Usefulness of Improved Crossing Methods for Hybridization to Develop Mapping Population for Seed Longevity in Soybean Glycine max (L.) Merrill

摘要

Seed longevity in soybean is a serious concern with respect to the availability of quality seeds for sowing in the next season. The identification of donors for seed longevity and QTL mapping for selection are the major concerns in soybean breeding for seed longevity. In the present study, the longevity of Local Black Soybean (LBS) was confirmed by evaluating black, green and yellow seed coat colour genotypes for longevity through accelerated ageing technique. Two contrasting genotypes for seed longevity i.e., LBS which showed highest germination of 85 per cent and JS 93-05 which recorded low germination (6 ) after accelerated ageing of seeds, were selected as parental lines to develop mapping population. These two parental lines differ for severalmorphological traits viz., growth type (indeterminate vs determinate), leaf shape (pointed ovate vs lanceolate), plant height (medium vs short) and pod colour (yellow vs brown), making it easy for identification of true F_1 through morphological traits.The success of hybridization through conventional method of emasculation in the previous evening followed by hybridization in the next day morning is very low. Hence, hybridization between JS 93-05 and LBS was carried out using two improved methods i.e., wet cotton and Kolot method for comparison. The F_1 plants were grown in the field and in both the methods both selfed and true hybrids were observed morphologically. True F_1 plants resembled male parent for dominant traits like indeterminate growth,pointed ovate leaf, higher plant height and higher number of pods per plant. The true F_1 were confirmed through parental polymorphic SSR marker. Higher crossing success rate was recorded in wet cotton method (50 ) as compared to Kolot method (16.67 ).Totally, 400 F_1 seeds (green colour) were produced from confirmed F_1 plants to develop mapping population for seed longevity.