Seedling growth and nutrient absorption of sweet potato affected by exogenous chlorine

Taking the seedlings of sweet potatoes Xushu22,Sushu11 and Ningzi1 as test materials,their nutrient absorption and plant growth under exogenous chlorine treatments( 0 mmol/L,42. 2 mmol/L,84. 4 mmol/L,168. 8 mmol/L, 211. 0 mmol/L) for 7 d and 21 d were investigated,by measuring plant fresh weight,chlorophyll content index( CCI),malondialdehyde( MDA) content,nitrate reductase( NR) activity,NO-3 content,and contents and accumulations of N,P and K. The results showed that the biomass and NPK-accumulations of Xushu22 declined by exogenous chlorine,however,they were maintained at certain levels. Lower concentrations of chlorine treatment( ≤84. 4 mmol/L) improved the growths of Sushu11 and Ningzi1. The CCI of 3 genotypes of sweet potato increased by exogenous chlorine with concentrations ranging from 42. 2 to 168. 8 mmol/L compared to the control. MDA levels were improved by chlorine. Twenty-one days of lower concentrations( ≤ 84. 4 mmol/L) of chlorine increased total nitrogen content by increasing NR activity and NO-3 content of sweet potato seedlings. These results indicate that chloride stress tolerance is genotype-dependent in sweet potato,and short-term and low-concentration exogenous chloride treatment is conducive to the growth of sweet potato seedlings.