than height reduction (generalized R 2 = 0.43). The predicted dicamba air concentration resulting in 10% injury to soybean was 1.60 ng m −3 d −1 for a single exposure. The predicted concentration from a single exposure to dicamba resulting in a 10% height reduction was 3.78 ng m −3 d −1. Dicamba was frequently detected in eastern Arkansas, and daily detections above 1.60 ng m −3 occurred 17 times in the period sampled. The maximum concentration of dicamba recorded was 7.96 ng m −3 d −1 , while dicamba concentrations at Marianna and Keiser, AR, were ≥1 ng m −3 d −1 in six samples collected in 2020 and 22 samples in 2021. Dicamba was detected consistently in air samples collected, indicating high usage in the region and the potential for soybean damage over an extended period. More research is needed to quantify the plant absorption rate of volatile dicamba and to evaluate the impact of multiple exposures of gaseous dicamba on non-targeted plant species.

Damage to non-dicamba resistant (non-DR) soybean [Glycine max (L.) Merr.] has been frequent in geographies where dicamba-resistant (DR) soybean and cotton (Gossypium hirsutum L.) have been grown and sprayed with the herbicide in recent years. Off-target movement field trials were conducted in northwest Arkansas to determine the relationship between dicamba concentration in the air and the extent of symptomology on non-DR soybean. Additionally, the frequency and concentration of dicamba in air samples at two locations in eastern Arkansas and environmental conditions that impacted the detection of the herbicide in air samples were evaluated. Treatment applications included dicamba at 560 g ae ha −1 (1X rate), glyphosate at 860 g ae ha −1 , and particle drift retardant at 1% v/v applied to 0.37-ha fields with varying degrees of vegetation. The relationship between dicamba concentration in air samples and non-DR soybean response to the herbicide was more predictive with visible injury (generalized R 2 = 0.82) than height reduction (generalized R 2 = 0.43). The predicted dicamba air concentration resulting in 10% injury to soybean was 1.60 ng m −3 d −1 for a single exposure. The predicted concentration from a single exposure to dicamba resulting in a 10% height reduction was 3.78 ng m −3 d −1. Dicamba was frequently detected in eastern Arkansas, and daily detections above 1.60 ng m −3 occurred 17 times in the period sampled. The maximum concentration of dicamba recorded was 7.96 ng m −3 d −1 , while dicamba concentrations at Marianna and Keiser, AR, were ≥1 ng m −3 d −1 in six samples collected in 2020 and 22 samples in 2021. Dicamba was detected consistently in air samples collected, indicating high usage in the region and the potential for soybean damage over an extended period. More research is needed to quantify the plant absorption rate of volatile dicamba and to evaluate the impact of multiple exposures of gaseous dicamba on non-targeted plant species.

Knowledge of crop–weed interference effects on weed biology along with yield penalties can be used for the development of integrated weed management (IWM) tactics. Nevertheless, little is known about the beneficial effects of soybean [Glycine max (L.) Merr.] density, an important aspect of IWM, on late Palmer amaranth (Amaranthus palmeri S. Watson) establishment time. Two field experiments were conducted in 2014 and 2015 to investigate how various soybean densities and A. palmeri establishment timings in weeks after crop emergence (WAE) affect height, biomass, and seed production of the weed but also crop yield in drill-seeded soybean. Soybean density had a significant impact on dry weight and seed production of A. palmeri that established within the first 2 wk of crop emergence, but not for establishment timings of the weed 4 wk and later in relation to crop emergence. Differential performance of A. palmeri gender was observed, regarding greater biomass production of female than ma...

Information about weed biology and weed population dynamics is critical for the development of efficient weed management programs. A field experiment was conducted in Fayetteville, AR, during 2014 and 2015 to examine the effects of Palmer amaranth (Amaranthus palmeriS. Watson) establishment time in relation to soybean [Glycine max(L.) Merr.] emergence and the effects ofA. palmeridistance from the soybean row on the weed’s height, biomass, seed production, and flowering time and on soybean yield. The establishment time factor, in weeks after crop emergence (WAE), was composed of six treatment levels (0, 1, 2, 4, 6, and 8 WAE), whereas the distance from the crop consisted of three treatment levels (0, 24, and 48 cm). Differences inA. palmeribiomass and seed production averaged across distance from the crop were found at 0 and 1 WAE in both years. Establishment time had a significant effect onA. palmeriseed production through greater biomass production and height increases at earlier d...

