Effects of the Araxá rock phosphate, calcareous and gypsum on seedlings of rubber tree

Abstract

The experiment was installed under greenhouse conditions in the Department of Agriculture of the Escola Superior de Agricultura de Lavras (ESAL), Lavras, MG, Brazil, to evaluate the effects of combinations of "Araxá" phosphate rock, dolomitic lime and gypsum on the growth and macronutrient uptake by rubber tree seedlings (Hevea sp.). Top-layer samples of a very clayey, Epiallic Dark Red Latosol "Cerrado" phase were used. The experimental design was in randomized blocks with 5² factorial (5 phosphate levels: 0, 50, 100, 150, 200 kg/ha P₂O₅ with 5 combinations of lime and gypsum being: no gypsum and no lime, 100% lime, 33% lime + 67% gypsum, 67% lime + 33% gypsum and 100% gypsum. The seedlings were allowed to grow for 12 months and them plant height, diameter, dry matter, concentrations of K, N, Ca, Mg and S on the leaves, Al concentrations on the roots and P accumulation on the leaves and total dry matter were determined. Analyses of variance and regression/correlations were performed on the data allowing the following conclusions: none of the lime and gypsum combinations affected plant height of diameter; combinations of lime and gypsum had no effect on dry matter yield, but they were superior to lime or gypsum applied separately.