The Effects of Temperature and Moisture on the Induction of Genetic Changes in Seeds of Barley, Broad Beans, and Peas during Storage

Seeds were ‘aged’ by treatments with various combinationsof temperature and moisture content so that viability was reducedto about 50 per cent. It was shown that such treatments inducednon-heritable morphological abnormalities in about 10 per centof the bean plants and 5 per cent of the pea plants; but nonon-heritable morphological abnormalities were observed in thebarley plants. In all species there was an increased frequencyof pollen abortion in the plants produced from ‘aged’seeds. From the examination of second and third selfed generationsit was shown that single-recessive and double-recessive chlorophyll-deficiencymutations of various types were usually induced in sectors ofabout 1–3 per cent of the plants grown from treated seeds. The evidence from pollen-abortion supports previous cytologicalevidence that, under most storage conditions, for a given lossof viability, a predictable amount of chromosome damage is foundin the surviving seeds, irrespective of how fast viability waslost or which environmental factor was mainly instrumental inthe loss of viability. A comparison of the frequency of chlorophyllmutations produced under different storage treatments was notas quantitatively precise, but this evidence also is at leastcompatible with the thesis that loss of seed viability is associatedwith chromosome damage which is reflected in gene mutation.It is concluded, therefore, that percentage seed viability isa good index of the loss of genetic purity resulting from mutationswhich accumulate during storage.     

The Influence of Temperature, Moisture, and Oxygen on Period of Seed Viability in Barley, Broad Beans, and Peas

The viability of seeds of barley, broad beans, and peas hasbeen examined in hermetic storage over a range of temperaturesfrom 25? to 45? C and over a range of moisture contents fromabout 12 to 18 per cent. It was found that the survival curvesunder nearly all conditions can be described as negative cumulativenormal distributions. Under very severe storage conditions,however, when the mean viability period is of the order of aweek or less, the survival curves may become slightly skew.The spread of the distribution is linearly proportional to themean viability period. There is a negative linear relationshipbetween log mean viability period and both temperature and moisturecontent. Because of these relationships it is possible to predictthe percentage germination of these species after any givenperiod under a wide range of storage conditions. This patternof loss of viability in barley, broad beans, and peas is consistentwith that previously shown for wheat and rice. Oxygen has been shown to have a deleterious effect on the viabilityof barley, beans, and peas. Most of the deleterious effect isproduced by increasing the oxygen level from 0 per cent (nominal)to 21 per cent at atmospheric pressure; a further increase to100 per cent has comparatively little effect. The deleteriouseffect of oxygen is more pronounced at high moisture contents.Experiments at a low moisture content (12 per cent) have demonstratedthat the effect of oxygen is independent of the activity ofmicro-organisms. There is also some indication that the effectof oxygen is independent of the rate of seed respiration. The gas-exchange of pea seeds has been investigated in hermeticstorage at 25? C and 18.4 per cent moisture content. The seedsshowed a constant rate of gas-exchange and a constant R.Q. (0.63)over a period of time during which the concentration of oxygendecreased from 21 to I.4 per cent and the carbon dioxide concentrationrose from 0.03 to 12 per cent.     

The Effect of Seed Storage Conditions on the Growth and Yield of Barley, Broad Beans, and Peas

The effect of various combinations of time, temperature, andmoisture content during seed storage have been investigatedin relation to their effect on the growth and yields of survivingseeds. In the species investigated here, percentage seed viabilityis an excellent indicator of the growth potential of the survivingseeds, irrespective of the particular combination of factorswhich led to the loss of seed viability or the rate at whichviability was lost. Seed deterioration associated with lossof viability during storage results in decreased early growthof roots and shoots and in increased variability of growth betweenplants. This early inhibition of growth-rate does not persistand there is some evidence that, under normal agricultural conditions,initial low rates of growth may be compensated at later stagesof development. Thus in the present investigations it was foundthat, providing the initial seed viability was not less thanabout 50 per cent, final yields were not significantly affected.But if the seed deterioration during storage was sufficientto reduce viability below about 50 per cent, the final yieldsof crops produced from surviving seeds were significantly decreased. A possible relationship between growth and the nuclear damagesustained during storage is outlined, and the practical implicationsof the results of this and previous papers in the series arediscussed. In the species investigated here, considerable lossof seed viability can be tolerated in seed used for food-cropproduction but not in maintenance stocks used for seed production.In either case, details of the storage history of the seed isunnecessary: it is sufficient to know only the percentage viabilityas determined by a simple germination test.     

