Genetic analyses of eating and processing quality parameters in rice (Oryza sativa L.).

摘要

A series of experiments were conducted to elucidate the genetic control of eating and processing quality parameters in rice at the Texas A&M University Agricultural Research and Extension Center near Beaumont, Texas. Results obtained from a six-parent diallel cross indicate that both additive and dominance gene effects are important in conditioning these endosperm characteristics. Furthermore, additive gene effects are significantly larger than dominance gene effects for all characteristics evaluated with the exception of amylographic peak viscosity in which both additive and dominance gene effects are equally important. No reciprocal differences are involved in influencing the endosperm characteristics studied. Heritabilities estimated for all characteristics studied are all high. Effects of general combining ability are significantly larger than those of specific combining ability.;Genetic systems deduced from the analysis of generation means for amylose content and amylographic breakdown viscosity show that an additive-dominance model without the complication of gene interactions is adequate to describe the data on amylose content, but not for amylographic breakdown viscosity. The genetic system conditioning amylose content is simply controlled by both additive and dominance gene effects, with high amylose content incompletely dominant. In contrast, the genetic system conditioning amylographic breakdown viscosity is controlled by both additive and dominance gene effects plus additive x dominance interaction effect, with low amylographic breakdown viscosity incompletely dominant.;Inheritance of amylose content was also studied using single-grain analysis. Intermediate to low amylose appears to be controlled by a single incompletely dominant gene in the crosses between intermediate and low amylose parents. Two incompletely dominant complementary genes conditioning high to low are suggested from the crosses of high with low amylose parents. A genetic hypothesis of a single incompletely dominant gene conditioning high to intermediate is fitted to the crosses between high and intermediate amylose parents.;A new small-sample size abridged amylograph test developed by the author under the direction of Dr. Webb, a Research Cereal Chemist, USDA, in 1991, was first used in this study. The result obtained focuses on the amylographic breakdown viscosity only, which appears highly consistent with that from a regular amylograph test.