Estudos sôbre a alimentação mineral do cafeeiro: XX. efeito da variação de pH no desenvolvimento e composição química do cafeeiro (Coffea arabica L., var. Mundo Nôvo) cultivado em solução nutritiva

Abstract

Young coffee trees were grown in nutrient solution at different pH values, from pH 4,0 to pH 7,5 at 0,5 pH units of interval. After 140 days the plants were harvested and the main conclusions are the following: 1. The best range of pH for high, number of leaves fresh and dry weight of the plants were: pH 4,0 to pH 6,0. 2. There were a decrease in dry weight percentage of the leaves eith increase of the pH solution. 3. With the increase of the pH there was a decrease in macronutrients content in the plants. 4. At higher levels of pH there was a percentual decrease in N, P, Ca and S in the leaves. At pH 4,0 did not effect K content, bu there was a slight decrease in Mg content. 5. There was a linear relation between pH and the K+Ca+Mg/N+P+S ratio.