汉中地区是稻麦(油菜)两熟地带,秋季多阴雨并伴随降温,如播期掌握不当,常形成大量空秕粒,造成“秋封”。但早于7月底出穗又有“高温逼熟”问题。因此选择最佳出穗期是水稻稳产高产的关键问题。汉中水稻安全齐穗期汉中地区8月上旬日平均温度26.43℃,日照时数85.9小时,分别较中旬高1.03℃,多7.7小时,较下旬高2.33℃,多16.3小时,是水稻尤其是现推广的杂交稻(南优、威优、汕优2、3号等)抽穗扬花的有利时期。齐穗后到8月下旬有10天左右较好的光温条件,对提高结实率和增加粒重更为有利。因 Hanzhong area is rice and wheat (rape) two ripening areas, more rainy autumn and accompanied by cooling, such as improper sowing date, often form a large number of empty tablets, resulting in “autumn seal.” However, as early as the end of July, there was a problem of “hot ripening” again. Therefore, choosing the best heading date is the key issue of stable and high yield of rice. Hanzhong rice in Hanzhong area has a safe average daily temperature of 26.43 ℃ and a sunshine duration of 85.9 hours in early August, which is 1.03 ℃ and 7.7 hours more than in the middle of the year, 2.33 ℃ and 16.3 h more than the latter, respectively. Of hybrid rice (Nam You, Wei You, No. 3, Shanyou, etc.) heading flowering favorable period. After heading to late August 10 days or so better light and temperature conditions, to improve the seed setting rate and increase grain weight more favorable. because