A Low-Moisture-Content Limit to Logarithmic Relations Between Seed Moisture Content and Longevity

Seeds of quinoa (Chenopodium quinoa Willd.), sunflower (Helianthusannuus L.) and linseed (Linum usitatissimum L.) showed negativelogarithmic relations between longevity and moisture contentsbetween 4.4 and 15.4, 3.2 and 13.0, and 3.2 and 15.5%, respectively,in hermetic storage at 65 °C. However, between 1.8 and 3.1,1.1 and 1.9, and 1.1 and 2.1%, respectively, longevity did notvary. The critical moisture content, below which further reductionin moisture content no longer increased longevity in hermeticstorage at 65 °C, for each species was 4.1, 2.04 and 2.7%,respectively. Quinoa, Chenopodium quinoa Willd., sunflower, Helianthus annuus L., linseed, Linum usitatissimum L., seed storage, improved viability equation, seed longevity, seed moisture content     

Limits to the Negative Logarithmic Relationship Between Moisture Content and Longevity in Conidia ofMetarhizium flavoviride

Conidia ofMetarhizium flavoviridewere hermetically stored at50 °C and 14 moisture contents between 2.5 and 31.8% (freshweight basis) for up to 146 d, and tested for germination onSabouraud Dextrose Agar at 25 °C for 24 h. Survival of conidiaconformed to cumulative negative normal distributions and all14 survival curves could be constrained to a common origin.There was a negative logarithmic relation between longevityand conidia moisture content, but limits to the relation weredetected: the lower-moisture-content limit was 4.6% [in equilibriumwith 10.7% relative humidity (RH) at 20 °C], below whichvalue further reduction in moisture content did not increaseconidia longevity; and an upper-moisture-content limit betweenabout 21.2 and 31.8% moisture content (between 77 and 90.0%equilibrium RH at 20 °C) above which conidia longevity nolonger decreased. The observations could also be described bya negative semi-logarithmic relation between conidia longevityand equilibrium relative humidity. In this model, each reductionin equilibrium relative humidity by 11.2% within the range 10.7to 80% RH doubled conidia longevity. The similarities in theserelations, and the limits to these relations, between the conidiaof this entomopathogenic fungus and the orthodox seeds of higherplants are discussed.Copyright 1998 Annals of Botany Company Conidia longevity, equilibrium relative humidity,Metarhizium flavoviride, moisture content, hermetic storage, viability equation     

Low Moisture Content Limits to Relations Between Seed Longevity and Moisture

Discontinuities at low moisture contents in the otherwise logarithmicrelations between seed longevity and seed moisture content (%,f. wt basis) in hermetic storage at 65 °C were detectedat 2–0% in groundnut (Arachis hypogaea L.), 3·5%in onion (Allium cepa L.), 4·5% in sugar beet (Beta vulgarisL.), 4·6% in barley (Hordeum vulgare L.), 5·3%in chickpea (Cicer arietinum L.) and wheat (Triticum aestinumL.), and 5·6% in cowpea [Vigna unguiculata (L.) Walp.].In contrast, the equilibrium relative humidity of seeds at thesevalues was similar, varying between 9·9% (onion and sugarbeet) and 11·5% (wheat). The mean value was 10·5%r.h. (s.e. 0.2). There was no significant (P > 0·05)effect of further reduction in seed moisture content below thesecritical values on longevity, except in wheat (P < 0·005),in which there was a further increase in longevity. In soyabean [Glycine max (L) Merrill], the logarithmic relation continueddown to the lowest moisture content investigated, 3·3%(11·4% equilibrium relative humidity). Above the criticalvalue, seed longevity in groundnut showed the least sensitivityto increase in percentage moisture content, while barley showedthe greatest, the values of the viability constant C_w (slopeof the negative logarithmic relation between longevity and moisture)being 4·089 (s.e. 0·278) and 5·966 (s.e.0·325), respectively. These differences in the valueof C_w among the eight crops were significant P < 0·005),whereas the relative sensitivity of seed longevity to changein equilibrium relative humidity above the critical moisturecontent did not differ significantly among the eight (P >0·10) and was equivalent to a doubling of longevity foreach 8·7% reduction in equilibrium relative humidity.Accordingly it is concluded that the relative effect of waterpotential on seed longevity can be considered to be the samefor these and probably also for many other orthodox species. Barley, chickpea, cowpea, groundnut, onion, soya bean, sugar beet, wheat, seed storage, seed longevity, seed moisture content, viability equation, water relations     

