Responses of Soybean Dry Matter Production, Phosphorus Accumulation, and Seed Yield to Sowing Time under Relay Intercropping with Maize

Soybean production under maize-soybean relay-intercropping system (MSICS) is vulnerable to shading. A study was initiated to investigate the effects of three sowing-times: ST1, 90; ST2, 70; and ST3, 50 days of co-growth period and two phosphorus-rates: P-0, 0; and P-60, 60 kg P ha(-1) on soybean under MSICS. Results revealed that ST3 significantly increased the photosynthetically active radiations, leaf area index, and photosynthetic rate by 72% and 58%, and 61% and 38%, and 6% and 8%, respectively, at full-flowering and full-pod stage of soybean than ST1. Treatment ST3, increased the total dry-matter (TDM) and the highest TDM was reached at full-seed (R-6) stage. Similarly, ST3 considerably increased the dry-matter partitioning to pods and seeds, relative to ST1, soybean under ST3 at R-6 had 35% and 30% higher pod and seed dry-matter, respectively. Moreover, ST3 exhibited the maximum seed-yield (mean 1829.5 kg ha(-1)) for both years of this study. Soybean under ST3 with P-60 accumulated 38% higher P, and increased the P content in pods and seeds by 36% and 33%, respectively at R-6 than ST1. These results imply that by selecting the appropriate sowing-time and phosphorus-rate for soybean, we can increase the TDM and seed-yield of soybean under MSICS.