Growth and development of soybean under changing light environments in relay intercropping system

Abstract

As compared to T0, treatment T6 increased the PAR_T and R:FR ratio at soybean canopy by 77% and 37% (V₂), 70% and 34% (V₅), and 41% and 36% (R₁), respectively. This improved light environment in T6 considerably enhanced the leaf area index, SPAD values and photosynthetic rate of soybean plants by 66%, 25% and 49% at R₁, respectively than T0. Similarly, relative to control, T6 also increased the stem diameter (by 29%) but decreased the plant height (by 23%) which in turn significantly increased stem breaking strength (by 87%) by reducing the lodging rate (by 59%) of soybean plants. Overall, under T6, relay-cropped soybean produced 78% of sole soybean seed-yield, and relay-cropped maize produced 81% of sole maize seed-yield. Our findings implied that by maintaining the optimum level of PAR_T (from 60% to 80%) and R:FR ratio (0.9 to 1.1), we can improve morphological and photosynthetic characteristics of soybean plants in MS_R. Therefore, more attention should be paid to the light environment when considering the sustainability of MS_R via appropriate planting pattern selection.