Study Of Water And Nitrogen Interaction Of Black Peanut Under Mulched Drip Irrigation

Water and nitrogen (N) are the main limiting factors affecting agricultural production in arid and semiarid region. Different water and nitrogen coupling have great effects on growth and yield of black peanut. Water and nitrogen are the necessary substance of crop growth. The anti canopy experiment was conducted to study the effects of different moisture conditions and different nitrogen amount on growth, photosynthetic effect, yield, quality, soil moisture dynamics and water use efficiency of black peanut with a 2-year field in order to obtain the best economic yield and reasonable nitrogen coupling scheme to provide a theoretical basis, and set up a new model for good quality and high yield evaluation of water-saving black peanut cultivation. The main results showed follows:(1)The plant height,leaf area and dynamic changes of dry weight of black peanut have different degrees of coupling effects under different modes of water and nitrogen. Under the condition of nitrogen application amount of N2, the increase of the amount of irrigation water on the plant height, leaf area and the accumulation of dry matter during the whole growth period was favorable. Under the condition of W3, the increase of the plant height could be improved by the appropriate increase of the amount of nitrogen. N2 treatment can promote the increase of plant height and the growth of leaf area, in the seedling stage, increasing the amount of water and nitrogen appropriately can increase the growth traits of black peanut, prevent excessive growth; W3N2 treatment has been able to provide enough material and water for vegetative growth of black peanut during the whole growth period.(2) Under different water and nitrogen coupling treatment, the net photosynthetic rate of black peanut leaves decreased gradually with the development of the growth process, namely pegging stage> pod setting stage> maturity stage. The photosynthetic rate and chlorophyll content of the leaves could be decreased by water deficit, while the nitrogen fertilizer could promote the photosynthetic rate and chlorophyll content, but the effect was not significant with too much nitrogen. The change of transpiration rate and stomatal conductance of black peanut leaves was consistent with the photosynthetic rate.(3) The yield (7954kg/hm2) of black peanut under treatment of high watering and medium nitrogen (W3N2) was the highest, which was not significantly different from the yield (7721.5 kg/hm2) of medium watering and medium nitrogen (W2N2) treatment. The yield of these two treatments increase by16.34% and13.83%, compared to low watering and low nitrogen (W1N1) treatments. Establish the model of coupling of water and nitrogen. In the model the objective function is the yield of the black peanut, the independent variables are irrigation water and nitrogen amount. According to the analysis of the model, the largest yield got when the irrigation water is W3 treatment and the amount of the nitrogen were N2 treatment.(4) The suitable amount of irrigation and nitrogen were beneficial to the synthesis of crude fat,protein,oleic acid and linoleic acid in black peanut seed kernel.and increase irrigation amount is conducive to the rise of the ration of O/L in black,while the amount of nitrogen has little effect on it.(5) The depth of soil water content generally changed within the range of 0-50cm. Especially the changes in 0-30cm was particularly intense, the greater the amount of irrigation, the more obvious changes.The soil moisture in each treatment did not change significantly within the range of 30-50cm.(6) Along with the nitrogen amount reducing, water use efficiency of low watering treatment was higher than high and medium watering treatments. As a whole, the water use efficiency (3.26 kg/m3) of low watering and medium nitrogen (W1N2) treatment was highest. Effects of different water and nitrogen treatment on water use efficiency of black peanut were significant. The water use efficiency had significant difference among different water and nitrogen treatment.The WUE increased with the increase of nitrogen, but it seems lower than before under N3 level. W2N2 treatment revealed a relatively high WUE; water use efficiency was 65.13% higher than W3N3 at the end of the experiment.So, when the amount of nitrogen and water was N2 and W3, yield and WUE of black peanut was respectively 7954kg/hm2 and2.04kg/m3, the main fruit qualities of black peanut were better, content of center crude fat, protein and O/L was pespectively 39.4%、27.45% and 1.20. W3N2 treatment was recommended as the best combination of water and nitrogen for the production of black peanut under drip irrigation and plastic film mulch in the semi-arid region of northeast China.