Effects of exogenous nitric oxide on physiological characteristics of peanut under iron-deficient stress

Nitric oxide (NO) plays an important role in crop growth and development. A hydroponic experiment was conducted to investigate the effects of sodium nitroprusside (SNP), a NO donor, on seedling growth, root activity, chlorophyll, photosynthetic characteristics, active oxygen metabolism and mineral element contents in peanut (Arachis hypogaea Linn.) plants and the change of pH in the culture medium. There were three treatments, 0, 10 and 100mol/L Fe(Ⅲ)-EDTA. The results show the plant growth, root activity, net photosynthetic rate (Pn), transpiration rate (Tr), stomatal conductance (Gs) and active oxygen metabolism are significantly increased under the application of 250mol/L SNP, while the intercellular CO2 concentration (Ci), the contents of MDA and phosphorus(P) are decreased. The effects are more significant under the Fe(Ⅲ)-EDTA concentration of 0 and 10mol/L than those of 100mol/L. Compared with the treatments of 0, 10 and 100mol/L Fe(Ⅲ)-EDTA, the contents of active Fe of leaves at 20 days cultivation are significantly increased by 130.7%, 136.4% and 56.1% under the treatments of SNP+0, 10 and 100mol/L Fe(Ⅲ)-EDTA. At the same time the total iron content of the plants, the percentage of shoots total iron absorption to that of the pants are also significantly increased. These indicate that the NO donor can increase the chlorophyll contents, the transportation of iron and the efficiency of utilization of iron. Under Fe(Ⅲ)-EDTA concentration of 0 and 10mol/L, the application of SNP obviously lowers the pH of nutrient medium, and the pH is the lowest at 14h.