不同施氮量玉米超高产群体特征研究

在采用高产品种密植、深耕、精细播种、灌溉等高产栽培管理措施的条件下,研究不同施氮量对与高产形成有密切关系的群体特征进行了分析。结果表明,随施氮量增加,玉米单产逐渐增加,施氮量为450kg/hm²时单产高达13980.84kg/hm²;生物学产量、收获指数、叶面积指数、群体粒数、粒叶比等反映群体特征的大部分指标随施氮量增加均有不同程度的增加,少数指标如百粒重的变化则不明显。综合分析得出:与收获指数相比,生物学产量对子粒产量的贡献大,玉米营养体建成期间的干物质积累是超高产形成的基础,而灌浆期间的干物质积累则是超高产形成的关键;对产量与其构成因素的通径分析表明,群体粒数是产量的主要贡献因子,百粒重对产量的直接效应不大;玉米超高产群体具有较高的最大叶面积指数(LAI),且其群体叶面积变化动态比较平稳;群体源与库通过增施氮肥均增加的同时,反映源与库在量上相对关系的粒叶比也得到增加。

Canopy Characteristics of Super-high Yielding Maize Under Different Nitrogen Application

Several canopy characteristics which directly related to the formation of super-high yielding maize has been studied under three level nitrogen rates treatment depending on excellent management conditions such as using high-yield hybrid high-density, deep-plowing, precise-sowing, adequate water-supplying, and so forth. The main results were that the grain yield significantly increased with nitrogen applied increasing, the highest yield of 13 980.84 kg/ha attained at high N level. Most Canopy characteristics(biomass, harvest index, leaf area index, canopy grains, and ratio of grain number to leaf area) increased with the increase of nitrogen applied, but some characteristics such as 100-grain weight did not differ among three N application levels. When statistical comparisons of all measurements were made, the results also showed that the biomass played a more important role in the formation of super-high yielding compared with harvest index, and the dry matter accumulation from silking to maturity is more crucial than that of seedling to silking. Canopy grain number was the main contributor to high yield formation, and 100-grain weight was less important. Super-high yielding population had higher maximum leaf area index(LAI), and the trends of LAI changed smoothly than others. Ratio of grain number to leaf area increased under the condition of source and sink increased simultaneously by increasing nitrogen application.