Broomrape (Phelipanche and Orobanche spp.) are obligate holoparasites that attack roots of almost all economically-important crops in semiarid regions of the world. Broomrape seeds are extremely small (dust-like seeds), averaging 200 to 300 μm in size and because of the miniscule seed size it is difficult to detect and confirm via conventional methods. In this study our aim was to develop a PCR-based assay specific for broomrape soil-borne seeds and sensitive enough to detect a single or few broomrape seeds in a soil sample. For this purpose, we used complementary polymerase chain reaction (PCR) primers based upon unique sequences in the internal transcribed spacer (ITS) regions of the nuclear ribosomal DNA of Phelipanche aegyptiaca. Genomic DNA was extracted from soil samples artificially infested with broomrape seeds or tissue of Phelipanche aegyptiaca Pers., Orobanche cumana Wallr. and Phelipanche crenata Forsk. and subjected to PCR analysis. Using ITS-350 primers, a specific PCR product (350 bp) was amplified and detected in all samples containing broomrape species, but was not detected in soil sample free of broomrape seeds or tissues. Additionally, the PCR-based assay was sensitive enough to detect even a single broomrape seed in the soil. As expected the universal internal control primers amplified a PCR product (555 bp) of genomic DNA extracted from soil samples with or without broomrape tissues or seeds. This diagnostic method is simple, reliable and rapid and could help for assessment of broomrape seed contamination in a crop field.

Broomrape (Phelipanche and Orobanche spp.) are obligate holoparasites that attack roots of almost all economically-important crops in semiarid regions of the world. Broomrape seeds are extremely small (dust-like seeds), averaging 200 to 300 μm in size and because of the miniscule seed size it is difficult to detect and confirm via conventional methods. In this study our aim was to develop a PCR-based assay specific for broomrape soil-borne seeds and sensitive enough to detect a single or few broomrape seeds in a soil sample. For this purpose, we used complementary polymerase chain reaction (PCR) primers based upon unique sequences in the internal transcribed spacer (ITS) regions of the nuclear ribosomal DNA of Phelipanche aegyptiaca. Genomic DNA was extracted from soil samples artificially infested with broomrape seeds or tissue of Phelipanche aegyptiaca Pers., Orobanche cumana Wallr. and Phelipanche crenata Forsk. and subjected to PCR analysis. Using ITS-350 primers, a specific PCR product (350 bp) was amplified and detected in all samples containing broomrape species, but was not detected in soil sample free of broomrape seeds or tissues. Additionally, the PCR-based assay was sensitive enough to detect even a single broomrape seed in the soil. As expected the universal internal control primers amplified a PCR product (555 bp) of genomic DNA extracted from soil samples with or without broomrape tissues or seeds. This diagnostic method is simple, reliable and rapid and could help for assessment of broomrape seed contamination in a crop field.

& Key message Creation of second generation Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) hybrids based on parents from geographically distant locations did not appreciably increase variance in height, frost damage and bud break. New and favorable trait combinations between height and the two adaptive traits were found in the F2 populations. & Context Increased genetic variance and new trait combinations can improve selection efficiency in terms of selection response and increased adaptability. & Aims This project tested a novel method for generating higher genetic variance and new trait combinations in Douglas-fir populations. & Methods Parents from Southern British Columbia (BC), Washington (WA), Oregon (OR), and Northern BC (NBC) were crossed within each provenance; then selections from BC were crossed with the other sources to create three F1 interpopulation generations. Unrelated random selections from the same F1 population were subsequently crossed to produce three F2 populations. The parental, F1 and F2 generations were concurrently grown in three field tests and were evaluated for height, frost damage, and bud break date. & Results Significant segregation variances were found only in the BCxNBC cross for height in two sites and frost damage in one site and in the BCxOR cross for bud break in one site. In the BCxNBC cross, correlations between breeding values for height and frost damage changed from 0.71 in F1 to − 0.04 in F2 and between height and bud break from − 0.71 to − 0.26. In the BC-OR cross, correlations between height and bud break changed from − 0.71 in F1 to − 0.49 in F2. & Conclusion Our results suggest that creation of wide-cross hybrids may not be very effective in increasing segregation variance in traditional tree improvement programs but in some cases may be considered to increase diversity of trait combinations.

