[Objective]By quantifying the amounts of soil-derived nitrogen(N)uptake by tomato aboveground and residual fertilizer N in soil,this study evaluated the impacts of tomato grafting and N fertilization on the fertilizer N fate,net residual fertilizer N,and N balance in soil-tomato production.[Method]A pot experiment with 15N-labeled urea and the experiment were conducted.Tomato varieties were Qidali and 017,included grafting(grafting and self-rooted),and fertilization(control and N-fertilization)treatments.The 15N tracer was used to distinguish the contribution of fertilizer-and soil-derived N in plants and soils,the fertilizer N fate and the added-N interaction(ANI,i.e.the difference of soil-derived N uptake between N-fertilized and-unfertilized treatments),and the N balance in soil-tomato production was also evaluated.[Result]The contribution of fertilizer N to whole plant N uptake was 35.9%-38.8%,and the contribution to aboveground plant N uptake(35.9%-39.9%)was higher than that in root N uptake(31.6%-36.2%).The ANI exhibited positive values in most treatments,and there was no significant impacts from grafting.Under all the treatments,the average fertilizer N allocated to aboveground,soil and loss was 4.0﹕2.6﹕3.4,and the total recovery of fertilizer N(aboveground N uptake + soil residue)was about 70%.At the fertilizer N level of 250 kg·hm-2,the residual fertilizer N in the soil could not compensate for the soil-derived N allocation to tomato aboveground,and this might cause the depletion of soil N stock in the long run.[Conclusion]The risk of fertilizer N loss was high if large rate of N fertilization was chosen compensate the consumption of soil native N.Compared with tomato 017 scion and self-rooted treatment,the combination of tomato Qidali scion and pumpkin rootstock increased the fertilizer N stay in soil and reduced the fertilizer N loss.Appropriate tomato scion and rootstock could be an feasible and effective measure to maintain the soil N fertility in tomato production.
维普
万方数据