Inheritance of Field Weathering Resistance in Soybean [Glycine max (L.) Merrill]

Abstract

A commercial variety of soybean, Chiangmai 60, which is susceptible to field weathering and two field weathering resistant varieties, GC 10848 and Kalitur, were grown and hybridized in the greenhouse at the Department of Agronomy, Kasetsart University. The F1 hybrid seeds and their parental
varieties were planted in the greenhouse to produce F2 seeds. Parental varieties, F1 hybrids and F2 progenies were grown in an experimental field during the 2008 dry season at the National Corn and Sorghum Research Center, Pakchong District, Nakhon Ratchasima province. Individual plots were 3×3 m², with six rows, composed of two rows of parents and four rows of F1 hybrids or F2 progenies for each cross. The spacing between rows was 50 cm and between hills was 25 cm. At physiological maturity, soybean pods were harvested, threshed and subjected to tests for accelerated aging (AA) and electrical conductivity (EC), and the seed coat percentage was measured. Field weathering resistance of the parental plants, F1 hybrids and F2 progenies was evaluated using germination percentages after AA testing and EC values of seed leachate and seed coat percentages. Dominance percentages of F1 hybrids and the frequency distribution of F2 progenies for the germination percentages after AA testing and EC values of seed leachate and seed coat percentages of the two soybean crosses revealed that field weathering resistance was controlled by a polygene with partial dominance.