INDUCED MODIFICATIONS IN REPRODUCTIVE TRAITS OF SALT-TREATED PLANTS OF SORGHUM BICOLOR

Abstract

Plants of Sorghum bicolor were grown hydroponically in a solution containing 150 mM NaCl, and the reproductive characters were analyzed at the end of the life cycle. A subpopulation was exposed to salinity on day 8 following germination (early-exposed plants), and another subpopulation was first exposed to salinity on day 21 following germination (late-exposed plants). Fertility and stem height, as determined per g shoot dry weight (DW), were similar for control and late-exposed plants. However, these parameters were largely modified in early-exposed plants. The population of late-exposed plants displayed an increase in phenotypic variability. However, the monomodal structure of the population remained similar to that of the population of control plants. In contrast, a large increase in diversity was observed in the population of early-exposed plants, and the frequency distribution of the reproductive characters appeared as plurimodal for this population. Early exposure to NaCl has been previously shown to induce an increase in salinity tolerance of the plant (termed salt adaptation). This effect was not observed for late-exposed plants. The significance of the induced modifications in reproductive characters is discussed in the light of the salt adaptation response in Sorghum.