播期和密度对南疆春大豆光合特性及产量的影响

Effects of Sowing Dates and Densities on Photosynthetic Characteristics and Yield of Spring Soybean in Southern Xinjiang

为探究播期和种植密度对南疆春大豆光合特性和产量及其构成因素的影响,设置4个播期B1(4月7日)、B2(4月17日)、B3(4月27日)和B4(5月7日),3个密度M1(51.02万株·hm^(-2))、M2(30.86万株·hm^(-2))和M3(22.68万株·hm^(-2)),研究播期和种植密度对春大豆生育进程、叶面积指数、光合特性、干物质积累、产量及产量构成因素的影响。结果表明:B4相较于B1延长生育期6.3 d,但缩短了R4~R6阶段10.7 d。B4叶面积指数在R6期显著低于其他播期,并且各播期下增大种植密度均能显著增加叶面积指数。在R4期,B1播期叶片净光合速率分别比B2、B3和B4高29.75%、23.09%和39.40%,并在R6期仍保持较高的净光合速率和蒸腾速率。在R4期,M3干物质积累量随播期推迟显著增大,R6期则相反。晚播和增大种植密度会降低分枝荚数、分枝粒数及分枝粒重,从而降低产量。综上,在本研究处理范围内早播和降低种植密度能够保证大豆在R4和R6期有充足的阶段发育时间和较强的叶片光合能力,维持R6期有较高的叶面积指数、干物质积累量,并且增大分枝荚数、分枝粒数及分枝粒重,从而显著提升产量。

In order to investigate the effects of sowing date and planting density on photosynthetic characteristics,yield and its yield components of spring soybean in Southern Xinjiang,four sowing dates B1(April 7),B2(April 17),B3(April 27)and B4(May 7),and three densities M1(510200 plants·ha^(-1)),M2(308600 plants·ha^(-1))and M3(226800 plants·ha^(-1))were adopted.The effects of sowing date and planting density on growth process,leaf area index,photosynthetic characteristics,dry matter accumulation,yield and yield components of spring soybean were determined.The results showed that compared with B1 treatment,B4 prolonged the growth period by 6.3 days,but shortened the R4-R6 stages by 10.7 days.The LAT of B4 at R6 stage was significantly lower than that at other sowing dates,and the increase of planting density at each sowing date could significantly increase the LAI.At R4 stage,the net photosynthetic rate(NPR)of B1 was 2975%,2309%and 39.40%higher than that of B2,B3 and B4 respectively,and the NPR and transpiration rate were still higher at R6 stage.The dry matter accumulation in R4 stage increased gradually with the delay of sowing date,and the dry matter accumulation in M3 plant increased significantly,while the dry matter accumulation in R6 stage was contrary.Late sowing and increasing planting density would reduce the branches pods number,branch seeds number and branch seeds weight,thus reduce the yield.In conclusion,in the treatments of this study,early sowing and decreasing planting density could ensure sufficient development time and strong photosynthetic capacity of soybean leaves in R4 and R6 stages,maintain the R6 period had higher leaf area index,dry matter accumulation,and increase the branches pods number,branch seeds number and branch seeds weight,thus significantly improve yield.