The Approaches For Exploring Summer Maize Yield And Study On Appropriate Cropping System In Hebei Plain

The field experiments were carried out in loam soil located at Shenzhou(Hebei province, China). In the experiments,through comparing the high-yield cultivation system with the conventional cultivation system, and the effects of removing redundant organs on yield formation of high-yielding summer maize, which helped us understand the two ways for improving the yield of summer maize:(1) the exploration of colony formation;(2) the exploration of individual functions. Through the characteristics of annual water utilization to understand the relationship between two harvests in one year production and water resource supply and requirement; Finally, through comparing the spring maize with summer maize to explore the right way to change the maize cultivation. The main results and significant conclusions were as follows:1 study on community structureThe results indicated that the high-yield summer maize with higher LAI、LAD and canopy photosynthesis ability; and the total dry matter accumulation became bigger than conventional cultivation condition after 12 th leaf expanded, and the dry matter accumulation transfered from Stem&sheath and leaf to grains; what’s more, the high-yield cultivation had more days of active growing stage and higher economic coefficient. Through increasing effective ears to improve the potential of the community structure, and the yield raised 21.4%.2 effects of removing redundant organs on individual functionsThe results showed that: after removing redundancy, which increased the net photosynthetic rate and maximum grain-filling rate, and promoted the matter transport from vegetative organs to grains, and increased the 1000-grain weight. Tassel removal could improve light distribution in canopy. leaf stripped could prolong grain-filling period and decrease water consumption or water stress in dry year. Compared with control, Detasselled、leaf stripped and leaf stripped & detasselled treatments increased yield by 12.3%, 2.6% and 3.0% in 2013(rainy year); leaf stripped and leaf stripped & detasselled treatments increased yield by 6.1% and 8.8%, and detasselled had no effect on yield in 2014(dry year). Furthermore, with redundant leaves removal, the water consumption amount was decreased by 34.5~42.5 mm, and the water use efficiency was increased by 14.3%~17.2% compared with control(CK). The results indicated that detasselling and leaf stripping may offer a new methods for increasing grain yield of high-yielding summer maize.3 characteristics of annual water utilizationThe results showed that:(1) 2011-2012, compared to CK(conventional wheat planting), the yield of annual crops with Soil-coated plastic film mulching had no significant effect, but rainfed fell 15.4% on yield. The annual WUE showed the Soil-coated plastic film mulching> rainfed > CK; 2012-2013, the summer maize had no significant effect on yield, the winter wheat fell 57.3% and 22.8% compared with the CK on yield of wheat and annual. The Soil-coated plastic film mulching had no significant effect on annual yield, but annual WUE had improved significantly; 2013-2014, the Soil-coated plastic film mulching with one-time 75 mm irrigation, rainfed, which yield had fell significantly, the annual yield had fell 3.4%~8.5% and 27.4%~59.8% compared to CK. The WUE showed the Soil-coated plastic film mulching> CK> B&RF(bare and rainfed).(2) Crop water consumption intensity and seasonal evapotranspiration showed the bare treatments > Soil-coated plastic film mulching before jointing of winter wheat, and then showed CK> The Soil-coated plastic film mulching > B&RF. In summer maize, the results showed CK> B&RF > The Soil-coated plastic film mulching in 2011-2013; in 2013-2014, the rainfed treatments showed a low level.(3) The soil water storage of 2 m depth soil body reduced irreversibly year by year.(4) The annual farmland water balance average consumption of Soil-coated plastic film mulching with one-time 75 mm irrigation, M&RF(Soil-coated plastic film mulching & rainfed), B&RF and CK were 200 mm、140 mm、160 mm and 390 mm.The results showed that conventional cultivation condition with 225 mm irrigation or Soil-coated plastic film mulching with one-time 75 mm irrigation in winter wheat and 75 mm irrigation before sowing summer maize couldn’t afford the water consumption for two harvests in one year production in Hebei Plain, enough irrigation was the necessary condition for the current cropping system.4 Compare spring maize with summer maizeSpring maize were better than summer maize on coupling of climate resources, the yield improved 8.8%. The ear growth rate of spring maize was slower, and reached later, but it had more days of active growing stage, the 1000-grain weight raised significantly. The yield potential of summer maize had not been exerted fully due to limitation of winter wheat growing season, the 1000-grain weight was lighter. Through expanding the capacity of grains, the yield of denghai 605 and denghai 661 increased 23.1% and 14.3% as spring maize. It’s a new way to combination of water-save and high-yield by expanding the capacity of grains and days of active growing stage, and to find new varieties for making full use of the climate condition.