Study On Suitable Nitrogen Application Rate In Different Growth Stages Of Tomato In Solar Greenhouse

Nitrogen plays an important role in agricultural production.Timely and appropriate nitrogen application can promote crop growth and development,increase yield and improve quality.In order to explore the suitable nitrogen application rate of tomato at different growth stages in solar greenhouse,five nitrogen application rates were set up in tomato flowering and fruit setting period,fruit enlargement period and fruit maturity period.During the flowering and fruit setting period,the nitrogen application rate was set to 0 kg/667 m2(AT1),0.9 kg/667 m2(AT2),1.8 kg/667 m2(AT3),2.7 kg/667 m2(AT4),3.6 kg/667 m2(AT5);During the fruit enlargement period,the nitrogen application rate was set at 0 kg/667 m2(BT1),4kg/667 m2(BT2),8 kg/667 m2(BT3),12 kg / 667 m2(BT4),16 kg/667 m2(BT5);During the fruit maturity period,the nitrogen application rate was 0 kg/667 m2(CT1),4kg/667 m2(CT2),8 kg/667 m2(CT3),12 kg/667 m2(CT4)and 16 k /667 m2(CT5).The effects of nitrogen fertilizer on yield,quality,photosynthetic characteristics,root activity,nutrient absorption and soil enzyme activity of tomato at different growth stages were studied in order to provide theoretical basis for scientific fertilization of facility tomato.The main results are as follows :1.The suitable nitrogen application rate for the growth and development of tomato in different growth stages is different.At the flowering and fruit setting stage,the stem diameter of the plant was higher than that of other treatments under the treatment of nitrogen application rate of 2.7 kg/667 m2(AT4),and the difference was significant.The photosynthetic pigment content,net photosynthetic rate and leaf nitrate reductase activity reached the highest level under the treatment of nitrogen application rate of 2.7 kg/667 m2(AT4).Root growth,root activity,total dry and fresh weight of plants,and nutrient content of different organs of plants were also the highest under the treatment of nitrogen application rate of 2.7 kg/667 m2(AT4).In the fruit enlargement period and fruit maturity period,under the treatment of 12 kg/667 m2(BT4,CT4),the photosynthetic pigment content,net photosynthetic rate and nitrate reductase activity of tomato leaves were the highest,the root growth was the largest,the root activity was the most vigorous,the total dry and fresh weight of the plant was the heaviest,and the nutrient content of different organs of the plant was the highest.2.Different nitrogen application treatments in different growth stages of facility tomato had different effects on final yield and quality.At the flowering and fruit setting stage,the final yield of the whole growth period was the highest under the treatment of nitrogen application rate of 2.7 kg/667 m2(AT4).The contents of soluble solids,soluble sugar,vitamin C,lycopene and soluble protein were the highest,and the organic acid was the lowest.In the fruit enlargement period and fruit maturity period,under the treatment of 12 kg/667 m2(BT4,CT4),the final yield of the whole growth period was the highest,the contents of soluble solids,soluble sugar,vitamin C,lycopene and soluble protein were the highest,and the organic acid was the lowest.3.Different nitrogen application rates had significant effects on soil physical and chemical properties at different growth stages of greenhouse tomato.Appropriate nitrogen application rate could improve soil nutrients and soil enzyme activities.At the flowering and fruit setting stage,the nitrogen application rate of 2.7 kg/667 m2(AT4)had the highest soil nutrients and soil enzyme activities.In the fruit enlargement period and fruit ripening period,the soil nutrient and soil enzyme activity were the highest under the treatment of 12 kg/667m2(BT4,CT4).