[Effects of shading and plant density on ear development and plant productivity of spring maize in Northeast China].

It is important to investigate the effects of shading on maize ear characteristics and yield, which can provide references to variety breeding and agronomic technique improvement for coping with climate change and dense planting. An experiment was carried out with two varieties (compact type hybrid ZD909, flat type hybrid ND4) and two planting densities (45000 and 90000 plants·hm) at Gongzhuling City, Jilin Province. Two treatments were conducted for each variety and planting density, including shading (with a shading degree of 65% from small bell mouth stage to mature stage) and no shading treatment (CK). The results showed that shading affected maize ear development significantly. Shading delayed maize anthesis and silking stages, especially prolonging the length of anthesis-silking interval by 3-15 days compared with the CK. Moreover, shading decreased dry matter accumulation of spring maize significantly, leading to more than 50% (50.8%-87.0%) of reduction in grain yield. The negative effects of shading on ear characteristics and yield of spring maize with dense planting was greater than that with sparse planting. The variety with a dense plant type achieved fewer effects on ear characteristics and grain yield than the variety with a sparse plant type under shading and dense planting. The variety with a dense plant type had strong adaptability to ecological environment change and the consistency in density-tolerance and shade-tolerance.