Tillering and Modifications in Leaf Tissue in Panicum Maximum Cv. Mombaça Irrigated and with Different Levels of Nitrogen Under Intermittent Grazing.

Tillering in Panicum maximum cv. Mombaça irrigated and with different levels of nitrogen under intermittent grazing The objective was to assess ther tiller appearance and the mortality rate and modifications in leaf tissue (leaf anatomy) in Panicum maximum cv. Mombaça irrigated and fertilized with different nitrogen rates in four seasons under intermittent grazing. The experiment was conducted in northwest of Parana – Brazil, and the soil was classified as red ultisol sandstone. The experimental design was a randomized block split-plot with four replicates, where the subplots were the four seasons: spring, summer, autumn and winter. The treatments (plots) were: Mombaça + 0 kg nitrogen (N) ha-1 year-1 (control), Mombaça + 200 kg N ha-1year-1, Mombaça + 400 kg N ha-1year-1 and Mombaça + 800 kg N ha-1year-1. The experimental area, divided into four blocks, and each block was divided into four paddocks (experimental units), totaling 16 paddocks of 1,600 m2 each. The grazing method used was intermittent stocking with variable stocking rate. The animals were placed in the experimental areas when pasture reached 95% of Light Interception, and removed after two days, at a 40 cm stubble height. Five clumps per paddock were marked for the tillering study, where the first mark was held in September 2011.The other markings (new tillers and senescent accounting were performed six to seven days after animal removal from the experimental unit. to evaluate the tillering, studied the rate of tillering (TApP) and tiller mortality rate (TMoP). The higher N dose had the lowest values of tiller mortality, and about the seasons, higher TMpP was observed during the winter. The tiller appearance rate is higher in non-fertilized pastures, the lowest tiller mortality ratewas found at the higher N dose applied. For leaf anatomy, there there was no significant effect of nitrogen applied and seasons for adaxial and abaxial epidermis, sclerenchyma, bundle sheath, and vascular bundle. For the mesophyll linaer positive effect was observed for increasing levels of nitrogen applied.