Banca de DEFESA: LUCIANA PEREIRA DAMAS

CUTTING MANAGEMENT STRATEGIES IN 'CUNHÃ' (Clitoria ternatea L.): IMPACT ON MORPHOLOGY, PRODUCTIVITY, NUTRITIVE VALUE AND N2 FIXATION

Bromatological composition. Digestibility. Harvest frequency. Harvest intensity. Forage legume. Fixed nitrogen (N). Forage production

The cultivation of forage legumes reduces the need for nitrogen fertilizers due to biological nitrogen fixation, reducing N₂O emissions. The study of the responses of forage legumes to cutting management can encourage their adoption in forage production systems. The objective was to evaluate Butterfly pea (Clitoria ternatea L.) under different frequencies (60, 75, 90, and 105 days) and cutting intensities (5, 10, and 20 cm). The experiment was conducted over two years in a dry tropical climate region in northeast Brazil (7°51’133” S and 35°14’102” W). The experimental design was randomized blocks in split plots with four replications. The cutting intensity did not influence the nutritional value of the wedge. The lower cutting intensity (20 cm) promoted greater development of the aerial part of the plants (49 and 55 cm in height and plant width), compared to the lower intensity (5 cm), as well as did not affect the N-derived from the air (about 80%) between the cutting frequencies. The annual forage production (6600 kg of DM ha^-1 year^-1), at intensities of 10 and 20 cm, the fixed N per year (226 kg of N ha^-1 year-1), at an intensity of 20 cm, as well as the proportion of leaves (50%), leaf/stem ratio (2.5), crude protein content (232 g kg of DM ^-1) and in vitro DM digestibility (524 g kg of DM^-1), were higher at the frequency of 60 days, notably when compared to the frequency of 105 days. Cutting every 60 days, at intensities of 10 or 20 cm, is recommended for Butterfly pea, considering the greater amount of N fixed per year and greater annual forage production, with better nutritional value, given the greater leaves proportion and leaf/stem ratio in harvested forage. This cutting management strategy can not only improve the productive efficiency of the production system and the animal diet, but it can benefit biological N₂ fixation, intensifying nitrogen availability in the soil over time.