Mineral nutrition of Andropogon gayanus Kunth var. bisquamulatus (Hochst) Hack: II. concentration and absorption of micronutrients

Abstract

As gamba grass (Andropogon gayanus Kunth, var. bisquamulatus (Hochst) Hack) to a promising species for raising cattle, this work was carried out to determine concentration and accumulataion of micronutrients from the 20 th day after germination up to flowering. For this purpose, an area comprising half a hectare of "Terra Roxa Estruturada" at Piracicaba, State of São Paulo, Brazil (latitude 20°41'31"S, longitude 47°38' 01" WG, elevation 540m) suitably fertilized, was planted. As intervals of 20 days after germination up to 140 days, plants were collected and sub divided into leaves and stem. The dry matter at 80°C was analysed for B, Cu, Fe, Mn and Zn. At the age of 80 days, the following quantities of nutrients were extracted from the grass: 0.15 mg of B; 0.05 mg of Cu; 3.74 mg of Fe; 1.15 mg of Mn and 0.29 mg of Zn. It was found that the concentration of Mn diminished in the leaves as the age of the plant advanced, th concentration of B in the leaves being not affected. In the stem there was a decrease in B, Cu and Fe as the age of the plant increased, the concentrations of Mn and Zn heing not affected.