Effects of salinity and drought stress on germination, biomass and growth in three varieties of Medicago sativa L.

Abstract

"To evaluate alfalfa (Medicago sativa L.) tolerance to osmotic stress induced by polyethylene glycol 6000 (PEG6000) and salinity (NaCl), germination and growth was investigated in early seedling stages in three genotypes: Dk166, Verdor and Salina varieties. This investigation was performed using a completely randomized design with five replications: energy and power of germination, length of leaves, fresh and dry weight from roots and leaves. Results showed that germination, in which both solutions were used, was delayed in all varieties, with differences between genotypes. Seedling growth under light stress showed an increase in aerial biomass, while in severe drought and salinity stress, the varieties died except var. Salina (tolerant). PEG caused death in Verdor variety that showed more sensibility to PEG than to NaCl. In roots, the more sensitive genotypes faced to light salt stress stop their growth and under light drought stress, they increased it. Our studies allowed us to define the commercial varieties of Medicago sativa as moderately tolerant to salinity and drought the Dk166 variety; as sensitive or intolerant to salinity and drought the Verdor variety and as highly tolerant to salinity and insensitive to drought the Salinity variety."