Protein Bodies from Developing Seeds of Barley, Maize, Wheat and Peas: The Effects of Protease Treatment

When isolated protein bodies of barley were treated with proteinase-kthey were almost completely digested. Similar results were obtainedwhen fresh homogenates, prepared by rapid chopping of barleyor wheat endosperms into isolation medium, were incubated withthe protease. In contrast, the protein bodies of developingmaize endosperms, or pea cotyledons were resistant to proteaseattack. The results are interpreted as indicating that isolatedprotein bodies of developing wheat and barley endosperms arenot surrounded by a complete membrane whereas those of the peacotyledons and maize endosperms are.     

Loss of Viability in Lettuce Seeds and the Accumulation of Chromosome Damage under Different Storage Conditions

Loss of seed viability in lettuce (Lactuca sativa L.) duringstorage is associated with an increase in the frequency of cellsin the surviving seeds showing chromosome damage during firstmitoses. The relation is linear when probit of the frequencyof aberrant cells is plotted as a function of probit percentagenormal germination. The slope of the relation, however, variesaccording to moisture content so that the proportion of aberrantcells for any given loss of germination increases with decreasein moisture content over the range 13.0–5.5 per cent.At 3.3 per cent moisture content, however, the proportion ofaberrations was no greater than at 5.5 per cent moisture content;and at 18.1 per cent moisture content the proportion was noless than at 13.0 per cent moisture content. Despite these differences,the increase in chromosomal aberrations per unit time for agiven temperature was always less the lower the moisture content.Diplontic selection markedly reduced the frequency of chromosomalaberrations and eliminated the differences in these frequenciesbetween the different storage treatments. But even after fiveweeks' growth, root tips from aged seed still contained abouttwice as many aberrant cells as compared with similar root tipsderived from the original seed stock. Studies on the frequencyof recessive mutations indicated that excessive amounts of heritablemutations were not present in the progenies of aged seed, evenwhen stored at moisture contents as low as 5.5 per cent. Allthis and other evidence reinforces the view that orthodox seedsfor genetic conservation should be stored at not more than about5 per cent moisture content, and that even lower moisture contentsare worth considering. The results also emphasise the need formaintaining a high regeneration standard, i.e. the percentageto which seed viability is allowed to fall during storage beforethe seed stock is regenerated. Lactuca sativa, lettuce, seed storage, seed viability, chromosomal aberrations, phenotypic mutations     

Effects of Fluctuating Temperature on Germination and Emergence of Seeds in Different Moisture Environments

Seeds of calabrese and carrot were sown in soil at differentmoisture contents or were germinated in polyethylene glycolsolution of equivalent water potential. The seeds were alsosubjected to temperature environments which were either constant,altering at 12 h intervals, or changing smoothly and continuouslyin a daily cycle. The environments had similar mean temperatures,similar accumulated numbers of day-degrees, and the changing-temperatureenvironments had similar upper and lower temperature limits.In soil, at low and moderate moisture stress, seedlings of bothcrops emerged faster in the changing-temperature environmentsthan at constant temperature; at high moisture stress, emergenceoccurred only in the changing temperature environments. In osmoticsolutions, germination (radicle emergence) of calabrese seedswas faster in changing-temperature environments, but germinationof carrot seeds was unaffected by the temperature treatments.The results indicate that interaction between moisture stressand temperature environment is important and that results ofexperiments run at both constant moisture stress and constanttemperature together may not relate directly to the field situation.     

A Comparison of the Quantitative Effects of Seed Moisture Content and Temperature on the Accumulation of Chromosome Damage and Loss of Seed Viability in Lettuce

The rate of accumulation of cells containing chromosome aberrationsin lettuce (Lactuca sativa L.) seeds is a positive functionof temperature and moisture content. It may be described byan equation similar to that for loss of seed viability. Therelative effect of temperature on the rates of loss of viabilityand accumulation of chromosome aberrations is the same. In contrast,the relative effect of moisture on the rate of loss of viabilityis greater than that for the rate of accumulation of aberrations.Hence considerably more chromosome damage accumulates beforedeath in drier lettuce seeds. Lactuca sativa, lettuce, seed storage, seed viability, seed longevity, chromosomal aberrations temperature, moisture content     

Effects of Moisture Content and Temperature on Storage of Metarhizium flavoviride Conidia

The effects of moisture content and temperature on the medium-term (3-4 months) storage of conidia of Metarhizium flavoviride were investigated. Conidia harvested after 24 days of culturing on rice showed greater tolerance to long storage than conidia from 12-day cultures. The moisture content of the conidia was of greatest importance; at harvest from the culture, conidial moisture contents could be 40%, while the optimal moisture content for storage was found to be 4-5%. Dried conidia stored in oil benefited from the addition of dried silica gel, as did conidia stored as powder. A range of mineral oils proved satisfactory for storage, and when dried silica gel was added to suspensions, germination levels were 79.8% after 105 days at 28-32 C. Dried conidia stored in oil maintained germination levels of up to 96 and 85% after 80 days at 10-14 C and 28-32 C respectively. Dried conidia stored as powder retained germination levels of 95% at 10-14 C, but only up to 27% at 28-32 C. In another experiment, dried conidia maintained greater than 90% germination over 128 days, with or without silica gel at 10 - 14 C or -15 - -18 C.     

