Studies on the Growth and Yields of Winter Wheat in Highlands : III. Effects of high temperature in winter and early spring upon the growth and yields of winter wheat : lV. Effects of high soil temperature in winter and early spring upon the growth and yields of winter wheat

Abstract

We have reported by the statistical study that the correlation coefficients between the yield-constitutional factors of winter wheat and atmospheric and soil temperatures before and after severe winter were very high in highlands. Therefore we studied experimentally the influence of raising atmospheric and soil temperatures during December to April upon the growth and yields of wheat. The results were as follows: 1) Higher atmospheric temperature and higher soil temperature treatments in early March to late March increased the number of ripened grains per ear, probably as the results of the recovery effect resulted from the vigorous vegetative growth and also healthy differentiation induced by higher temperature. Higher temperature in early to mid-April increased the number of ears, probably as the results of effective spring tillering. By these reasons the yields were increased by the above two treatments. 2) Though higher temperature in December to February increased the number of stem in early spring period, it was decreased at the harvest time on account of the death of spikelets by subsequent cold weather. Consequently the yields were not increased by these treatment, although the growth of wheat was promoted