Viability is usually measured in order to assess the suitability of a seed lot for a particular purpose, most commonly to produce a crop but also for industrial purposes, especially the malting of barley. Techniques for its measurement are also essential in research. Different criteria apply according to the purpose of the examination. In order to judge the suitability of seed for sowing it is necessary to determine its ability to produce plants in the field, so that information is required about the development of the seedling following rupture of the seed coat. But for the assessment of malting quality tests are needed to indicate the number of live grains, the incidence of dormancy and the most suitable steeping procedures (Pollock, 1962); they take no account of seedling development after sprouting (Institute of Brewing, 1967) since this stage is not involved in the malting process. This chapter will deal with the measurement of viability for crop production purposes, and the special circumstances of industrial processing will not be considered further; nor will there be more than very occasional reference to tree seeds.

The Measurement of Viability

The relationship between initial mobilization of 11-S globulin storage protein (leading to solubilization of its Bsubunit) and germination performance after priming was studied in sugarbeet (Beta vulgaris L.) seeds. Priming was conducted for 2 d either in water (hydropriming) or in ‐2.0 MPa polyethylene glycol-8000 (osmopriming), at various temperatures ranging from 5 to 40°C and oxygen concentrations in the atmosphere ranging from 0 to 21%. For both types of pre-treatments, the range of temperatures and the concentrations of oxygen which were effective in priming were very similar to those which allowed solubilization of the B-subunit of 11-S globulin, supporting the robustness of this protein marker for optimization of sugarbeet seed priming. Furthermore, the temperature and oxygen dependence of priming efficiency closely paralleled that for germination of the untreated seeds, reinforcing the finding that the beneficial effect of priming corresponded to the advancement of germination sensu stricto (i.e. phase II of the germination process). For priming times longer than 2 d, particularly for osmopriming, there was a very dramatic decrease in germination of the treated seeds. For instance, following a 14 d osmopriming at 25°C as much as 60% of the pre-treated seed population failed to germinate when transferred to water. This loss in germination performance quite closely paralleled degradation of LEA (late embryogenesis abundant) proteins, notably a heat-stable seed-specific protein of about 60 kDa and a seed-specific biotinylated LEA protein.

https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0960258500000271

Sugarbeet seed priming: effects of priming conditions on germination, solubilization of 11-S globulin and accumulation of LEA proteins.

The basic B-subunit of the seed storage protein 11-Sglobulin (an 11-S-legumin type protein) is the majorpolypeptide in soluble protein extracts from primedsugarbeet {Beta vulgaris L.) seeds. In contrast, only asmall amount of this protein is present in correspondingextracts from untreated dry mature seeds. Here, and asfor all 11-S globulins describe B-chaid so far isn, thelinked to other polypeptide(s), corresponding mostpresumably to an acidic A-chain, through the formationof disulphide bridge(s). Polyacrylamide gel electrophoreticanalyses of total and soluble protein extracts fromuntreated and primed seeds strongly indicate that thispriming-induced solubilizatio B-chain of resulte thne dfrom an endoproteolytic attack on the A-chain.Microscopical immunolocalization showed a uniformdistribution of the 11-S globuli B-chain oven r the proteinbodies of the embryonic cells from the untreated seeds.For the primed seeds, however, the B-subunit of 11-Sglobulin diffused out of the protein bodies and invadedthe cytosolic compartment. This phenomenon occurredindependently of the manner of priming, being observedwith hydroprimed and osmoprimed seeds, as well as withsugarbeet seeds that had been primed by a prehydrationtreatment. Quantitative analyses of the amounts ofsoluble 11-S globuli B-chain havn e enabled the primingof sugarbeet seeds to be optimized.Keywords: germination, 11-S globulin mobilization,immunocytochemistry, seed priming, storage proteins,sugarbeet.CorrespondenceAbbreviations: DTT = dithiothreitol; PAGE = polyacrylamidegel electrophoresis; PEG = polyethylene glycol; SDS =sodium dodecyl sulphate.

The solubilization of the basic subunit of sugarbeet seed 11-S globulin during priming and early germination

Cell cycle activity in dry and germinating untreated and treated (soaked in water and subsequently in fungicide) seeds of two sugarbeet cultivars, collected at commercial harvest time (late mature seeds) and about 2 weeks before this (immature seeds), was investigated by flow cytometry, and by immuno-detection of b-tubulin and the B-subunit of the 11 S globulin. Germination capacity and field emergence were tested. With dry seeds of both cultivars, higher G 2 /G 1 ratios were observed in the radicle tips of late mature seeds, as compared with those from immature seeds. The late mature seeds contained more partly degraded (soluble) B-subunit of 11 S globulin, typical of germinating or primed sugarbeet seeds. Thus events associated with the onset of germination had occurred in the seed lots collected at commercial harvest time. The cytoskeleton protein b-tubulin was not detectable in dry seeds from either harvest. Western blotting revealed an accumulation of b-tubulin during germination and this was faster in the late mature harvested seeds which was correlated with the onset of DNA replication. Soaking enhanced the rate of cell cycle activation during germination as well as vigour, germination capacity, and field emergence. There was positive correlation between the G 2 /G 1 ratio and the traits examined in laboratory and field tests. It is concluded that a combined analysis of proteins and cellcycle-related events can be used in understanding and predicting sugarbeet seed quality.

Effect of harvest time and soaking treatment on cell cycle activity in sugarbeet seeds

Guayule (Parthenium argentatum Gray) is a rubber-producing plant native to the semi-arid region of north central Mexico and southwestern Texas. As a member of the family Asteraceae, the seed dispersal unit in guayule is comprised of an achene enclosed by two staminate florets and a bract. The seeds in this condition are dormant and need special treatment in order to germinate. Threshing, prolonged washing, and/or chemical treatments prove effective in improving the germination. Experiments showed that chaff influenced germination and seedling emergence. Bioassays of aqueous extracts of guayule chaff and the seed coat showed a significant inhibition of germination and radicle growth of guayule, lettuce, and tomato seeds. Highperformance liquid chromatography enabled the identification of at least seven phenolic acids from guayule chaff extract. These, in order of decreasing concentrations, included p-hydroxybenzoic, protocatechuic, p-coumaric, ferulic, benzoic, vanillic, and cinnamic acids. All of them are well-known germination and growth inhibitors, and seem to play an important role in the

https://www.jstor.org/stable/pdfplus/2442895.pdf

Germination and growth inhibitors in guayule (parthenium argentatum gray) chaff and their possible influence in seed dormancy

Evidence was obtained for the presence of germination inhibitors in the aqueous extract from sugar-beet clusters. A positive correlation was shown between the germination of cress seeds moistened with aqueous extracts from clusters of twenty sugarbeet plants and the germination characteristics of other clusters from the same plants. Inhibition was thus greater in extracts from clusters with poor rather than good germination, and also in extracts from immature clusters or those which had received overhead irrigation. The inhibitory effect was found to be located in the perianth and pericarp tissue rather than in the true seed.

J. P. Battle

Papers

The relation between inhibitory substances and variability in time to germination of sugar beet clusters