Study on the Alleviating Effects of Exogenous Gibberellin on Alfalfa Seedlings under Salt Stress

PurposeTo study the effects of exogenous gibberellin (GA₃) on physiological alleviation of alfalfa seedlings under salt stress.

MethodsThe seedlings of Medicago sativa ‘Adina’ and ‘Longmu801’ were used as experimental materials, the seedlings were subjected to 200 and 150 mmol/L NaCl+Na₂SO₄ salt stress, respectively, and then the leaves were sprayed with 30, 60, 90, 120 and 150 mg/L GA₃, respectively. The physiological regulation effect of GA₃ on the salt stress of alfalfa seedlings were analyzed, and the comprehensive evaluation was carried out by membership function method.

ResultsAfter spraying GA₃ on alfalfa seedlings under mixed salt stress, the contents of proline, betaine, soluble sugar and soluble protein, and the activities of SOD, POD, CAT, APX and PAL in alfalfa leaves increased first and then decreased with the increase of mass concentration of GA₃. 60-150 mg/L GA₃ could accumulate four osmotic adjustment substances and improve five enzyme activities.

ConclusionApplying exogenous GA₃ can effectively alleviate the salt stress of two alfalfa seedlings. 30-150 mg/L GA₃ can alleviate NaCl+Na₂SO₄ salt stress to a certain extent. The effect of alleviating mixed salt stress is the best when the mass concentration of GA₃ is 60-90 mg/L.