Phenomorphological characterization of vegetable soybean germplasm lines for commercial production

Abstract

Growing demand for vegetable soybean [Glycinemax (L.) Merr.] has renewed interest inproducing the crop in the United States, a significantimporter of vegetable soybean despitebeing the world’s largest producer and exporterof grain-type soybean. Field studies were conductedover 3 yr to(i) compare phenomorphologicaltraits of vegetable and grain-type soybeanand (ii) identify candidate lines for vegetablesoybean production in the North CentralUnited States, the nation’s leading soybeanproducingregion. A total of 136 vegetable soybeanentries from 22 sources were comparedto 14 grain-type cultivars representing a rangeof maturity groups. Germination and emergenceof vegetable soybean were poorer thangrain-type entries. Seedling growth traits andrate of phenological development were higherin vegetable soybean. However, by the time ofcrop harvest (i.e., R6 growth stage), vegetablesoybean produced shorter, smaller plants thangrain-type soybean. Seed mass accounted forsome of the variation in emergence and seedlingtraits. Filtering entry responses by criteriaessential to viable commercial production,including a sensory evaluation, 12 entries fromeight seed sources were identified as the mostpromising candidate lines for use in the NorthCentral United States. By comparing vegetablesoybean responses to grain-type soybean,this work puts into perspective the agronomicperformance of vegetable soybean germplasmavailable to growers in the United States andpoints to specific areas of future research andcrop development.