Combining Ability for Yield and Yield Components in Upland and Lowland Rice Crosses

Abstract

The study of combining ability for yield and yield components in upland and lowland rice crosses was conducted during the rainy season (July 2002 – January 2003) at Agronomy Farm, Faculty of Agriculture, Chiang Mai University. Six F2 hybrid crosses derived from diallel cross among 4 conventional upland and lowland rice cultivars namely RD 7, Pathum Thani 1, Jow How and R 258 were planted along with their respective parents. Results from estimation of general and specific combining ability indicated that flowering date, plant height, number of panicles per plant, number of good grains per plant and 1,000-grain weight were controlled by both additive and non-additive genes but additive gene effects seemed to be more influences than non-additive effects. However, non-additive gene effects were found specifically for grain weight per plant. Estimation of general combining ability revealed that two upland rice varieties: Jow How and R 258 performed good general combiner for early flowering, moderate plant height and large in seed size. Two lowland rice varieties; RD 7 and Pathum Thani 1 showed good general combiner for late flowering, short plant height and increasing of panicles per plant. Estimation of broad-sense heritability indicted the flowering date, plant height, number of panicles per plant, number of good grains per plant, 1,000-grain weight and grain weight per plant were rather high for all of these traits. Narrow-sense heritability values were high for flowering date, plant height, number of panicles per plant and 1,000-grain weight but moderate values were observed in number of good grains per panicle and grain weight per plant. In summary, high yielding of upland rice varieties could be developed by selection of promising breeding lines derived from crossing among upland and lowland rice parents which either of them will provide good combining abilities of desirable agronomic traits.