EFFECT OF TEMPERATURE ON GERMINATION AND SEEDLING EMERGENCE OF GRAIN-SORGHUM GENOTYPES

Poor emergence under high soil temperature conditions is a serious problem in adoption of new grain sorghum [Sorghum bicolor (L.) Moench] cultivars in semiarid areas, Field emergence studies were conducted under high temperature conditions in Niger, and the United States. These results were related to % germination obtained in the laboratory over a range of temperatures. Genotypes P1044 and P1056 emerged best across environments, but the genotype P954035 emerged best in Niger. Per cent germination on the gradient table was highest at 27-33 degrees C for all genotypes. At these temperatures, genotypes P1056, P1006, P967083, P1016, and P1045 had the highest % germination (>80%). Correlation of % germination with % emergence was greatest at 30/30 degrees C with values ranging from 0.44 to 0.76 and decreased to correlations of 0.20 to 0.48 as temperature increased to 30/45 degrees C, indicating that other factors in addition to temperature influenced emergence. Based on % germination and emergence, genotypes P1044 and P1056 merit further study as potential germplasm sources for improving stand establishment of grain sorghum.