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Seed density selection in winter wheat populations

Higgins, Charles Russell, Jr.

Ph.D., Colorado State University, 1981, 149 pages

1981

บทคัดย่อ

SEED DENSITY SELECTION IN WINTER WHEAT POPULATIONS.

Plant breeders using mass selection techniques have attempted to select for seed density without knowing what agronomic characters are associated with it.  High (1.380g/cm('3)) and low (1.360g/cm('3)) seed density selection, using carbon tetrachloride and ethanol mixtures calibrated to (+OR-) 0.001 g/cm('3), was practiced in three F(,2) populations of winter wheat (triticum aestivum L.) and again in the F(,3)'s.  The liquid separation made a highly significant seed density separation but did not significantly affect preplant seed weight.  Two years of selection did not significantly affect yield components in the F(,4)'s.  High or low selection caused very small differences in post-harvest seed density; therefore, realized heritability estimates were very low.  Mean F(,4) protein values for two of the three populations were highly significantly reduced in high speed density treatments.  Mass selection using seed density as the only selection criterion is not recommended.  The selection for high

 density would probably increase high yield-small seeded-low protein genotypes within populations.

 Changes in density and protein caused by selection for high density seed were localized in the terminal floret positions within central spikelets.  Seeds from terminal spikelets and from terminal florets within central spikelets were highly significantly denser, lower in seed weight, volume, and protein than seeds from basal florets in central spikelets.  Packing of lower density gluten between relatively high density starch granules in the endosperm is offered as an explanation for low density-high protein seeds.

 Separation of bulk populations with a gravity table resulted in a mean 1000 seed weight difference of 7 grams between the top one-third and bottom one-third of preplant seed lots.  Seed density differed 0.023 g/cm('3) between the top and bottom lots.  Preplant seed quality was not affected by gravity table separation if seed fragments were removed prior to separation.  F(,4) seed weight and test weight after two generations of high gravity table selection increased in some populations, but realized progress varied between populations and sites.  Yield and postharvest seed density were not significantly affected.