Physiological characteristics of cloned cacao trees treated with nitrogen fertilization

Abstract

Cacao is native to the Amazon rainforest and has adapted well to the climate and soils of southern Bahia. The potential expansion of cacao farming to non-traditional areas could generate foreign exchange for the country by reducing imports or even allowing the country to return to the role of cocoa bean exporter. It is known that nitrogen fertilization is essential for cacao cultivation, due to its high demand for this nutrient. Accordingly, the influence of fertilization of two nitrogen sources (urea and calcium nitrate), on total soluble protein (PTN), total soluble sugars (AST), reducing sugars (RA), sucrose, Nitrate Reductase enzyme (NR) activity and chlorophyll indexes of cloned cacao in the Lower São Francisco Valley were investigated. The experimental format was a randomized complete block design, in a 5 x 2 factorial scheme, the first factor being five cacao clones (PH-16, CCN-51, PS-1319, CCN-10 and TSH-1188), and the second factor, two sources of nitrogen (calcium nitrate and urea), with three replicates. The different nitrogen sources presented different behavior in relation to the physiological characteristics of the clones evaluated. Regardless of the nitrogen source, the nitrate reductase enzyme showed greater levels of translation activity in cacao leaf than in root tissue.