Viability of rape (Brassica napus L.) seeds following selection on the basis of newly-emerged radicles then subsequent drying and storage

Germinating rape seeds selected on the basis of newly-emerged radicles (1 ± 0.5 mm) were dried to an equilibrium moisture content (c. 11%) in air at 20°C and 80% relative humidity without loss of viability. Storage life of these low-moisture-content germinating (LMCG) seeds at 15°C was limited to 7 days before viability was significantly reduced. However, viability of LMCG seeds was maintained for 84 days in storage at -20°C. Longer periods in store reduced viability, but 96% of seeds still remained viable after 336 days at - 20°C. Increasing periods of storage at -20°C reduced the subsequent seed longevity at 15°C, indicating a reduction in vigour during storage. Storage under reduced pressure or in a nitrogen atmosphere had little significant effect on seed longevity. Reduction of moisture content below 11% using vacuum drying at a range of temperatures reduced seed vigour.     

A comparison of Brussels sprout seedling establishment from ungerminated and low-moisture-content germinated seeds

The moisture content of newly-germinated Brussels sprout seeds (radicles 1 ± 0·5 mm long) was reduced to 16% without loss of viability when compared with untreated newly-germinated seeds. Seedling emergence and growth from these low-moisture-content germinated (LMCG) seeds and ungerminated seeds were compared in cellular trays and seedbeds. A greater number of seedlings emerged more uniformly and more rapidly from LMCG seeds than from ungerminated dry seeds, leading to larger, more uniform seedlings for subsequent transplanting. Post-germination separation in sucrose solutions before drying resulted in a seed batch with 98% of germinated seeds. As there was a positive relationship between the rate of germination and subsequent seedling growth, it is suggested that germinated-seed separation techniques could be used to select the most vigorous seedlings.     

Germination-associated events and the desiccation sensitivity of recalcitrant seeds — a study on three unrelated species

The storage behaviour of recalcitrant seeds was assessed using three diverse species: a gymnosperm, Araucaria angustifolia (Bert.) O. Kuntze; a herbaceous monocotyledon, Scadoxus membranaceus (Bak.) Friis Nordal; and a woody dicotyledon, Landolphia kirkii Dyer. Seeds were stored under conditions of high relative humidities that maintained seed moisture content and under low relative humidities that caused drying. At regular intervals moisture content was determined, germinability assessed and the ultrastructure of radicle meristem cells examined. Under storage at high relative humidity, seed moisture content was maintained at the original level and subcellular germination events were initiated in the short-term. Such seeds showed enhanced rates of germination when removed from storage and planted. Long-term storage under these conditions resulted in the initiation of subcellular damage which intensified with time and ultimately resulted in the loss of viability. The rate at which germination events proceeded varied among the three species, and could be directly correlated with the period of viability retention under humid storage conditions. Storage under desiccating conditions resulted in subcellular damage and rapid loss of viability. The rate at which the seeds dried varied among the three species. The proportion of water loss tolerated by the different species before loss of viability, correlated with the rate of drying. The storage behaviour of the seeds of these three species is discussed in terms of a previously described model.     

Physiological characteristics underpinning successful cryopreservation of endemic and endangered species of Bromeliaceae from the Brazilian Atlantic Forest

The germination requirements and the basis of the optimal water content before and after cryopreservation were studied for ten endangered Brazilian species of Bromeliaceae. Constant and alternating temperature regimes were used to determine the best conditions for seed germination. The relationship between seed water content and relative humidity was evaluated using water sorption isotherms at 15 °C. Seeds were cryostored at four water contents (3, 5, 7 and 9%) and three storage periods (0, 180 and 365 days), and loss in viability and vigour were estimated. Fresh seeds of all species showed maximum germination in < 30 days at temperatures between 20 and 30 °C, indicating the absence of a physical/morphological dormancy. A sigmoidal relationship between seed water content and relative humidity was observed with no apparent differences in sorption characteristics among the species. The optimum water content for cryopreservation of most of these species was c. 7%. Ultra‐drying (3% seed water content) had a detrimental effect on seed viability and vigour. Our experiments suggested orthodox storage behaviour for all species of Bromeliaceae examined as they are able to survive desiccation and freezing. This study has shown the feasibility of ex situ conservation in seed cryobanks of endangered bromeliads from the Brazilian Atlantic Forest to support future reintroduction of these species in nature. © 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176 , 567–576.     

