Avalia？？o do estado nutricional do nitrogênio em batateira por meio de polifenóis e clorofila na folha

the objective of this work was to evaluate the effect of n rates on physiological indexes related to nitrogen nutrition in potato, and to verify the possibility of indirectly estimating leaf n contents. flavonol (flvi), chlorophyll (chli), and the nitrogen balance (nbi) indexes were evaluated, and estimations of leaf n contents were made at 21 and 42 days after emergence using the dualex leaf？clip instrument. the experiment was carried out from november 2010 to february 2011, in a randomized complete block design, with five n rates (0, 50, 100, 200, and 300 kg ha？1 of n, applied as urea) at pre？planting, and four replicates. there was an increase in chli and nbi and a decrease in flvi with the increasing n doses. the indexes determined with dualex were correlated with n and extractable chlorophyll content in the fourth leaf and with potato tuber yields. dualex can be used to evaluate n nutritional status in potato plants, and for the prognosis of final tuber yield with readings.