Logarithmic Relationship between Moisture Content and Longevity in Sesame Seeds

The relationship between seed moisture content and seed longevityin sesame (Sesamum indicum L.) in hermetic storage at 50 °Cis logarithmic. The logarithmic relationship is maintained from15 per cent down to 2 per cent – the lowest moisture contenttested — but above 15 per cent this ‘air-dry’relationship no longer holds since further increase in seedmoisture content does not reduce longevity. Tentative estimatesof constant values for the improved seed viability equationare provided, and implications for long-term storage are discussed. Sesame, Sesamum indicum L., seed storage, improved viability equation, seed moisture content, seed longevity prediction     

含水量对种子贮藏寿命的影响

建立以收集种子为主体的基因库乃是当今保护植物种质资源最为普遍且可靠易行的方式,在世界库存约 61 0 0 0 0 0份种质资源中,近 90 %是以种子形式保存于约 1 30 0个基因库中。低温贮藏仍是目前基因库中种子种质保存的主要方法。种子含水量和贮藏温度是影响种子在贮藏期间生活力和活力保持的关键因素。传统的经验认为控制温度比控制水分来得安全有效,因而趋向于向低温或超低温的贮藏方向发展。国际植物遗传资源研究所（ＩＰＧＲＩ）曾推荐 5%～ 6%的含水量和 - 1 8～- 2 0℃低温作为各国长期保存种子的理想条件。目前,世界各国都把更多的…     

洋葱种子含水量与贮藏温度对其寿命的影响

不同含水量（MC7.1％～1.2％）的洋葱种子贮藏在35℃、室温、15℃和5℃条件下1～3年,适度超干处理能延长种子的贮藏寿命;种子的贮藏寿命与种子含水量和贮藏温度密切相关。种子贮藏的最适含水量随温度的改变而发生相应的变化,35℃时MC为3.4％;室温时为3.4％～4.5％;15℃时为4.5%～5.1％。MC≤2.2％不利于延长种子寿命。在室温自然条件下贮藏1～3年,适度超干种子（MC3.4％）内MDA和H2O2含量、O－*2产生速率和LOX活性明显地低于未超干种子（MC7.1％）和高度超干种子（MC1.2％）,而抗氧化酶AsA-POD、CAT和SOD的活性显著地高于未超干种子（MC7.1％）和高度超干种子（MC1.2％）。据此认为对脂质过氧化的抑制作用是适度超干种子耐贮藏的生理原因之一。     

The Viability of Rice Seed in relation to Temperature, Moisture Content, and Gaseous Environment

The seed viability of a tropical variety of rice has been investigatedin hermetic storage under a range of conditions of temperatureand moisture content. The results confirm a previous suggestion,which was made on the basis of data from temperate cereals,that the relationship between these factors and viability canbe described in simple mathematical terms. In addition, a comparisonhas been made of the effects on viability of hermetic storagein air, oxygen, nitrogen, and carbon dioxide.     

The Effect of Temperature and Moisture Content on the Longevity of Seed of Ulmus carpinifolia and Terminalia brassii

