NITROGEN AND N,P,K RELATION AFFECT TOMATO SEEDLING GROWTH, YIELD AND EARLINESS

The seedlings were fertirrigated with nutritional solution (200 ml/plant) containing N at 2, 4, 8, 16 meq l^-1 in factorial combination with N:P₂O₅:K₂O at 1.0:0.4:1.2, 1.0:0.8:2.4, 1.0:1.2:3.6 and 1.0:1.6:4.8. Plants were transplanted into the plastichouse on 22 May 1991 (37 d treated) and identically irrigated and fertilized.

The nursery results showed N as the major factor affecting tomato seedling growth, positively increasing its concentration. The effects of different N,P,K relations influenced the measured variables, affected by N rates, except the leaf number and SLA. The best result for stem and total fresh weight was obtained with 1.0:0.8:2.4. For plant height, leaf area, leaf fresh weight, dry weight of leaves, stem and total plant with 1.0:1.2:3.6 relation. The interaction between N rates and N,P,K relations was significant relating to root fresh and dry weight, RGR and NAR.

The increasing N levels affected positively the early production as a result of higher fruit number and higher fruit weight. The lowest N,P,K relation reduced the early production (number and weight of fruits).

The total fruit production was poorly influenced by the N level treatments: only 2 and 4 meq l^-1 rates affected positively the total weight of fruits.

The analysis of the stepwise multiple linear regressions with variables describing the nursery growth of seedlings and the production enhanced a positive relationship between the leaf dry weight and the early production, as fruit weight and number.

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