Assessment Of Yield, Grain Quality And Combining Ability Of Selected Rice Cultivars In Kenya

Abstract

Rice is an important crop in Kenya, mostly grown by small scale farmers as a commercial and food crop. The existing cultivars are low yielding, late maturing, and low grain quality. There is need to improve locally adapted cultivars to be high yielding and have desirable grain qualities. This study was aimed at evaluating rice cultivars for performance and combining ability of yield and grain quality traits. Thirty one genotypes, comprising of parental lines and F1 progenies were sown in a randomized complete block design in Mwea Research Station of KARLO during 2016/2017 rainy seasons. The genotypes were scored for grain yield, grain quality and other agronomic traits and data analyzed using GenStat 15th Edition program. There were significant differences among genotypes for all the traits studied. Genotypes, Nerica 1, Nerica 2 and Basmati 370 were early maturing; Basmati 370 had higher grain yields in all the seasons indicating wide adaptability. Generation of cross NERICA 10 x MWUR 4 exhibited slender grain shape. Genotype Basmati 370 had strong aroma, NERICA 3 x Basmati 370, NERICA 2 x Basmati 370 and NERICA 1 mild aroma, but those of K1-99 x KOMBOKA and NERCA 10 were non aromatic. Grain yield was positively correlated with days to maturity, plant height, number of productive tillers, number of filled grains and 1000 grain weight and negatively correlated with number of empty grains. Out of the 10 cultivars, evaluated for general combining ability, three cultivars Basmati 370, (0.88**), Nerica 3 (0.42**) and Nerica 2 (0.36**) were high general combiners for yield. From 21 hybrids evaluated for specific combining ability, three crosses namely, Mwur 4 x Nerica 3 (0.71**), Dourado x Nerica 1 (0.24**) and Komboka x Basmati 370 (0.21**) had high combining values for grain yield. Cultivars with high GCA for grain yield such as Basmati 370 and Nerica 2 turned out to have low SCA values as shown in generation of crosses Dourado x Basmati 370, Komboka x Nerica 2 and Mwur 4 x Basmati 370. General combining ability (GCA) variances were higher than specific combining ability (SCA) variances indicating that additive genetic effects were more important in determining genetic variability than dominance effects. From the results obtained in this study, improvement for grain yield would be easier through indirect selection of yield components traits such as days to maturity, number of productive tillers per panicle, number of filled grains per panicle and thousand grain weights. However, there is need xiv to advance the segregating populations to F3:F4 generations in order to ascertain their agronomic, grain quality and yield potential in multi-location trials. Keywords: Rice (Oriza Sativa) combining ability for grain quality, grain yield and earliness