Seeds of the Smooth-leafed Elm (Uimus carpinifolia) and of thetropical forest tree Terb (Terminalia brassii) were stored hermeticallyand sampled at intervals for periods of up to two years. Bothspecies possess ‘orthodox’ seed (increasing longevityis observed as either moisture content or temperature are reduced)within the temperature ranges from — 13 to 52°C (Elm)and from —4 to 42°C (Terb) and within the moisturecontent ranges from 3 to 19 per cent (Elm) and from 5 to 14per cent (Terb) on a fresh weight basis. Elm seed stored at—75°C showed the expected relationship between longevityand moisture content, but did not differ significantly in longevityfrom seed kept at — 13°C when moisture contents wereheld constant. Probit analysis of the relationship between germinationpercentage and time was performed for each storage environment,yielding a slope from which the standard deviation of the distributionof seed deaths over time () was calculated. Standard deviationvalues were used in turn to determine the values of constantsin a viability equation which had previously been applied toseed of barley, chickpea, cowpea and soybean. The equation,which gave a good fit to the results obtained, can be used topredict viability for seed in storage over a wide range of environmentalconditions. Some limitations to the applicability of the viability equationwere defined. At 22 per cent and higher moisture contents Elmseed survived longer than predicted. Furthermore, all Elm andTerb seed was killed quickly on placing in —75°C at22 and 20 per cent moisture content respectively, but high viabilitywas retained for several days at 19 and 17 per cent respectively.Practical implications of the results are discussed. Uimus carpinifolia Gleditsch, Smooth-leafed Elm, Terminalia brassii Exell, Terb, seed longevity, seed storage, moisture content, temperature     

Dynamics of Imbibition in Phaseolus vulgaris L. in Relation to Initial Seed Moisture Content

The seed moisture level marking the onset of imbibitional injury (breakpoint) was determined for two cultivars of Phaseolus vulgaris L. cvs `Tendercrop' (TC) and `Kinghorn Wax' (KW). At 20°C the breakpoints were 0.15 gram H₂O/gram dry weight (gram per gram) for TC and 0.11 gram per gram for KW. When seeds were imbibed at 5°C, the breakpoints were 0.19 gram per gram (TC) and 0.16 gram per gram (KW). Below the breakpoint germination changed 4.6%/0.01 gram per gram for all treatments. Imbibition rates were maximal at 0.07 gram per gram and 0.33 gram per gram after 20 minutes imbibition. Rates of electrolyte leakage were correlated with the imbibition rate maximum at 0.07 gram per gram but were unaffected by the maximum at 0.33 gram per gram. The transition from tightly bound to semibound water occurred at 0.09 gram per gram and 0.11 gram per gram for KW and TC, respectively. T1 values increased exponentially as seed moisture decreased from 0.47 gram per gram to 0.05 gram per gram. ¹³C-NMR sugar signals increased at moisture levels above 0.14 gram per gram and plateaued at approximately 0.33 gram per gram seed moisture. These results suggest that the breakpoint moisture level for imbibitional damage is a function of temperature while the injury process is similar at both 5 and 20°C. Imbibition and leakage rate maxima reflect transitions in the states of seed water. NMR data support the application of the Water Replacement Hypothesis to seeds. Thus, imbibitional injury may be related to specific, temperature dependent moisture levels that are determined by water binding characteristics in the seed tissue.     

Moisture Content and the Longevity of Seeds of Phaseolus vulgaris

The lower limit to the negative logarithmic relation betweenseed longevity and moisture was determined in bean (Phaseolusvulgaris L.). Sub-lots of seed were hermetically stored at 65°C and 11 moisture contents (3.26–13.6% f. wt) forup to 80 d, tested for germination and the seedlings evaluated.In accordance with the seed viability equation, there was anegative logarithmic relation between moisture content (%, f.wt) and longevity. Two different criteria for estimating theslope constant of this relation gave similar values of 4.76(s.e. 0.26) and 4.82 (s.e. 0.24). The calculated lower moisturecontent limits to the relation were 5.7 and 5.6%, respectively,values at equilibrium with 10.6–10.8% relative humidity(rh). Further drying to 3.26% had little additional effect onlongevity, but initial germination was slightly reduced. Theresults are discussed in relation to water potential and comparedwith other crops. Arguments against transforming germinationvalues to disregard the seeds initially failing to germinateare emphasized. Common bean, Phaseolus vulgaris L. cv. Provider, seed storage, seed longevity, seed moisture, viability equation, water relations     

