(pp. 67-78)
Effect of Preharvest Sprouting on Germination, Storability, and Field Performance of Red and White Wheat Seed1
Sabry Elias and L.O. Copeland2
ABSTRACT:
Three experiments were conducted to measure effects of preharvest sprouting of two soft white and two soft red winter wheat (Triticum aestivum L.) cultivars on germination, storability and field performance in 1985 and 1986. Eight levels of sprouting were studied.
At higher sprouting levels, seed of red cultivars maintained germinability better than that of white cultivars for the first 6wk. After 8wk, no differences in germination occurred.
Exposure of unthreshed heads to moisture caused sprouting, accompanied by a gradual decrease in germination of the white cultivar Augusta. The red cultivar Hillsdale resisted sprouting and maintained a high germination level for 12wk of storage. As number of sprouted seeds increased, germination decreased. Seeds of the red cultivar Hillsdale, with sprouting damage up to a split in the pericarp over the embryo could be safely stored for 3mo and planted without affecting field performance. However, any sprouting damage significantly reduced the yield of the white cultivar, Augusta.
Additional index words: Cold treatment, Emergence index, Triticum aestivum L.
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(pp. 79-90)
Differences in Lipid Profiles From Fresh and Aged Letuce (Lactuca sativa L.) Seed Determined by Capillary Supercritical Fluid Chromatography and GC/Mass Spectrometry1
R.M. Hannan and H.H. Hill, JR.2
ABSTRACT:
Since lipids play a role in the survival of seeds, it is important to understand the lipid chemistry in seeds as they age. Significant differences in the extractable, nonpolar lipid fraction of naturally aged and fresh seeds of lettuce (Lactuca sativa L.) were observed using liquid carbon dioxide extraction followed by capillary supercritical fluid chromatographic separation and flame ionization detection. In the aged seed, both low molecular weight products and high molecular weight polymeric products were detected with a concomitant decrease in the two major triglycerides relative to those in the fresh seed.
The analytical methodology developed for this study was found to be quantitatively reproducible for a mixture of five standard triglycerides with a coefficient of variability of less than 0.6%. Nine triglycerides were identified using supercritical fluid chromatography. Identities of four free fatty acids were confirmed by capillary gas chromatography/mass spectrometry. While the appearance of degradation products has previously been associated with the aging process, the appearance of polymeric products in association with seed degradation has not been reported, but was made possible through the use of supercritical fluid chromatography. This new information may provide further insight to why seeds loose vigor and viability.
Additional index words: Liquid gas extraction, Triglyceride, Fatty acid, Seed quality, Seed deterioration
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(pp. 91-96)
The Relationship Between Internal Disease Organisms and Germination of Gin Run Cottonseed (Gossypium hirstum L.)1
A. Seneewong, C.C. Baskin and W.E. Batson Jr.2
ABSTRACT:
Occasionally, large differences occur between actual germination and germination potential of gin run cottonseed as estimated in a tetrazoliurn test. The reason for these differences is not always apparent. One possibility is the presence of internal microorganisms. To test this hypothesis, 36 samples of gin run cottonseed were evaluated using the standard germination test. Twenty-seven of the 36 samples were selected for tetrazolium testing, The remaining nine lots were eliminated because of similarity in the standard germination tests. Nine of the 27 samples tested using the tetrazolium test were selected for microorganism analysis. These nine samples were selected based on
differences between standard germination and estimated germination In the tetrazolium test and number of dead seed per lot. Seed from each sample were acid delinted using concentrated H2SO4. Microorganisms were isolated from inside the seed coat and from the embryos of 100 randomly selected seed from each lot. Bacteria were found more often than fungi. Enterobacter agglomerans was the dominant bacterium and the most prevalent fungi were in the genus Fusarium. Only 2.9% of the embryos contained bacteria and 1.4% contained fungi. Fungi inside the seed coat were also low. Only 2.7% of the seed coats were infected. Total bacteria inside the seed coat were much higher with 15.2% of the seed coats being infected. The number of embryos containing fungi was negatively and significantly correlated with germination. r=0.655, while the number of bacteria inside the seed coat and in the embryo was positively and significantly correlated with germination, r=0.852 and 0.891 respective!y. All three correlations were significant at the 0.05 level of probability. Results obtained from this study indicate that internally borne microorganisms contribute little to the reduced germination of gin run cottonseed.
Additional index words: Fungi, Bacteria, Tetrazolium testing.
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(pp. 97-104)
Implications of the Interaction Between Seed Size and Scarification on Developing and Conditioning Hardseeded Soybean1
S.H. Moore2
ABSTRACT:
The hard seed coat trait in soybean (Glycine max (L.) Merr.) has been utilized to reduce seed deterioration in humid climates; however, cultivars with high levels of hardseededness require post-harvest scarification to allow rapid imbibition and germination. The purpose of this experiment was to determine how seed size and scarification interact to affect the percentage of hard seed in a seed lot.
Four seed lots derived from 'D86-4565' and 'D87-4629' (hardseeded experimental strains) were screened for size and scarified. Initial hard seed percentages ranged from 26 to 89%. Hard seed increased with seed size to a maximum value and then decreased in three of the four seed lots, indicating that the smallest seed were not always the hardest. Large seed were more easily scarified than small seed in two of the lots. In the largest seed size category of a conditioned seed lot of D86-4565, scarification reduced the percentage of hard seed below 1%. These results implied that the difficulty of scarifying hard seed could be reduced by selecting for large seed in breeding programs and screening for seed size during conditioning.
Additional index words: Glycine max (L.) Merr.), Seed coat, Water impermeable, Dormancy, Deterioration, Weathering.
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