Evaluation of Simulated Fall Freeze, Planting Date, and Cultivar Maturity in Soybean

摘要

In a warmer-than-normal year, yields of Maturity Group I or II cultivars did not exceed those of Maturity Group 0 cultivars. In a cooler-than-normal year, late maturing cultivars Kasota and Sturdy yielded less than adapted cultivars Dawson and Glenwood. There was no advantage in extending the length of the growing season by early planting of late maturing cultivars. In a cooler-than-normal growing season with an early fall freeze, an early planting increased yields of adapted Maturity Group 0 cultivars. Soybean producers on the northern fringe of the U.S. soybean belt can increase yield in many years by planting between 7 and 21 May. The risk of planting early is that a spring freeze may destroy the seedlings. If a spring freeze does occur, however,producers have the option of replanting. The replanted crop may still produce a good yield, provided an early fall freeze does not occur. Most samples of soybean prematurely killed by a fall freeze produced grain that could be marketed without a quality discount. When the plants were killed as early as stage R6 and allowed to mature in the pod before harvest, most samples were U.S. grade No. 1.