三种兜兰属植物种子发育过程及其与无菌萌发的关系

某些兰科植物的种子成熟前,在无菌萌发过程中有较高的萌发率,而成熟后萌发率急剧下降。本研究针对这一现象,对三种兜兰属植物种子的发育过程进行了解剖学观察,并对授粉后不同时期的种子进行无菌播种,80d后统计其萌发率,以探究种子发育过程中的解剖学特征与萌发率之间的关系。研究结果表明种胚刚发育到椭球形胚的时候,胚柄尚存,种皮细胞尚未皱缩,此时三种兜兰的萌发率都能达到较高水平,表明这是适合兜兰属植物萌发的最佳时期;此后,种皮开始皱缩,木质素类物质积累导致种皮透水性下降,推测这可能是导致其后期萌发率下降的主要因素之一。     

Seed Longevity of Rice Cultivars and Strategies for their Conservation in Genebanks

Changes in seed quality during ripening were studied in sixteencultivars of rice, representing the three ecogeographic racesofOryza sativa, and one cultivar ofO. glaberrima, grown duringone dry season (Nov. –May) 1992 –1993 at Los Baños, Philippines. Mass maturity (defined as the end ofseed filling period) among the cultivars was attained between18.5 and 21.6d after anthesis (DAA). The seed moisture contentat mass maturity varied between 24 and 40%. Germination abilityof seeds in the early stages of development varied significantly,but as mass maturity approached, germination increased to themaximum and no significant differences were found among cultivars.The seeds were stored hermetically at 35 °C with 15±0.2%moisture content and the resultant seed survival data were analysedby probit analysis. Potential longevity (quantified by the valueof seed lot constantK_iof the seed viability equation) was greatestbetween 33 and 37 DAA, i.e. about 2 weeks after mass maturity.The stage during development at which seeds achieve maximumpotential longevity is described by the term storage maturity.Lowlandjaponicacultivars, large seeded accessions (seed mass40mg) andO. glaberrimahad shorter storage longevity ( , standarddeviation of the frequency of seed deaths in time=1.47 weeks)while cultivars with purple pericarp survived longer than othercultivars ( =2.33 weeks). The initial germination of thejaponicacultivarsat storage maturity was high (99 –100%) and the estimatesof maximum potential longevity (K_i) which ranged between 3.3(Shuang cheng nuo) and 4.4 (Minehikare) were close to thoseof theindicacultivars. This research suggests that seed production environment betweenNov. and May at Los Ba ños is benign for the temperatejaponicacultivars.The implications of these results on management of rice geneticresources are discussed. Oryza sativaL.; rice; germplasm conservation; seed production environment; seed development; seed longevity     

The Viability of Cereal Seed in Relation to Temperature and Moisture: With eight Figures in the Text

Critical examination of previous work on the viability of cerealseeds shows that there is a simple mathematical relationshipbetween temperature, moisture content, and period of viability.There is evidence that this relationship is similar for wheat,barley, and oats. If the moisture content and temperature ofthe seed is known it is possible to predict the expected lifeof the seed; or alternatively, it is possible to predict variouscombinations of storage conditions necessary to achieve a requiredperiod of viability. These results are discussed in relationto current theories concerned with factors which cause lossof viability in seeds.     

3种锦鸡儿种子萌发对温度和水分的响应

对本地种白毛锦鸡儿（Caragana licentiana）和甘蒙锦鸡儿(Caragana opulens)以及外来种中间锦鸡儿（Caragana intermedia）种子进行了室内和野外萌发试验。结果表明,白毛锦鸡儿种子最适萌发温度为20℃,5℃时种子不萌发,甘蒙锦鸡儿最适萌发温度为10-20℃,在5℃和30℃时萌发率显著低于其它温度下的萌发率,中间锦鸡儿种子最适萌发温度为15-30℃,5℃下的萌发率为8.5%。室内萌发试验和野外萌发试验都表明白毛锦鸡儿种子萌发的速度缓慢,这体现在达到最大萌发率需要的时间长,萌发速度慢,且有4.0%的硬实种子,甘蒙锦鸡儿种子萌发的速度快,无硬实种子,高温下萌发受到一定的抑制。中间锦鸡儿种子在高温下萌发率高,速度快。启运白毛锦鸡儿种子萌发的最低土壤含水量为1.25%,甘蒙锦鸡儿和中间锦鸡儿的分别为3.75%和2.50%。白毛锦鸡儿种子萌发需要的土壤含水量低,种子萌发慢,且有小部分硬实种子,这可能是白毛锦鸡儿适应特殊环境的对策之一。     

