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Screening Cotton Germplasm for Variation in Water Use Efficiency and Epidermal Conductance

David A. Fish and Hugh J. Earl

ABSTRACT

High water use efficiency (WUE) and low minimum leaf epidermal conductance (ge) are two traits that may enhance productivity of cotton under drought stress conditions. In the present work, a selection of twenty-two commercial cultivars, primitive race stocks and converted lines were screened for variability for these two traits in a greenhouse experiment, under both control (water replete) and cyclic drought stress conditions. WUE was calculated as the ratio of total plant dry matter accumulated to total water used over the period from planting to 40 days after planting. Minimum epidermal conductance was measured for two mainstem leaf positions using leaf gas exchange techniques. Significant genotype differences were found for WUE under drought conditions but not under control conditions. The watering treatment did not affect ge, but there were significant genotype differences for this trait. Regression analysis revealed a negative correlation between WUE and ge.





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Document last modified April 16, 2003