Assessing the Physiological Basis of Yield Response to Irrigation in Cotton Cultivars with Expected Differences in Crop Water Use Efficiency

Drought is known to reduce cotton yield, and while the effects on its final yield have been the subject of many studies a detailed assessment of the physiological processes contributing to final yield is still needed. To this end, a study was conducted at the Stripling Irrigation Research Park in Camilla, GA using three different irrigation treatments: well-watered (100% of ETc), over-irrigated (125% of ETc), and dryland. The data collection started after squaring and continued throughout the growing season. Data collected included predawn water potential (ψ_PD), midday water potential (ψ_MD), predawn and midday gas exchange and fluorescence parameters, growth parameters, light interception, radiation use efficiency, harvest index, yield components, and fiber quality. We expect to see a reduction in yield under water deficit stress but we expect each of the aforementioned parameters and/or processes to exhibit differential sensitivities to drought. This information should assist us in identifying the weak link(s) in cotton's response to drought.