春玉米中单909农艺性状和产量对密植的响应及其在东北不同区域的差异

增密是实现东北春玉米大面积增产的关键技术，水热和土壤等区域生态条件是决定作物密度高低的关键因素。东北的区域生态条件差异显著, 阐明作物对密度和区域生态条件的综合响应对东北春玉米增密增产具有重要的理论与实践指导意义。本研究以中单909为供试品种, 在代表东北不同生态条件的辽宁沈阳、吉林公主岭、黑龙江哈尔滨、吉林桦甸和吉林洮南等5个试验点设置密度试验, 研究春玉米农艺性状与产量对密度和区域生态条件的综合响应。结果表明, 密植导致株高与穗位高增加, 茎粗降低。区域生态条件主要影响玉米株高, 对茎粗和穗位高的影响不显著。随密度增加, 群体叶面积指数(LAI)显著增加, 尤其是随热量条件改善, 群体LAI呈显著增加趋势。在一定范围内, 密植可以通过提高群体干物质生产力弥补单株生产力的下降, 从而获得高产; 本试验条件下, 中单909在9.00万株 hm^-2左右密度下的密植增产潜力得到充分发挥, 而区域间因生态条件不同, 高产种植密度存在显著差异, 其适宜密植范围在8.6~9.6万株hm^-2之间。

Effects of Plant Density on Agronomic Traits and Yield in Spring Maize Zhongdan 909 and Their Regional Differences in Northeast China

It is well evidenced that higher plant density will give higher grain yields, and the ecological situations of precipitation, air temperature and soil conditions are the key factors of plant density decision. Given the great regional variations of precipitation and temperature, to learn the integrated responses of crop growth to plant density and regional ecological situation will play an important role in designing optimal density with higher yield in Northeast China. Field experiments were conducted in Shenyang, Gongzhuling, Harbin, Huadian, and Taonan using spring maize cultivar Zhongdan 909 to determine the comprehensive effects of plant densities and regional ecological conditions on crop agronomic characters and grain yield. The results showed that, higher plant density significantly increased the plant height and ear height, and decreased the stem diameter. Regional ecological conditions had significant effect on plant height but less effect on ear height and stem diameter. With the increase of plant density, the population leaf area index (LAI) increased significantly. Meanwhile, the increment of heat and precipitation increased the LAI. The increase of population dry matter accumulation under higher plant density offset the decrease of dry matter accumulation per plant which ensured the higher grain yield. Under the plant density of 9.00 × 10⁴ plant ha^-1, the potential productivity for cultivar Zhongdan 909 was fully developed in the experiments. But regional differences of precipitation, air temperature and soil characters influenced the appropriate plant density. The optimum plant density should be from 8.6 to9.6×10⁴ plant ha^-1 under different ecological conditions in Northeast China.