Inheritance of root regrowth as an indicator of apparent aluminum tolerance in triticale

Aluminum (Al) toxicity is a predominant growth-limiting factor in acid soils. Better understanding of the genetic mechanisms by which plants tolerate toxic Al expedites the development of tolerant plant genotypes. The genetic behavior of apparent Al tolerance in two triticale crosses as measured by root regrowth of seedlings at a level of 10 mu g.g(-1) Al stress in nutrient solutions was analyzed by following a bi-parental (BIP) mating design. The validity of the additive-dominance genetic model was tested with relevant gene effects estimated. The continuous variation of regrown root length showed that apparent Al tolerance was a metrical character in nature. Both the additive and dominance effects were responsible while the additive effects played a major role in the expression of Al tolerance. Non-allelic interaction (or epistasis) was indicated from the inadequacy of the model and different types of epistatic gene effects were detected in the two crosses. These results suggest that Al tolerance was of polygenic system rather than simply inherited. One to three pairs of genes were involved in apparent Al tolerance for the parental difference. The moderately high value of estimates of heritability together with the estimates of genetic advance (GA) could be used in planning a selective breeding program aimed at greater Al tolerance.