Efeito do fósforo e da micorriza sobre o crescimento e a absorção de nutrientes por mudas de seringueira (Hevea brasiliensis muell arg.).

Abstract

A greenhouse experiment was carried out to determine the effects of MVA and different phosphorus rates on the growth of rubber (Hlevea brasiliensis) seedlings. Treatments were three levels of Phosphorus application (0.9; 1.8: and 2.7 g P,O,/seedling), as triple superphosphate, and two michorrizae inoculation (non-inoculated and inoculated with Gigaspora margarita), both in a sterilized soil. The parameters analyzed were root infection, plant height and diameter, shoot dry weight, concentration and absorption of N, P K, Ca, Mg, S, B, Fe, Mn and Zn in the shoots. Plants were harvested nine months after planting of rubber seedlings. Phosphorus rates increased root infection, plant growth in height and diameter, dry weight of shoots. P rates also increased the concentrations of P, S, B and decreased the concentration of K in the leaf. The highest P rates increased the absorption of N. P, Ca, Mg, S, B, Fe but did not influence the absorption of K, Mn and Zn by the plant. The root analysis did not show the presence of the inoculated MVA fungus Gigaspora margarita. However, there was evidence of infection caused by Rhizoctonia sp., which was correlated higher plant growth at the highest P level. The boron supply in the soil, at the concentration of 1 mg/kg, induced plant toxicity.