Saturday, 15 July 2006

Nitrogen Deficiency Diagnostic by the Chlorophyll Meter Evaluation.

Enes Furlani Jr., Andre Rodrigues dos Reis, and Marcelo Andreotti. São Paulo State Univ, Brasil avenue, 56, Ilha Solteira, 15385-000, Brazil

Nitrogen is the most required nutrient by coffee crop and its management is very important. Depending on the season when N is supplied, the losses of the nutrient can be very high, especially during the rainy season. The study was developed in Sud Mennucci county (northwest of São Paulo State - Brazil) in an Alfisol in order to evaluate the effect of different rates and application times of nitrogen on the chlorophyll and nitrogen content in coffee leaves, and to establish correlations with productivity. The experimental design was the completely randomized, in a factorial outline 5x3, constituted by combination of 5 rates (0, 50, 150, 250 and 350 kg ha-1) of nitrogen (urea) in three application times (a single application in December; two applications: splitted in November and January and three applications: splitted in November, December and January). The leaf chlorophyll content and nitrogen leaf content were evaluated during the frutification and productivity was measured. The chlorophyll concentration was positively correlated with the leaf nitrogen content and production of grains. Using a quadratic model function with rates of applied N, it was determined that the rate of 210 kg ha-1 of nitrogen promoted the largest productivity. Estimated chlorophyll content was shown promising for detection of N deficiencies in coffee crop.

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