[Effects of row spacing on canopy structure and grain-filling characteristics of high-yield summer maize]

Using two summer maize (Zea mays L.) varieties Zhengdan 958 and Xianyu 335, a field experiment was conducted to study the regulatory effects of row-spacing (equidistant row and narrow-wide row) and plant-spot spacing arrangement (1 plant per spot, 2 plants per spot, 3 plants per spot) on grain yield components, canopy structure and photosynthetic characteristics after anthesis under plant population density 7.5 x 10(4) plants x hm(-2). Moreover, the characters of grain-filling were simulated by Richards' model. The results suggested that yield, dry matter accumulated, crop growth rate, grain-filling rate, canopy photosynthesis capacity were higher under wide-narrow row than under equidistant row, and were higher for 2 plants per spot than for 1 or 3 plants per spot. The highest maize yields (13.12 and 13.72 t x hm(-2) for Zhengdan 958 and Xianyu 335, respectively) were observed under wide-narrow row with 2 plants per spot. Under this pattern, internal illumination condition of the canopy, net photosynthetic rate and leaf area index were improved, and the contradiction between the plant individual and group was alleviated. Meanwhile, grain-filling capacity was promoted and accumulated amount of dry matter was elevated ultimately. It was concluded that wide-narrow pattern with 2 plants per spot is an effective cultivation pattern to increase maize yield in Huang-Huai-Hai Plain.