Systematic overestimation of Salicaceae seed survival using radicle emergence in response to drying and storage: implications for ex situ seed banking

Biodiversity conservation programmes are underpinned by seed banking following drying to low water contents (WC), and supported by both the assessment and prediction of seed viability over time. The means of judging viability is thus crucial to the comprehension of seed vigour. We selected seeds of three species and one hybrid in the Salicaceae likely to have variation in tolerance to drying, processing and storage, including in relation to cryobanking, and compared survival growth as radicle emergence (germination) and normal seedling production. With three seed lots of Salix gracilistyla, air-drying to 8–10 % WC enhanced seed survival after 40 days’ storage at 5 °C as compared with non-treated seeds at 14–20 % WC. Four seed lots of Populus alba × P. glandulosa showed equally high germination (88–100 %) and proportions of normal seedlings (81–99 %) when stored at 5 °C for 7–10 weeks. Among seven seed lots of S. gracilistyla, two groups with different storage behaviour could be statistically distinguished with normal seedling production ranging from 0 to 45 % after storage at 5 °C for 13 weeks. Seed tolerance to WC manipulation and cryopreservation was very variable among species and seed lots. Seed lots of S. hallaisanensis and S. gracilistyla with ~80 % germination survived cryopreservation at 10 % WC, but were sensitive to lower WCs. In contrast, Populus seeds had greater desiccation tolerance combined with cryopreservation capability. With seed lots of all species and hybrids, cryopreservation had little effect on viability unless the high moisture freezing limit had been exceeded (~10–20 % WC, depending on seed lot). However, under all conditions of handling (drying, rehydration, storage at 5 °C or cryopreservation) using germination as the only indicator of viability over-estimated survival compared with normal seedling production.     

The germination and emergence of seeds of winter oilseed rape stored and sown in admixture with pelleted methiocarb

The possibility that pellets of the molluscicide Draza (a.i. methiocarb) might reduce field emergence of seeds of winter oilseed rape (Brassica napus, cv. Jet Neuf) when sown admixed, laboratory germination when stored admixed, or field emergence when both stored and sown admixed was the subject of three separate investigations. Admixture at sowing did not influence the emergence of five seed lots (P > 0·05). Neither did admixture influence loss in germination or change in moisture content during 2 months' storage of one lot in four different regimes (P > 0·05). Field emergence following 2 months' storage in paper bags was not influenced by admixture (P > 0·05), whereas a 12% reduction in field emergence resulting from storage in admixture within polyethylene bags was detected (P < 0·05). Thus short-term storage within paper sacks of winter oilseed rape seeds in admixture with slug pellets containing methiocarb did not damage the seeds. The emergence of five seed lots differed considerably within and between field sowings. Tentative advice on the calculation of sowing rates for different seed lots of winter oilseed rape is provided to account for this variation.     

The effect of abscisic acid on the growth and storage of germinating rape (Brassica napus L.) seed dried following selection on the basis of a newly-emerged radicle

Abscisic acid at 1 × 10^–4M concentration controlled the progress of the emerging radicle from germinating rape seeds and apparently restricted it to the dehydration tolerant phase. ABA treatment during germination followed by washing reduced the deleterious effects of drying the seeds following selection based on a newly-emerged radicle. Furthermore, the longevity of these low-moisture-content germinating seeds at a range of temperatures was improved by the ABA treatment. The viability of the treated seeds stored at –20°C was maintained for up to 100 days.     

