Variability in soluble carbohydrates of the stem and its contribution to grain yield in wheat

Abstract

In wheat, the capacity to store soluble carbohydrates (CHS) in the stem and to remobilize them towards the grain, constitutes a desirable characteristic to be incorporated in the germplasm directed to regions where terminal drought frequently occurs. The objective of the work was to evaluate the variability in the accumulation and remobilization of water-soluble carbohydrates (CHS) and their contribution to grain yield when the post-synthesis source is altered by defoliation and water stress. The experiments were carried out in the summer-autumn 2013 cycle (temporal, exp. 1) and winter-spring 2013-2014 (irrigation, exp. 2) in Toluca, Mexico, at a density of 350 seeds m^-2, in the exp 1 the defoliation was performed 7 days after anthesis and in the exp. 2 was not watered after anthesis. In the exp. 1 60 wheat elite lines and two source reduction treatments (defoliated and defoliated, called environments onwards) were studied under a split plot design with 2 replications. The exp. 2 consisted of 20 genotypes selected from exp. 1 and subjected to two water regimes (irrigation and post-flowering drought) in a randomized complete block design with 3 replications where each water regime was considered an environment. Great variability was observed for grain yield (RG) and the associated physiological characteristics. The RG was reduced by an average of 14% due to defoliation and post-anthesis drought. The greater contribution of CHS was in line with a greater efficiency of remobilization. There are promising genotypes for use in breeding programs with a view to incorporating physiological characteristics to increase the potential yield under conditions of biotic or abiotic stress in post-anthesis.