Abstract
Tomatoes were planted in containers to which liquid mixed fertilizer was drip-applied during the cultivation at different rates. In the control plot, straight N, P, K fertilizers were applied before planting. Uptake of plant nutrients was determined and the nitrogen recovery was calculated. Growth of tomatoes depended upon the rates of nitrogen. At 5 g N plant^<-1>, the level usually recommended for the tomato culture, the nitrogen recovery by drip application was 62%, whereas it was 44% in the control plot. The nitrogen recovery with the preplant application was lower at 5 g N plant^<-1> (44%) than at 2.5 g (70%), whereas it did not decrease with the drip-application (from 64 to 62%). This strongly indicated the latter application was more efficient in supplying nitrogen to a crop which has comparatively small root zones. The nitrate concentrations in petiole sap and bleeding sap were higher, when compared at the same rates, for drip application than for the preplant application. In the drip-applied plot, the nitrate concentrations in petiole sap increased with the increasing rate of fertilization. On the other hand, the anion concentrations other than nitrate in petiole sap decreased with an increase in the rate of fertilization.
