| In order to explore the new cropping system which fit to the change of cilmate, to take full advantage of high photosynthetic and high resources utilization efficiency of C4 crop, the cropping systems, adaptability of varieties and key cultivation techniques of yield , yield performance, resources efficiency were studied on double cropping system in Huanghaihai regions.The results showed as follows:Comparing the grain yield performance and resource efficiency between double cropping maize and winter wheat-summer maize cropping system, the results showed that the annual yield of double cropping maize was slightly high, the average yield of two years increased by 2.3%; annual light energy and temperature production efficiency increased by 26.1% and 6.5% , respectively; the economic benefit increased by 1 628 Yuan ha-1 and there was a farmland fallow of 140 days. It showed that the double-cropping maize system with facilitating soil fallow and avoiding winter freezing injure and drought was of high light and temperature efficiency, good economic efficiency, simplified planting patterns, and ecological security model, which would be a supplement to winter wheat-summer maize model, and also be a remedy to winter wheat loss in Huanghaihai regions.The adaptability of varieties in different seasonal conditions was studied. The results showed that: the accumulated temperature of early spring and late summer in different areas and years had different impacts on each growth processes of species. Most varieties, about 33.2% of the total, seeded in early spring and late summer could get a medium level of output(5 737–8 639 kg ha-1), accounting for important indicator of variety selection. Yinong 103 was carried with characteristics of high and stable yields in the early spring, Zhengdan 958 was carried to ensure stable production at the second quarter in the late summer. Meanwhile, the adaptability of one variety in early spring and late summer to examine varieties adaptability with the environment, also can reflect the comprehensive performance of fine varieties.Analysis on yield effect, resource allocation and matter production efficiency of double cropping maize b the sowing date, the results showed that the whole year yield was the highest at the first season sowing on March 23 and March 29, the second season sowing on July 22. And temperature ratio of double season close to 1:1, the ratio of light energy close to 1.3:1, it means early spring biased allocation of light resources, accumulated temperature distribute close to 1/2. Suitable sowing date for early spring was earlier and using plastic film mulching, for avoiding frost damage. Late summer sowing date should be after the first season crop harvest, and delay the harvest date to increase the utilization of resources。Analysis on yield performances of maize in different densities. The results showed that: As the density increased, the changes of yield performance parameters were different, and the value of EN(ear number), MLAI(mean leaf area index) were increased, MNAR(mean net assimilation rate), HI(harvest index), GN(grain number per ear), GW(grain weight) were decreased. The density and yield are accordant, when the density increased to 8.25×104 plant ha-1, the yield would be decreased, the anniversary highest yield of planting density was 8.25×104 plant ha-1on early spring and late summer.Three cultivation ways were designed, including strip deep tillage, traditional tillage and no-tillage. The results showed that strip deep tillage yield increased by 11.1% and 17.6%, respectively; dry matter yield increased by 8.5% and 12.9%, respectively, comparing to that of the conventional tillage and no-tillage treatments. LAI after flowering under long duration benefit for increasing dry matter accumulation in strip deep tillage. The increases of group LAD(leaf area duration), MCGR(mean crop grow rate), MLAI, MNAR, flowering ear leaf SPAD value and Pn(net photosynthetic rate) enhanced photosynthetic rate and rate of photosynthetic product transfer to the grain, also increased the grain number and grain weight. Strip deep rotary tillage improves the yield performance of spring maize, so as to acquire high yield.
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