Yield in Response to Accumulated Temperature before Winter in Winter Wheat

Abstract

The purposes of this study were to recommend optimal sowing dates of commercial wheat cultivars in middle part of Hebei province, China and screen out wheat cultivars acclimatized to late sowing. A field experiment was carried out with split plot design (main plot of sowing date and subplot of cultivar) in Gaocheng of Hebei province from Autumn 2011 to Summer 2014 to evaluate the effect of sowing date on 12 major cultivars and the response of cultivars to accumulated temperature before winter. The results showed that sowing date had significant influence on grain yield, and the 12 cultivars had different responses to sow- ing date. According to yield changing rate subject to late sowing, the 12 cultivars were classified into insensitive, intermediate, and sensitive types. Insensitive cultivars showed stable spike number and yield under late sowing condition, indicating a wide range of preferred sowing date. The desired accumulated temperature before winter was 324-560℃. Intermediate cultivars also had a long period of sowing date with 362-566℃ before winter. Late sowing resulted in the increase of grain number but the de- creases of spike number and yield in intermediate cultivars. Sensitive type had a narrow range of sowing date and was not suitable for late sowing, because at least 511℃ before winter was required. Late sowing resulted in obvious declines of spike number and yield in sensitive cultivars. In the middle part of Hebei province, we recommend that the optimal sowing time in wheat production is Oct. 7-22 for insensitive cultivars, Oct. 7-19 for intermediate cultivars, and Oct. 5-10 for insensitive cultivars.