Effects of Nitrate Nitrogen on Root System Development and Fluorescence System Activity of Sweet Potato under Salt Stress

Li Luyao; Ding Xiaodong; Li Weiwei; Zhang Delong; Liu Qing; Shi Yanxi; Zhang Shirong

doi:10.14083/j.issn.1001-4942.2017.09.019

Abstract：Using J23 (salt-tolerant genotype) and S19 (salt-sensitive genotype) as materials,a hydroponic cultivation experiment with two salt-nitrogen levels (NaCl as 1,120 mmol · L-1;NO3--N as 1,10 mmol · L-1)was designed to study the effects of nitrate nitrogen on root growth and leaf fluorescence system activity of sweet potato under salt stress.The results were as follows.(1) Under the same salt and nitrogen coupling,there was no significant difference in root length of different salt-tolerant genotypes of sweet potato,the root activity of S19 was limited compared with J23.Under the same level of salt stress,the root dry weight of J23 showed a lower trend with the increase of nitrogen concentration,while the situation of S19 was opposite.The root number of S19 was more than that of J23 under both low-salt and high-salt level.(2) There was no significant difference between salt-tolerant and salt-sensitive sweet potato in the maximum photochemical efficiency average value,therefore,the impact differences of salt tolerance on the maximum photochemical efficiency of sweet potato were not significant.(3) In the same level of nitrogen,with the increase of NaCl concentration,the total root length,root surface area,root volume,root activity and maximum photochemical efficiency of sweet potato all decreased.(4) Under the same level of NaCl,the nitrate nitrogen content of sweet potato cells increased with the addition of nitrogen nutrition,so were the root total length,root surface area,root volume,root activity and maximum photochemical efficiency.(5) The supply of nitrate nitrogen could alleviate the inhibitory effects of salt stress on root biomass,root activity and chlorophyll fluorescence system of sweet potato.