Dark Induced Senescence as a Tool in Breeding Wheat for Optimum Senescence Pattern

Abstract

Senescence can influence: (1) leaf area duration, (2) area of transpiring tissue and (3) translocation of nutrients — mainly nitrogen to grain. Therefore, selection for optimum senescence pattern might be efficient for improving performance of wheat in a given environment. This study was conducted to investigate the feasibility of a seedling test for estimating genotypic differences in senescence rate of wheat. We studied the response of several wheat genotypes to dark exposure of seedlings, by measuring the rate of chlorophyll loss in the first leaf. The rate of chlorophyll loss varied significantly among genotypes, the highest rate being more than double of the lowest. Linear regression accounted for most of the chlorophyll content variation during dark treatment in all cultivars. Significant correlation was found between the rate of chlorophyll loss following exposure to darkness and chlorophyll loss during aging in an environment relatively free of diseases and stresses. A good correlation was also found between the response of several genotypes to dark exposure and chlorophyll loss of seedlings following starvation. We conclude that a seedling test for dark induced senescence might allow an easy characterization of senescence pattern, allowing increased genetic progress in its optimization.