Growth, development and yield of tomato plants grown in substrate under three nitrogen concentrations of the nutrient solution.

摘要

The effect of N concentration in the nutrient solution on growth and yield of tomato (hybrid Monte carlo) grown in a polyethylene tunnel was studied in autumn and spring growing periods. Sowing was conducted on 8 February and 5 July 2002, and seedlings were planting inside the tunnel 36 and 40 days later, in autumn and spring, respectively. Plants were grown in plastic bags filled with 5.5 dm3 of commercial substrate (Plantmax), with one plant per bag and a plant density of 3.3 plants m-2. Nutrients were supplied to plants by a complete nutrient solution, with the following composition, in mmol litre-1: KNO3 (5.5), KH2PO4 (1.3) and Ca(NO3)2 (2.75), MgSO4 (0.75), with iron chelate and micronutrients. Treatment T2 consisted of the nutrient solution described above, with 11.0 mmol litre-1. For treatment T1, the N concentration of the nutrient solution was reduced to 5.5 mmol litre-1, whereas for T3, the N concentration was increased to 15.16 mmol litre-1. Plants were harvested at 33, 48, 55, 62, 69, 76 and 83 days after planting (DAP) in autumn, and at 55, 62, 69, 78, 85 and 92 DAP in spring. Crop yield was determined based on the fresh weight of fruits. The number of leaves was lower in T3 plants in autumn and spring, whereas the number of fruits was higher in T1 plants in spring. Fruit dry mass accumulation did not significantly vary among the treatments in autumn. In spring, the lowest value of this variable was recorded for T3 plants. Mean values of fresh fruit weight reached 5.4, 5.5 and 5.2 kg m2 in autumn, and 6.7, 7.7 and 5.8 kg m-2 in spring for T1 T2 and T3, respectively, fitting well a polynomial model with estimated maximum fruit yield of 7.8 kg m-2 at a N concentration of 9.3 mmol litre-1.