(pp. 1-8)
Flourescence of Oat, Seed and It's Value as a Cultivar Purity Indicator1
J. Van de Crommert, D. L. Reeves, P. Evenson, Q. Schultz2
ABSTRACT:
The accuracy of oat fluorescence test used by seed laboratories to test for varietal purity is suspect. Environmental influences on oat seed fluorescent characteristics, and the usefulness of the oat fluorescence test in analyzing cultivar purity will be reported. Thirteen midseason oat lines grown at 13 locations and 6 early oat lines from 11 locations were studied.
Data collected for each variety or location included seeds per 25 g, fluorescent and non-fluorescent seeds per 25 g, yield, test weight, longitude, latitude, altitude and general temperature conditions. True-to-type seed number was highly correlated with seeds per 25 g. Other factors were of little value for explaining differences in fluorescence. The fluorescence test is reliable in determining cultlvar purity, However, true-to-type seeds must be adjusted for total number of seeds per unit weight, Using the technique developed, only one oat line, SD 780383, was found to be impure, and this selection had not been purified for seed type. Since only one line was impure, an additional eight midseason oats, which were segregating F3 generations with a wide diversity of parents, were studied. These eight represent impure lines, and all were found to be impure by this technique.
Additional index words: Avena sativa, Fluorescent, Ultraviolet.
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(pp. 9-18)
Influence of Etched Seed Coats on Phomopsis Infection and Electrolyte Leakage of Soybean Seeds1
P. R. Thomison, M. M. Kulik, and D. A. Morris2
ABSTRACT:
Soybean [Glyclne max (L.) Merr.] seedlots with etched (imperfect) seed coats are often associated with low seed germination and Phomopsis seed decay. The objective of this study was to determine the relationship between etched seed coats, electrolyte leakage from seed, and seed infection by Phomopsis spp. Seeds from the cultivar Douglas' and four experimental soybean lines were separated into etched and non-etched (normal) subsamples and evaluated for infection, germination, electrolyte leakage, and seed weight.
There was little or no difference in the incidence or severity of seed infection by Phomopsis spp. and seed germination between seeds with varying levels of seed coat etching. Electrolyte leakage, as indicated by the conductivity of seed leachates, was 16 to 26% greater in etched seeds compared to non-etched seeds. The increased electrolyte leakage of etched seeds may result in a more rapid loss of seed vigor and viability. Weights of etched seeds were 3 to 15% greater than normal seeds. The larger size of etched seeds may predispose such seeds to more damage during and after harvest.
Additional index words: Glycine max, Seed germination, Seed leachate, Seed vigor, Phomopsis spp., Diaporthe phaseolorum, Phomopsis longicolla, Phomopsis phaseoli.
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(pp. 19-23)
Sequence of Deterioration in Rice Embryos During Accelerated Aging of Seeds1
V. Krishnasamy and D. V. Seshu2
ABSTRACT:
Hot and humid climates prevailing in the rice (Oryza sativa L.) growing regions of the world favor rapid seed deterioration. Physiological and biochemical events that occur during seed aging in rice are well documented. However, no attempt has been made to morphologically examine the sequence of deterioration in rice embryos. Seeds of the two advanced breeding lines of rice 'lR39379-90-2-2-2-2' and 'IR9782-111-2-1-2' were subjected to accelerated aging (43%; 100% RH) for 4,8, and 12 d.
The sequence of deterioration in the embryos was determined using 0.5% tetrazolium chloride. The deterioration pattern was identical in both varieties except that it was delayed for 4 d in lR39379-90-2-2-2-2. The coleoptile was the first tissue to deteriorate followed by the epiblast, lateral scale, ventral scale, coleorhiza, plumule, radicle, mesocotyl, and scutellum. A highly significant correlation (r = 0.999**) between the percentage of the seeds showing tetrazolium staining at the coleoptile region and the percent germination was observed. Hence, while assessing rice seed viability based on topographical tetrazolium staining, seeds showing unstained coleoptiles should be considered non-germinable irrespective of staining of the other tissues.
