Effects Of Subsurface Irrigation Methods And Different Nitrogen Application Amount On Cucumber Growth And Nitrogen Use Efficiency On Protected Field

Sectional subsurface irrigation is a irrigation method, when it's irrigating, subsurface irrigation tubes buried underground petechially effluent. In the system of greenhouse vegetable cultivation,sectional subsurface irrigation shows high crop yield and excellent quality,at the same time,it has advantages of water saving,labour saving,warming and pests inhibition and so on.It has good application prospect.Experiment was conducted in plastic greenhouse of research base of shenyang agriculture university in 2009. A field plot experiment on protected field was to study the effects of sectional subsurface irrigation and common subsurface irrigation and different nitrogen application on cucumber growth and development,yield,nitrogen use efficiency,phosphorus use efficiency and potassium use efficiency,in order to choose irrigation method and suitable nitrogen amount.Split-plot experimental treatment is a factorial combination of two irrigation scheduling regimes and five nitrogen amount (0,75,225,375 and 525 kg·ha-1). The main area is irrigation method and the subplot is nitrogen amount.All plots have the same low irrigation limit and irrigation maximums and planned moisture layer. Difference significance of yield and nitrogen use efficiency of all plots is compared in the method of analysis of variance and regression analysis. The profile observation results of soil moisture are analysis results.1. The effect of Irrigation methods and nitrogen amount to cucumber growth index (plant height, stem diameter, maximum leaf area, rootshoot ratio, dry matter weight) is obvious. Compared with common subsurface irrigation, sectional subsurface irrigation is more beneficial to the growth of cucumber.also,it can increase the functional leaf area, root-shoot ratio and promote dry matter formation of cucumber, with the increase of nitrogen amount, it presents a tendency of increasing at first and then decreasing for the plant height, stem diameter, leaf area and dry matter weight of cucumber with the processing of sectional subsurface irrigation and common subsurface irrigation. All the growth indexes have a maximum value at the nitrogen application level of 375 kgN·ha-1.Too much or too less nitrogen amount is not conducive to plant growth. The dry matter of cucumber follows the growth law of logistic under the Irrigation methods and nitrogen amount, Moreover compared with common subsurface irrigation, sectional subsurface irrigation treatment increases dry matter accumulation potential of cucumber. With the increase of nitrogen amount,the maximum dry matter accumulation quantity of cucumber presents a increasing at first and then decreasing tendency.2. Cucumber physiological indexes (chlorophyll content, root activity) in different irrigation methods and different nitrogen amount treatment are different. In growth period, chlorophyll SPAD value of functional leaf and root activity of sectional subsurface irrigation and common subsurface irrigation showed a trend of first increase and then decrease with the increase of nitrogen amount. The physiological indexes have a maximum value at the nitrogen application level of 375 kgN-ha"'. It shows that too much or too less nitrogen amount causes vegetables chlorophyll content and root activity reduced. Compared with common subsurface irrigation, sectional subsurface irrigation is higher.3. Irrigation method and nitrogen amount effect cucumber yield and water use efficiency significantly. In the same nitrogen amount, cucumber yield and water production efficiency of sectional subsurface irrigation treatment are significantly higher than that of common subsurface irrigation. With the increase of nitrogen amount, cucumber yield of sectional subsurface irrigation and common subsurface irrigation showed a trend of first increase and then decrease, and the yield of treatment 375kgN·ha-1 is highest. Use a unary quadratic equation to do regression analysis of the relationship between cucumber yield and nitrogen amount.when sectional subsurface irrigation and common subsurface irrigation obtain maximal cucumber yield by the equation,the heoretical nitrogen amount of them are 439.71 kg·ha-1 and 383.90 kg·ha-1 respectively.4. With the increase of nitrogen amount, nitrogen recovery efficiency and nitrogen agronomic efficency of sectional subsurface irrigation and common subsurface irrigation showed a trend of rise first then fall. In the same nitrogen amount, sectional subsurface irrigation treatment is higher than common subsurface irrigation. In the different nitrogen amount and the same irrigation method, nitrogen recovery efficiency and nitrogen agronomic efficency of treatment 375kgN·ha-1 is highest. Excess nitrogen amount causes too much nitrogen residual or loss in soil, then reduces nitrogen use efficiency.5. With the increase of nitrogen amount, the accumulative amount of phosphorous and potassium in cucumber of sectional subsurface irrigation and common subsurface irrigation showed a trend of first increase and then decrease, and the accumulative amount of treatment 375kgN·ha-1 is highest. Appropriate nitrogen amount can promote cucumber on phosphorus and potassium uptake. Increasing nitrogen amount significantly increases cucumber dry matter weight and phosphorus and potassium accumulation quantity of sectional subsurface irrigation. Especially significantly increases accumulation proportion of cucumber flowering stage and ending fruit stage. In the same nitrogen amount, cucumber accumulative amount and nutrient use efficiency of phosphorus and potassium of sectional subsurface irrigation treatment are significantly higher than that of common subsurface irrigation.Soil moisture profile observation results show that, protected vegetable cultivation should select sectional subsurface irrigation for irrigation and fertigation, sectional subsurface irrigation can play a better coupling effect of water and fertilizer, cucumber yield and nitrogen use efficiency of sectional subsurface irrigation is better. The appropriate optimum nitrogen amount to cultivation cucumber is about 375 kg·ha-1 in both of irrigation methods.