Rafael Ruiz S.1 y Walter Rathgeb P.2
Phosphorus nutrition was more important than N nutrition in seedlings of tomatoes, at the nursery. The opposite occurs under field conditions. This results can be explained by the different way these two nutrients are absorbed. It was also demonstrated that an excess of phosphate during the seedling stage, produces a faster growth and a larger early production of fruits. Also, these experiments showed that in the case of a mild to medium phosphorus deficiency (without P, the yield was 77% of the maximum), the application of high doses of P at the nursery can obviate the need of P under field conditions. In this experiment, the best yield was obtained with high doses of P in nursery, plus an optimal dose in the field, according to previous experimental determinations. The absorption of N, P and K increases sharply from transplantation to flowering, period in which the rate of absorption reaches up to 1.4, 0.25 and 1.75 kg/ha/day, respectively. This rates are demanded by vegetative growth, principally. The maximum absorption rate of N and K occurs at the beginning of the harvest period (1.9 to 1.75 kg/ha/day) and is demanded by the actively growing fruitlets. The absorption of P does not increase in this periodo Absorption rates of the three nutrients decreases sharply, towards the end of the growing season.
1 Estación Experimental La Platina (INIA), Casilla 439, Correo 3, Santiago, Chile.
2 ANASAC. Almirante Pastene 300. Providencia, Santiago, Chile.