Correlations among anatomical, morphological, chemical and agronomic characteristics of leaf blades in Panicum maximum genotypes

Tropical forage grasses present high growth rates and biomass yields, partly due to its C4 photosynthetic pathway. Considering this, the anatomy of the grasses related to morphology and chemical composition of leaf blades may influence consumption and digestibility, thus interfering in the forage quality. Agronomic, morphological, anatomical and chemical characteristics of leaves of nine Panicum maximum genotypes were evaluated in Brazil, to verify if these characteristics and the associations among them may influence the quality of the leaf blades. A randomized complete blocks design was used with nine treatments and three replications. Three evaluation harvests were done in the rainy season and one in the dry season to evaluate forage yields and quality. Quality was determined through NIRS - Near Infrared Spectrometer. One day prior to each harvest, four leaf blades per plot were harvested for morphological and anatomical evaluations. Results were subjected to analysis of variance and mean comparison by Tukey test, and to simple linear and canonical correlations by SAS. Leaf width was positively correlated with mesophyll. The parenchyma bundle sheath was associated with leaf area and specific leaf area. Neutral detergent fibre was positively correlated with the parenchyma bundle sheath area and specific leaf area. The specific leaf area was negatively correlated with in vitro organic matter digestibility. Morphological differences among P. maximum genotypes did not interfere in biomass accumulation. Considering this, leaf width may be a supplementary tool, that may be used in the early phases of the process of genotype selection, for discriminating qualitatively promising high yielding materials.