Effect Of Drip Irrigation Frequency And Nitrogen Fertilizer On Tomato Growth And Soil Nitrogen Distribution

In the northern solar greenhouse conditions,the commonly used fresh tomatoes were used as test materials.This experiment has two factors of irrigation frequency and nitrogen application rate.The irrigation quota was 1800m³/hm²,and there were 2 irrigation frequencies（1 time in 2 days and 10 days）,as well as 2 nitrogen levels（360 and 600kg/hm²）established.In 2016,a total of four treatments were applied.In 2017,two sets of control treatments without applying nitrogen fertilizer were added.The effects of different treatments on tomato growth characteristics,fruit yield quality,and nitrogen metabolism-related enzymes were investigated during the period of tomato growth.The analysis of water content,ammonium nitrogen and nitrate nitrogen in different soil layers provides a theoretical basis for setting a reasonable amount of nitrogen for irrigation.Conclusion:1.The irrigation quota is the same as above.The irrigation frequency of two days can significantly increase the plant height and stem diameter of the tomato,reaching 173 cm and15.37 mm,respectively.Thus,leaf area increases,and the photosynthetic utilization efficiency is high.The effect of the tomato fruit was as follows:the yield of W1N1 reached76840.05 kg/hm²and significantly higher than other treatments（P<0.05）,but the content of soluble sugar and organic acid in fruits did not reach significant levels.2.The activities of NR and NiR in leaves showed a bimodal curve with the development process in each treatments.The maximum values were found at the seedling stage and NiR occurred earlier.The two had a positive correlation.The increase of enzyme activity effectively promoted the absorption and transformation of nitrogen.At the same time,the activity of GS was low in the early stage,increased during the fruit setting period,and the GDH activity was higher at the seedling stage,followed by a downward trend,and there was a negative correlation between the two.3.The amount of irrigation water remains unchanged,and high-frequency irrigation methods maintain the soil moisture and nitrate nitrogen content in the root activity area of100-300 mm.The low-frequency and multiple-irrigation methods lead to plant growth due to the long interval between irrigation intervals.Water demand cannot receive moisture supply in time and subject to drought stress,or it cannot effectively absorb the deep leakage of moisture and nitrogen.Therefore,it is important to control the frequency and amount of irrigation during production.4.The correlation between CO₂ emission flux and air temperature is relatively high,showing the daily variation characteristics of"high night and low nighttime".The maximum value of 14:00 was reached at noon,and the high nitrogen treatment improved compared to regular nitrogen treatment.The absorption peak was reached from 18:00 to20:00.The overall performance was fertilization treatment>control treatment;N₂O emission flux showed a single peak change with temperature,peaking at 14:00-16:00 noon.5.Combined with the results of the two-year experiment,the high-frequency nitrogen-tolerant treatment effectively increased the growth and yield of tomato plants,maintained the soil moisture content in the concentrated root distribution area,effectively reduced nitrogen leaching and groundwater pollution,and at the same time reduced greenhouse gas emissions.It is recommended that the nitrogen level in solar greenhouse drip irrigation is 360kg/hm²,the irrigation quota was 1800m³/hm²,and the irrigation frequency is1 time in 2 days.