The optimal time of wheat harvest is the second fortnight of April, while Bt cotton is sown in March in cotton-based cropping systems of Pakistan. There is a time conflict of four to six weeks between harvesting of wheat and sowing of Bt cotton. Relay-intercropping of cotton in wheat crop near to maturity could help to resolve the conflict. The information regarding the effect of relay-intercropping on growth and quality of cotton is scanty. This two-year study compared the growth and fiber quality of relay-intercropped Bt cotton (sown in early/late March) in standing wheat crop with conventionally-tilled (CT) cotton planted after wheat harvest in late April. The relay-intercropped cotton was sown on ridges/beds in wheat, whereas CT cotton was sown after wheat harvest in late April or sown on fallow land in early or late March at Multan and Vehari sites. The CT Bt cotton grown on fallow land in early March had the best performance as indicated by plant growth and fiber quality. However, the relay-intercropped Bt cotton in bed-sown wheat had better growth and fiber quality than the CT cotton planted after wheat harvest in late April. At both sites, the taller plants and higher biomass production were recorded in relay-intercropped Bt cotton in bed-sown wheat in early March as compared with the CT cotton sown after harvest of flat-sown wheat in late April. Fiber firmness, its uniformity, length and strength were also improved in the relay-intercropped Bt cotton in bed-sown wheat in early March as compared to CT cotton sown after wheat harvest in late April. In conclusion, relay intercropping of Bt cotton in the standing wheat during early March improved plant growth and fiber quality in cotton-wheat cropping system.
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