[Response of grain filling characteristics of maize to sowing date.] / 玉米籽粒灌浆特性对播期的响应.

To study the effect of different sowing dates on the process of grain filling characteristics, Jingke 528 (JK528) and Zhengdan 958 (ZD958) were used in the field experiment with two sowing dates (10th April and 14th May). The results showed that the 100-grain dry mass and yield of JK528 and ZD958 with the early spring sowing were significantly higher than that with the spring sowing date, which increased by 6.8% and 10.1%, 17.8% and 9.2%, respectively. The maximum grain filling rate (Gmax) and the average grain filling rate (Gave) were higher with the early spring sowing than that with the spring sowing date, while the active grain filling period (P) showed an opposite trend. The 100-grain mass and yield of JK528 were significantly improved by 7.4 g and 1189.6 kg·hm-2 compared to ZD958, with the increase of 21.6% and 10.8%, respectively. The P of ZD958 was higher than that of JK528, while Wmax, Gmax, Gave and Tmax of JK528 were higher than that of ZD958. The average grain filling rate of JK528 during early and mid grain filling stages was higher than that of late grain filling stages, which was also higher than that of ZD958 at the same sowing date. Furthermore, correlation analysis revealed that the mean temperature and the accumulated temperature were significantly positively correlated with the grain dry matter accumulation. Therefore, the full use of hot-ray resources and the increase of the mean grain-filling rate could improve maize grain yield. The higher grain filling rate during early and mid grain filling stages in JK528 could compensate for the short active grain filling period, leading to higher yields under different sowing dates.

[Dynamic characteristics of leaf area index and allocation characters of ecological resources for different yielding spring maize populations].

By using 3-year field experimental results and related meteorological observation data, the dynamic characteristics of leaf area index (LAI) and the allocation characters of ecological resources for different yielding spring maize (Zea Mays L.) population in Huadian of Jilin Province were studied. The results showed that the dynamic characteristics of relative LAI, with the relative growth days of test population, relative effective accumulated temperature, relative sunshine hours and relative rainfall as independent variables, fitted rational formula y = (a + bx) /(1 + cx + dx2), and the regression equation of maize yield with the ratios of growth days before and after silking (x1), effective accumulated temperature before and after silking (x2), rainfall before and after silking (x3), and sunshine hours before and after silking (x4) was y = 5465.19 + 17810.64x(1) - 23236.14x(2) + 4093.41x(3) + 6287.37x(4) (R2 = 0. 8187, P < 0.01), with the effects of these ecological factors on yield being in the sequence of x1 > x2 > x3 > x4 according to the absolute values of partial regression coefficients. In super high yielding (15499.86 kg x hm(-2)) spring maize population, the allocation ratios of x1, x2, x3, and x4 were 1.43, 1.41, 1.44, and 1.40, respectively. Therefore, in Northeast China, appropriate early sowing of spring maize to prolong its growth days with more rainfall and sunshine hours before silking could attain high yielding, and high or super high yield could be achieved when the allocation ratios of x1, x2, x3, and x4 were all about 1.4.