Genetic Analysis of Root Traits and its Effect on Yield for Drought Tolerance breeding in Rice (Oryza sativa)

Rice (Oryza sativa L.) is the staple food for over half of the world’s population. Rice is particularly susceptible to water stress. Drought is a serious limiting factor in rice. Grain yield can be drastically reduced if drought stress occurs during flowering. Breeding of new rice cultivar with drought tolerance not only saves a great amount of water but also helps to increase and stabilize the yield during the periods of uncertain rains. The indirect selection for carefully selected secondary traits can be helpful in improving selection response. This investigation was aimed at studying the drought tolerant traits viz., root length, root dry weight, root : shoot ratio, root volume of ADT 43, ADT 45, ANNA 4, CO (R) 49, CO (R) 50 MDU 5, RMD (R) 1, and TKM 9 as lines and five local land races viz., Chandikar, Chinnar 20, Nootripathu, Norungan Vellaichitraikar as testers and 40 hybrids resulted from crossing these parents in Line x Tester fashion were used for estimating combining ability, heterosis, correlation and path coefficient analysis to assess the breeding value of lines, testers and their hybrids. The study revealed that the parents and hybrids differed significantly among themselves for all the characters. This suggested that a wide variability existed among the genotypes for all the characters studied. On the basis of per se performance, sca effects and standard heterosis, the hybrid ANNA 4 × Norungan was suitable for heterosis breeding since it expressed high values for traits viz., root length, root dry weight, root : shoot ratio, root volume and grain yield per plant. The hybrid CO (R) 49 × Chinnar 20 could be considered as next best as it showed high for these traits. These hybrids can be effectively utilized for commercial exploitation of hybrid vigour through heterosis breeding programme.