Chemical composition of Panicum maximum ‘BRS Zuri’ subjected to levels of salinity and irrigation depths
ABSTRACT The study of cultivars with moderate flood tolerance is essential to their use in pastures irrigated with saline water. The aim of this study was to evaluate the chemical composition of Panicum maximum ‘BRS Zuri’ under the effect of different irrigation depths and levels of salinity. A randomised block design of split plots was used with five replications per treatment. The treatments resulted from the combination of three levels of water salinity (S1 = 0.6, S2 = 1.8 and S3 = 3.0 dS m-1) and four levels of irrigation (I1 = 60%, I2 = 80%, I3 = 100% and I4 = 120% of the evapotranspiration). The chemical composition of the grass, Panicum maximum ‘BRS Zuri’, cut at 28 days, was evaluated over two cycles. There was an interaction between the factors (salinity x irrigation depth x cycle) for the dry matter (DM) content. With the increase in irrigation depth, there was a linear reduction in the crude protein (CP) content in both cycles. The neutral detergent fibre (NDF) and cellulose (CEL) content increased linearly as a function of the irrigation depth, while the lignin (LIG) content decreased linearly with irrigation depth. It was concluded that high levels of salinity cause reductions in the dry matter content in response to increased water availability and extension of the cultivar cycles. The reduction in saline levels under low water availability results in a higher CP content. Salinity has a negative effect on the NDF, ADF, HEM, CEL and LIG content as the irrigation depth increases.