Seed vigour and water relations in wheat

The laboratory germination (criterion radicle emergence) of seven seed lots of winter wheat cv. Slejpner was similar. However, they differed in vigour as demonstrated by differences in germination after controlled deterioration carried out at a range of seed moisture contents, at two temperatures and for different times. A vigour assessment for each lot was quantified by calculating a value for the seed lot constant K_i, of the viability equation. Germination in lower water potentials reduced the uptake of water, radicle and coleoptile emergence and radicle and coleoptile extension. There was no difference in the water uptake of seed lots differing in vigour. However, seed lots of lower vigour showed less radicle emergence, less coleoptile emergence and shorter radicles than higher vigour seed lots in low water potentials. Similarly, controlled deterioration resulted in reduced radicle and coleoptile emergence and growth compared to unaged seed, and also to a greater sensitivity to low water potentials. The implications for field establishment are discussed.     

Improving germination and vigour of aged and stored onion seeds by matriconditioning

Germination and vigour of accelerated aged (AA) and naturally stored onion seeds were examined. Accelerated ageing was conducted at 40 °C and 100 % relative humidity (RH). Non aged seeds were stored for 34 months at 3 or 15 °C and 40, 60 or 90 % RH. To restore seed viability, stored and aged seeds were matriconditioned with Micro-Cel E. A distinct loss of germination was observed after 5 days of accelerated ageing. Naturally stored seeds maintained high viability for 34 months, when stored at 3 °C and 40, 60 and 90 % RH or at 15 °C and 40 %. An increase of RH to 60 and 90 % at 15 °C caused loss of germination and vigour. Matriconditioning improved germination and increased endogenic ethylene release and in vivo ACC oxidase activity of both aged and stored seeds.     

Effect of water content and temperature on seed longevity of seven Brassicaceae species after 5 years of storage

Maximising seed longevity is crucial for genetic resource preservation and longevity of orthodox seeds is determined by environmental conditions (water content and temperature). The effect of water content (down to 0.01 g·H₂O·g^?1) on seed viability was studied at different temperatures for a 5‐year storage period in taxonomically related species. Seeds of seven Brassicaceae species (Brassica repanda, Eruca vesicaria, Malcolmia littorea, Moricandia arvensis, Rorippa nasturtium‐aquaticum, Sinapis alba, Sisymbrium runcinatum) were stored at 48 environments comprising a combination of eight water contents, from 0.21 to 0.01 g·H₂O·g^?1 DW and six temperatures (45, 35, 20, 5, ?25, ?170 °C). Survival curves were modelled and P50 calculated for those conditions where germination was reduced over the 5‐year assay period. Critical water content for storage of seeds of six species at 45 °C ranged from 0.02 to 0.03 g·H₂O·g^?1. The effect of extreme desiccation at 45 °C showed variability among species: three species showed damaging effects of drying below the critical water content, while for three species it was neither detrimental nor beneficial to seed longevity. Lipid content could be related to longevity, depending on the storage conditions. A variable seed longevity response to water content among taxonomically related species was found. The relative position of some of the species as long‐ or short‐lived at 45 °C varied depending on the humidity at which storage behaviour was evaluated. Therefore, predictions of survival under desiccated conditions based on results obtained at high humidity might be problematic for some species.     

顽拗性竹柏种子的贮藏特性

文章对竹柏(Podocarpus nagi)种子的脱水耐性和贮藏特性进行了研究,结果表明:竹柏种子成熟时初始含水量约为(35±0.7)%,种子对脱水敏感,其最低安全含水量约为(16.86±0.73)%,具有顽拗性种子的典型特征;湿藏和半干藏都可以作为短期保存竹柏种子的方法,且以4℃保存优于15℃保存,但不管种子含水量如何,零下低温保存对竹柏种子都是致命的;半干藏法保存实验中,未进行脱水处理的种子(对照)在4℃贮藏6个月,种子萌发率没有发生明显下降,但贮藏期延长到9个月时,临界含水量的种子萌发力保存最高;不管贮藏介质的含水量高低,也无论贮藏在4℃还是15℃,湿藏种子在9个月的贮藏期内萌发率均没有明显的降低,但当贮藏到12个月时,15℃湿藏种子的萌发率显著高于4℃贮藏的种子,但15℃湿藏的种子在贮藏到3个月时即发现种子在贮藏期间萌发,且随着贮藏介质含水量的升高和贮藏期的延长,萌发的种子增多;竹柏的离体胚经过2 h硅胶快速脱水至含水量7%后再冷冻即可获得90%以上的融后存活率,且超低温保存1年的离体胚解冻后,与只保存1周的存活率没有明显差异,表明超低温长期保存竹柏种子是可行的。本研究可以为进一步探究顽拗性种子的短期贮藏和长期保存提供理论基础和基础资料。     

