Genetic aspects of aluminum tolerance in sorghum

Abstract

To obtain crops tolerant to aluminum (Al) toxicity in acid soils, several methods have been used to screen different plant species and genotypes to this production constraint. Little is known about the effect of the method on genetic analyses and breeding method suggested. Three genetic studies were conducted to examine evaluation method on inheritance and gene action of sorghum [Sorghum bicolor (L.) Moench] to Al toxicity as measured by seedling dry matter production.

Results of acid soil and solution culture studies indicated that tolerance to Al toxicity was inherited as a dominant character. Narrow-sense heritability estimates in the greenhouse acid-soil study were low for shoot and root dry matter production. Six of the same hybrids tested in solution culture produced high additive-genetic variance and had narrow-sense heritability estimates of 72% for shoot and 65% for root DM yields. Griffing's diallel analysis showed that seven of nine restorer lines had substantially higher specific than general combining ability variances for both root and shoot dry matter yields.

Inconsistencies between the acid soil and solution culture techniques showed that different genetic responses to the treatments were being measured. The solution culture study indicated to the plant breeder that genes conditioning Al tolerance could be incorporated into pure lines while the greenhouse acid-soil study would predict that this would not be possible. The diallel study of plants grown in solution culture showed that developing both Al-tolerant varieties and hybrids would be possible depending upon Al-tolerant germplasm used. Acid-soil field studies of actual genetic gain for Al to lerance are needed.