Additional index words: Oryza sativa L., Tetrazolium chloride, Coleoptile, Seed quality, Seed vigor.
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(pp. 24-30)
Correlation of Seedling Emergence Force With Field Emergence of Soybean
S. H. Moore1 and D. E. Longer2
ABSTRACT:
lncreasing seedling emergence force in soybean [Glycine max (L.) Merr.] seed has been proposed as a means to improve stands in soil crust conditions which commonly occur in the South. However, seedling emergence force has never been shown to significantly correlate with field emergence. These experiments were initiated to determine if seedling emergence force is correlated with field emergence and to determine if this parameter is a viable indicator of seed vigor.
Seedling emergence force was determined on individual seeds by measuring the vertical displacement of a 65 g mass inside an acrylic piston. Uniformity studies conducted on 'Forrest' and 'Narow' (Maturity Group V cultivars) showed that seedling emergence force does not have a normal and independent distribution, but is skewed heavily toward low values. Field studies indicated seedling emergence force was significantly correlated with field emergence in 1985, but not in 1986. Correlation coefficients between seedling emergence force and field emergence were generally smaller than those for germination, accelerated aging, and tetrazolium staining. Best correlations for seedling emergence force with field emergence were obtained when the number of seeds in a seedlot displacing a 65 g weight more than 1 mm was used as an index. The index may have actually measured germination. The results of this experiment indicate that seedling emergence force can be an indicator of seed vigor; however, it is an inferior measurement when compared to standard germination, accelerated aging, or tetrazolium staining tests.
Additional index words: Accelerated aging, Germination, Glycine max, Normal distribution, Seed vigor, Tetrazolium staining.
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(pp. 31-38)
Germination of Seeds of Sulphur Flower (Eriogonum Umbellaturn Torr.)
James A. Young1
ABSTRACT:
Germination of seeds of Sulphur Flower (Eriogonum umbellatum var. umbellatum Torr.) was investigated at constant and alternating temperatures. The seeds were collected from native stands located on the eastern slopes of the Sierra Nevada. The seeds of Sulphur Flower germinate without pretreatment over a wide range of incubation temperatures. Apparent quality of seeds differed from year to year with few or no seeds produced by native stands on given years.
The best quality seed produced germination as high as 90% at optimum incubation temperatures. Germination at 55 temperature regime germination profiles averaged 40 to 56% in repeated trials. Optimum germination, defined as not lower than the maximum observed and its confidence interval (P5 0.0.1), average from 71 to 76%. The optimum temperatures for incubation of Sulphur Flower seeds were widely fluctuating temperatures of 10/30 (10o C. for 16 h 30o C. for 8 h in each 24 h), 10/35,15/30 and 15/35o C. The occurrence of optimum temperatures for germination in the fluctuating classes of seedbed temperatures suggests that seeds of Sulphur Flower should be planted near the soil surface.
Additional index words: Temperature, Wildland species, Revegetation species.
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(pp. 39-44)
Effect of light and Storage Temperature on Seed Germination in Hygrophila auriculata (Schumach.) Haines
Dilip Amritphale,1 S. Iyengar2 and R. K. Sharmal1
ABSTRACT:
Freshly harvested seeds of Hygrophila auriculata (Schumach.) Haines displayed nearly complete dependence on light for germination. In one of the three seedlots studied at least two brief red (R) light exposures, placed 1h apart, were required to promote germination to the maximum level.
Interposition of a 1h dark period between two R irradiations was necessary, presumably to increase the level of some factor(s) other than water uptake. In the early period of storage, the requirement for two brief R light exposures was reduced to one. Photosensitivity was gradually lost, with a temperature dependent increase in dark germination during later periods of storage. A bypass of the phytochrome controlled pathway of germination is suggested to occur in later periods of dry storage.
Additional index words: Dormancy, Photoreversibility, Phytochrome
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