Tillage & Cultivation · Physiology & Biochemistry
Yuanhang GUO, Hongbo WANG, Baowei BAI, Lei ZHANG, Fengnian ZHAO, Dongxue LÜ, Ting JIA, Xingpeng WANG
To investigate the effect of exogenous melatonin (MT) on salt tolerance of soybean seedlings,and to screen the appropriate application concentration under different salt stress.The soybean variety Tianyou-2986 was used as the test material,and 3 salt concentrations (low salt S3:3 g/L,medium salt S5:5 g/L,high salt S7:7 g/L ) and 6 MT concentrations were set(M0:0 μmol/L,M1:25 μmol/L,M2:50 μmol/L,M3:75 μmol/L,M4:100 μmol/L,M5:150 μmol/L),the morphological parameters,biomass,antioxidant enzyme activity and osmoregulatory substance content of soybean seedlings were analyzed.With the increase of salt stress,the root morphological parameters,biomass,root-shoot ratio,antioxidant enzyme activity and osmoregulatory substance content of soybean seedlings decreased,while the malondialdehyde content increased.Under low salt (S3) and medium salt (S5) stress,The number of total length,lateral roots,SOD and POD of 50 μmol/L MT were increased by 52.30%,19.98%,74.10%,40.03% (low salt) and 68.52%,19.24%,81.72% and 37.42% (medium salt),respectively.Under high stress (S7),75 μmol/L MT increased by 71.17%,19.11%,80.79% and 27.01%,respectively.Under salt stress,exogenous 25—100 μmol/L MT promoted soybean seedling growth and improved salt tolerance to different degrees.The overall evaluation of the affiliation function showed that 50 μmol/L MT was the most effective in alleviating salt damage under low and medium salt stress,and the suitable concentration of MT was 75 μmol/L under high salt stress,and the main reason for the alleviation of salt damage in soybean seedlings was that MT increased the activities of antioxidant enzymes and osmoregulatory substance content,and reduced the content of malondialdehyde,which could alleviate oxidative and osmotic stresses of soybeans under salt stress.