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选用不同穗型、株型品种浚单20、内单314和京单28为材料,在3种种植密度(7.5万、8.25万和9.0万株/hm2)下,比较研究花粒期冠层不同层位叶片光合性能和根层根系活力的垂直变化及其关系,明确高密度条件下超高产春玉米生育后期根冠早衰及其相关机理,探索防衰增产的调控途径。结果表明,花粒期叶片的叶面积指数(LAI)均随密度增加逐渐增大,而不同层位叶片的SPAD值、光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)和根系活力均随密度增加而降低;浚单20各性状对密度变化的反应较内单314和京单28敏感,浚单20在高密度下子粒产量最高;灌浆期浚单20根系活力最大值出现在30～40 cm的土层,内单314和京单28最大值出现在20～30 cm的土层,浚单20根系活力下移速度比内单314和京单28快,这与后期植株叶片的SPAD值、LAI、Pn、Tr和Gs的下降有着必然联系。春玉米衰老过程中地上部与地下部密切相关,叶片衰老进程与根系活力空间下移进程一致。
In this study, different varieties of Xundan 20, Nendan 314 and Jingdan 28 were used to study the effects of different canopy types and plant types at three planting densities (75,000, 82,500 and 90,000 plants / hm2) The vertical changes of photosynthetic characteristics of leaf layer and the root activity of root layer and their relationship were studied. The preponderance of root and crown of super high yield spring maize and its related mechanism were clarified under high density to explore the regulation pathway of anti-aging and yield increase. The results showed that leaf area index (LAI) increased with the increase of density, but the leaf photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and Root vigor decreased with the increase of density; Xundan 20’s response to changes in density was more sensitive than Nei 314 and Jingdan 28, and Xundan 20 had the highest seed yield at high density; In the soil layer of 30-40 cm, the maximal values of inbred 314 and Jingdan 28 appeared in the soil layer of 20-30 cm. The vigor of Xundan 20 roots moved down faster than that of inbred 314 and Jingdan 28, SPAD value, LAI, Pn, Tr and Gs have a certain relationship. During the senescence process of spring maize, the aboveground and underground parts are closely related, and the leaf senescence process is consistent with the downward movement of root activity space.