Water Management in Cotton

Population growth, water shortage and climate change are among the major challenges to global food security. Extreme temperature events and a change in precipitation pattern are expected to occur with various intensities in different parts of the world. Historical climate data suggest an increase in temperature, erratic rainfall and events of drought. Although cotton (Gossypium species) is a drought-tolerant crop, flowering and blooming are the sensitive stages in life cycle where water stress can cause detrimental impact on yield and fiber quality. In this scenario, improved irrigation management mitigates the negative effects associated with drought. Supplemental irrigation can prevent dryland yield fluctuations for greater yield and better fiber quality. Meeting the full crop water requirement is a challenge due to limited water resources and high pumping costs. All these factors increase the importance of water management in cotton. Cotton is one of the moderate water-consuming crops, but the water requirement varies with soil and weather conditions. Various factors determine the water requirement of cotton such as temperature, rainfall (amount and distribution), relative humidity, wind speed, sunshine hours, cultivar, length of the growing period and soil characteristics. Different growth stages of cotton have different water requirements, and it varies from 2.5 mm/day in seedling stage to a maximum of 6.2–10 mm/day in peak flowering stage, and then progressively decreases toward boll development (5.1 mm/day) and reaches to a minimum of 2.0 mm/day during boll bursting stage. The water requirement of cotton in terms of total seasonal water use is 20, 40, 30, and 10% up to first flower, during first flower to peak flower, during peak flower to bursting of few bolls and up to maturity, respectively. Poor water management during critical growth stages of cotton may result in 50–80% yield reduction. Therefore, optimizing water supply based on growth stage and exploiting various water-efficient techniques could be viable options for maintaining higher cotton productivity and water use efficiency.