Nutritional aspects of potato plants for seed tuber production in protected condition / Aspectos nutricionais da batateira para produção de tubérculo-semente em ambiente protegido
Hector Manuel Coraspe-Leon
DATA DE PUBLICAÇÃO
In spite of its importance and the great number of studies on the potato (Solanum tuberosum L.) crop, in the tropical conditions the existing researches on mineral nutrition of the potato plant grown for seed tuber production, in field and in protected conditions, are scarce. The seed tuber production in protected conditions, as the system used by IAC (São Paulo State Research Institute at Campinas), should be better understood to be subject of technological improvements. Among the cultivars for industrial use in Brazil, the cv. Atlantic stands out for being one of few adapted ones for the purpose and with high yield potential, occupying around 80% of the national market of the potato processed as "chips". The objective of the present work was to study the mineral nutrition of potato plant, Atlantic cv, for the production of basic class seed tubers, in protected conditions with nutrient solution in expanded clay as substratum. Three experiments were carried out in greenhouse with the purpose: a) to evaluate N and K rates and their possible interactions on the seed tubers production; b) to determine the nutrients ( macro and B, Cu,Fe, Mn and Zn) absorption time course in potato plants for seed tuber production; and c) to determine the preferential nitrogen form taken up by potato plant for seed tuber production, using the 15N isotope. The production of dry matter and the accumulation of nitrogen in the tubers and in the shoot were directly related with the N rate in the nutrient solution. The potassium accumulation in the shoot was directly related with the supply of nitrogen and potassium, while in the tubers, only of K. There was positive interaction between nitrogen and potassium, resulting in decrease in the loss of weight of the tubers after storage period. The lowest dehydration of tubers was obtained with the combination of 12.65 mmol L-1 of N and 7.03 mmol L-1 of K.. The sequence of maximum accumulation of the macronutrients was: potassium>nitrogen>sulfur>calcium>phosphorus>magnesium, while of micronutrients was: iron>manganese>copper>zinc>boron. The preferential form of nitrogen absorption in the early stage of plant growth was the NH4, not having difference between the N forms at intermediate growth stages (28 and 49 days after transplanting), changing to NO3 after 56 days (tuber formation). The utilization of N by the plants was, however, always larger with NH4 form in all stages, with the exception at 28 days and the end of cycle.
ambiente protegido plantas expanded clay nutrientes minerais do solo nutrição vegetal solução nutritiva ammonium-15n absorption time course mineral nutrition nutrient solutions batata nitrate-15n tubérculos