Sorghum Grain Yield Reductions Caused by Duration and Timing of Freezing Temperatures

摘要: Management practices, as well below-normal temperatures that occur late in the growing-season, can delay grain sorghum [Sorghum bicolor (L.) Moench] maturity northern Great Plains. Delaying increases probability of a freeze occurring before crop reaches physiological maturity. Studies were conducted during 1988 and 1989 using greenhouse- field-grown plants Kansas to determine caryopsis weight test reductions from exposure subfreezing air temperatures. Treatments 0, -2, - 4°C for 2, 4, 8 h growth chamber when developing had attained approximately one-half its maximum weight. A second experiment studied effects -2°C 4 at different stages grainfill. Caryopsis weights progressively reduced temperature was 0 -4°C. Effects time on not consistent year year. Air or lower plants, whereas only -4°C greenhouse-grown plants. Exposure 81% 200, 57% 300, 25% 450, 3% 600 growing degree days (GDD, base 5.7°C) after anthesis (maturity 850 GDD). Test response similar with exposed freezing 200 300 GDD than other treatment times control. These results indicate minimum is primary factor determining