EVALUATION OF NITROGEN MONITORING, BUD FERTILITYAND ‘THOMPSON SEEDLESS’ GRAPEVINE PRODUCTION ON DIFFERENT ROOTSTOCKS

Portuguese. RESUMO Adotaram-se métodos de análise de N em tecidos de folhas em laboratório, teores de nitrato na seiva de pecíolos e o índice relativo de clorofila (IRC, em unidade SPAD), bem como foram avaliados as taxas de fertilidade de gemas, os aspectos produtivos e qualitativos de cachos e bagas da videira ‘Thompson Seedless’, enxertada sobre os porta-enxertos ‘Harmony’, ‘Jales’ ‘Paulsen 1103’ e ‘SO4’. A dose de N aplicada foi de 80 kg ha-1, e o experimento foi instalado no Submédio do Vale do São Francisco, Brasil. O delineamento experimental utilizado foi blocos ao acaso, com quatro tratamentos e cinco repetições, sendo que a parcela experimental foi constituída por cinco plantas. Além das análises de N pelos métodos citados, avaliaram-se comprimento e largura (cm) e massa fresca de cacho (g), comprimento, diâmetro (mm), volume (mL), massa da matéria fresca de bagas (g), teor de sólidos solúveis (SS), acidez titulável (AT), relação SS/AT, fertilidade de gemas potencial (gemas frutíferas, vegetativas, mortas e escuras, em %) e fertilidade de gemas real (%). Verificaram-se diferenças entre teores de nitrogênio na folha, nitrato na seiva e IRC da ‘Thompson Seedless’ em relação aos porta-enxertos, e quando enxertada sobre o ‘Harmony’, a ‘Thompson Seedless’ expressou melhor potencial para o desenvolvimento de cachos e bagas.

English. ABSTRACT Methods of nitrogen analysis were adopted in leaf tissues in the laboratory, nitrate content in the sap of petioles and chlorophyll relative index (CRI, in SPAD unit), as well as the evaluation of the buds fertility rates, production and qualitative aspects of cluster and berries of ‘Thompson Seedless’ vine, grafted on rootstocks ‘Harmony’, ‘Jales’ ‘Paulsen 1103’ and ‘SO4’. The applied dose of N was 80 kg ha-1, and the experiment was installed in the Submédio do Vale do São Francisco, Brazil. The experiment was performed in a randomized blocks design, with four treatments and five replicates, with the experimental plot represented by five plants. In addition to the analysis of N, cluster length and width (cm) and fresh mass (g), berries length, diameter (mm), volume (mL), mass of fresh matter of berries, soluble solids (SS), titratable acidity (TA), SS/TA ratio, potential bud fertility (productive, vegetative, dead and dark buds in %) and real bud fertility (%). There were differences in nitrogen content in the leaves, nitrate in sap and CRI of ‘Thompson Seedless’ in relation to rootstocks. ‘Thompson Seedless’ expressed better potential for the development of clusters and berries when grafted on ‘Harmony’.