温度、土壤水分和NaCl对黄顶菊种子萌以的影响

光照和黑暗条件下的黄顶菊种子萌发无显著差异;种子萌发的适宜温度为25～35℃:种子萌发率随着NaCl浓度的升高而下降;种子萌发的最佳土壤含水量为35%～45%.在最适温度下,种子萌发耐受NaCI的临界值为89.919 mmol·L-1,极限值为218.92 mm01.L-1;不同温度和NaCl以及二者共同作用使黄顶菊种子萌发受到的抑制都极显著.     

Effects of Kinetin and Salinity on Germination of Tomato, Barley and Cotton Seeds

The effects of kinetin and the interaction between kinetin andsalinity on seed germination of three plant species namely Lycopersiconesculentum, Hordeum vulgare and Gossypium hirsutum were studiedKinetin was applied exogenously to the seeds in order to determinewhether this growth-promoting hormone would promote germinationand to see if osmotically-induced dormancy caused by NaCl couldbe alleviated The results indicate that kinetin is capable ofbreaking dormancy in these species and there is a significantinteraction with salinity in tomato and cotton Kinetin, germination, salinity, water stress, salt stress, Lycopersicon esculentum Mill, tomato, Hordeum vulgare L, barley, Gossypium hirsutum L, cotton     

Effect of Temperature and Desiccation during Storage on Germination and Keeping Quality of Kochia indica Seeds

Data are given for Kochia indica seeds showing retention ofviability after storage for various periods of time open tothe air under laboratory conditions, open at 30° C., openat 38° C., and sealed over CaCl₂ at 30° C. Seeds have been stored without deterioration at 30° C. sealedover CaC1₂ for over 14 months. Rapid deterioration of seed inopen storage at laboratory temperature and at 30° C. showsthat loss of viability is accelerated by moisture more thanby temperature.     

The Nature of the Virido-albina/striata Mutant Induced During Storage in Barley Seeds

A single striata mutant (green and yellowish-white striped leaves)was observed in first generation (A₁) barley plants grown fromaged seeds. In the following generation (A₂) normal, striataand virido-albina (yellowish-white leaves and pale yellowish-greentips) phenotypes were observed. The segregation of the progenywas examined in A₂ and A₃ and it was found that the large majorityof normal and virido-albina phenotypes bred true, whereas mostof the A₂ striata phenotypes segregated normal, striata andvirido-albina phenotypes in variable ratios. The expression of both mutant phenotypes is temperature-dependentand normally only observed when the initial temperature forseedling growth is about 5 °C. In the vast majority of individualsthe symptoms disappear on transfer to 7 °C or more. Evenat 5 °C the expression of the striata phenotype is variable,ranging from seedlings which are little different from the normalphenotype to those which are difficult to distinguish from thevirido-albina phenotype. The genetical status of this mutant is discussed in relationto these observations and previous reports of the anomolousbehaviour of the striata character. It is suggested that thesymptoms could be the result of a single gene mutation showingincomplete dominance, and that the anomalous segregation ratiosresult mainly from difficulties in categorizing the heterozygousgenotype at the extremes of its phenotypic expression. However,there is insufficient evidence to exclude the possibility thatthe symptoms derive from a cytoplasmically inherited extrachromosomalmutation. Hordeum distichum L., barley, mutation, virido-albina phenotype, striata phenotype, phenotypic temperature sensitivity     

Effect of Temperature, Oxygen, and Gibberellic Acid on the Development of Photosensitivity in Oldenlandia corymbosa L. Seeds during Their Incubation in Darkness

Two successive phases can be distinguished in the development of the responsiveness to light in Oldenlandia corymbosa L. seeds during their incubation in darkness. During phase I, the responsiveness to light increases with time if there is sufficient O₂, and the higher the temperature, the faster the increase. This phase is stimulated by gibberellic acid. During the following phase (II), seeds remain responsive to light at 10 or 20°C, but lose their responsiveness at higher temperature (≥30°C). This second phase depends on O₂: loss of responsiveness is accelerated at lower O₂ concentration. Phase II is only slightly affected by gibberellic acid. The results are discussed in terms of variation of phytochrome and of a reaction along the transduction chain initiated by phototransformation of this pigment, which is finally expressed in germination.     

贮藏温度和种子含水量对洋葱种子发芽率的影响

贮藏温度低于15℃时,温度对洋葱种子发芽率影响变小,种子含水量低于8.8%时,其衰老过程变慢,高含水量种子在高温下贮存,衰老过程加快,含水量为100%和13%的种子在25℃下贮存分别不到5个月和2个月就失去商品性。     

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。