CORRELATIONS BETWEEN SPAD READINGS, CHLOROPHYLL AND LEAF NITROGEN IN COFFEE CULTIVARS DURING FRUITING STAGE

Resumo

The methods currently used to determine the chlorophyll content and the amount of nitrogen present in leaves takes a long time to work, as well as the collection and destruction of the leaf tissues. Therefore, we have been studying the use of recent portable meters of chlorophyll, which enables a quick reading without requiring the destruction of leaves. The objective was to correlate the concentration of chlorophyll (a, b and total) as well as the concentrations of Nitrogen in the leaf tissue with indexes of SPAD-502 in four cultivars of arabica coffee. The experiment was conducted in the field during the agricultural year of 2006/2007. The experimental design was completely randomized, and the material was collected from the fourth pair of leaves below the apex of the plagiotrophycal, at the half height of the plants and on the two exposed sides between the lines of the coffee plantation. 20 leaves from four cultivars of arabica coffee, Topázio MG-1190, MG-1192 Rubi, Catuaí IAC-99 and Catucaí 2 SL, were used during four stages of leaf development, varying the intensity of green color of the leaves, consistent in the treatments. The estimations with SPAD - 502 showed high accuracy levels of chlorophyll (a, b and total) in the leaves, also there was a high correlation with the amounts of N extracted by the traditional method. Thus, the use of SPAD - 502 to evaluate the nutritional diagnosis of coffee leaves provides correlation, as well as being able to be repeated quickly, accurately and non-destructively.