Absorção, metabolismo e diagnóstico do estado de nitrogênio nas plantas de batata.

Summary - This revision aims to address the metabolic regulations related to the absorption and assimilation of nitrogen ( N ) as well as mention the plant parameters ( physiological or agronomic rates ) that can be used as indicators of the state of N in potato to predict the need for nitrogen topdressing . Also mentioned was the correct management of fertilizer to obtain the optimum or near optimum productivity with the goal of generating sustainable agriculture . In precision farming , diagnosis of the state of N needs to be done mainly in real time. The high consumption and inefficient use of nitrogen fertilizers continues to be problem in potato . ON is absorbed as NO3 - and NH4 + and incorporated into amino acids in roots and shoots. The NO3- is assimilated by two enzymes: nitrate reductase (NR) and nitrite reductase ( NiR ), which catalyze the reduction of NO3- to NO2 - and NH4 + to NO2- , respectively. After reduction, N metabolism has two paths , one for glutamine synthetase (GS) and glutamate synthase to another ( GOGAT ), using as source of N glutamine . Optimization of N management for each cultivar is important to maximize the productivity and quality of tubers . The N status of potato can be estimated through the analysis of N in dry matter . Alternatively , you can use rapid procedures and the content of NO3 - in the petiole , chlorophyll meter ( SPAD index and Dualex ) , color table and physiological indices for assessing the state of N in potato plants .