Effects Of Sulfur Application Level On Dry Matter Accumulation And Photosynthetic Characteristics Of Soybean

Sulfur is one of the necessary nutrient elements for plant growth,this paper aims to study the effect of sulfur on soybean in different growth stages.This experiment was conducted in the glass rainproof shed in Northeast Agricultural University in 2021.Taking Heinong 84（high protein variety）and Heinong 87（high oil variety）as experimental materials,soybean was cultivated by sand culture and leaching nutrient solution.After the opposite true leaf of soybean was fully unfolded,the nutrient solution with sulfur concentrations of 0.5 mmol/L,2.0 mmol/L and 8.0 mmol/L was used to irrigate daily.The phenotypic data and photosynthetic characteristics of soybean were measured at different growth stages.The dry weight of each period was measured;the yield of each treatment of the two varieties was me asured at the maturity stage of soybean,and the effects of different sulfur levels on soybean phenotype,dry matter accumulation,photosynthetic characteristics and yield were studied.The results show that:（1）The relationship of plant height of Heinong 84 and Heinong 87 under different sulfur levels in V3-R6 was medium sulfur>high sulfur>low sulfur.The leaf area of soybeans at different developmental stages was also different due to different sulfur levels.The correlation between the sulfur levels of the leaf area of the two varieties at V3–R6 stages was medium sulfur>high sulfur>low sulfur.（2）The correlations of dry matter weight of roots,stems,leaves,petioles,pods and whole plant of the two soybean varieties at different sulfur leve ls at different growth stages were medium sulfur>high sulfur>low sulfur.The root dry matter weight of the two varieties accumulated slowest in V₃-R₁ and fastest in R₂-R₄.The accumulation of stem dry matter weight was the slowest in V₃-R₁ stage and the fastest in R₂-R₄ stage;the accumulation of leaf dry matter weight was slow in V₃-R₁,the accumulation of leaf dry matter weight of Heinong 84 was the fastest in R₄-R₅,and that of Heinong 87 was the fastest in R₂-R₄.The accumulation of stem dry matter weight was the slowest in stage V₃-R₁,and the fastest in stage R₂-R₄;the dry weight of whole plant accumulated slowly in V₃-R₁ and rapidly in R₅-_R6.The effect of sulfur level on root dry matter weight of soybean was the smallest at V₃ stage,and Heinong 84 was the most affected at R₆ stage,while Heinong 87 was the most affected at R₂ stage.The effect of sulfur level on stem dry matter weight was the smallest in V₃,Heinong 84 was the largest in R₆,and Heinong 87 was the largest in R₂.The effect of sulfur level on leaf dry matter weight of Heinong 84 in R₂ and Heinong 87 in V₃ was the least,and that of R₆ was the most.The effect of sulfur level on stem dry matter weight of Heinong 84 and Heinong 87 was the least in R₂and V₃,and the greatest in R₆.The effects of 8mmol/L and 0.5 mmol/L sulfur on dry matter weight of Heinong 84 at R₂ stage were the smallest,and the effects of 2 mmol/L and 8 mmol/L and 0.5 mmol/L sulfur at V₃ stage were the smallest.Heinong 87 had the least effect on dry matter weight of soybean plants at V₃ stage,and the effect of sulfur level on dry matter weight of soybean plants was the largest at R₆ stage.（3）When the sulfur level was 2 mmol/L,it was the most favorable for the number of two-seed pods,three-seed pods,four-seed pods,total pods,grains per plant,total grain weight and100-seed weight of soybean.When the sulfur level was 0.5 mmol/L,it was the most unfavorable for the number of two-seed pods,three-seed pods,four-seed pods,total pods,grains per plant,total grain weight and 100-seed weight of soybean.（4）The correlations of Phi2,PhiNPQ,Relative Chlorophyll,Fm,Fs and Fv/Fm at V₃-R₆ stages under different sulfur levels were all medium sulfur>high sulfur>low sulfur,while the correlations of Phi NO and F0 at V₃-R₆ stages were all low sulfur>high sulfur>medium sulfur.Phi2 and Relative Chlorophyll increased first and then decreased in V₃-R₆.Phi2 of the two varieties was the largest at R₂ stage,Heinong 84 was the smallest at V₃ stage,and Heinong 87 was the smallest at R₄ stage.Relative Chlorophyll of two varieties was the lowest in V₃,Heinong 84was the highest in R₅ and Heinong 87 was the highest in R₄.Fm,Fs and F0 decreased first and then increased in V₃-R₆,and Fm,Fs and F0 of the two varieties were the largest in V₃,Fm,Fs and F0 of Heinong 84 were the smallest in R₄,and Fm,Fs and F0 of Heinong 87 were the smallest in R₂.（5）GOGAT,GS and SPS activities of 黑农84 and 黑农87 in different periods were medium sulfur>high sulfur>low sulfur.