Study of Quantitative Inheritance in Some Mutants of Rice

Abstract

Nine agronomic characters viz., plant height, effective tillers per plant, panicle length, flag leaf length, flag leaf breadth, flag leaf area, primary branches per panicle, grains per panicle and grain yield per plant of rice (Oryza sativa L.) were studied in two separate investigations. Biometrical techniques were applied in analyzing the data.Gene Action: Inheritance of nine agronomical characters were studied in a single cross of rice ( Oryza . sativa L.) using segregating (F2 , F3 , B1 and B2 ) and non-segregating (parents and F1 ) generations. The means of segregating and non-segregating generations (F1 , F2 , F 3 , B1 and B2 ) were within the parental ranges in all the characters. Both additive and non-additive types of gene· effects were involved in the inheritance of these characters but the former was of much importance than the latter. Epistatic gene effects were detected. The absolute magnitude of epistatic gene effects was always less than the mean effect. Additive x additive (i) type of epistasis was more pronounced in most of the characters. Duplicate type of epistatic gene effects was observed in most of the cases. Additive (D) type of genetic variation formed the major part whereas dominance (H) type of genetic variation contributed very little to the phenotypicvariation in all the cases. All type of heritability estimates were high in most of the cases. Broad sense heri tabi 11 ty ( Hb) ranged from 41 . 27% for panicle length to 80.24% for grain yield per plant. Narrow sense heritability (Hn) ranged from 98 . 18% for panicle length to 143.19% for plant height. Heritability estimated by parent offspring regression ranged from 68 . 42% to 108. 33% for panic le length and plant height, respectively. Partial dominance in F1 and F2 and both partial and overdominance in F 3 were noticed. No linkage was detected for all the characters. Positive isodirectionally distributed polygenes for all the characters were common in the parents. Number of effective factors were 2-3 in majority of the cases .