Mineral nutrition of tropical forrages: II Micronutrient deficiencies in tobiatã (Panicum maximum) Grass

Abstract

Tobiatã grass has an apparently great future in the Tropical and is use by many rangers in Brazil. Unluky very few informations on the mineral nutrition of these grass exist. An experiment was carried out with young seedlings which were cultivated in pots containing fine quartz sand a substract and irrigated with nutrient solutions without one of the micronutrient (-B, -Cu, -Fe, -Mn and -Zn). After 81 days the plants were harvested and divided into dry leaves, old leaves, new leaves and stem. The material was dried at 70-80°C and analyse for the micronutrients. The autors concluded that: - The production of dry matter was affected by the omission of the micronutrients in the following order: Cu >; Zn = B, Mn >; Fe. - Clear cut symptoms were obtained for the elements. - Preliminary levels of deficiencies of the micronutrients, founded in the sound leaves were: -B = 23 ppm; -Cu = 0.5 ppm; -Fe = 81 ppm; -Mn=41 ppm and -Zn = 37 ppm.