Estimativa n?o destrutiva do teor foliar de nitrogênio em cacaueiro utilizando clorofil?metro

摘要

The replacement of the traditional method for evaluating the nitrogen (N) in the plant by the use of portable chlorophyll meter SPAD is promising because it is a portable device that provides a nondestructive, instant and low cost index.This study aimed to determine the ability of this device in estimating leaf N content of cocoa. The area covered by this study involves the wet and humid climate zones of the sub humid cocoa region of Bahia. Were selected ten farms, in each area, with crops in agroforestry system and that the area had renewed by grafting of basal shoot with clones tolerant to witches' broom. In each farm, four plants over the age of four years were selected in different topographic and soil conditions. It was collected eight healthy leaves per plant and in each, was made six SPAD readings of the index. Furthermore, were determined the N content, N content, leaf area (LA) and specific leaf mass (SLM). The SPAD index was significantly positively correlated with leaf N content (r = 0.74), with AF (r = 0.62) and negatively with the MFE (r =-0.57). There was no correlation between N content and SPAD index. There was no correlation between N content and SPAD index. The simple linear regression model to predict the N content from SPAD index, without distinction of environments was more appropriate.