Submitted to: Irrigation Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/14/2014
Publication Date: N/A
Citation: Interpretive Summary: A combination of increased demand for and decreased supplies of agricultural water are creating a need for improved methods for managing irrigation worldwide. In this study the temperature of cotton plants, in the field, was measured near-continuously over growing seasons. The results show that cotton yield was highest when plant temperatures were within a range from 25°C to 28°C (77°F to 82°F). Reduced irrigation resulted in elevated temperatures, reduced yield and lower fiber quality. Plant temperature provides a tool for irrigation management that can be used to balance water use and yield and quality. Breeders may use this information to identify varieties that are better suited to reduced irrigation.
Technical Abstract: Crop canopy temperature (Tc) is associated with transpiration and Tc has been used in crop water stress detection. This study investigates the effect of surface drip and furrow irrigation regimes on cotton Tc. It outlines the relationship between Tc and lint yield, fiber quality and total water-use efficiency (WUEtotal, kg ha-1mm-1 total applied water) in a high input, high yielding (>1800 kg ha-1) cotton system. Canopy temperature between flowering to crop maturity was monitored in both drip and furrow irrigation field experiments. Yield reductions occurred when Tc exceeded 28°C. Reductions in fiber length outside the ideal range (>28.6 mm)occurred when Tc exceeded 31°C, while desirable micronaire (3.8 to 4.5)was observed at Tc between 25 and 32°C. Desirable fiber quality and peak lint yield can be realized if an irrigation scheduling protocol maintains average canopy temperatures below 28°C. However, maximum WUEtotal was observed at a higher average Tc (30°C) than peak lint yield (28°C), which would correspond to a predicted 23% reduction in lint yield from the peak (3030 kg ha-1). Therefore, the trade-off between peak yield and WUEtotal needs to be considered in conjunction with irrigation water costs and availability when scheduling irrigations based on canopy temperature.