RESUMO
Methods used to detect N deficiencies during the growing season include chlorophyll meter readings, destructive plant sampling, and soil sampling. Furthermore, diagnostic methods like FT-IR techniques that take advantage of the optical properties of leaves are another possibility to assess the nitrogen status of plants in a field and to assess nitrogen fertility effects on yield. The use of effective FT-IR techniques would eliminate the need for extensive field sampling. Fourier Transform Infrared [FT-IR] spectroscopic technique was used in the present work to study the effect of N-fertilization levels on the concentrations of chlorophyll and nitrogen in grape leaves. Ammonium nitrate [N-fertilizer] was applied after the beginning of vegetative growth by supplying 33.3%, 66.6%, 100%, 133.3%, and 166.6% of the recommended N-fertilizer level, according to the Ministry of Agriculture [50 units N which is considered the level of 100% for comparing during N application]. To establish a range of leaf chlorophyll levels, each treatment was applied to definite row; thus there were 5 different rows, three vines in each line were selected to make the application