Variability in Soybean Progenies Developed by Single Seed Descent at Two Plant Populations1

Abstract

Progenies from three soybean (Glyelne max (L.) Merr.) crosses were advanced four generations by single seed descent in the greenhouse. Plants were grown at two populations, three plants/15 cm pot and nine plants/15 cm pot. Plant losses averaged 19% of the original population at the low density and 55% of the original population at the high density at the end of the four generations.Gene frequencies for flower and pubescence color did not deviate from theoretical frequencies in the low density populations. At the high density population, significant deviations from expected values occurred for flower color in two crosses andf or pubescencceo lor in all three crosses. In two crosses the incidence of plants heterozygous for the gene controlling reaction to race 1 of Phytophthora megasperma Drechs. var. sojae Hildebrand was higher than expected.A two replicate field test was used to evaluate progenies from the low and high density populations for maturity, lodging, plant height, and seed size. Progenies advanced from the high density population averaged 0.5 to 3.6 days later in maturity, 0.I to 0.2 higher in lodging score, and 0 to 4.3 cm taller than progenies advanced from the low density population.