EFFECT OF SIX SINGLE SALT STRESSES ON GERMINATION OF ALFALFA (MEDICAGO SATIVA)

This article deals with the changes of germination index and physiological index under six single salts calcium chloride (CaCl2), sodium chloride (NaCl), sodium sulfate (Na2SO4), sodium bicarbonate (NaHCO3) magnesium chloride (MgCl2), sodium bi-carbonate (Na2CO3). The single salt has a concentration gradient ranging from 25-150 mmol L-1 and the material for the experiment is alfalfa (Medicago sativa). The result of the experiment showed that with the rise of the concentration, the germination rate, germination vigor, germination index and vitality index declines (P<0.01). Also, the length of the embryo, radicle and the weight of biomass declines extremely prominently (P<0.01). The proline accumulation amount increases significantly under salt stress (P <0.01). Alfalfa seeds have different tolerances to the six single salts. The order of tolerance to positive ions is Mg2+>Ca2+>Na+. The order of tolerance to negative ions is Cl->SO42->HCO3->CO32-. The study also shows alkaline salt is more harmful than saline neutral salt. The result provides a reference framework for planting alfalfa according to the types of saline soil and the levels of concentration.