The Influence of Genotype, Temperature and Moisture on Seed Longevity in Chickpea, Cowpea and Soya bean

Seed of three chickpea (Cicer arietinum L.), three cowpea [Vignaunguiculata (L.) Walp.] and four soya bean [Glycine max (L.)Merr.] cultivars were hermetically stored for up to 2 yearsin various constant environments which included temperaturesfrom —20 to 70 °C and moisture contents (fresh weightbasis) from 5 to 25 per cent. In all cases the survival curvescould be described by negative cumulative normal distributions.The longevity of the various seed lots differed but the valueof the standard deviation (the reciprocal of which gives theslope of the survival curve when percentage germination is transformedto probit) was the same for all cultivars within a species whenstored under similar conditions. Within each species the relativeeffects of moisture and temperature on longevity did not differsignificantly between cultivars. In all three species therewas a negative logarithmic relationship between seed moisturecontent and longevity, but the relative effect of moisture contentdiffered between the species: differences in the longevity ofsoya bean seed as a function of moisture content were less thanfor either cowpea or chickpea. The relative effect of temperatureon seed longevity did not differ between the three species,and the seed of all three species showed increasing temperaturecoefficients for the change in rate of loss of viability withincrease in temperature. The complete pattern of loss in viabilityin all three species can be described by a single equation whichwas developed for barley and has also been shown to apply toonion seed. The constants applicable to the three grain legumeshave been calculated so that it is now possible to predict percentageviability of any seed lot of these species after any storageperiod under a very wide range of storage conditions. Cicer arietinum L., chickpea, Glycine max (L.) Merr., soya bean, Vigna unguiculata (L.) Walp., cowpea, seed longevity, seed storage, moisture content, temperature     

The Effect of Chilling and Moisture Status on the Germination, Desiccation Tolerance and Longevity ofAesculus hippocastanumL. Seed

Effects of 2 °C chilling on the threshold moisture contentsand water potentials for various physiological processes wereestimated forAesculus hippocastanumL. seed. Seed harvested atthe time of maximum seed fall exhibited a dual response to drying:partial drying from near 50% to 32–40% moisture contentprogressively increased germination percentage (at 16 °C)up to various peak values; further desiccation was detrimental,confirming that the seeds are ‘recalcitrant’. Themoisture content for optimum germination was increased by atleast 10% as the chilling period was raised from 0 to 9 weeks.A negative linear relationship was found between log₁₀mean timeto germinate and probit final germination, regardless of pre-treatment,indicating that partial desiccation and chilling are interchangeablein promoting germination of hydrated seed. For nearly fullyhydrated seeds, increasing the chilling period from 6 to 26weeks increased the viability-loss onset point for desiccationinjury from near 40% to about 48% moisture content without alteringthe drying rates of seed tissues. Extending moist chilling invarious seed lots from 0 to 26 weeks decreased subsequent longevityat 16 °C. For 26-week-chilled seeds longevity (the periodto lose one probit of germination) differed above and belowa threshold moisture content of 48%. It remained constant inthe moisture-content range 48–38%, but increased progressivelyas moisture content was raised above 48%. This threshold moisturecontent coincided with the value above which chilled seed pre-germinatedin storage. The results indicate that post-harvest desiccationand chilling alter the water relations of various physiologicalprocesses and a schematic summary is presented which relatesthe results to an axis water sorption isotherm.Copyright 1998Annals of Botany Company Aesculus hippocastanumL., horse chestnut, chilling, moisture content, water potential, desiccation tolerance, longevity, recalcitrant seed, embryo axis, maturation, germination.     

