Genetic studies on gel consistency of rice (Oryza sativa L.)

Inheritance of gel consistency in rice was studied in a 6 x 6 full diallel cross involving parents with hard, medium, and soft gel consistency, and having high amylose content, low gelatinization temperature, and similar agronomic characteristics. The single grain analysis of parents, F1, F2, B1F1, and B2F2 seeds and their reciprocals from a single-season harvest, showed that the differences between hard and soft, hard and medium, and medium and soft gel consistency were controlled by a single gene with major effect, along with several minor genes and/or modifiers. Hard gel consistency was expressed as dominant trait over medium and soft gel consistency, and medium gel consistency was dominant over soft gel consistency. Graphic analysis of Wr-Vr confirmed the possible involvement of one major gene in governing the expression of the trait. The regression line cutting the Wr axis above the point of the origin, suggested the average dominance being within the range of incomplete dominance. Analysis of genetic components of variance and combining ability showed both additive and non-additive gene effect being of importance. The narrow sense heritability (h (ns)=0.78) of the trait was high. The results obtained suggested that selection for desirable gel consistency can effectively be done in early segregating generations. Selection for intermediary segregants from the crosses of hard X soft gel consistency parents would be ineffective because of major gene control of the trait. Effective selection for soft or medium gel consistency can be done involving soft or medium gel consistency parents, respectively. Estimates of variation for amylose content, gel consistency, gelatinization temperature, and grain elongation of 245 rice varieties from 27 countries revealed the existence of wide variability in cooking quality characteristics. A few rice varieties had excellent combinations of the four traits in cooking and eating quality characteristics preferred by most rice consumers.