密植条件下玉米品种混播对夏玉米光合性能及产量的影响

探究密植条件下玉米品种混播对夏玉米光合性能及产量的影响。在82 500株 hm ^-2种植密度下, 选用郑单958 (ZD958)和登海605 (DH605), 在大田条件下设置M(两种子相同数量混合后随机混播)、1行郑单958和1行登海605混播(1:1)、2行郑单958和2行登海605混播(2:2)、单播郑单958 (SZD958)和单播登海605 (SDH605) 5个水平, 研究密植条件下玉米品种混播对黄淮海夏玉米产量、群体干物质积累量、净光合速率、叶片衰老酶活性、冠层透光率等的影响。两年结果表明, ZD958和DH605混播可显著改善玉米生育后期群体透光率, 使叶面积指数、叶绿素含量和穂位叶净光合速率较单播显著增加, 干物质积累量显著增加。混播处理较单播增加生育后期超氧化物歧化酶(SOD)、过氧化物酶(POD)活性和可溶性蛋白含量, 与此同时, 丙二醛(MDA)含量降低。混播显著增加玉米群体产量, 究其原因是穗粒数和千粒重的有效增加。M、1:1、2:2处理的两年平均产量较SZD958和SDH605分别增加11.47%、8.70%、8.48%和9.30%、6.42%、6.20%, 其中M、1:1、2:2处理间没有显著差异。混播处理通过优化冠层结构, 改善群体通风透光条件, 延缓叶片衰老, 减缓花后叶面积指数和叶绿素含量降低, 保持较高的净光合速率, 致使群体干物质积累量增加, 产量提高。可见, 合理品种搭配的混播栽培可显著提高密植夏玉米产量, 是提高黄淮海区夏玉米产量的可选途径之一。

Effects of Mixed-cropping with Different Varieties on Photosynthetic Characteristics and Yield of Summer Maize under Close Planting Condition

During the 2016 and 2017 growing seasons in Shandong, a province in the North China Plain, using Zhengdan 958 and Denghai 605 for five treatments, including M (random sowing after mixing in the same proportion), 1:1 (raw ratio of ZD958 to DH605 is 1:1), 2:2 (raw ratio of ZD958 to DH605 is 2:2), and two monoculture treatments (SDH605 and SDH605). This experiment was conducted to explore the effects of mixed-cropping on grain yield, amount of dry matter of groups, net photosynthetic rate, anti-oxidative metabolism, canopy structure of summer maize under a density of 82 500 plants ha ^-1. The two-year results showed that mixed-cropping significantly improved canopy light transmittance, leaf area index, chlorophyll content, net photosynthetic rate and dry matter accumulation. Superoxide dismutase (SOD), peroxidase (POD) activities and soluble protein content increased significantly, but the content of MDA decreased under mixed-cropping. The grain yield of summer maize increased significantly under mixed-cropping, due to the increase in grains per spike and 1000-kernel weight. Compared with SZD958 and SDH605, the two-year average grain yields of M, 1:1, 2:2 increased by 11.47%, 8.70%, 8.48% and 9.30%, 6.42%, 6.20%, respectively. There were no significant difference among M, 1:1 and 2:2 treatments. Mixed-cropping formed high-efficiency canopy structure, created better aeration and transmittance conditions, delayed leaf senescence, slowed down the decrease of leaf area index and chlorophyll content after anthesis, maintained higher net photosynthetic rate and increased dry matter accumulation, eventually resulted in the higher grain yield of summer maize. It is concluded that mixed-cropping with reasonable varieties can significantly increase the yield of close planting summer maize, which is one of the optional cultivation patterns to increase maize yield in the Yellow-Huaihe-Haihe Rivers Plain．