Response of six varieties of sugarcane to potassium dosages on savannah (cerrado) ecosystem

Abstract

The Savannah areas of Roraima has a well defined weather, with rain seasons (April to August) and dry seasons (October to March), favors the production of sugar cane. This study was carry out to evaluate the effect of potassium dosages on six sugarcane varieties response. The statistical design used was the random blocks, in factorial scheme 6 x 5, six sugarcane varieties (RB72454, SP881-3250, SP79-1011, SP80-1816, RB867515 and RB855536) and five dosages of potassium (0; 80; 160; 240 and 320 kg ha^-1 of K₂O), with four replications. It was evaluated the number of stalks per meter, the size of the stalks, average diameter of the stalk, average mass of the stalk, amount of potassium in the leaf, productivity of the stalks, ^oBrix and index of maturation. The varieties answered in a quadratic way to potassium dosages for all studied variables, except ^oBrix and the maturation index; all varieties showed a ten months cicle with ^oBrix overcoming 18%. The potassium dosages determined improved between 55 and 186% in stalk productivity; the highest maximum economic efficiency dosage varied from 94 to 165 kg ha^-1 K₂O. The varieties that showed the best results were RB72454 and RB867515, with average stalk productivity of 50,39 and 56,86 t ha^-1, respectively.