Effects of Nitrogen Nutrition on Physiological Traits of the Aquilaria Sinensis Seedlings Under Simulated Water Stress
An experiment of taking three Aquilaria sinensis provenances,two levels of nitrogen supply and two levels of water stress by PEG-induced,was conducted to study the response of physiological and biochemical indices.The results showed that the different nitrogen supply and water stress levels had significant effects on the relative conductivity,the superoxide dismutase(SOD)activity,proline mass fraction and malondialdehyde(MDA) molality.Under the appropriate water condition,although the high nitrogen supply was beneficial to improve the antioxidant enzyme activity and free proline mass fraction,it caused a certain degree of osmotic stress,representative by the increasing of MDA molality and relative conductivity.Under the water stress condition,the relative conductivity and the molality MDA of the high nitrogen treatment were lower than that of the low nitrogen treatment,on the contrary,for the catalase(CAT)activity and free proline mass fraction.The peroxidase(POD) activity was not actively responded by the nitrogen supply and water stress.There was significantly difference in relative conductivity among the three provenances.The value in Qiongzhong provenance was higher than that of Chenmai provenance,and that of Lingao provenance was between them.Although SOD activity and CAT activity,as well as proline mass fraction and MDA molality were some different among the three provenances,high nitrogen supply was helpful for improving their drought resistance under-0.63 MPa water stress conditions.