Effect Of Different Nitrogen Level On The Growth Of Kosteletzkya Virginica Under Nacl Stress

This study tries to explore the impact of different nitrogen level treatment on the growth of Kosteletzkya virginica under NaCl stress,through evaluating the effects of physiological characteristics, as photosynthetic characteristics, and photochemical characteristics of PSⅡthat were impacted by different concentrations of NaCl. The main results are as follows:1. Effect of different nitrogen level treatment on the growth of Kosteletzkya virginica under NaCl stressUnder 0 mmol/L NaCl treatment, the fresh weight and dry weight of Kosteletzkya virginica increased with the nitrogen level,and achieve maximum under 5 mmol/L N ,and then decreased under 10 mmol/L N.2.Effect of different treatment on photosynthetic characters of Kosteletzkya virginicaWithin a certain range, raise the level of nitrogen can increase Pn of Kosteletzkya virginica. Under the treatments with 150, 300 mmol/L NaCl, Pn increased with the increase of N up to 5 mmol/L, and then decreased a little at 10 mmol/L. Under same nitrogen level, Pn of Kosteletzkya virginica decreased with the increase of NaCl.The change tendency of Gs is similer with Pn,but under 0 mmol/L NaCl,Gs achieve maximum under 5 mmol/L N ,and then decreased under 10 mmol/L N. Ci decreased with the increase of Pn,but under 300 mmol/L NaCl, Ci remarkable enhancement, indicating that non-stomatal limiting factor at this time is the main reason for lower Pn. Under the treatments with 0, 150 mmol/L NaCl, the comparative content of Chlorophyll increased with the increase of N up to 5 mmol/L. Under the treatments with 0.1, 10 mmol/L N, the comparative content of Chlorophyll decreased with the increase of NaCl.Under the treatments with 0 mmol/L NaCl,φPSⅡincreased with the increase of N, the difference is remarkable. During each processing the difference is remarkable. Under the treatments with 150, 300 mmol/L NaCl,φPSⅡincreased with the increase of N up to 5 mmol/L, and then decreased at 10 mmol/L. 3.Effect of different nitrogen treatment on the MDA content of Kosteletzkya virginica under NaCl stressIn each salt treatment, the MDA content decreased with the increases of nitrogen . This phenomenon is particularly evident under high-salt treatment. Therefore, nitrogen can maintain the integrity of the cell membrane of Kosteletzkya virginica under salt stress, reduce the damage of salt stress on plants and promote its growth.4.Effect of different nitrogen treatment on the NRA of Kosteletzkya virginica under NaCl stressThe levels of nitrogen affect NRA. In the same salt treatment, the NRA of Kosteletzkya virginica 'leaf and root is advanced with the increase of nitrogen. And in each salt stress ,nitrogen make plants maintain a degree of nitrogen assimilation rates, so that make the plants have a normal growth. At the same time,the tests also show that the reduction of NR mainly carried out in the leaves of Kosteletzkya virginica.5.Effect of different nitrogen treatment on the PSⅡof Kosteletzkya virginica under NaCl stressIn each salt treatment, the low level of nitrogen obviously affects PHI(Po) of Kosteletzkya virginica. Under the treatments with 0, 150 mmol/L NaCl, PHI(Po) increased with the increase of nitrogen. Under the treatments with 300 mmol/L NaCl, PHI(Po) achieve maximum under 5 mmol/L N .PHI(Eo) increased with the increase of nitrogen, Under the treatments with 0 mmol/L NaCl, The difference between low level of nitrogen treatments (0.1,0.5 mmol/L) and high level of nitrogen treatments (5,10mmol/L)is remarkable. Under the treatments with 150, 300 mmol/L NaCl, PHI(Eo) achieve maximum under 5 mmol/L N .The change tendency of PHI(Do) is on the contrary of PHI(Eo).Under the conditions of the various salt,The ratio of variable fluorescence FK to the amplitude FJ -Fo (WK) decreased with the nitrogen level increases. And slightly higher in 300mmol / L NaCl and 10mmol / L N treatment,shows that nitrogen can be applied to alleviate the damage of salt stress on plant oxygen-evolving complex (OEC) some extent.The density of active reaction centers per excited cross-section (RC/CSo) of Kosteletzkya virginica increased with the nitrogen level increases under the treatment with 0,150 mmol/L NaCl, and achieve maximum under 5 mmol/L N with the treatment of 300 mmol/L NaCl,and then decreased under 10 mmol/L N.The change tendency of trapping (TRo/RC) and electron transport per active reaction centers (ETo/RC) is similer.They are decreased with the increase of nitrogen.Both normalized complementary area corresponding to the J-P phase (Sm) and turn over number of QA in the time span from J-step to P-step (N) increased with the raise of nitrogen, and achieve maximum under 5 mmol/L N, the difference between low level of nitrogen treatments (0.1,0.5 mmol/L) and high level of nitrogen treatments (5,10mmol/L)is remarkable. Relative variable fluorescence at J-step (VJ) sharply decreased with the increase of nitrogen. dVG/dto sharply decreased with the increase of nitrogen.But under 300 mmol/L NaCl and high level of nitrogen treatments, dVG/dto enhanced.Under each salt treatment,Performance index (PIABS) and driving force (D.F.) on absorption basis both increased with the nitrogen level advance, and achieve maximum under 5 mmol/L N ,and then decreased a little under 10 mmol/L N. from which we can deduce that nitrogen promote primary photochemical reactions of PSⅡin Kosteletzkya virginica under NaCl stress . However, if use excessive nitrogen , the role in promoting slow , or even get it down, This discovery make very important significance for studying the salt tolerance of Kosteletzkya virginica .