播期对大豆花荚期光合碳代谢及产量性状的影响OA

To clarify the effects of different sowing dates on photosynthetic carbon metabolism and yield of soybean at the flower and pod stage under water-fertilizer integration cultivation in the second accumulated temperature zone of Heilongjiang Province.field experiments were conducted at Heping pasture using cultivars Henong 71 and Longken 324.Three sowing treatments-early sowing(May 1st),normal sowing(May 10),and late sowing(May 16)-were applied to evaluate their effects on growth stages,agronomic traits,photosynthetic parameters,chlorophyll fluorescence,SPAD values,carbohydrate content,dry matter accumulation,and yield components.The results showed that with the delay of sowing date,the time required by soybean plants from sowing to R3 stage was gradually shortened,but the duration of R3 to R5 stage was gradually increased.Compared with the control,early sowing treatment prolonged vegetative growth period of soybean plants,promoted plant development,increased plant height,nodes number,gas exchange parameters,chlorophyll fluorescence parameters,carbohydrate content and dry matter accumulation,and finally increased the pods number per plant,seeds number per plant,seeds weight per plant,100-seed weight and yield.In 2023-2024,the soybean yield under early sowing treatment was the highest,and the soybean variety Henong 71 and Longken 324 increased by 2.4％-3.5％and 5.5％-5.6％compared with the control.Taken together,when the average temperature of the5 cm soil layer reaches(9.6±0.2)℃within3 days,it is the best sowing time for the second accumulated temperate zone in Heilongjiang Province.This study provides a theoretical basis for optimal sowing date selection of soybean in the second accumulated temperature zone of Heilongjiang Province.