Effects of GA3 on physiological metabolism and ion absorption of ‘Paulownia 1201’ seedlings under NaCl stress

Abstract

To explore the alleviation effect and physiological mechanism of gibberellin (GA3) on the growth of ‘Paulownia 1201’ seedlings under NaCl stress, this study took ‘Paulownia 1201’ seedlings as materials, different NaCl and GA3 concentrations were set to determine and analyze the physiological indexes, photosynthetic indexes and ion transport capacity of ‘Paulownia 1201’ seedlings under NaCl stress alleviated by GA3. The results were as follows: (1) Under 150 mmol·L-1 NaCl stress, the growth of ‘Paulownia 1201’ seedlings decreased significantly (P<0.05), which was more than 50%. The appropriate concentration of exogenous GA3 significantly increased the plant height, root length and biomass of ‘Paulownia 1201’ seedling. The dry weight of 400 mg·L-1 GA3 treatment increased by 69.71% compared with A0. (2) With the increase of GA3 concentration, the activities of three antioxidant enzymes (SOD, POD, CAT) increased significantly; content of MDA decreased significantly; chlorophyll content and gas exchange parameters (Pn, Tr, Ci, Gs) were increased, and the photosynthetic efficiency increased; the contents of each ion (K+, Ca2+, Mg2+) increased first and then decreased. The Na+ contents in leaves and roots of 400 mg·L-1 GA3 treatment group decreased by 23.59% and 11.92% compared with A0. (3) Correlation analysis and PCA analysis showed that there was a correlation between each index, seedlings which treated with different concentrations of GA3 had obvious differences, and the best alleviating effect was found when the concentration of GA3 was 400 mg·L-1. In summary, foliar spraying GA3 can enhance the antioxidant capacity of ‘Paulownia 1201’ seedlings under salt stress, alleviate the membrane lipid peroxidation reaction caused by the increase of reactive oxygen species under salt stress, promote the accumulation of photosynthesis and biomass of plants, reduce the absorption of Na+ by plants, promote the accumulation of nutrient ions, adding 400 mg·L-1 GA3 can improve the resistance of ‘Paulownia 1201’ seedlings best. This study provides a basis for further understanding of Paulownia salt tolerance mechanism identification, and also provides a scientific reference for the development and utilization of Paulownia in saline land.

Keywords

• ‘paulownia 1201’
• nacl stress
• gibberellin
• ion uptake
• pca analysis