The Effect of Moisture Content on the Low Temperature Responses of Araucaria hunsteinii Seed and Embryos

The effect of moisture content on the low temperature responsesof 'recalcitrant' Araucaria hunsteinii seed and excised embryoswas investigated in relation to germination and storage. At6°C seed longevity was decreased as mean moisture contentwas reduced from 45 to 30% (fresh weight basis); the time predictedfor the loss of one probit of germination,     

Seed Production Environment, Time of Harvest, and the Potential Longevity of Seeds of Three Cultivars of Rice (Oryza sativa L.)

Changes in seed quality (assessed by potential longevity, i.e.the value of the seed lot constant K₁ of the seed viabilityequation) in three contrasting cultivars of rice (Oryza sativaL.) were monitored during seed development and maturation intwo temperature regimes, viz 28/20°C and 32/24°C (12/12h), provided by controlled environments. Mass maturity (definedas the end of the seed-filling phase) varied only between 18and 20 d after 50% anthesis. In five of the six treatment combinationsmaximum potential longevity was not achieved until 12-19 d aftermass maturity. In contrast, the maximum potential longevityof seeds of a japonica rice cultivar produced in the warmerregime was obtained in the first harvest after mass maturity.After mass maturity, the potential longevity of the japonicarice seed lots produced in the warmer environment was much lessthan that for the cooler environments. Maximum potential longevitywas also consistently greater in the cooler than the warmerregime for the two indica cultivars, although the differencein K₁ was small (0·3-0·5). The deleterious effectof increase in temperature on seed quality development was notdetected until after mass maturity. Maximum potential longevityin the cooler regime was greatest in the glutinous indica (K₁= 3·9) and least in the japonica cultivar (K₁ = 3·1).It is concluded that the japonica cultivar is not as well adaptedto warm seed production regimes as the indica cultivars. Consequently,subject to confirmation, this research suggest that the seedproduction of japonica cultivars for long-term genetic conservationshould be undertaken, whenever possible, in warm temperate environments.Copyright1993, 1999 Academic Press Oryza sativa L., rice, genebanks, seed development, seed storage, seed longevity, temperature     

沙芥和斧形沙芥种子萌发对土壤含水量的适应性

以中国特有种沙芥[Pugionium cornutum(L.)Gaertn.]和濒危种斧形沙芥(Pugionium dolabratum Max-im.)的种子为研究材料,利用自然生境的沙土在室内进行种子萌发人工模拟试验,研究沙芥和斧形沙芥种子萌发、幼苗出土和幼苗生长对土壤含水量的适应性。结果表明:沙芥和斧形沙芥果实适宜萌发的土壤含水量范围均为6%～12%,适宜出苗的土壤含水量范围均为6%～16%。当土壤含水量低于2%时,果实不能萌发;当土壤含水量低于3%时,幼苗不能出土定居;当土壤含水量为6%～12%时,最有利于幼苗的生长。当土壤含水量分别为3%～8%和4%～8%时,沙芥和斧形沙芥植株根冠比最大。因此,沙芥和斧形沙芥种子萌发机制对沙生环境有着极强的适应性;植株将更多的同化物用于根系生长,以吸收更深层次的水分,从而适应含水量低的土壤。     

The Relation Between Seed and Fruit Development in the Peach (Prunus persica L.)

The ontogeny of the peach seed and its organs correlates wellwith the stages of growth of the pericarp of peach fruit. Theinitial stages of rapid f.wt (FW I) and d.wt (DW I) increasecoincide with the period of rapid f.wt increase of the wholeseed and rapid size increase of the endosperm respectively.The period of slow f.wt increase of the fruit (FW II) coincideswith the period of rapid size increase of the embryo. The seed and pericarp compete strongly for assimilates throughoutfruit development and the seed is the weaker competitor. Thereis no period however when the growth of the seed or one of itsorgans inhibits the sink strength of the pericarp to allow theseed to develop. The data presented indicate that the periodsof high nutrient demand (DW I and DW III) are created in thepericarp in response to a stimulatory signal from the seed andthe period of low nutrient demand (DW II) results from the absenceof this signal after the endosperm reaches full size.