Studies on Types of Gene Effects in Some Crosses of Rice (Oryza Sativa L.)

الملخص

A field investigation was conducted at the Faculty of Agriculture Experimental Farm, Alexandria University, Alexandria, Egypt, during the 1972-1974 seasons. The relative importance of types of gene effects was studied on yield and yield components in the two rice crosses, namely; Giza 159 x I.R.8 (cross I) and Giza 159 x Taichung (N.)l (cross II). Population means of parents, F,, BCt, BC2, and F2 were used, on plant basis, in estimating the different types of gene effects on five agronomic characters, according to Gamble's method (12).
Significant additive gene effect was detected for grain yield per plant and plant height in cross I; and for plant height, 100-grain weight, and panicle length in cross I. The dominance gene effect was significant for grain yield per plant, plant height, and panicle length in cross I. On the other hand, this effect was significant for all characters except the grain yield per plant in cross II.
The characters that showed significant additive x additive type of epistasis were grain yield per plant, plant height, and panicle length in cross I. This type of epistasis was significant for all characters in cross II. The additive x dominance type of epistasis was significant for grain yield per plant and plant height in cross I; and for number of ear-bearing tillers per plant and panicle length in cross II. Significant dominance x dominance epistatic effect was detected for panicle length in cross I; and for grain yield per plant, 100-grain weight, and panicle length in cross 11.