Resposta da cana-de-açúcar a diferentes níveis de zinco, em presença de fósforo

Abstract

It was studied the effect of phosphorus on zinc content in the soil and in the plant, through the aplioation of two P levels (180 and 360 kg P 2O5/ha), combined in a factorial experiment with five Zn levels (0, 10, 20, 40 and 80 kg Zn/ha). The soil chemical analysis was done with two extractors (0.1N HCl and 0.05N HCl + 0.025N H2SO4) at several different sampling time; it was also perforned the chemical analysis of different plant tissues at 4 and 9 months after planting and at harvest time. It was observed that 0,1N HCl extracted larger Zn quantities than the 0,05N HCl + 0.025N H2SO4 extractor; howe- wer, the correlations with the different plant tissue at 4 months were greater for the double extractor, eventhough the results with both extractors correlated significantly with the production data. In the soil, it was observed and increase in Zn concentration, regardless the extractor used, for the highest Plevel applied. However, in the plant, the highest P level corresponded to the lowest Zn content in the tissues analysed, indicating that the antagonic effect of P on Zn occurs in the plant. The best sampling time was around 4 months after planting and the best tissue for zinc determination was the leaf +3. There was no significant differences in production between P levels; however, the production was significantly lower in the non zinc treatment than the treatments with increasing zinc levels.