Study On The Mechanism Of Nitrogen Absorption And Utilization Of Processing Tomato Based On The Critical Nitrogen Concentration Model Of Plant

In view of the problems existing in the production of drip irrigation processing tomato in China,such as unstable yield,excessive nitrogen application,inefficient coordination between plant growth and nitrogen supply.Based on the critical nitrogen concentration model of processing tomato,through the field nitrogen operation experiment(no nitrogen application,200 kg·hm^-2application,300 kg·hm^-2application and 400 kg·hm^-2application,represented by N0,N1,N2,N3,respectively)and ¹⁵N isotope tracer and field experiment（no nitrogen application and optimized nitrogen application,represented by N0 and NY,respectively）,study on the regulation mechanism of nitrogen absorption and utilization in processing tomato.（1）During the planting-flowering stage of processing tomato,each nitrogen application control had no significant difference（P>0.05）in the growth of processing tomato;after fruit setting,N2 promoted the plant height,stem thickness,total dry weight above ground,and root system of processing tomato more than other control.The increased in total dry weight,total length,total surface area and total volume,and significantly（P<0.05）increased the yield of processed tomatoes,up to 120 t·hm^-2,with higher soluble sugar and lycopene content.（2）N1 reduced the residual amount of nitrogen in the soil,but also reduced the utilization rate of nitrogen.N3 had a higher risk of nitrogen leaching.Nitrogen mainly distributed in the soil during harvest,which reduced nitrogen utilization.Nitrogen absorption under N2 was the highest,reached 289.49 kg·hm^-2and 263.59 kg·hm^-2,respectively in two years,and nitrogen was mainly taken out of the soil by crop absorption,and the distribution of soil nitrate nitrogen was relatively balanced.It was beneficial to increased the apparent utilization rate of nitrogen fertilizer and reduced the residual rate of nitrogen fertilizer.（3）The nitrogen nutrition index of N1 was the closest to 1 during the planting-flowering stage of processed tomato,and the nitrogen nutrition index of N2 after the flowering period was recently connected to 1,and the nitrogen deficiency was closest to 0.Therefore,it was recommended that the optimal nitrogen fertilizer application amount of Xinjiang drip irrigation processing tomato was 278 kg·hm^-2,and the nitrogen application rates during planting-flowering,fruit setting,red ripening,and seedling pulling were 44,72,135,and 27kg·hm^-2,respectively.（4）The dry matter accumulation,nitrogen accumulation,and¹⁵N accumulation of the processing tomato at various growth stages under the optimized nitrogen application program reached 13.87 t·hm^-2,306.51 kg·hm^-2,and 128.92 kg·hm^-2during the seedling pulling period,respectively.The proportion of¹⁵N in various organs of processed tomato accounted for38.34%-56.73%of the total nitrogen accumulation of the organ.As the growth period progressed,¹⁵N in the stem and leaves transferred to the fruit,and the¹⁵N absorption rate of the fruit in the seedling pulling reached 31.91%.The total nitrogen residue during the seedling pulling period was 234.72 kg·hm^-2,and the residual rate and loss rate of ¹⁵N in the soil were33.53%and 20.10%,respectively.