Avaliação da Folha e do Colmo de Topo e Base de Perfilhos de Três Gramíneas Forrageiras. 2. Anatomia

Abstract

The tissue proportions, the degree of simple linear correlation of this characteristics with the in vitro dry matter disappearance (IVDMD) and their chemical composition were determined in transversal sections of the botanical fractions, leaf blades and sheath and stem sampled from the top and bottom tillers of dwarf elefantgrass (Pennisetum purpureum, Schumach cv. Mott, setariagrass (Setaria anceps, Stapf ex Massey cv. Kazungula)) and jaraguagrass (Hyparrhenia rufa, Nees Stapf). The jaraguagrass, with high percentage of parenchyma bundle sheath (PBS) in its leaf blade and lignified vascular tissue (LVT) and sclerenchyma (SCL) in the leave blades and sheath, presented a less compatible proportion of tissues with a high nutritive forage value, as compared with dwarf elefantgrass and setariagrass. The leaf blades characterized by showing higher epidermis proportion, lower proportion of SCH, LVT and parenchymal cells (PCA) in relation to leaf sheath and stem. The proportion of SCH negatively correlated with IVDMD of the leaf blade from the top of the tiller, stem, and the total tiller fractions. The proportion of PCA positively correlated with IVDMD of the leaf sheath, r = 0,68, while the proportion of LVT presented a positive correlation with IVDMD, when all tiller fractions were considered, r = 0.31. The proportions PBS, LVT and SCH positively correlated with the neutral detergent fiber and acid detergent fiber content of the forages, while the proportions of mesophyll and epidermis showed a negative correlation.