Chromosomal location of genes influencing plant characters and evapotranspiration efficiency in bread wheat

Little is known of genes that influence root development and drought resistance in bread wheat. The evapotranspiration efficiency (ETE = ratio of vegetative dry weight to total water used) of spring bread wheat tall landrace 'Chinese Spring' is relatively high. We used 42 ditelosomic and dimonotelosomic lines of Chinese Spring to identify chromosome arms that influence plant characters and ETE. Multiple regression analyses indicated that 96% of the variation observed in ETE was explained by variation in vegetative dry weight and total water used. Variation in plant height, number of spikes (tillers), root dry weight and shoot dry weight (excluding grains) together explained 88% of the variation observed in plant vegetative dry weight. Chromosome arms involved in expression of days to heading and maturity, plant height, number of spikes, root dry weight, shoot dry weight, number of grains, grain weight, and carbon isotope discrimination (a) were identified. Specifically, both arms of chromosome 2A, the long arm of chromosome 2B, and the short arm of chromosome 2D might carry genes with positive effects on number of spikes, root dry weight, and shoot dry weight. None of the aneuploids produced grain yield greater than Chinese Spring. The short arms of chromosomes 6A and 4D might carry genes that suppress Delta. Chromosome 1D might carry genes that decrease relative water loss. The chromosome arms belonging to homoeologous group 2 might carry genes with positive effects on ETE. The genetic basis of ETE in modern wheats could be broadened by substituting specific chromosome arms of landrace wheats carrying desired characters into their genomes.