Selection for Seedling Cold Tolerance in Grain Sorghum1

Abstract

Improvement in cold tolerance for sorghum (Sorghum bicolor (L.) Moench] would allow expansion of this crop into cooler regions than the current production areas, as well as lessen stand reductions in cool soils currently in production. Experiments were conducted in 1981 and 1982 to evaluate effectiveness of selection for cold tolerance in sorghum. A genetically broad‐based, random‐mating grain sorghum population, Purdue Population 9 (PP9), was used as the source population for increasing seedling cold tolerance. Purdue Population 9 Cold Tolerant (PP9CT) was developed through a phenotypic recurrent selection procedure utilizing natural selection in early spring plantings. Progress from selection was evaluated in early spring plantings in 1981 and 1982. In 1981, the C0 to C3 generations of PP9CT and two check genotypes were evaluated in plots planted with 100 seeds in a randomized complete block design. In 1982, the C4 generation was also included. Results from the first year indicated that a 10.6% increase in cold emergence had been accomplished after three cycles of selection. Data from 1982 indicated a 14.9% increase in cold emergence after four cycles of selection. Regression analysis on the combined tests showed a linear increase of 2.8% cycle−1. Plant height, days to half bloom, seed color, and grain yield were evaluated in trials planted at normal planting dates to determine the correlated responses in PP9CT following selection for seedling cold tolerance. Plant height showed an irregular response, days to half bloom decreased by 0.55 days cycle−1, seed color increased by 0.13 color units cycle−1, and grain yield increased by 197.7 kg ha−1 cycle−1.