Seleção de cultivares de forrageiras para o agreste alagoano

Abstract

With the aim of evaluating and selecting forages adapted to arid ecosystem were evaluated 04 cultivars of Panicum maximum (Mombaça, Milenio, Tanzania and Massai) and 03 cultivars of Brachiaria brizantha (Xaraés Marandu Piatã). The experiments were conducted at the Universidade Federal de Alagoas Campus Arapiraca in a completely randomized design with three replications in plots measuring 4.0 square meters. The cultivars of B. brizantha were sown in the field to haul exeprimental and when the plants reached about 30 cm to 15 cm were collected. Cultivars of the species P. maximum were germinated on plastic trays containing substrate commercial farming and were later transplanted to the experimental area and were taken according to the height of each cultivar as follows: Milênio cultivars and Mombaça were cut to a height of 90 cm and 15 residue cm; cultivar Tanzania was cut to 70 cm high and 30 cm of waste and cultivate Massai was cut to 50 cm high and 20cm residue. After cutting the plants were separated into leaves, stem and dead material and after drying were evaluated for the production of total dry mass, leaf dry mass of stem and dead material. The morphogenesis (leaf appearance rate, phylochron, leaf elongation rate, rate of senescence and leaf life span), structural (total number of leaves and length of blades) and tillering (appearance rate, mortality and survival tiller) of the cultivars were measured from assessments on tillers and tussocks previously identified with colored rings. Cultivars of the species B. Brizantha were evaluated qualitatively. Evaluations of producing a square of 2.5 m2 was allocated randomly to the plots when the plants reached the height of cut. Immediately after the cuts the plants were weighed and separated into leaves, stem and dead material, then the botanical components were dried in a forced air oven at 55 ° C until constant weight. The results estimated the total dry matter yield, dry leaf, dry stem and dead material. Samples were ground, identified and sent (1 g / plant) for nutritive value assessments, which were held in Near-Infrared Reflectance Spectrocospy (NIRS) in Animal Nutrition Laboratory at Embrapa Beef Cattle, which proceeded the analysis of crude protein (PB) of leaves, stem CP, Neutral Detergent Fiber (NDF) leaf, stem NDF, acid detergent fiber (ADF) stem, in vivo digestibility of organic matter (IVDMO) leaves, stalks IVOMD, lignin in the leaf stem. Cultivar Massai showed low rates of senescence and high density of tillers showing the most suitable among cultivars of the species P. maximum. Cultivars Marandu, Xaraés and showed higher rates of tillers, leaf life span, the final length of the blade, blade productivity and lower rates of mortality of tillers, so we can conclude that these are among the best adapted grasses cultivars of the species B. brizantha. For quality characteristics of species B. brizantha cv. Marandu and Piatã showed good levels of protein and digestibility when compared with the grass Xaraés. For the species P. maximum, the cultivar Tanzania presented qualitatively superior to the others with higher digestibility and higher protein content. Partial results indicate that cultivars Marandu, Xaraés (B. brizantha) and Massai, Tanzania of (P. maximum) are those with higher productivity in the ecosystem Agreste.