Influence Of Nitric Oxide On Growth And Physiological Brassica Pekinensis Seedlings Under Low Light Intensity

III Low light intensity is one of the main factors that can limit plant the productivity of many cultivated crops. However, the growth of plants under the condition of weak light is promoted according adjust the nutrient substance, this is one of the hotspots in agricultural research. Previous studies have, however, shown that moderate ammonium: nitrate(10:90, total nitrogen was 5mmol/L) could reduce the adverse effect of low light intensity in mini Chinese cabbage seedlings. An hydroponic experiment was conducted to demonstrate the rote of nitric oxide(NO) in the ammonium and nitrate regulation of growth of mini C hinese cabbage seedlings under low light intensity. Experimental material used mini C hinese cabbages seedling, nutrient solution planting. A total of six treatment: CK, SNP, N+SNP, N+L-NAME, N+Na N3 and N+Hb were studied in an illumination incubator the illumination intensity is 100 μmol·m-2·s-1, photoperiod is 12 h/12 h, day temperature 22±1 ℃, nighttime temperature 18±1 ℃,humidity is 60%. Eight(8) days after subjecting the seedlings to the treatments, the following parameters were measured: antioxidant enzyme activities, osmotic adjustment substances content and NOS、NR activities of mini C hinese cabbage seedlings and the quantity and location analysis of NO. To verify N itric oxide involved in the moderate ammonium: nitrate of mini C hinese cabbages seedling under low light intensity. Provides theory basis for actual production. The findings of the study were as follows:1. Plants supplied with SNP compared with CK had increased chlorophyll content, but had no significant difference in fresh shoot and root weight, total leaf area, photosynthetic characteristics and chlorophyll fluorescence were not significant. However, when the NO scavenger(N+Hb) and inhibitor(N+L-NAME, N+Na N3) were added into the ammonium nitrate solution, the fresh shoot and root weights, total leaf area, net photosynthetic rate(Pn), stomatal conductance(Gs), maximum quantum yield of PSII(Fv/Fm) and electron transport rate(ETR) of plants decreased in different levels. Compared with CK, total leaf area decreased by 15%, 24% and 40%, Pn declined by 31.2%, 35.8% and 56.7%. In all, NO scavenger inhibited and eliminated the promotion effect of moderate ammonium: nitrate in mini C hinese cabbages seedling growth under low light intensity. Moreover, exogenous NO had the same function with moderate ammonium: nitrate, which can promote the growth of mini C hinese cabbage seedling under low light intensity. Therefore, NO was involved in the moderate ammonium: nitrate=10: 90 promotion of photosynthetic characteristics of mini Chinese cabbages seedlings under low light intensity stress.2. Under low light, plants supplied with SNP compared with CK had increased SOD activities, decreased MDA content, but there was no significant difference in Pro content. However, when the NO scavenger(N+Hb) and inhibitor(N+L-NAME, N+Na N3) were added into the ammonium nitrate solution, the SOD activitie, MDA content, Pro and soluble protein content increased significantly but soluble sugar content decreased significantly. The SNP relieved oxidative damage of mini C hinese cabbages seedling under low light intensity, osmotic adjustment substance had accumulate, effect in osmotic adjustment system disorder. Therefore, N itric oxide was involved in the moderate ammonium: nitrate regulated SOD activitie, MDA, Pro, soluble sugar and soluble protein content of mini C hinese cabba ges seedling under low light intensity.3.Under low light, the SNP promoted the growth of mini Chinese cabbages root system obviously, increased the root absorption area and number of lateral root. Based on the NOS and NR,s activitie which are two key enzymes in producing NO, the supply of with NO inhibitor(N+L-NAME), NOS activitie was weakened, NR activitie was enhanced; supplied with NO inhibitor Na N3, NR activitie was weakened and NOS activitie was enhanced. This, therefore demonstrated the L-NAME and Na N3 inhibition pathways. The NO content was measured qualitative and quantitative, Conclusion is moderate ammonium: nitrate and exogenous NO can make NO’s content increased,therefore plants supplied with NO inhibitor and scavenger decreased NO’s content obviously, meanwhile, fluorescence staining drawing can find this phenomenon.Moreover, NR way could main route in moderate ammonium: nitrate al eviate low light intensity stress in mini Chinese cabbage seedlings.