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.     

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 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.     

Morphological and functional aspects of volatile-producing glands in bees (Hymenoptera: Apidae)

Abstract In this paper we focus on the occurrence and morphological aspects of exocrine glands in several bee species. Morphology of head labial, mandibular, Dufour, and abdominal tegumentar glands was investigated under light microscopy, scanning electron microscopy and transmission electron microscopy. Most of such glands present cells with cytoplasm homogeneous and acidophilic, or contain small apparently empty vacuoles. The cytoplasm cells' ultrastructure showed a well developed smooth endoplasmic reticulum, many polymorphic mitochondria, rare Golgi, lipid droplets, myelin figures, and many basal and apical plasma membrane infoldings. All these results are discussed in the text.     

Effects of Temperature, Moisture, and Oxygen on the Induction of Chromosome Damage in Seeds of Barley, Broad Beans, and Peas during Storage

The effects of temperature, seed moisture content, and oxygenlevel on the production of chromosome aberrations during seedstorage have been investigated. It has been found that an increasein any of these factors increases the rate of loss of seed viabilityand that any treatment which leads to a loss of viability alsoleads to an accumulation of aberrant cells in the embryo. Undermost storage conditions, irrespective of the combination offactors which leads to loss of viability or the rate at whichviability is lost, the relationship between percentage viabilityand mean frequency of aberrant cells in the surviving seed populationis always the same. Under very severe storage conditions, whichresult in half-viability periods of about a week or less, however,the relationship is altered so that for any given percentageviability the mean frequency of aberrant cells in the survivingseeds is less than is typical of more normal storage conditions.In all treatments (except the most severe) the curve showingmean frequency of aberrant cells in surviving seeds againsttime eventually became asymptotic to a critical value peculiarto the species. It is suggested that these results are compatible with the hypothesisthat under most storage conditions death of the embryo is theresult of the accumulation of nuclear damage which is reflectedin chromosome breakage; it is emphasized, however, that thevisible chromosome breakage itself is probably not criticalto the seed's survival. When the nuclear damage has reacheda critical level, of which the frequency of aberrant cells isan index, the seed is no longer capable of germinating. Undervery severe storage conditions, additional factors appear tobe involved. An effort was made to test the frequently suggested hypothesisthat chromosome aberrations produced during the ageing of seedsare the result of the accumulation of automutagenic substances.Attempts to demonstrate the presence of mutagenic substancesin water-, ethanol-, and ether-extracts of fresh and aged seedsgave negative results. Aqueous extracts showed antimitotic andgermination inhibitory activity, but this was the same fromboth aged and fresh seeds.