Burial and removal techniques with seed bags were used to examine the viability and longevity of Melaleuca quinquen- ervia seeds at four field sites representing different soil types and hydrological conditions in South Florida. Seed viability was determined over different burial durations in the soil through a combination of germination tests and 2,3,5-triphe- nyl-tetrazolium chloride (TTC) treatments. Control seeds kept

Background: Soybean, an important oilseed crop of India, is rich in protein, oil, vitamins, isoflavones and minerals. Being an oilseed crop and the inherent physiological and biochemical properties, soybean seeds looses itsviability andvigour rapidly during storage, resultinginto poor stand establishment and productivity, upon subsequent planting. The current study aimed to understand the mechanism of antioxidants and antioxidant enzymes in soybean seed longevity. Methods: Ten good storer and ten poor storer, identified after storing for 8 months in ambient laboratory condition, were phenotyped biochemically to understand the mechanism of antioxidants [tocopherols (4 isomers) and isoflavones (12 isomers)] and antioxidant enzymes [catalase (CAT), peroxidise (POX), superoxidedismutase (SOD) and glutathione reductase (GR)]in seed longevity. Result: Good and poor storer genotypes recorded a mean initial germination of 99 and 96%, decreased to 91 and 67%, respectively upon eight months of laboratory ambient storage. Significant differences were observed in the activities of SOD, CAT, GR, alpha (α-T) and delta (δ-T) tocopherol between good and poor storer genotypes. Isomers of tocopherols ie. α-T and δ-T were found to beeither negatively (r=-0.55) or positively (r= 0.60) associated with seed longevity, indicated the role of individual tocopherol isomer than those to total tocopherols in seed longevity.

Viability and vigour are seed quality parameters that affect the seed chain. Seed vigour is a measure of accumulated damage in seed as viability declines from physiological maturity. This study aimed at determining the seed vigour of various sorghum genotypes stored ex situ for 10 years using the Heat Shock Stress Test (HSST), Cold Test (CT), Standard Germination Test (SGT) and field germination. The samples from the regeneration trial were kept in ex situ storage at 0-4°C and 40% relative humidity from 2003 to 2014. The experiments were arranged in a completely randomised design with four replication and differences in radicle length, shoot length for the 65 genotypes evaluated at 5% level of significance. An unpaired T-test was used to compare the accuracy of the quality methods in predicting field emergence. All the evaluated genotypes responded differentially to all the vigour test methods. There were significant differences (P<0.01) in the performance of genotypes with respect to radical and shoot length in response to the CT, HSST and the SGT. The results of CT and HSST predicted field emergence better than the standard germination test. None of the quality test methods and a strong and significant correlation with field emergence. Genotypes IS 30260 and IS 34637 were vigourous as they had the highest shoot length of 43.75 and 42.38 mm and IS 30063 had 45.52 mm in root length after 48 h of incubation. Overall, this study showed that field emergence of sorghum cannot be accurately predicted from a standard germination, HSST and CT.

Freshly harvested seeds of ten genebank accessions of rice (Oyza sativa L.) were dried by either immediately placing them in the genebank dryroom (15% RH, 15°C) or by placing them in a batch dryer (air heated to 45-50°C) for 4 d before transferring the seeds to the dryroom. Monitoring the eRH during the first 4 d of drying showed that moisture loss was more rapid using the batch dryer. Controlled deterioration tests were carried out after seed cleaning, in which seeds at approximately 24% moisture content were placed at 45°C and sampled after 24, 48, and 72 h for germination testing. For seeds of eight of the ten accessions, there was greater germination of seeds that had been initially dried using the batch dryer rather than the genebank dryroom. For good seed quality, including longevity during long-term genebank storage, it may be important to initially dry rice seeds at a higher temperature than that recommended in the genebank standards.

We investigated whether plant species with longer-lived seeds in the soil had lower rates of local extinction between 1950 and 1985 than species with shorter-lived seeds in 26 intact remnants of extensively used calcareous grasslands. In a previous study we had found higher rates of local extinction for smaller populations, for species with shorter life cycles, and for species with higher habitat speci®city. We compiled information on seed longevity from recent literature. Seed longevity had a highly signi®cant eect on the rate of population extinction. Rates of local extinction were lower for species with seed longevity >5 years (33.8%; 31 species) compared with species with shorter-lived seeds (1±5 years: 60.7%, 46 species; <1 year: 58.5%, 81 species). The integration of seed longevity into our analysis did not change our previous conclusions on the dependence of local extinction rates on habitat speci®city and on life form. Species in our data set with higher habitat speci®city tended to have shorter-lived seeds than species with lower habitat speci®city. Thus, most characteristic species of calcareous grassland do not persist in the seed bank and can not rely on this mechanism as a buer against local extinction.

