| This experiment conducted in the condition of farm field. By using split-plot design with three variety (Xianyu 335, Denghai 618 and Jindan73) and five densities (from 4000-8000 plants /666.7 m2), researched on effect of planting density on plant traits, photosynthetic characteristics, dry matter accumulation and distribution characteristics, yield and yield factors of super-high-yield (1300-1500 kg/666.7 m2) maize. The study results as follows:1. Being processed different varieties and densities, Jindan 73 is 1448.44kg/666.7 m2 that has the highest yield of 8000 plants/666.7 m2, which exceedes the national record of Denghai 618. It explains that Jindan 73 is more adaptable than Denghai 618 about the ecological environment of Ningxia. It has the major yield-increasing potential and can be used as the one of preferred super-high-yield cultivated variety2. Analysis by synthesis, over 1300 kg yield levels of density processing results that: Super-high-yield maize varieties of over the 1300 kg/666.7 m2 yield level in Ningxia irrigation area, the reasonable plant density limit should be more than 7000 plants/666.7 m2.3. The super-high-yield maize yield components of factors on the yield of the regression equation is y=1115.55+0.06x(actual kernels)+13.87x(lines per spike)-3.32x(number of grains per line)-7.30x(100-grain weight), the liners per spike and actual kernels are major factors of all the factors. Therefore, by increasing the planting density to raise the number of harvested grain is the basic requirement of super-high-yield.4. With the increasing of planting density, plant height, ear height, the plant lodging percentage and barren tip length were increased, however, stem diameter, ear length, ear diameter, liners per spike, number of grains per line, grain weight per ear,100-grain weight and test weight show different degrees of decline with the increasing of planting density.5. Planting density affects on the photosynthetic traits of each type mainly in later period. Single plant leaf area, chlorophyll content, transmittance rate of different layers of corn at silkin, Fv/Fm and Fv/Fo of ear leaf were declined with the increasing of the density. But LAI and leaf Fo were increased with the increasing of the density.6. Analysis by synthesis, more than 1300kg/666.7 m2 that dry matter accumulation of each processing results, the references about dry matter accumulation at different development stages of Ningxia super-high-yield maize are:Seedling stage is 2.95 kg/666.7 m2, Jointing stage is 188.17 kg/666.7 m2, Big trumpet stage is 505.21 kg/666.7 m2, Silking stage is 1049.29 kg/666.7m2,15-day after silk is 1501.35 kg/666.7 m2; 15-day after silk is 1824.20 kg/666.7 m2 and maturity stage is 2534.31 kg/666.7 m2.7. Among the super-high-yield maize organs dry matter transfers, stem sheath has the biggest amount of dry matter transfer and rate of contribution to the grain. Although maize bracts has the biggest transfer rate because of the dry matter accumulation quantity is little, so the rate of contribution about the yield is smaller. For the super-high-yield maize, the rate of contribution of vegetative organs dry matter transfer to the grain accounted for 17.70%.8. The reference value of main agronomic characters of super-high-yield (1300-1500 kg/ 666.7m2) maize in Ningxia is:plant height is about 360 cm, grain weight per ear is about 215 g, spike grain number is about 580 grains, ear length is at 16-17 cm, ear diameter is at 5.0-5.5 cm, test weight is about700 g/L and 100-grain weight is at 37-38 g. |
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