Water Use, Yield and Fiber Quality Response of Six Upland Cotton Cultivars to Irrigation

The declining Ogallala Aquifer combined with the unpredictability of precipitation and heat unit accumulation during the growing season in the Southern High Plains results in elevated production risks for cotton (Gossypium spp.). Cotton cultivars that can use water more efficiently and sustain yield and fiber quality under water stress is essential for sustainable cotton production in the region. A field study examined the phenotypic response of six upland cotton (G. hirsutum L.) cultivars (early to medium maturity) to four irrigation rates during two growing seasons (2016 and 2018). Crop water use was estimated using soil water balance in conjunction with measurements of root zone soil water, precipitation, reference evapotranspiration, and irrigation depths. Plant development was monitored throughout the growing season and lint yield was determined by hand-harvesting two inner plot rows of each replicate. The seed cotton from harvested plots was ginned to determine lint yield and the resulting lint was evaluated for quality using standard procedures. Profile water use and inferred rooting depth did not vary with cultivar within each irrigation level. In both years, cultivar significantly influenced lint yield. In 2016, irrigation did not influence lint yield except for one medium maturity cultivar (DP1219) that exhibited declining yields with increasing irrigation levels. In 2018, irrigation significantly increased lint yield for all cultivars. The effects of irrigation level, water stress, and cultivar on crop phenology, yield components, and lint quality will also be presented.