Myroxylon balsamum is a valuable tropical tree; besides the good quality of its timber it also provides valuable nontimber forest products: balsam and resin. High deforestation rates in the area of distribution and the unregulated extraction of its resin and wood have led M. balsamum to be endangered or threatened. Its regeneration through seeds has been poorly studied, and there are no reports of germination and plasticity under controlled conditions. We evaluated the effect of scarification (longitudinal cut of the fruit and embryo fully exposed) and environmental factors (different levels of light intensities and changing temperatures) on seed germination and the development of seedlings. From the aforementioned, M. balsamum seeds are orthodox and show physical dormancy. In view of these characteristics, M. balsamum can be managed efficiently to initiate conservation programs and restoration in degraded land.

Understanding the composition and dynamics of soil seedbanks beneath mature conifer plantations is important for managing biodiversity in rotational forestry systems and in the restoration of former communities following the removal of tree crops. We examined the role of the buried seedbank in vegetation development after clear-felling of stands within coniferous plantation forest in eastern England. The buried seedbank of 29 mature stands planted in the early to mid 20th century on lowland heathland and marginal arable was determined by germination of seeds from soil cores (30 bulked cores per stand). Seedbank density was highly variable, with a mean of 3950 (S.D. AE 2400) seeds m À2. Ninety-eight species germinated, of which 37 were present in the surface vegetation of the mature stands; these 37 species had a higher density of seeds than the 61 species absent from the surface vegetation. Of those 61 species, 21 were recorded in the surface vegetation of recently replanted stands, suggesting that the seedbank may increase the plant diversity of replanted stands following clear-felling. The seedbank of mature stands was dominated by Urtica dioica and Holcus lanatus. Comparison of seeds in the top 20 cm of soil between four paired mature and replanted stands showed felling and cultivation prior to replanting had little effect on either the density of the buried seedbank or the vertical seed density profile. Twenty-nine of the species recorded in the buried seedbank of mature stands were characteristic of heathland assemblages of the region, but were present at low densities. Notably, a number of perennial grass species characteristic of heathland were absent, while Calluna vulgaris occurred in the seedbank of few stands and then at low density. The potential for grass-heath restoration following clear-felling of first rotation conifer stands investigated in this study is likely to be low.

Calophyllum brasiliense Cambess. (guanandi) is a native species with medicinal potential and also generates expectation for commercial use (wood) and for recovery of degraded areas. These seeds have physical and mechanical dormancy, requiring techniques for dormancy release; knowledge of seed and seedling morphology that assists laboratory analysis and propagation of the species is also necessary. The objective of this study was to describe the morphological structures of the seeds and normal and abnormal seedlings of guanandi, and also investigate if complete extraction of the endocarp and the seed coat to overcome dormancy will affect the morphology and initial plant development, and consequently production of transplants. Guanandi seeds are large (1000 seed weight of 1480.9 g) with a hard seed coat; cotyledons account for most of the embryo and serve as a reserve; the embryonic axis is small (1.0-2.0 mm) in relation to the seed, yet it is differentiated. The seedlings have hypogeal cryptocotylar germination, with cotyledonary petioles, taproot, and epicotyl developing into a long stem and a tip protected by cataphylls. The main abnormalities in seedlings are related to the root system. Extraction of the endocarp and seed coat does not alter the morphology of seedlings and promotes their greater development, which may be an advantageous strategy.

