Volume 14, No. 1, 1990

Download Cover and Contents

(pp. 1-12)
Effect of Soybean Seed Vigor and Size on Seedling Growth
D.B. Egli, D.M. TeKrony and R.A. Wiralagaz
Soybean [Glycine max (L.) Merrill] seed vigor can affect yield either indirectly by influencing plant populations or more directly by affecting plant growth. Greenhouse experiments were conducted to evaluate the relationship between seed vigor and seedling growth.

Seed lots of six cultivars with acceptable standard germination (≥82%) and high- and low-vigor levels based on the speed of germination and accelerated aging  germination tests were selected. In a first set of experiments, large and small size classes were selected from each seed lot of two cultivars (DeSoto and Pershing) using round hole screens. Seeds were planted in the greenhouse and seedling dry weight (excluding the cotyledons) and leaf area were measured at 5, 10, 15, and 20 d after emergence (DAE) on seedlings that exhibited no cotyledon injuries and emerged on the same day. Within a vigor level, seedlings from large seeds were heavier at the first and final harvests than seedlings from small seeds by an average of 55 and 57%, respectively. Seed size had no effect on specific growth rate (SGR) (mg mg'l day1) or net assimilation rate (NAR) (g m-2 d-1). Seed vigor had no effect on SGR, NAR, or seedling weight at 20 DAE. In a second set of experiments, individual seed conductivity of seeds from high- and low-vigor seed lots of four cultivars ('SS443', 'Harper', 'BE-29' and 'Williams 82') was measured and related to seedling dry weight accumulation. There was no significant relationship between conductivity and seedling dry weight at 20 DAE for seedlings with no cotyledon injury. However, an average of 49% of the seedlings from low vigor seedlots showed cotyledon injury at emergence vs. 20% for high-vigor seedlots. Seedlings with cotyledon injury emerged slower and had less dry weight at 20 DAE. The data indicate that seed vigor has no effect on the ability of the seedling to accumulate dry weight if there is no injury to the cotyledons
Additional index words: Glycine max (L.) Merrill, Growth analysis, Germination, Physical injury, Conductivity.
Download entire article

(pp. 13-18)
Sterase Isoennzyme Electrophoresis as a Method of Separating Colonial and Creeping Bentgrass Mixtures1
G.W. Freeman and F.A. Yoder, Jr2
Rapid and efficient methods are needed to differentiate between creeping bentgrass  (Agrostis palustris Huds.) and colonial bentgrass (Agrostis tenuis Sibth.) species and to complement both visual evaluation of seeds and growth chamber tests. This study was initiated to determine if varying proportions of colonial bentgrass seeds could be detected in creeping bentgrass seeds using esterase isoenzyme polyacrylamide gel electrophoresis (PAGE) and to determine at what lower proportion level esterase isoenzyme PAGE was no longer capable of resolving the creeping bentgrass admixture.

The PAGE procedures revealed that colonial and creeping bentgrass seed extracts had distinct esterase isoenzyme banding patterns and the staining intensity of bands at RF 0.55 to 0.70 could be used to detect mixtures of creeping and colonial bentgrass. Proportions as low as 10% colonial bentgrass seeds in creeping bentgrass seeds were detected by visual examination of PAGE gels and proportions as low as 5% were detected using densitometricscans of the gels. This study demonstrated that PAGE esterase isoenzyme analysis was an effective method to detect colonial bentgrass contamination in creeping bentgrass and can provide the seed analyst with another test to supplement visual evaluation of seeds and growth chamber tests.
Additional index words: Agrostis palustris Huds., Agrostis tenuis Sibth., Species identification, PAGE.
Download entire article

(pp. 19-29)
The Effect of Seed Treatment on Laboratory and Field Performance of Navy Bean (Phaseolus vulgaris L.) Seed Exposed to Prolonged Wet, Humid Weather Prior to Harvest1
L.O. Copeland, R. Baalbaki and N.B. Lee2
Chemical treatment of navy bean (Phaseolus vulgaris L.) seed exposed to prolonged wet, humid weather prior to hatvest improved germination more in cold and warm soil tests than in standard warm germination tests at all levels of quality between 56 and 97% germination. However, performance in all tests was improved by seed treatment, especially at lower quality levels. There was no consistent increase in performance after six weeks of storage under warm laboratory conditions. Both laboratory germination and field emergence were improved by most combinations and concentrations of seed treatment chemicals.
Additional Index Words: Germination, Cold test, Warm soil germination.
Download entire article

(pp. 30-40)
The Effect of Seed Treatment on Laboratory and Field Performance of Soybean (Glycine max L.) Seed Exposed to Prolonged Wet, Humid Weather Prior to Harvest1
L.O. Copeland, R. Baalbaki, and N.B. Lee2
Chemical treatment of soybean (Glycine max L.) seed exposed to prolonged wet, humid weather prior to harvest resulted in more improvement in cold soil tests than either standard germination tests or warm soil tests over untreated controls at varying levels of quality between 51 and 92% germination. However, results of all tests were generally improved by seed treatment, especially at the lower quality levels, as was field emergence.

