Genetic control of seedling tolerance to aluminum toxicity in rice

An uncomplete diallel analysis was conducted for 56 F1 progenies derived from 8 male × 7 female parents with differential Al tolerance based on root tolerance index (RTI) in a solution culture with Al concentration of 1 mM Al. Remarkable variation in RTI among the parents was observed after 6 weeks in culture. Significant (P < 0.001) general combine ability (GCA) variance for both male and female parents and specific combine ability (SCA) variance were observed. The variance of GCA was much higher than that of SCA, indicating greater additive expression of the tolerant trait. Higher narrow-sense heritability (48%) was detected, indicating the possibility of a genetic gain in selection for Al tolerance based on RTI. The tolerant performance of F1 progenies appeared to be influenced by the susceptible genotype. suggesting the inconsistent dominance effect. The possible mechanisms of the apparent inconsistent dominance was discussed in terms of the genetic background in wheat. Two restore lines, Pedel and 02428, and one sterile variety, XieqinzaoA, were found to be high in the GCA effect and SCA variance in this case. These genotypes may be useful in development of hybrid rice production on acid soils. This revised version was published online in July 2006 with corrections to the Cover Date.