Saussurea costus (Falc.) Lipschitz (Asteraceae), an economically important medicinal herb, is categorized as critically endangered. The plant is cultivated in some parts of Lahaul (Himachal Pradesh, India) in North West Himalaya. However, in the recent past, the cultivation has declined owing to an array of reasons including a long cultivation cycle, greater profits from other cash crops (mainly pea, potato, hops) and formalities to be completed in obtaining the export permits. Therefore, the possibilities of ex situ (in areas other than Lahaul) cultivation/conservation needs to be explored. In this context, the understanding of seed physiological characteristics would be of immense help. Since there is a dearth of information concerning the storage-depenedent changes in seed physiological status of S. costus, we have analyzed these aspects for a long-term ambient storage (66 months) in a population from Lahaul. The freshly harvested seeds exhibited high viability (95%) with 65% germination that could be enhanced through GA3 and chilling pre-treatments. During storage,the seed germination increased after 12 months suggesting the seeds to be partially dormant that required an after-ripening prior to the commencement of germination. GA3 and chilling treatments appeared to substitute such requirement. Further,the seed viability was completely maintained at least for 18 months and even after 30 months storage, 82% viability retention associated with the production of healthy seedlings was evident. However, beyond 30-month-storage, both seed viability and germination declined substantially. Maintenance of reasonably high viability status, germination and seedling vigour even after substantial storage of seeds under ambient conditions suggests the suitability of seeds for regeneration/cultivation of this species.

A 60 months study was carried out to assess the seed longevity and effect of duration of storage period on viability, germination and seedling vigour in Rheum australe D. Don. (rubarb), a highly valued medicinal herb. The species is in high demand and has endangered status therefore, required conservation/cultivation interventions. The study was carried out using seeds of same lot after storage of every six months (0, 6, 12, 18 and so on) till complete loss of seed viability. Freshly harvested seeds exhibited high seed viability (94%) and were non-dormant; above 80% germination occurred within a week. The above status was completely retained till 12 months storage. Beyond this period both seed viability and germination declined consistently with the progression of storage period. A complete loss of viability was observed beyond 60 months storage. Seed pre-treatments tested namely, GA 3 , KNO 3 and chilling neither affected significantly the final germination of fresh seeds (86, 80 and 78%, respectively) nor differentially stored seeds. However, GA 3 (1 mM) and chilling significantly reduced the time required for germination. The seed longevity (time taken for 50% decline in seed viability) of R. australe was about 45 months, but a storage period of no longer than 24 months can be recommended. During 24 months storage period the seed viability and germination were reasonably high and resulted in the production of healthy seedlings with high survival rate. The outcome was favourable for the conservation/cultivation of the species.

Phytolacca acinosa Roxb., the Indian pokeweed, is a multipurpose herb that serves as a source of medicine, food and pigments, and possesses strong phytoremediation potential. Here, we report the storage (30-month) dependent changes in the status of seed viability, dormancy and germination of P. acinosa from W. Himalaya with an emphasis on seed longevity. The freshly harvested seeds exhibited 100% viability but were dormant as evident from lack of germination in control. The acid scarification and pre-treatment of seeds with GA 3 and sodium nitroprusside (SNP; a nitric oxide donor) led to 50, 27 and 20% germination, respectively. During a 30-month ambient storage of seeds, the seed germination increased till 12 months and gradually declined thereafter. The decline was essentially paralleled by reduced viability, decrease in the triphenyl tetrazolium chloride reduction ability of seed tissue (a measure of dehydrogenase activity) and amylase activity. The seed pretreatment dependent changes in amylase activity and increased levels of malondialdehyde (MDA, a measure of lipid peroxidation) and proline during storage signify the role of reserve hydrolysis and oxidative stress in seed germination and viability. A complete seed viability loss occurred after 30 months of storage. The seed longevity (time taken for a 50% decline in seed viability) of P. acinosa, stored under ambient conditions was found to be more than 24 months that appears reasonably high for successful seed-based propagation and conservation of the species.

Genetic banks manage seed collections for the conservation and utilization of plant genetic resources. AGB implements standards for genebank management recommending a temperature of -18 ± 3°C for long-term storage of the base collection and 5-10°C for medium-term storage of the active collection.The germination energy of the 12 maize accessions taken in the study has relatively low initial values. The values of germination energy, even after 20 years of seed storage, do not deviate much from the initial data (from 2000) and from those from 2010 (10 years of seed storage). The germination data for the three years of testing are somewhat small in the initial testing. The average capacity germination for all 12 accessions under study in the 2010 test is 4.2% lower than the initial test (year 2000), so there is a decrease in capacity germination. Whereas in the testing of 2020, i.e. after storing the seed for 20 years in the genetic bank, there was a decrease in capacity germination on ...

