Growth and physiological metabolism of cucumber seedlings in response to different concentrations of salt stress

A cucumber cultivar Xintai Mici was used in this experiment to study the effects of different concentrations of NaCl( 0,0. 3%,0. 6%,0. 9% and 1. 2%) on growth and physiological metabolism of substrate-cultured cucumber( Cucumis sativus L.) seedlings. Under NaCl stress,the photosynthetic rate( P n),stomatal conductance( G s),stomatal limitation value( L s),transpiration rate( T r) and water use efficiency( WUE) decreased,and while the intercellular CO 2 concentration( C i),cell membrane damage rate,malondialdehyde( MDA) and soluble protein contents increased,superoxide dismutase( SOD),peroxidase( POD) and catalase( CAT) activities improved. The change of each index was more obvious with the increase of salt concentrations. High concentrations( 0. 9% and 1. 2%) of NaCl stress inhibited the growth of leaves, lowered survival rates of seedlings,and each physiological index significantly changed compared with control. In conclusion,0. 3% NaCl treatment had little effect on the growth and physiological metabolism of cucumber seedlings, 0. 6% and 0. 9% NaCl treatments caused biomass significantly decrease,and 1. 2% NaCl might be the highest concentration that cucumber seedling could tolerate.