INHERITANCE OF TOLERANCE TO MANGANESE DEFICIENCY IN SOYBEAN

Manganese deficiency is a recurring problem in soybean [Glycine max (L.) Merr.] grown on high pH soils. Presently, the application of chemical fertilizers is used to alleviate yield losses associated with this deficiency. Because chemical control is often ineffective, genetic tolerance could be used in areas where Mn deficiency Is a problem. The development of soybean genotypes tolerant to Mn deficiency is facilitated if the mode of inheritance is understood. The F-2 and F-2:3 progeny of the tolerant germplasm line A14 and the intolerant cultivar Pride B216 were evaluated in the field for tolerance to Mn deficiency. The observed wide range In progeny response to Mn deficiency suggested digenic inheritance. This model was supported by the results of a cluster analysis applied to the F-2:3 family mean ratings and variances. Low estimates of narrow sense heritability (($) over cap h(2) = 0.19) in the F-2 generation indicated that F-2 phenotypic differences were largely due to environmental variation, thereby making yield selection for tolerance to Mn deficiency in the F-2 generation difficult. Estimates of narrow sense heritability based on F-2:3 family means were greater (h(2) = 0,70), indicating that selection based on F-2:3 family means should be effective.