Identification of Characters for Selecting Increased Water Use Efficiency in Cotton
Feb 6, 2019
Water supply is a major determinant of cotton yield. In Australia, unreliable rainfall means that irrigation supplies can not be guaranteed. In addition, 20 % of the industry is raingrown and depends on the same unreliable rainfall. The aim to determine if it is possible to identify and select characters that enhance the leaf and crop water use efficiency (WUE) of cotton. The occurrence of differences in WUE between genotypes was identified. Crosses were made between relatively diverse germplasm and F2’s produced. 160 single F2 plants were measured for a range of gas exchange characters including photosynthesis, stomatal conductance, intercellular CO2 concentration and transpiration. Physiological WUE was calculated from these measurements. Each F2 plant was grown in an F3 row the following year. For the purpose of more intensive measurements, selections were based on the F2 data, and 24 F4’s were measured for the same characters as the F2’s. Estimates of narrow sense heritability (h2) were also calculated. Relatively low estimates of h2 were obtained (0-0.5) for gas exchange characters compared with the high h2 for characters such as lint percentage (0.9). However, some h2’s were significant, indicating that it will be possible to select lines with improved physiological WUE. These lines can then be screened for other agronomic characters. We believe this procedure will produce improved raingrown types than has been possible with our previous procedure in testing successful irrigated types for dryland adaptation.