针对近年来夏玉米生产过程中播种过深和播深不一致的问题,探讨播种深度对夏玉米冠层结构和光合特性的影响。选用郑单958(ZD958)和先玉335(XY335)为试验材料,设置3、5、7和9 cm 4个播种深度,并以4个播种深度混播作为对照(CK),研究播种深度对夏玉米冠层结构、光合特性和产量的影响。结果表明,播深不一致显著降低株高、穗位高、果穗长度等性状整齐度,影响群体冠层结构,造成ZD958和XY335的产量较3、5 cm分别下降2.6%、3.2%和0.9%、3.9%。播种过深,整个生育期内的植株性状整齐度和叶面积指数较低,穗位及底层透光率增加；SPAD值及比叶重较低,净光合速率和单株干物质积累下降；导致ZD958和XY335播深9 cm的产量较3、5 cm分别下降5.9%、6.4%和6.1%、8.8%。播深不一致及播种过深均显著降低群体整齐度,影响夏玉米产量形成；播深7和9 cm,即播种过深,夏玉米群体密度降低,冠层透光率增加,但其叶面积指数、SPAD值和比叶重降低,净光合速率和单株干物质积累下降,最终降低夏玉米产量。
英文摘要:
Owing to the problem of nonuniform and non-optimal sowing depth for summer maize production in China, this study was to explore the effects of sowing depth on canopy structure and photosynthetic characteristics of summer maize. Two summer maize hybrids, Zhengdan958 (ZD958) and Xianyu335 (XY335), were used as experimental materials. BySusingSuneven sowing depth as control (CK), 4 sowing depths (3, 5, 7 and 9 cm) were designed to investigate the effects of sowing depth on canopy structure, photosynthetic characteristics and grain yield of summer maize. The results showed that uneven sowing depth reduced the uniformity of plant traits (plant height and ear height) and ear length significantly, influencing canopy structure. Grain yield of ZD958 and XY335 at uneven sowing depth reduced by 2.6% and 0.9%, compared to the sowing depth of 3 cm; While reduced by 3.2% and 3.9%, compared to the sowing depth of 5 cm. Sown too deeply, leaf area index (LAI) and uniformity of plant traits of whole growth period were lower, and light transmission of ear layer and ground floor increased; SPAD value and specific leaf weight (SLW) were lower, and net photosynthetic rate and dry matter accumulation per plant decreased. Grain yield of ZD958 and XY335 at the sowing depth of 9 cm reduced by 5.9% and 6.1%, compared to the sowing depth of 3 cm; and reduced by 6.4% and 8.8%, compared to the sowing depth of 5 cm. Both uneven and too deep sowing depth reduced uniformity of plant traits significantly, then affecting yield formation. Sown too deeply, canopy density decreased and light transmission of canopy increased; But LAI, SPAD value, SLW, net photosynthetic rate and dry matter accumulation per plant were lower, finally reducing yield of summer maize.
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