UN Sustainable Development Goal 2 Target 2.5 focuses on the conservation of genetic diversity in soundly managed genebanks. In examining the term “soundly managed”, it becomes quickly evident that there is much more to long-term conservation than placing samples of seeds or other germplasm in long-term conservation conditions. There are several important factors that determine whether germplasm samples will remain viable in storage for long periods of time. To manage these factors efficiently and effectively, genebanks require sound data and quality management systems. The CGIAR Genebank Platform, coordinated by the Crop Trust, put in place a number of mechanisms that enabled effective online reporting, performance management, quality management, audit and external review and validation. These mechanisms do not conform to the usual monitoring systems put in place for research programs and have only been possible thanks to the flexibility of CGIAR in recognising that the genebanks we...

Understanding the relative longevity of different seed lots, perhaps of different species or genotypes, but also following production under different environments or using different cultivation methods, or following different post-harvest treatments, is relevant to anyone concerned with the retention of seed lot viability and vigour during storage. However, different scientists over the years have used different conditions to assess seed lot longevity, as well as different variables as the measure of ‘longevity.’ Here, we give some of the backgrounds to how two standard protocols, with an open and closed system respectively, were derived, and explain why we considerp50, defined as the time during storage when seed lot viability, as measured through a germination test, has declined to 50%, is a suitable longevity trait parameter.

In each of two experiments, freshly harvested seeds of two cultivars of rice were dried and then rehydrated to different moisture levels. In experiment 1, seed equilibrium relative humidity (eRH) and moisture content (MC) were determined at each moisture level so that moisture desorption and adsorption isotherms could be constructed. Seed storage experiments were also carried out for seeds equilibrated at each moisture level, in sealed aluminium foil packets at 45°C. In experiment 2, storage experiments at 45°C were carried out on seeds dried to 12% MC and seeds dried to lower moisture levels and then rehydrated to 12% MC.The moisture adsorption isotherm was shifted to lower MC at a given eRH compared with the desorption isotherm. This hysteresis effect was seen both when seeds were dried to &lt;6% MC and then allowed to adsorb moisture to different levels, and when seeds were dried to different levels (10, 8, 6 or 4% MC) and then allowed to adsorb moisture up to 12% MC. The log-log...

Extended seed longevity in the dry state is the basis for the ex situ conservation of &#39;orthodox&#39; seeds. However, even under identical storage conditions there is wide variation in seed life-span between species. Here, the effects of seed traits and environmental conditions at the site of collection on seed longevity is explored for195 wild species from 71 families from environments ranging from cold deserts to tropical forests. Seeds were rapidly aged at elevated temperature and relative humidity (either 45 degrees C and 60% RH or 60 degrees C and 60% RH) and regularly sampled for germination. The time taken in storage for viability to fall to 50% (p(50)) was determined using Probit analysis and used as a measure of relative seed longevity between species. Across species, p(50) at 45 degrees C and 60% RH varied from 0.1 d to 771 d. Endospermic seeds were, in general, shorter lived than non-endospermic seeds and seeds from hot, dry environments were longer lived than those fr...

Genebanks underpin global food security, conserving and distributing agrobiodiversity for use in research and breeding. The CGIAR collections include >700,000 seed accessions, held in trust as global public goods. However, the role of genebanks in contributing to global food security can only be realized if collections are effectively managed. Examination of the historical viability monitoring data from seven CGIAR genebanks confirmed that high seed viability was maintained for many decades for the various crops and forage species. However, departures from optimum management procedures were revealed, and there were insufficient data gathered to derive reliable estimates of longevity needed to better forecast regeneration requirements, estimate the size of seed lots that should be stored, and optimize accession monitoring intervals.

Good weed management relies on the proper timing of weed control practices in relation to weed emergence dynamics. Therefore, the development of models that predict the timing of emergence may help provide growers with tools to make better weed management decisions. The aim of this study was to validate and compare two previously published predictive empirical thermal time models of the emergence of Abutilon theophrasti growing in maize with data sets from the USA and Europe, and test the hypothesis that a robust and general weed emergence model can be developed for this species. Previously developed Weibull and Logistic models were validated against new data sets collected from 11 site‐years, using four measures of validation. Our results indicated that predictions made with the Weibull model were more reliable than those made with the Logistic model. However, Weibull model results still contained appreciable biases that prevent its use as a general model of A. theophrasti emergenc...