[Effects of different colored plastic film mulching and planting density on dry matter accumulation and yield of spring maize.].

In order to investigate the effect of different colored plastic film mulching and planting density on spring maize dry matter accumulation and yield in the rain-fed area of the Northeast China, a complete combination field experiment which was comprised by three types of mulching (non-mulching, transparent plastic film mulching and black plastic film mulching) and five densities (60000, 67500, 75000, 82500 and 90000 plants·hm), was conducted to analyze the water and heat effect, dry matter accumulation and yield of spring maize (Liangyu 99). The results showed that, compared with the other mulching treatments, the black plastic film mulching treatment significantly increased the maize dry matter accumulation and maize biomass by 3.2%-8.2%. In mature stage, the biomass increased firstly and then decreased with the increasing plant density. When planting density was 82500 plants·hm, the biomass was the highest, which was 5.2%-28.3% higher than that of other plant density treatments. The mean soil temperature in prophase of transparent plastic film mulching treatment was 0.4-2.7 ℃ higher than that of other treatments, which accelerated the maize growth process and augmented the dry matter transportation amount (T), dry matter transportation efficiency (TE) and contribution rate of dry matter transportation to the grain yield (TC) of maize stalk and leaf. The T, TE, TC of leaf and leaf-stalk under 60000 plants·hm treatment were the highest. The highest T, TE, TC of stalk were observed under 75000 plants·hm treatment. In heading period, the water consumption and daily water consumption intensity of maize under the treatment of black film mulching were the largest, which were 9.4%-10.6% and 10.6%-24.5% higher than that of other mulching treatments, respectively. The highest water consumption and daily water consumption intensity were both obtained under 90000 plants·hm treatment, which increased by 6.8%-15.7% and 7.0%-20.0% compared with other plant density treatments. The combination of black film mulching and density of 82500 plants·hm significantly improved the water use efficiency of maize, which increased by 4.6%-40.9% compared with other treatments. In addition, it increased yield by 3.0%-39.7% compared with other treatments. At heading stage, the correlation between the dry matter amount of stalk and leaf and the yield and yield components was the biggest. Decreasing 1 kg·hm dry matter amount of stalk and leaf would decrease the population yield by almost 0.79 kg·hm. Decreasing 10% dry matter amount of stalk and leaf would decrease the yield by almost 10%. Based on increasing plant density, black film mulching was beneficial for increasing the dry matter accumulation and improving grain yield and water use efficiency of spring maize.