密度对中熟春大豆冠层结构及光合特性的影响

Density Affecting Canopy Structure and Photosynthetic Characteristics of Medium Maturity Spring Soybean

为明确种植密度对滴灌中熟春大豆冠层结构及光合特性的影响规律。试验以中熟春大豆品种‘新大豆27号’和品系‘11-109’为试验材料,大田条件下设置18.0万株/hm^2(D_1)、28.5万株/hm^2(D_2)、36.0万株/hm^2(D_3)3个不同种植密度,并对其群体上、中、下3个冠层的叶面积指数(LAI)、叶绿素含量(SPAD值)、净光合速率(Pn)、干物质积累量及产量做了系统测定。结果表明,密度由D_1增加到D_2,叶面积指数、干物质积累量、产量均显著增加;密度由D2增至D3,叶面积指数继续增加,而干物质和产量不再继续增加;植株7节以下叶片的叶绿素含量和净光合速率明显降低,提高结荚节位,降低单株粒数、粒数和经济系数;‘新大豆27号’的叶面积指数、干物质积累、叶片光合速率等对密度的响应不如‘11-109’敏感。D_2是两品种(系)的适宜密度,‘新大豆27号’籽粒产量为5551.13 kg/hm^2,较‘11-109’高14.73%。超高产春大豆品种的冠层结构、光合特性及产量对密度的响应不如高产品种敏感。

The aim is to investigate the effect law of planting density on canopy structure and photosynthetic characteristics of medium maturity spring soybean under drip irrigation.‘Xindadou 27＇and‘11-109＇were used as the experiment materials, and three densities [18.0×10~4（D1）, 28.5×10~4（D2）, 36.0×10~4（D3）/hm^2] were set in the field experiment, and the canopy leaf area index（LAI）, chlorophyll content（SPAD）, net photosynthetic rate（Pn）, dry matter accumulation and yield were determined systematically under different treatments. The results showed that with the density increased from D1 to D2, LAI, dry matter accumulation and yield increased significantly; with the density increased from D2 to D3, LAI continued to increase, while dry matter and yield no longer increased. With the planting density increasing, SPAD and Pn of leaves below the seventh joint position decreased significantly, and the podding position was raised. Besides, grain number per plant, grain number and economic coefficient also decreased significantly;‘Xindadou 27＇was not sensitive to density change compared with‘11-109＇on LAI, dry matter accumulation and Pn. D2 was the suitable density for the two varieties（strains） of spring soybean, the grain yield of‘Xingdadou 27 ＇was 5551.13 kg/hm^2, which was 14.73%higher than that of‘11-109＇. The responses of canopy structure, photosynthetic characteristics and yield of super-high yield varieties to planting density were not as sensitive as those of high yield varieties.