Dinâmica de nutrientes na cana-de-açúcar em sistema irrigado de produção

Abstract

One of the main investments in the alcohol and sugar sector is the technological innovations searching for increments in the productivity of the sugar cane fields, as an example, the genetic improvement of the sugar cane producing new varieties more productive and environmentally adapted. The productive capacity of these varieties, however, may have being under estimated due to lack of research in the several areas that involve all the production system of the sugar cane. They are distinguished, among others, those that involve the knowledge of the capacity of extraction of the nutrients for the new introduced varieties. This project aimed to study and to evaluate the capacity of extraction and exportation of nutrients N, P, K, Ca and Mg in eleven varieties of sugar cane and to related the vegetative growth and the agro industrial characteristics of each variety. The work was carried out in a complete randomized block design and the plants were grown under irrigated conditions. Performance indicators of the varieties were analyzed to quantify the allocation of each nutrient in the stem, leaves and shoots, at different stages of growth (120, 180, 240, 300 and 360 DAP). In the growth parameters, the RB92579 and SP81-3250 was distinguished with the biggest values of tillering and production of dry matter. On the other hand, the RB72454 presented the largest stem length while for the diameter of the stem RB867515 highlighted are among the others.The concentration of N, P, K, Ca and Mg in the stem decreased with the development of the culture. The accumulation of nutrients showed that the extraction followed the order: K>Ca>N>Mg>P. It was observed that until the 120 DAP, the extraction of nutrients N, P and K it was bigger in the leaves, while the largest extraction of Ca and Mg occurred in the stem. The varieties hadpresented different answers for the efficiency of use of the different nutrients. Regarding to N the RB863129 was most efficient, for P and K it was the RB92579 and for Ca and Mg the SP79-1011. The varieties RB763710, SP81- 3250 and RB92579 had been the ones that had presented the biggest agricultural productivities. As far as the technological aspects, RB72454 and RB763710 had presented the lesser values of BRIX, PC, POL and ART.