Produtividade e valor nutritivo de gramíneas tropicais em monocultivo e em consórcio com milho na segunda safra

Abstract

This study aimed to assess productivity and nutritional value of the tropical grasses Brachiaria brizantha cv. Piatã, Xaraés, and Marandu, Panicum maximum cv. Mombaça, and B. ruziziensis cv. Kennedy in the interseason of an integrated crop-livestock (ICL) system since alternatives are needed for forage production for animal grazing in Autumn and Winter. The experimental design was a randomized block design in a split-split plot scheme with four replications. The treatments of plots consisted of five grasses, subplots consisted of three cropping systems (monoculture, intercropping with corn and unsuppressed grass, and intercropped with corn and suppressed grass), and sub-subplots consisted of four cutting intervals of grasses (50, 90, 125, and 195 days after emergence - DAE). The experiment was carried out from February to September 2014. Dry matter (DM) productivity, obtained at 195 DAE for the three cropping systems (monoculture grass, unsuppressed and suppressed grass in intercropping), were 18.45, 7.15, and 3.05 t ha?1, respectively, and average crude protein contents of leaf blades of grasses decreased linearly between the cutting intervals of 50 to 195 DAE from 19.95 to 9.70%, respectively. Under integrated systems, the studied grasses showed better yields and nutritional quality when compared to traditional grazing systems. Panicum maximum cv. Mombaça and Brachiaria brizantha cv. Xaraés and Piatã had the highest leaf and crude protein yields when compared to Brachiaria ruziziensis cv. Kennedy and Brachiaria brizantha cv. Marandu. In terms of nutritional value, Brachiaria ruziziensis cv. Kennedy was superior to Mombaça and Xaraés grasses but had lower total dry matter yield. Finally, Xaraés, Piatã and Mombaça grasses are recommended choices ICL systems when fodder grass production is the goal.