Evapo-transpiration based scheduling of irrigation through drip for cotton (Gossypium hirsutum)

A field experiment was conducted during the winter season of 2001–02 and 2002–03 and summer season of 2002 and 2003 at Coimbatore, to find out the water requirement and water saving due to irrigation scheduling based on evapotranspiration (ET) through drip system compared to conventional irrigation for upland cotton (Gossypium hirsutum L.) crop. Scheduling of irrigation through drip at 0.8 Etc (crop evapotranspiration) was on a par with 1.0 Etc through drip. The total water requirement was 426.5 mm for winter crop and 467.3 mm for summer crop at 0.8 Etc compared to 902.8 mm and 1,002 mm, respectively, for conventional irrigation. The yield enhancement due to drip system during summer was 28.9, 44.5 and 61.5%, respectively, at 0.6, 0.8 and 1.0 Etc, while the yield enhancement was negligible during winter, as it coincided with heavy effective rainfall of 238 mm.