A rapid method for the prediction of germinability of French beans*

Sun-dried French bean seeds, moisture content 10 ± 0·8%, aged at ambient temperature for 2 months, 1, 2, 3 and 4 yr were incubated in hot water at 58 × 1°C for 30 min. Buffering capacity of incubation water (IWBC) due to solutes leaked out into hot water was highly correlated with electrolyte leakage into single seed steep water. The IWBC was examined for its ability to predict seed quality of ageing stocks. The technique does not require any instrument. Thus it may prove useful as a rapid, simple, inexpensive and highly predictive vigour test.     

Sowing seasons and drying methods during post-harvest influence the seed vigour of soybean (Glycine max (L.) Merr.)

Experiments were conducted to study the influence of sowing seasons and drying methods on the seed vigour of two spring soybean (Glycine max (L.) Merr.) cultivars. Two cultivars, ‘Huachun18’ and ‘Huachun 14’, were sown in three seasons viz., spring, summer and autumn and the harvested seeds were dried using three different methods. The results showed that soybean sown in spring had a higher number of branches per plant, pods per branch and seed weight, and consequently resulted in higher seed yields than that of soybean sown in autumn or summer seasons. Seeds sown in the autumn season had the lowest values of electrical conductivity during seed imbibitions, higher peroxidase (POD) activity in germinated seedlings and lower contamination by the seed-borne fungi on the MS medium, which indirectly improved the seed vigour, which was followed by summer sown seeds. Seeds sown during the spring season resulted in poor seed vigour. In addition, the effect of drying methods on the seed vigour was also clarified. Seeds that hung for four days before threshing and then air-dried had the poorest seed vigour which was determined by germination, electrical conductivity, POD activity and seed borne fungal growth. There was no difference in seed vigour between other methods, i.e. seeds threshed directly at harvest and then air-dried on a bamboo sifter or concrete floor. These results indicated that autumn sowing soybean and the drying method in which seeds were threshed directly at harvest and then air-dried on a bamboo sifter resulted in higher seed vigour.     

Survival and Vigour of Lettuce (Lactuca sativa L.) and Sunflower (Helianthus annuus L.) Seeds Stored at Low and Very-low Moisture Contents

Seeds of lettuce (Lactuca sativa L.) and sunflower (Helianthusannuus L.) were stored hermetically at 35 °C with 11 differentmoisture contents between 1·3 and 6·9%, and between1·3 and 7·1% of fresh mass, respectively. Germinationand vigour (mean germination time, root length, seedling dryweight) were determined after storage for 0, 8, or 16 weeks(sunflower) or 0, 8, 16, or 48 weeks (lettuce) in these environmentsfollowed by various humidification treatments (to avoid imbibitioninjury). The range of seed storage moisture contents over whichdeterioration was minimized depended upon the criterion of deteriorationused, and varied somewhat between species. Comparison of theseranges for seeds stored for the longest durations showed thatfor some criteria seed performance was poorer (P < 0·05)at both the lowest and highest moisture contents investigatedthan at certain of the intermediate storage moisture contents(e.g, most rapid germination occurred in sunflower followingstorage at 2·2-4·7% moisture content), whereasfor other criteria all the drier storage moisture contents weresuperior to the more moist (e,g. greatest seedling growth occurredin sunflower following storage at 1·3-5·1% moisturecontent). But none of these results suggested that lettuce andsunflower seeds stored hermetically at 2·5-3·0%or 2·2-2·5% moisture content, respectively, wereless vigorous than at any other moisture content tested. Inboth species, these storage moisture contents are in equilibriumwith about 8-10% relative humidity (r.h.) at 20 °C, whichis similar to and indeed marginally less than the 10-13% r.h.recommended following earlier studies on the longevity of seedsin hermetic storage at much warmer temperatures. Thus, theseresults show no evidence that the optimum seed moisture contentfor storage increases with decrease in temperature, at leastover the range 35-65 °C, as has been suggested elsewhere.We conclude that the international recommendation for the long-termseed storage for genetic conservation at 5 ± 1% moisturecontent should not be revised upwardly, and that in situationswhere refrigeration cannot be provided storage at even lowermoisture contents is worthy of further investigation for thoseseeds in which desiccation at 20 °C to equilibrium at 10%r.h. results in moisture contents well below 5%.Copyright 1995,1999 Academic Press Helianthus annuus L., sunflower, Lactuca sativa L., lettuce, desiccation, seed storage, seed vigour     

