Abstract
Cotton-wheat (CW) is an important cropping system in Pakistan; however, delayed cultivation of cotton after wheat significantly deceases system productivity. Late-sown cotton crop suffers from heat stress, high fruit shedding and infestation of various pests and cotton leaf curl virus (CLCV). Therefore, early sowing of cotton is preferred to overcome these challenges. However, cotton planting is overlapped with the harvesting of wheat crop in CW cropping system. Since fallow land is unavailable, relay intercropping of cotton in wheat crop seems a viable option for early planting. This three-year field study evaluated the role of relay cropping of cotton in improving the productivity of CW cropping system and lowering CLCV infestation. Wheat was planted in 22.5 cm rows with no row skipped (W1), one row skipped after every three (W2), and six rows (W3) for planting cotton in 0.75 and 1.50 m apart rows. Early cotton was planted in fallow land (C1) and standing wheat in 0.75 (C2) and 1.50 m (C3) apart rows and conventional planting after wheat harvesting (C4). Yield losses of wheat crop ranged from 8.16 to 19.81% in W3 and W2, respectively compared W1. However, C2 and C3 treatments improved cotton yield by 86.07% and 64.89% suppressed CLCV infestation by 68.14% and 65.86%, respectively compared to C4. Moreover, net benefits from relay cropping (W2C2) were 2190.1 $ ha-1 in 2013-14, 1954.4 $ ha-1 in 2014-15 and 2559.5 $ ha-1 in 2015-16 in comparison with C1 (1543.5, 1311.7 and 1892.3 $ ha-1 during 2013-14, 2014-15 and 2015-16, respectively). The W2 resulted in higher cotton yield compared to W3 which is mainly attributed to double number of cotton rows in W2 than W3. It is concluded that cotton relay cropping (W2C2) resulted in the highest economic returns with minimum CLCV infestation. Therefore, W2C2 is recommended for improving the system productivity of CW cropping system.