Effect of Meteorological Factors on Grain Filling Rate of Semi-Winter Wheat
Four semi-winter wheat varieties Tanmai 98, Shannong 18, Xumai 33 and Wanmai 52 in Huanghuaihai winter wheat area were selected as test materials. Through the sowing date tests, the trends of grain filling rate and the influence of meteorological factors on the filling rate were analyzed by means of analysis of variance, correlation analysis, stepwise regression and path analysis. The results showed that the fluctuation of grain filling rate is the least and the 1000-grain weight is the highest in the normal sowing period, the late-sowed 10 d winter wheat has the highest volatility and smallest 1000-grain weight. The grain filling rate of Tanmai 98 is most stable and the 1000-grain weight is the highest in winter wheat area of North China, while the grain filling rate of Wanmai 52 is the highest in Huanghuai winter wheat area. The grain filling of semi-winter wheat usually lasts 35-39 days. The climate difference between north and south is one of the reasons for the different filling rates of winter wheat. The variation trends of the filling rate of semi-winter wheat in each sowing period are the same, and the change of filling rate is consistent with the change law of related significant meteorological factors. The peak period of grain filling generally appears 15-25 days later than flowering, and the appearance time is earlier of the maximum fil-ling rate of late-sowed winter wheat than the control treatment, which is not conducive to increasing the grain weight. The temperature conditions have significant effects on the grain filling rate of winter wheat, of which the highest temperature factor is the common key factor affecting the filling rate of different sowing dates and varieties. Path analysis showed that the effect of maximum temperature on filling rate is determined by its direct effect, while the effect of sunshine hours and minimum temperature on filling rate is consistent with indirect effect. The average of highest temperature has the most important effect on fil-ling rate, while the sunshine time and averaged minimum temperature influence the filling rate weakly. The averages of highest and lowest temperature and the sunshine hours are the limiting factors of the filling rate, of which the average of highest temperature has the greatest decision-making effect on the change of filling rate.