Vegetative and enzymatic analysis of the initial stages of Coffea arabica L. grown from seeds treated with humic substances

Arabica coffee is a perennial crop usually propagated by seeds, which must be healthy and able to form normal plants. The objective of this study was to analyze the vegetative and enzymatic reactions in the initial stages of Arabica coffee seedlings treated with different humic substances and at different concentrations. A germination test was conducted with Arabica coffee seeds of the Topazio MG 1190 cultivar using humic substance doses of 0, 5, 10, 25, 50, 50 and 50 mg.dm-³. The percent germination was evaluated at 15 days; the percent germination and root length were measured at 30 days; and the seedlings were removed at 45 days and stored at -80°C for subsequent evaluation of the enzymatic activity of catalase, superoxide dismutase, alcohol dehydrogenase, esterase, and H+-ATPase. It is concluded that germination did not differ with the use of humic substances, and root length was greater at the 0 mg.dm-³ dose. Although H+-ATPase responded positively to the application of humic substances, the catalase, superoxide dismutase, alcohol dehydrogenase, and esterase activities were also better at the lowest dose. Humic substances do not present agronomic benefits at the seedling stage for Arabica coffee and are not recommended as a possible seed treatment under these conditions. Key words: Fulvic acid, humic acid, coffee, seedling formation.