Effect of salt stress on growth and physiology in Melia azedarach seedlings of six provenances

Abstract

Effects of salt stress on growth and some physiological changes were investigated in the Melia azedarach L. seedlings of six provenances (Zhongmou (ZM), Yangling (YL), Hangzhou (HZ), Changsha (CS), Pingtan (PT) and Nanning (NN)). Plants were submitted to four salt treatments, 0, 2, 4 and 6% NaCl, for 48 days in containerized culture. Seedling growth and some physiological indicators were measured during different stages of salt stress. The results showed that: (1) Height growth, shoot length increment and leaf area in all six provenances were significantly reduced after salt stress treatments. Leaf area had the biggest decline. (2) Proline accumulated in response to salt stress in seedlings of all provenances, but there were big differences in sensitivity between provenances. Soluble protein content decreased with both increased salt concentration and treatment duration. (3) Malondialdehyde (MDA) contents first increased then declined and increased with the elongation of time of salt stress, and there were pronounced differences between provenances. (4) Water potential in 6 provenances was affected to decrease by salt stress, but its changing width was not big. (5) SOD activities were influenced obviously to decline constantly by salt stress, but POD activities had the trend of increasing, and reached the peak under 2%, and then decreased with increased salt concentration. Compared comprehensively with morphological and physiological index synthetically by using mathematical models, the rank of tolerance to salt stress was: PT > ZM > HZ > YL > NN > CS.