Improving Irrigation Scheduling and Water use Efficiency in Cotton

Cotton (Gossypium hirsutum L) is an important crop in the southern United States. The crop is grown in both irrigated and rainfed situations and is seldom free from periods of water shortages at some stage during the season. In recent years the need for consistency in yields and a stable cash flow has resulted in a rapid expansion in the number of irrigated acres of cotton in the Mississippi Delta. Irrigation research has, however, not kept pace with this expansion. This project represents a start at meeting this urgent need. The influence of weather patterns necessitates that these studies be conducted over several years, and the results given here are, therefore, only preliminary observations. The early termination of irrigation has not resulted in any significant decrease in yield or lint quality on the Sharkey clay, although there was a slight detrimental trend when irrigation was terminated too early in August. These studies have helped to clarify the relationship between soil-moisture deficit and plant stress, especially as relates to yield, for cotton cropped on a Sharkey clay soil. Evaluation of crop indicators of water deficit showed that leaf water potential and the air-canopy temperature differential are reliable indicators of the onset of water stress. Leaf extension growth is also a sensitive indicator, but of no practical value in irrigation management. With further research, leaf water potential and canopy-air temperature differentials could provide useful indicators for use in conjunction with traditional methods of scheduling irrigation for cotton in the humid mid-south. A better understanding of the irrigation requirements of the crop will improve management and will have a very significant dollar reduction in the cost of production of the crop

Summaries of Arkansas Cotton Research in Progress in 2001

Cotton yields in Arkansas increased steadily during the eighties, but in recent years there has been a leveling off. Of more significance, however, is that extreme year-to-year variability in yields has occurred in the last decade, which is a major point of concern with cotton producers. It has been suggested that this may be related to extreme weather conditions during the boll development period in July and August. Average maximum temperatures in the 2001 season were a few degrees above normal. Recent research in Arkansas has indicated that elevated night temperatures during boll development may be a major contributory factor to low and variable yields. There is also evidence that yield variability in stressful seasons may be related to genotypic changes in the components of yield, seed number, and fiber per seed, over the last 30 years. Yield stability for Arkansas cotton producers has become a major focus for new in-state collaborative research projects