Submitted to: Journal of Applied Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/5/1997
Publication Date: N/A
Interpretive Summary: The complete set of the D-genome chromosome substitutions in the durum wheat cv. Langdon and its parents were studied in two factorial experiments under high and low nitrogen nutrition. At the shooting and maturity stages, the effects of individual D-genome chromosomes on the nutrient use efficiency and tolerance to nutrition stress were identified. The D-genome substitutions did not improve the efficiency of nitrogen and phosphorus use at the vegetative growth stage. At this stage, the D-genome chromosomes may enhance low N tolerance, with the most consistent effects associated with chromosomes 2D and 5D. There was no consistency between the tolerance indices obtained at shooting and at maturity. Genes located on almost all D-genome chromosomes improved the efficiency of water use (WUE) only in the vegetative plant tissues, with the strongest effects associated with chromosome 7D. Genotypically specific stress-induced changes in the harvest index and major yield components closely correlated with low N tolerance suggesting that mechanisms which partition dry matter between straw and grain were important for tolerance. Chromosomes 7D and 4D may increase the low N tolerance at the reproductive stages.
Technical Abstract: The durum wheat (Triticum turgidum L. var. durum, 2n=28, genomes BBAA) is frequently cultivated under suboptimal water and nutrients accessibility. However, progress in breeding programs concerned with tolerance to the environmental limitations has been limited by narrow genetic variation. D-genome chromosome and the chromosome substitutions in 'Langdon' durum wheat and donor (Ch. Spring) were studied in two factorial experiments with two soil N levels. Results indicated that: 1) at both growth stages, the variation in the tolerance to the environment was partly due to compensative abilities of the D-chromosomes and to effects of interaction between the Ds and the A- and B-chromosomes; 2) the D-genome substitutions did not improve the efficiency of nitrogen and phosphorus use at the vegetative growth; 3) the genotypically specific, stress-induced relative changes in the harvest index, grain weight per spike and grain number per spike indicated close correlations with low N tolerance indices, and suggest that mechanisms responsible for distribution and translocation of plant assimilates were important for the tolerance of the studied material; 4) genetic factors which could improve the low N tolerance of the durum wheat substitutions at the vegetative growth stage are mainly located on chromosomes 2D and 5D, while those which enhance the tolerance at plant maturity are on chromosome 7D.