Avaliação de linhagens de tomateiro rasteiro quanto à eficiência na absorção de nutrientes e respostas à adubação

The employment of supplementary fertilization is an essential practice in food crop agroecosystems. However, without taking into consideration technical criteria, the fertilization practice might lead to environmental pollution, increased production costs and make the crop systems economically not viable. Thirty processing tomato inbred lines were evaluated for their efficiency in nutrient uptake and in their response to fertilization. Two field assays were carried out at Embrapa Vegetable Crops (Gama-Federal District, Brazil) with distinct fertilization dosages in 2006. In the first assay 1/3 of the total fertilization was applied when compared with the second assay. The experiments were conducted using a completely randomized design with three replications. The criteria to rank the inbred lines in both assays were the DRIS (Diagnosis and Recommendation Integrated System) index value and fruit yield. The critical values in order to distinguish efficient versus non-efficient as well as responsive versus non-responsive inbred lines were the average increase in both DRIS index value and fruit yield. The average increase in the DRIS index of N, P, K, Ca, S, B and Cu were 100.8, 307, -326, -203, 356, 310 and 230, respectively. The average increase in yield was 7.4 Mt ha. Differences were detected among inbred lines for the uptake efficiency for all nutrients and for response to fertilization. The inbred lines 3, 4, 9 and 22 were classified as responsive to fertilization and efficient in N uptake; the inbred lines 3, 4, 9, 13, 15 and 29 were for P; 3, 5, 10, 21, 22, 25 and 27 for K, 5, 10, 21, 22, 25, 27 and 29 for Ca; 4, 13, 15, 27 and 29 for S and B; 3, 5, 9, 10 and 27 for Cu. The inbred line with the best performance in the assays was the 27, displaying an uptake efficiency of 71.4% of the nutrients under analysis. The inbred lines 3, 4, 5 and 29 displayed a frequency of 57.1% and of them were responsive to fertilization.