| Improved seedling cold tolerance is needed in sorghum to obtain earlier emergence and more vigorous seedling growth in cool soils. Improved tolerance would make the crop more competitive with weeds in cool soils and allow spring earlier planting to increase the length of the growing season in marginal production areas. Three experiments were conducted to study the genetics and improvement of seedling cold tolerance in grain sorghum.;In a seven-parent diallel field experiment, cold tolerance was controlled primarily by additive gene effects. Heterosis favored seedling vigor but dominance was bi-directional for emergence. SCA effects were significant for seedling dry weight, but not for emergence. Maternal effects were generally unimportant. Pre-emergence and post-emergence performance were genetically independent. SD106 had the best performance overall for emergence and seedling growth. Ma9 appears to have favorable dominant alleles unique to the other lines.;In a comparison of three populations, the Nebraska Cold Tolerant Sorghum Population (NPCT) was superior in performance and genetic variability for seedling cold tolerance traits. NBCT is tall and late maturing, but the population of choice for improving seedling cold tolerance.;The genetics and improvement of seedling cold tolerance were studied in the partially adapted NPCT population. Two hundred half-sib and 100 S1 families were evaluated in both stress and non-stress environments. For emergence and seedling vigor, respectively, estimates of inbreeding depression effects at 100% homozygosity were... |
