Effects of different width configurations on photosynthetic characteristics, dry matter and nutrients accumulation, and yield of waxy sorghum in waxy sorghum-soybean intercropping system

【Objective】 The purpose of the study was to investigate the effects of different width configurations of waxy sorghum-soybean intercropping system on photosynthetic characteristics,dry matter and nutrient accumulation and yield of waxy sorghum,and to provide reference for the selection of suitable width configurations of waxy sorghum-soybean intercropping system and the high-yield,efficient and sustainable production of waxy sorghum.【Method】 Sole cropping waxy sorghum(CK) was used as control. Four width configurations were arranged based on the pattern of two rows of waxy sorghum intercropped with one row of soybean,which were T1:120 cm of width with 40 cm of narrow row spacing for waxy sorghum,80 cm of wide row spacing for waxy sorghum,and 40 cm of spacing between waxy sorghum and soybean;T2:130 cm of width with 50 cm of narrow row spacing for waxy sorghum,80 cm of wide row spacing for waxy sorghum,and 40 cm of spacing between waxy sorghum and soybean;T3:140 cm of width with 40 cm of narrow row spacing for waxy sorghum,100 cm of wide row spacing for waxy sorghum,and 50 cm of spacing between waxy sorghum and soybean;and T4:150 cm of width with 50 cm of narrow row spacing for waxy sorghum,100 cm of wide row spacing for waxy sorghum,and 50 cm of spacing between waxy sorghum and soybean. Photosynthetic characteristics of leaves of waxy sorghum were measured at flowering stage. Agronomic traits were measured at maturity stage. Dry matter accumulation,nutrient content,accumulation and yield were measured after harvest.【Result】 Width configuration had extremely significant effects on the SPAD value,net photosynthetic rate(P_n),stomatal conductance(G_s),and transpiration rate(T_r) of waxy sorghum leaves(P<0.01,the same below),but had no significant effect on the intercellular CO₂ concentration(C_i) of waxy sorghum(P>0.05,the same below). The SPAD value,P_n,G_s,and T_r,among different treatments were in the order of T3>T4>T1>T2>CK. Width configuration had extremely significant effects on dry matter accumulation in all organs of waxy sorghum(root,culm,leaf and spike). The dry matter accumulations of organs among different treatments were in the order of T3>T4>T1>T2>CK. Width configuration had extremely significant effects on the nutrients(nitrogen,phosphorus,potassium) contents and accumulations of organs(root,culm,leaf,and spike) in waxy sorghum. The nutrients contents and accumulations of each organ under different width configurations treatments were significantly higher than those of CK(P<0.05). Width configuration had extremely significant effects on the yield, spike length,grain number per spike and 1000-grain weight of waxy sorghum,while having no significant effects on the plant height and culm diameter. The yield,spike length,grain number per spike and 1000-grain weight among different treatments were in the order of T3>T4>T1>T2>CK.【Conclusion】 Suitable width configuration can improve the plants light environment,enhance the leaf photosynthetic capacity,promote the dry matter formations and nutrients absorption and accumulation in organs,optimize the spike structure,and thus increase yield of waxy sorghum plants. The 140 cm of width with 40 cm of narrow row spacing for waxy sorghum,100 cm of wide row spacing for waxy sorghum,and 50 cm of spacing between waxy sorghum and soybean can be used as the suitable field configuration of waxy sorghum-soybean intercropping system in Guizhou.