The use of an ELISA to quantitate the extent of 11S globulin mobilization in untreated and primed sugar beet seed lots

Seed priming (controlled imbibition) is a widely used technique for improving crop establishment, because it allows a reduction of the time to radicle emergence following seed imbibition and synchronization of individual seeds within seed lots with respect to germination timing. The major problem encountered in seed priming is the control of seed imbibition to a level permitting pre-germinative processes to proceed but that blocks radicle emergence. If not, the consequence of drying back the seeds to initial moisture content for storage purposes could be a total loss of the treated batch. This is because, as long as radicle growth has not begun, seeds may be re-dried without any permanent deleterious effects upon subsequent germination or growth. Recently, we reported the discovery of a molecular marker of sugar beet seed priming, corresponding to the basic B-subunit of the seed storage protein 11S globulin. An ELISA based upon this molecular marker has been used to analyse how different sugar beet seed lots respond to a priming treatment. The results demonstrate that this ELISA allows us to readily distinguish between the primed seeds and the corresponding untreated seeds.     

Desiccation and storage studies on Dipterocarpm seeds

The relationship of seed moisture content (fresh weight basis) to germination, and the effect on viability of various storage conditions were examined for five species of the tropical forest tree genus Dipterocarpus. It was shown that seeds fall into two groups with regard to desiccation tolerance. Firstly, D. obtusifolius and D. turbinatus cannot be dried below about 45% moisture content without damage; a sigmoid curve was found to fit the relationship between germination and moisture content for the latter species. Secondly, D. intricatus, D. tuberculatus and D. alatus can be safely dried to 10%, 12% and 17% moisture contents respectively, but desiccation to near 7% moisture content reduced viability by at least a half. Storage studies showed that seed of D. intricatus and D. tuberculatus possessed increased longevity as moisture contents were reduced within the range 6–20%. It was concluded that seeds in the first group are ‘recalcitrant’ and that those in the second group are ‘orthodox’ in their storage physiology, according to the categories described by Roberts (1973). Wide differences between species in seed desiccation rates were observed. In 15% relative humidity D. intricatus dried to 7% moisture content within a week, whilst D. obtusifolius retained 30% moisture content even after 5 wk; other species had intermediate desiccation rates. Seed size and structure may partly account for the differences observed. Correlations were observed between seed storage physiology and other factors which were investigated. ‘Orthodox’ seeds had quicker desiccation rates, were derived from drier habitats, and had smaller embryos than those of ‘recalcitrant’ seeds. ‘Orthodox’ seeds, with the possible exception of D. alatus, should be kept at 0–3°C with about 12% moisture content in the short term and, provided less than 10% germination is lost on freezing, at-18°C with about 8% moisture content in the long term. ‘Recalcitrant’ seeds should be stored in ventilated containers at 21°C and with moisture contents above 45–50%.     

The effect of time of harvest on the viability and pre-emergence mortality in soil of pea (Pisutn sativum L.) seeds

A series of harvests from field plots of peas showed that the younger seeds were at the time of harvest the lower was their percentage viability and the greater their percentage mortality in soil. Young seed also showed a high degree of solute leaching into steep water and had a high moisture content at harvest compared with older seeds. Heavy rainfall just prior to harvesting reduced the percentage viability of the dried seed and increased the moisture content of the seed at harvest as well as the leaching of solutes from the dried seed into steep water. Comparisons of moisture content at harvest and seed condition after drying suggested that cotyledons and embryo axes were only able to withstand enhanced drying after removal from the plant if the seed moisture content had already begun to decline whilst the seed was still on the plant.     