After six weeks of storage in warm, dry laboratory conditions, germination in all tests tended to increase and there was less difference between treated seed and untreated controls. Both laboratory and field performance were generally improved over untreated controls for all of 17 different combinations and concentrations of seed treatment chemicals. These results show the value of a wide range of chemical treatments in increasing the performance of soybean seed.
Additional Index Words: Germination, Cold test, warm soil germination.
Download entire article

(pp. 41-46)
Effect of Geographical Location of Seed Production on Performance of a Hybrid Alfalfa1
E.H. Jensenz
Alfalfa seed is mostly produced in geographical locations other than where it will be planted for forage production. The effect of geographic area of seed production on performance of the progeny of hybrid alfalfa (Medicago sativa L.) seed is not well known. This study was conducted to determine the effect of geographic location of alfalfa seed production on the performance of the progeny.

Seeds of a self-sterile alfalfa clone 191 were produced in cages under two environments ["cool" (average temperature = 25.6o C.) and "hot" (average temperature 32.3o C.)] at Logandale, Nevada and in the field at Tucson, Arizona; Moscow, Idaho; and Bozeman, Montana. The progeny were grown under field conditions at Reno and Logandale, Nevada.
Plants grown in trials at Reno and Logandale, Nevada showed no significant (P=0.05) difference in plant height, dry matter yield or crown diameter due to geographical location or environment of seed production in alfalfa clone 191.
Additional index words: Seed quality, Environment, Seedling vigor, Medicago sativa L.
Download entire article

(pp. 47-55)
Effect of Freeze-thaw Cycles on Hard-seededness of Alfalfa
D.G. Stout1
Freezing at an ultralow temperature and thawing was shown in 1930 to decrease hard-seededness of alfalfa but the method has never been applied commercially. Freezing equipment now exists that could be adapted for freezing batches of alfalfa seed. Thus this study was conducted to evaluate the effectiveness of freeze-thaw treatments to reduce hard-seededness of two alfalfa seed lots known to have hard seed. A study was also conducted to determine if freeze-thawing of seeds has any negative effects on subsequent plant growth.

Freezing to -10o C. was ineffective but freezing to -80o C. was highly effective at decreasing hard-seededness. Freeze-thaw treatments effectively decreased hard seed content of seed lots of a purple flowered alfalfa (Medicago sativa L.) cultivar, Peace, and a yellow flowered alfalfa (Medicago falcata L.) cultivar, Anik. Hard seed content decreased exponentially with the number of freeze-thaw cycles. With a freeze-thaw cycle consisting of 2 h exposure to -80o C. and 2 or 18 h thaw at 20o C., it took 1.6 cycles to decrease Peace hard seed by 50% and 2.6 cycles to decrease Anik hard seed by 50%. The -80o C. freeze-thaw treatments increased rate of germination based on total seed population, total germination, rate of seedling development, and number of seedlings established. Freeze-thawing does not affect nonhard seeds since the freeze-thaw treatment had no effect on the rate of seed germination when based only on the population of seeds germinating. Freeze-thaw treatment of seed had no effect on seedling vigor as measured by dry matter production. The freeze-thaw treatment is an effective method for decreasing alfalfa hard-seededness; thus, an economic analysis of its use for commercial application is required.
Additional index words: Medicago, Germination, Seedcoat, Permeable, Temperature.
Download entire article

(pp. 56-60)
The Relationship between the Tetrazolium Test, Soil Cold Test and Standard Germination Test in Assessing Sorghum [Sorghum bicolor (L.) Moench] Seed Quality1
S. Paliwal, C.C. Baskin, and J.C. Delouchez2
Tetrazolium tests, soil cold tests, and standard germination tests were conducted on 40 lots of grain sorghum [Sorghum bicolor (L.) Moench]. Based on tetrazolium evaluations, seeds were grouped into high vigor, medium vigor, low vigor, and non-germinable categories. The high plus medium vigor categories of tetrazolium were significantly correlated at the 0.01% level of probability with emergence in soil cold test (r=0.936). The high plus medium plus low vigor categories were significantly correlated at the 0.01% level of probability with standard germination (r=0.900). These results demonstrate the potential of the tetrazolium test for assessing seed quality in sorghum.
Additional index words: Germination, Vigor testing, Seed quality evaluation.
Download entire article

(pp. 61-73)
Plant Diasphore Funcitons1
D.T. Booth2
Diaspore has previously been defined in the botanical sense, as a disseminule; especially one specialized for dispersal. That definition implies that diaspore morphology reflects the single function of dispersal. The plant science literature is reviewed, and ample evidence presented to show that diaspore structure and function reflect many facets in the processes of seedling recruitment. The functions reviewed include dispersal, protection, seed positioning and orientation, seed fixation, moisture adsorption, light filtering and regulating seed respiration. An enlarged definition of diaspore is offered to reflect a multiple-function concept.
Additional index words: Disseminule, Seedbed ecology, Native plants, Plant recruitment, Dispersal unit, Seedling vigor, Seeds
Download entire article