Effects Of Water And Nitrogen Coupling On Greenhouse Fruit And Vegetable Production And Soil Environment Under Negative Pressure Irrigation

Water and fertilizer is an important factor affecting crop production and agricultural environment.At present,the utilization rate of agricultural irrigation water in China is low and the quality of soil caused by blind application of fertilizer is serious.Increasing crop water use efficiency and fertilizer use efficiency is an important content of sustainable development of agriculture in China,and the rational allocation of agricultural water and fertilizer resources is an important subject for the development and promotion of new agricultural technology.This study is based on the task of research on the optimization of water nutrient parameters of negative pressure irrigation technology in conjunction with the National Science and Technology Program(863 Program)"Crop Growing Water and Nutrition Habitat Regulation Technology(2013AA102901-1)".The experiment was conducted at the end of June 2015 to the end of June 2016 in the solar greenhouse of the Agricultural Science and Technology of the Chinese Academy of Agricultural Sciences.The vegetable crop pepper and tomato were used as the research object.The negative pressure irrigation system was used to study the effects of different negative(W1:-5kPa,W2:-10 kPa,W3:-15kPa)and the amount of nitrogen applied(N1: low fertilizer,N2: medium fertilizer,N3: high fertilizer)on potted pepper and tomato plant physiological index,Quality and basic physical and chemical properties of soil,and provide theoretical guidance and practical basis for high yield and high quality cultivation of facility agriculture.The results of this study are as follows:(1)Effects of water and nitrogen coupling on growth,yield and quality of hot pepper under negative pressure irrigationThe plant height,stem diameter and leaf number of capsicum were increased with the increase of nitrogen application rate and irrigation amount.The plant height,stem diameter and leaf number of capsicum were the highest at 74.00 cm,6.04 mm,60.59,respectively Higher than other processing.The yield of pepper was increased with the increase of N application rate,while the yield of pepper increased with the increase of irrigation amount under the same nitrogen application rate.The content of vitamin C in pepper showed the first increase and then decreased with the increase of nitrogen application rate.The content of vitamin C treated with W2N2 was the highest,which was 93.63 mg / 100 g.The soluble sugar content of pepper was the highest in W2N3 treatment,followed by W2N2 treatment,which was 4.79% and 5.09%,respectively,which were significantly higher than others.The protein content of chili was highest at W2N3 treatment,reaching 0.31% and significantly higher than that of others.(2)Effects of water and nitrogen coupling on soil physical and chemical properties of greenhouse pepperThe effect of irrigation amount and nitrogen application rate on soil alkali-hydrolysable nitrogen was significant,and the increase of irrigation promoted the decomposition of soil available N and the absorption and utilization of pepper.There was a positive correlation between the amount of available nitrogen in soil and the amount of nitrogen applied.The effect of irrigation amount and nitrogen application rate on soil available phosphorus was significant,while the effect of irrigation and N application rate on soil available phosphorus was not significant.Under the same irrigation condition,the nitrogen application rate increased,and the content of available phosphorus decreased first and then increased.Under the same irrigation condition,the content of available potassium increased with the increase of nitrogen application rate.Under the same nitrogen application condition,the content of available potassium decreased with the increase of irrigation amount.Under the same irrigation condition,the content of soil organic matter increased with the increase of nitrogen application rate,but the increase was not significant.Under the same nitrogen application rate,the content of organic matter increased with the increase of irrigation amount.Under the same irrigation condition,the soil pH value increased first and then decreased with the increase of nitrogen application rate.Under the same nitrogen application condition,the soil pH increased with the increase of irrigation amount.Appropriate amount of nitrogen fertilizer can increase soil urease,catalase and sucrase activity,but high nitrogen reduces the activity of catalase and sucrase.Increased catalase and sucrase activity increased with increased irrigation,but decreased urease activity.(3)Effects of water and nitrogen coupling on growth,yield and quality of tomato in greenhouseThe plant height and stem diameter of tomato increased gradually with the increase of nitrogen application rate and irrigation amount.The fruit index of tomato decreased with the increase of nitrogen application rate and irrigation amount.The dry weight and dry weight of root The increase of the first increase and then show the trend of decreasing,-10 kPa irrigation conditions conducive to aboveground dry weight and root dry weight accumulation.Root and shoot ratio with the increase in water content to maintain a basic trend to reduce.Under the same nitrogen application rate,the yield of tomato increased with the increase of irrigation amount,and the increase of different treatments reached a significant level,and the total yield of tomato treated with W2N2 was the highest.N2 significantly increased the content of vitamin C in tomato fruit,but the content of vitamin C decreased with the increase of irrigation amount.The total acidity of tomato increased with the increase of fertilizer application rate,and decreased with the increase of water content.Soluble sugar content increased first and then decreased with the increase of fertilizer application rate,and decreased with the increase of water content.The soluble protein content increased with the increase of fertilizer application rate,and decreased with the increase of water content.(4)Effects of water and nitrogen coupling on soil physical and chemical properties in greenhouse tomatoUnder the same irrigation condition,the contents of soil available N in the growth period increased with the increase of nitrogen application rate.Under the same nitrogen treatment,the content of soil available N decreased with the increase of nitrogen application rate,and with the growth period The content of alkaline hydrolysis of soil decreased gradually.Under the same irrigation condition,the soil pH value decreased with the increase of nitrogen application rate in the same period.Under the same nitrogen application rate,the soil p H increased with the increase of irrigation amount.Under the same irrigation condition,the soil organic matter content increased with the increase of nitrogen application rate.Under the same nitrogen application rate,the content of soil organic matter was not significantly different in the long period,and decreased with the increase of irrigation amount at both the flowering stage and the mature stage.Soil organic matter content decreased with the growth period of tomato.Under the same nitrogen condition,the soil electrical conductivity decreased with the increase of irrigation amount.Under the same irrigation condition,the soil conductivity increased correspondingly with the increase of nitrogen application rate.