Índices de nitrogênio na planta e produção de batata-semente básica influenciados pelo parcelamento do fertilizante nitrogenado / Nitrogen plant index and production of basic seed potatoes influenced by the subdivision of the nitrogen fertilizer

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

26/07/2011

RESUMO

This study aimed to evaluate the effect of dose and mode of division of the nitrogen fertilizer on plant characteristics, in the potato reference leaf and production in three seasons of the crop cycle and the production of tubers at harvest. Additionally it was aimed to select among the characteristics evaluated, possible indexes for the status of plant nitrogen (N) diagnosis and the potato tubers productivity prognosis. Treatments were four N rates (0, 115, 230, 460 mg dm-3) and five application modes: Mode 1 - 10% at planting + 90% at 21 days after emergence (DAE); Mode 2 - 10% at planting + 3% daily (21 to 51 DAE); Mode 3 - 50% at planting + 50% at 21 DAE; Mode 4 - 50% at planting + 1.6% daily (21 to 51 DAE) ; Mode 5 - 100% at planting. The experiment was installed in a protected environment, on the Department of Plant Science at the Universidade Federal de Viçosa, from 20/09/2010 to 22/12/2010. It was planted cultivar Atlantic , using commercial mini-tuber of the basic category as propagating material. Plants were grown in 3 dm3 pots containing commercial substrate Tropstrato. It was used randomized block design in factorial arrangement 4x5 (doses x modes), with three replications. At 21, 35 and 56 DAE were evaluated plant and reference leaf characteristics. Plant characteristics evaluated were: length of main stem (CHP), diameter of main stem (DHP) and numbers of stems (NH) and leaves (NF). In reference leaf was evaluated: SPAD index, chlorophyll (CHL), flavonoids (FLV) and N balance (NBI), green intensity of the leaf by the color table or index number (IN), number of leaflets (NFO ), length (CF), width (LF), base of the petiole diameter (SD), leaf area (ARF), content of N-NO3- in the petiole sap (NIF), fresh and dry matter (MFF and MSF), N content (TN) and amount of accumulated N (QNA). With the dried plants, the harvest was done and determined the number of tubers (NT) and fresh and dried tubers mass (TFM and MST). The datas were subjected to analysis of variance, regression, average test and correlation. At harvest, no combination of dose and mode of nitrogen application influenced the NT that hit the estimated average value of 4.75/pot. On the other hand, was no effect of the application method on the MFT and MST. There was a decreasing linear effect of doses on MFT and MST when they were applied by modes 1 and 3. In the other modes there was no effect of dose on these variables. Also in the harvest, only when was applied the highest dose, the mode of application influenced the MFT and MST variables whose observed values lower in mode 3. In this mode of application, at 21 DAE, no variable was influenced by N rate, except for NFO and CHP that have been influenced negatively and linearly. At 35 DAE, there was a decreasing linear effect of N on the variables CHP, CF, LF, NFO, MFF, QNA and MSF, along with increasing linear effect on SPAD, TN and CHL. The reference leaf was gradually greener , detected by the SPAD and Dualex equipment and not by the color table, and gradually higher N concentration. It is concluded that in the organic substrate used in the experiment, the concentrated application of N at the beginning of the filling period of the tubers (modes 1 and 3) decreases the mass production of them also having negative or toxic in other plant characteristics evaluated along cycle. It is intended to measure at 35 DAE the CF or LF to estimate indirectly the QNA or the TN in the reference leaf, respectively. It is intended to measure the DHP at 21 DAE and at 56 DAE the CHP to predict the NT in the future harvest. Likewise, the MFT can be predicted by FLV and CHP measured at 35 DAE and by SPAD, NIF, MSF and NF measured at 56 DAE. Equations being presented to it.

ASSUNTO(S)

fitotecnia propagação nutrição solanum tuberosum solanum tuberosum nutrition propagation

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