Effects of Salt Stress on Root Ions and Enzymes and Microbial Population in Rhizosphere Soil of Black Locust (Robinia pseudoacacia L.)

Ren Hong; Tang Qi; Han Congcong; Xun Shouhua; Zheng Chengshu; Mao Xiuhong

doi:10.14083/j.issn.1001-4942.2018.02.008

Abstract：Using the black locust cultivars Duocai Qingshan with high salt tolerance and Ziyan Qingshan with weak salt tolerance as materials,a pot experiment was conducted to study the changes of the root ion adsorption and the enzyme and microbial populations in rhizosphere soil of black locust under two treatments of salt stress and black control.The results were as follows:(1) under salt stress,the contents of Na +,K +,Ca2+ and Mg2+ in the roots of Duocai Qingshan and Ziyan Qingshan changed in different degrees.Among them,the Na + content increased slowly at the early stage and then increased rapidly with the extension of salt stress;the K+ content increased firstly companied with Na+,and then decreased gradually;the contents of Ca2+ and Mg2+ displayed the trends of decreasing slowly.The fluctuation amplitude of the 4 ion contents of Duocai Qingshan were smaller than that of Ziyan Qingshan.(2) The activities of urease,invertase,neutral phosphatase and eatalase in the black locust rhizosphere soil decreased significantly under the salt stress treatment.After stressed for 28 days,the soil enzyme activities of urease,invertase,neutral phosphatase and catalase in Duocai Qingshan decreased by 44.97％,60.87％,36.96％ and 23.80％ respectively,while those in Ziyan Qingshan decreased by 52.45％,74.48％,42.52％ and 36.67％ respectively.(3) Under the salt stress treatment,the numbers of rhizosphere bacteria,fungi and actinomycetes significantly decreased in black locust,and those of Duocai Qingshan decreased by 39.04％,49.45％ and 44.19％ respectively,while those of Ziyan Qingshan decreased by 53.41％,57.05％ and 47.53％ respectively.(4) There were significantly negative correlations between the Na + content and the rhizosphere soil enzyme activities and microbial populations;there were significantly positive correlations between the K + content and the rhizosphere soil urease and catalase activities and bacteria number.In conclusion,the ion balance in roots of black locust was broken,and the enzyme activities and microbial populations in rhizosphere soil were inhibited under salt stress.The salt tolerance of black locust cultivars were related to the ion balance in roots,the maintaining of rhizosphere soil enzyme activities and microbial populations.The suppression degree of Duoeai Qingshan with high salt tolerance were lower than that of Ziyan Qingshan with weak salt tolerance.