Study On Annual Utilization Of Solar And Heat Resources Of Summer Maize And Winter Wheat In Double Late-cropping Patterns

The summer maize-winter wheat rotation is the main crop system in North China plain. The double late-cropping patterns of summer maize and winter wheat is of importance for annual high yield and high efficiency. In order to quantitatively analyze the effects of double late-cropping patterns of summer maize and winter wheat on increasing yield and high resource use efficiency, two cultivars of summer maize(Zhengdan958 and Denghai661) and one cultivar of winter wheat(Denghai5197) were sowed in the No.16 farmland of Denghai Seed Co. Ltd in Laizhou City, Shandong Province in 2008-2009. In addition, summer maize experiment was made simultaneously in Jining Institute of Agricultural Science and Liaocheng Institute of Agricultural Science. The effects of different sowing dates on the dry matter production, the photosynthesis characteristics and physiological characteristics of leaf, and annual yield performance of summer maize and winter wheat were analyzed, and distribution and utilization of annual solar and heat resources of summer maize and winter wheat were studied compared. The principal results were as follows:1. Annual yield and yield components of summer maize and winter wheat in double late-cropping patternsThe grain yield of direct-seeding of summer maize was higher than interplant, and harvest ears were increased significantly, but thousand-grains weight was reduced. The correlation coefficient between yield components and yield showed that harvest ears were the main factor and there was a positive and significant relation between harvest ears and yield components. There was a negative relation amang grains number, thousand-grains weight and yield components, but the correlation coefficient was smaller and insignificant. the spike number of winter wheat was deceased, and thousand-grains weight was increased, and grain number per spike and grain yield was increased firstly and then decreased with the sowing date postponed, the maximum yield occurred on October 15. The annual yield of summer maize (change interplant to direct-planting, and the sowing date postponed to June 15) and winter wheat (the sowing date postponed to October 15) in double late sowing-cropping patterns was the highest.2. Annual distribution and utilization of solar and heat resources of summer maize and winter wheat in double late-cropping patternsThe total growth days of direct-seeding of summer maize was shorter obviously than interplant, and the accumulative temperature and total solar radiation of direct-seeding were decreased respectively than interplant, which implied that distribution rate of solar and heat resources was lower than interplant. But utilization of solar resources of direct-seeding had obvious advantages, especially utilization of solar resources of grain was obviously improved.The accumulative temperature and total solar radiation of traditional sowing date of winter wheat was evidently higher than late sowing date due to the total growth days of traditional sowing date was more by 6-11d than late sowing date. The utilization of solar resources of stem, leaf, grain and whole plant of winter wheat which sowed on October 15 was higher on average than which sowed on October 8 and 22. That indicated that winter wheat which postponed sowing date properly could improve utilization of solar resources.The annual utilization of solar resources and accumulative temperature of summer maize which direct-seeding on June 15 and winter wheat which late sowed on October 15 were the highest by 3.6%-17.9% and 5.1%-25.0% than other sowing-date combinations.3 Accumulation and distribution of dry matter of summer maize and winter wheat in double late-cropping patternsDirect-seeding of summer maize had a higher accumulation of dry matter and a faster crop growth rate before flowering and after flowering compared with interplant, but the harvest index of direct-seeding was lower than interplant. The distribution rate of stem of summer maize was the biggest on flowering, and distribution rate of stem of direct-seeding was higher than interplant, but distribution rate of leaf was lower; the distribution rate of ear was the biggest on maturity, and distribution rate of ear of direct-seeding was lower than interplant. The correlation coefficient between distribution proportion of stem and leaf and distribution proportion of ear in different growth stages showed that there was a negative relation between distribution proportion of leaf and distribution proportion of ear on maturity, which meaned that the transport rate of dry matter from leaf to ear decreased.Accumulation of dry matter and crop growth rate of winter wheat declined with delay of sowing date before flowering, but which increased firstly and then decreased with the sowing date postponed after flowering. Accumulation of dry matter and crop growth rate of sowing on October 15 were higher respectively than which sowed on October 8 and 22.4 The photosynthesis characteristics of leaf of summer maizeThe key period of grain yield performance and gradual senescence of physiological function of leaf was after flowering. Net photosynthesis rate of ear leaf of maize decreased gradually with growth course. Leaf area index and net photosynthetic rate of direct-seeding were higher than interplant significantly from flowering to 30d after anthesis, then it was decreased faster, especially rate of decline of leaf area index and net photosynthetic rate of direct-seeding was larger than interplant, and which was obviously lower on maturity.Characters of grain filling by Richards'model showed direct-seeding reached the maximal grain-filling rate earlier than interplant, and the starting potential of direct-seeding was higher than interplant, while the grain filling period, active grain-filling period and Wmax were lower than interplant. The correlation coefficient between characteristic parameters of grain filling rate and thousand-grains weight showed that there was a positive and significant relation between active grain-filling period, growth weight during the period of maximal grain-filling rate, maximal grain-filling rate and thousand-grains weight. It showed the reason that active grain-filling period was shorter, growth weight during the period of maximal grain-filling rate was smaller, maximal grain-filling rate was slower which lead to decrease thousand-grains weight.The differences of content of chla and chl(a+b) of leaf of direct-seeding was smaller than interplant from flowering to 30d after anthesis, but which decreased faster from 30d after anthesis to maturity. On the whole filling period, content of chlb of leaf of direct-seeding was lower respectively than interplant. On the contrary, chl a/b and carotenoid content of leaf of direct-seeding was higher respectively than interplant.5. The aging enzyme activity of leaf of summer maizeActivity of SOD, CAT, POD and soluble protein content of leaf were different significantly between direct-seeding and interplant from flowering to middle filling period, and which were lower than interplant on maturity. MDA content promoted gradually with growth stage postponed. Content of MDA of direct-seeding was lower on average than interplant from flowering to middle filling period. But Content of MDA of direct-seeding ascended faster and higher significantly than interplant on later filling period. It indicated the lipid peroxidation extent of leaf of direct-seeding had enlarged on later filling period.Thus, the double late-cropping patterns had good performances on grain yield and resource use efficiency. The high annual yield and high production efficiency in double late-cropping patterns were mainly subject to the cropping season of maize, a C₄ plant with high photosynthetic efficiency. Directing-seeding was proved to be superior to interplant under the field planting condition. In order to enhance high solar and heat utilization efficiency and excavate yield potential, it's essential to improve the leaves photosynthesis efficiency and postpone their aging.