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为探求不同行距配置下高密夏玉米群体光合性能及产量形成对群体光环境变化的响应,本试验在75 000(D1)和90 000(D2)株/hm2 2个种植密度下,研究了3个行距配置(等行距S1:60cm+60cm;大宽窄行S2:80cm+40cm;小宽窄行S3:60cm+45cm)对夏玉米(郑单958)群体光分布、全株叶片光合特性及产量的影响。结果表明:1)随着种植密度增加,夏玉米群体上层光截获显著增加,下层光截获显著降低。与等行距相比,大宽窄行处理中下层透光率增加,但群体光总截获降低。小宽窄行处理显著增加了穗位层的光截获。2)全株叶片SPAD值、最大光能转换效率(Fv/Fm)和同一光照水平下净光合速率(Photosynthetic rate,Pn)随冠层垂直深入呈现出单峰曲线变化,峰值出现在穗位层;随密度增加全株叶片SPAD值、Fv/Fm和Pn呈现降低趋势,下部叶片降低显著,行距配置之间全株叶片光合生理活性总体上表现为小宽窄行>大宽窄行>等行距。叶片Pn与冠层内光照强度具有极显著正相关关系,表明光照强度是限制玉米冠层中下部叶片Pn的主要原因。3)密度增大后产量增加,但未达显著水平。同一密度处理下,小宽窄行处理产量显著增加。随着密度增加,宽窄行增产效应增加。总体表明,密植条件下,小宽窄行处理下玉米冠层内光分布比较合理,群体穗位层截获光合有效辐射较多,光合能力和干物质生产能力增强,更有利于夏玉米产量提高。
In order to explore the response of photosynthetic characteristics and yield formation of high density summer maize populations under different row spacing to the changes of population light environment, under the density of 75 000 (D1) and 90 000 (D2) plants / hm2, Effects of row spacing (S1: 60cm + 60cm; wide and narrow lines S2: 80cm + 40cm; small and narrow lines S3: 60cm + 45cm) on light distribution, photosynthetic characteristics and yield of whole plant in summer maize (Zhengdan 958) . The results showed that: 1) With the increase of planting density, the light interception of upper maize population increased significantly and the light interception of lower maize decreased significantly. Compared with the same row spacing, the light transmittance of the middle and lower layers increased while the total light interception decreased. Small width line treatment significantly increased the panicle light interception. 2) The SPAD value, Fv / Fm and the photosynthetic rate (Pn) of the whole plant showed a single peak curve with the vertical depth of the canopy, and the peak appeared in the ear layer The SPAD value, Fv / Fm and Pn of the whole plant tended to decrease with the increase of the density, and the lower leaves decreased significantly. The photosynthetic physiological activities of the whole plant in the row spacing configuration generally showed the width, width, width and width. There was a significant positive correlation between leaf Pn and light intensity in the canopy, indicating that light intensity was the main reason for limiting Pn in the middle and lower leaves of corn canopy. 3) Yield increased with increasing density, but did not reach significant level. Under the same density treatment, the production of small width and narrow row output increased significantly. As density increases, widening and narrowing production increases. Overall, under close planting conditions, the light distribution in maize canopy under small width and narrow row treatment was more reasonable, photosynthetic active radiation was intercepted at ear layer, and the photosynthetic capacity and dry matter production capacity were enhanced, which was more conducive to the increase of summer maize yield.