Effect of Lanthanum Nitrate on Seed Germination and Seedling Growth Characteristics of Switchgrass under NaCl Stress

To investigate the effect of La(NO3)3on seed germination and seedling growth characteristics of switchgrass(Panicum virgatum L.)under NaCl stress,we measured seed germination,seedling growth, relative electrical conductivity,MDA,proline and chlorophyll contents in incubator.Seeds were soaked in different concentrations(0,0.05,0.1,0.5and 1.0mmol/L)of La(NO3)3for 24h,and then added 100 mmol/L NaCl solution,with distilled water as control.The results showed that:(1)0.05 mmol/L La(NO3)3could relieve 100mmol/L NaCl effect on seed germination;(2)There was no significant effect on shoot length with different treatments,but 0.1mmol/L La(NO3)3treatment significantly increased thefresh weight and leaf area of seedlings.When the concentration≥0.5mmol/L,root length,root shoot ratio,fresh weight and leaf area were all inhibited significantly;(3)The relative electrical conductivity and proline content of seedling leaves decreased firstly and then increased with increasing La(NO3)3concentration, of which 0.05and 0.1mmol/L La(NO3)3treatment were better,the MDA content increased with increasing La(NO3)3concentration has been reduced.The chlorophyll content increased with 0.05mmol/L La(NO3)3treatment comparing with NaCl,and decreased with increasing La(NO3)3concentration.However, there were no significant difference among different concentration treatments.(4)Different factors between the germination potential and germination rate,had a significantly positive correlation between root length and chlorophyll content,and had a significantly negative correlation with the root shoot ratio,relative electrical conductivity,and proline content.However,it was no significant correlation between germination potential and shoot length.This research indicated that low concentration(0.05mmol/L)of La(NO3)3could alleviate NaCl stress,high concentration(1.0mmol/L)of La(NO3)3could increase the stress.