Detection of Genotypic Differences in Early Growth Response to Water Stress in Wheat using the Snow and Tingey System

Abstract

Early detection of genotypic differences in response to water stress would help in increasing selection intensity in breeding drought tolerant wheat (Triticum aestivum L.). However, detection of small differences requires adequate control of the stress level. A system was used to determine if differences among genotypes in growth response to water stress could be detected. Haun stage and shoot dry weight were determined after 20 d in 25 cultivars grown with adequate water supply or with a water deficit imposed by lowering the water table by 8 cm and by interposing a porous ceramic disk, with an air exclusion value of 0.5 MPa, in the conducting medium between the water table and the roots. Significant differences were found among cultivars in the response to the imposed water deficit. Hann stage reduction varied between 13% in the spring wheat ‘Klasic’ and 36% in ‘Apollo’, while shoot dry weight reduction was between 21% in Klasic and 67% in the club wheat ‘Moro’. The coefficient of correlation between the Haun stage and shoot dry weight response to water stress was highly significant (r = 0.78). Although no direct comparison could be made between response of early growth to water deficits and yield response in the field under drought stress, the results of the seedling growth test corresponded well with previous knowledge about the performance of the tested cultivars under water stress. Our results verified that the system could be useful for rapid evaluation of drought response in wheat breeding.