The Influence Of Nitrogen Nutrition Diagnosis And Controls Of Cucumber On Yield And Quality

Nitrogen fertilizer application can improve the plant yield. Total nitrogen content of plant vegetables has good reaction to the nitrogen nutrient of plant, which has close correlation with crop yields. Plant total nitrogen content is a good diagnosis index. However, chemical analysis methods of plant total nitrogen not only need to destroy the plants, but also need a long time and complex procedure to test plant samples, so this method can not guide N fertilization timely. Therefore excessive nitrogen application occurs frequently in agricultural production. In order to increase crop yield and quality, quick judgment of the plant nitrogen nutrition is an important issue.In the condition of sunlight green house, effects of different N application and different proportion of NO3--N and NH4+-N on the growth of cucumber were studied through random block experiment and solution culture experiment. To determine the nitrate contents of new leaves and mature leaves of cucumber, SPAD-502 and nitrate meter were used under different growth stages. The study results showed as follows:To study the influences of different nitrogen fertilizer on growth and development of greenhouse cucumber, six nitrogen treatments were designed in this experiment, i.e., N0, N150, N300, N600, N900, and N1200kg/hm2. The results showed that SPAD readings and nitrate content in plant had good correlation with total nitrogen and chlorophyll contents. With increase of N fertilizer application, the contents of chlorophyll and nitrogen in cucumber plants increased. When the nitrogen application came to 600 kg/hm2, the plants in this treatment had higher fruit marketable rates and yield, higher contents of Vc and Soluble protein in fruits, lower nitrate content, and better fruit quality than that of other fertilizer levels.Different proportion of NO3--N and NH4+-N fertilizer had different effects on the plant growth. When the proportion was 1:1, the fruits had higher yield, lower nitrate contents, higher Vc content,organic acid,soluble protein and better quality than that of other treatments. However, different proportion of NO3--N and NH4+-N fertilizer had no significant differences in the SPAD values of plants. In the same treatment, different leaf location showed significant SPAD differences, which showed flower leaf > fruit leaf > early flower leaf. With the increase of nitrate-N level, SPAD values of the flower leaves, fruit leaves and early flower leaves increased. In the same treatment, the net photosynthesis rate, Cond, Ci, the transpiration rate had the same changing rules, which was flower leaf > fruit leaf > early leaves.Under the condition of the sunlight greenhouse, different concentrations of nitrogen nutrient showed different differences on plant growth in solution culture. N2 (336 mg/L) treatment showed the highest yield, the highest Vc, soluble solids and soluble sugar contents among all treatments, nitrate contents lower than of other treatments.