Volume 3, No. 1, 1978

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(pp. 1-9)
Seed Dormancy of Beardless Wildrye (Elymus triticoides Buckl.)1
Allen D. Knapp and Loren E. Wiesner2
The use of beardless wildrye (Elymus triticoides Buckl.) as a forage grass is limited by slow germination and poor stand establishment. Little research has been done on the germination of beardless wildrye. The purpose of this research was to study the germination behavior of beardless wildrye in an effort to define factors contributing to slow germination.

We studied the effect of temperature on imbibition and germination, and the effects of stratification, seed size, embryo excision and high oxygen concentrations on germination.
Temperature did not affect total imbibition, however, imbibition at 30 and 20 C induced greater germination when transferred to a 15-25 C alternating germination environment.
The application of oxygen induced the greatest germination response of all treatments (57 %). Excised embryos germinated rapidly and percentage germination was equal to  viability of the seed lot. The response to oxygen and the rapid and complete germination of excised embryos indicates that dormancy in beardless wildrye is imposed by the outer coverings of the seed. Germination was not influenced by seed size. 
Additional index words: germination, dormancy breaking, seed size, imbibition, oxygen
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(pp. 10-18)
Factors Causing Variations in the Conductiviy Test for Soybean Seeds
Kar-Ling J. Tao1
Several factors with potential to cause variations in results of the conductivity test for soybean seed (Glycine max (L.) Merr) vigor were investigated.

The ion content in the filter paper increased the conductivity and its effect depended upon the kind of filter paper and the volume of filtrate used. The use of tap water increased the conductivity compared to the use of deionized water. The variation in the size of a soaking container had no significant ef­fect on the conductivity.  When seeds were soaked at various temperatures, conductivity increased as temperature increased. The seed size showed a slight effect in one seed lot but not in another. Low initial seed moisture content (8.8 % or less) and injured seed caused a significant increase in the conductivity. The conductivity test for soybean seed vigor should be conducted without filtration and with uninjured seeds having a moisture content of 13% or higher.
Additional index words: vigor, Glycine max (L.) Merr., imbibition.
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(pp. 19-26)
Evaluation of 'Forrest' Soybeans With Damaged Seed Coats and Cotyledons1
Viola M. Stanway2
The seed coat serves as a protective covering for the embryo. Germination of soybeans (Glycine max (L.) Merr.) can be greatly affected by condition of the seed coat and cotyledons. In this study, laboratory germination of Forrest soybeans, a cultivar with small seeds, was reduced to about 40% of that of visibly undamaged seeds when the seed coat was cracked or shattered even though the cotyledons were intact.

Field germination was reduced to about 15% of that for visibly undamaged seeds. Transverse breaks across the cotyledons caused similar decreases in laboratory germination. When breaks were completely through the cotyledons, laboratory germination was reduc­ed and limited to those pieces with an embryonic axis intact. This study supports previous work indicating that criteria for pure seed of soybeans should be revised.
Additional index words: germination, purity analysis.
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(pp. 27-37)
A Modified Accelerated Aging Seed Vigor Test for Soybeans1
Miller B. McDonald, Jr. and Bangalore R. Phaneendranath2
The previously recommended box and jar accelerated aging systems were evaluated using soybeans. The number of seeds per sample affected the ex­tent of accelerated aging. A small sample (200 seeds) deteriorated more rapidly than a large sample (400 seeds).

Seeds placed in a wire-mesh basket in a jar failed to demonstrate uniform moisture absorption. Seeds located in the bottom one-third of the basket had higher moisture and lower germination percentages than seeds situated elsewhere. These data suggest that the accelerated aging seed vigor test can be improved by specifying the number of seeds per sample and positioning the seeds in a single layer in order to provide more uniform seed exposure to high relative humidity. The capability of the jar and tray accelerated aging systems to distinguish three vigor levels was compared. Both systems successfully delineated the three seed vigor levels at 96 hrs aging but the degree of deterioration was more marked in the tray system. The data revealed 48 hrs to be the optimum aging period for the tray system. Further studies indicated that the level of water in the trays up to 48 hrs aging had little influence on subsequent germination. The tray accelerated aging method is inexpensive, subjects all seeds to uniform aging conditions, and is more rapid than previously recommended procedures.
Additional index words: soybean, germination, seed moisture, seed deterioration, Glycine max (L.) Merr., imbibition.
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