Evidence for Repair Processes in Onion Seeds during Storage at High Seed Moisture Contents

Survival curves of four seed lots of onion held at 15%, 20%and 25% seed moisture content (me) and 45 ° C for 24 h showeda fall in seed germination at all moisture contents. The rateof loss of viability was less for seeds held at 20% and 25%me than that of seeds held at 15% me, with low vigour seedsshowing the greatest reduction in the rate of deteriorationat the high moisture contents. This is interpreted as evidencefor the activation of repair processes in seeds during periodsof partial seed hydration and discussed in relation to seedinvigoration treatments. Key words: Seed moisture content; Storage, Repair, Priming, Invigoration     

The Development of Desiccation-tolerance and Maximum Seed Quality During Seed Maturation in Six Grain Legumes

‘Physiological maturity’, i.e. the time when seedsreach their maximum dry weight during development, occurredwhen maturation drying on the parent plant in the field hadreduced seed moisture content to approximately 60 per cent infaba bean (Vicia faba L.), lentil (Lens culinaris Medic.), chickpea(Cicer arietinum L.), white lupin (Lupinus albus L.), soya bean(Glycine max [L.] Merr.) and pea (Pisum sativum L.) The onsetof desiccation-tolerance, i.e. the ability of seeds to germinatefollowing harvest and rapid artificial drying, coincided withphysiological maturity, except in pea where it occurred a littleearlier at about 70 per cent moisture content. Maximum seedquality as determined by maximum viability, minimum seedlingabnormalities and maximum seedling size occurred in pea, chickpeaand lupin when seeds were harvested for rapid drying at physiologicalmaturity; but for maximum seed quality in the other speciesmaturation drying had to proceed further - to about 45 per centmoisture content in soya bean and to about 30 per cent moisturecontent in lentil and faba bean seed crops. Much of this variationamongst the six species, however, was due to differences inthe variation in maturity within each seed crop. Results forindividual pods showed that peak maturity, i.e. maximum seedquality following harvest and rapid artificial drying, was achievedin all six species once maturation drying had reduced the moisturecontent of the seeds to 45–50 per cent. In pea, faba beanand soya bean there was a substantial decline in viability andan increase in seedling abnormalities when harvest was delayedbeyond the optimal moisture content for harvest.     

A butenolide, isolated from smoke, can overcome the detrimental effects of extreme temperatures during tomato seed germination

The butenolide, 3-methyl-2H-furo[2, 3-c]pyran-2-one, is an highly active compound isolated from plant-derived smoke. This compound is known to stimulate seed germination in a wide range of plants akin to smoke or aqueous extracts of smoke. The present study attempted to elucidate the role of the butenolide in overcoming detrimental effects of low and high temperatures on tomato seed germination and seedling growth. The germination percentage followed a parabolic curve for temperatures ranging from 10 to 40°C, with 25°C being the optimum for all treatments. Control seeds showed radicle emergence at two extreme temperatures (10 and 40°C) and seedlings failed to develop further, even upon prolonged incubation. By comparison the butenolide-treated seeds grew into phenotypically normal seedlings at these non-optimum temperatures. The smoke–water-treated seeds had an intermediate response as only a fraction of germinated seed developed into normal seedlings. Seedling vigour indices as well as seedling weight were significantly higher (p ≤ 0.05) for butenolide-treated seeds at all temperatures. Furthermore, seedlings developed in the presence of the butenolide had about a 1:1 correspondence between root and shoot length. Butenolide-treated seeds grew better than the control seeds in the temperature shift experiments. A gradual decline in the vigour index values was recorded with an increased duration of incubation at the extreme temperatures. Results of the present study are very important from an horticultural point of view as they indicate the potential use of the butenolide compound in restoring normal seed germination and seedling establishment in tomato below and above optimum temperatures.