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 chemic al fertilizers is used to alleviate yield losses associated with this deficiency. Because chemical control is often ineffective, genetic tol erance could be used in areas where Mn deficiency Is a problem. The de velopment of soybean genotypes tolerant to Mn deficiency is facilitate d 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 B 216 were evaluated in the field for tolerance to Mn deficiency. The ob served wide range In progeny response to Mn deficiency suggested digen ic inheritance. This model was supported by the results of a cluster a nalysis applied to the F-2:3 family mean ratings and variances. Low es timates 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 to lerance 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 sho uld be effective.