Management of nitrogen fertilization and of water tension on the production of dry matter and leaf area index of Tifton 85 cultivated in the Cerrado region

This work was carried out to evaluate the influence of water tensions (35, 60, 100 and 500 kPa) and nitrogen levels (0-Control, 45, 90, 180, 360 kg/ha) on the dry matter (DM) yield, the dry matter yield rate (DMYR) and the leaf area index (LAI) of Cynodon spp. cv. Tifton 85 bermudagrass. A randomized blocks design in a split splot scheme with three replications was used; split plots were represented by the water tensions and the plots, by the nitrogen (N) levels. The dry matter yield was influenced by the nitrogen levels for all tensions, where the highest productivity (41.8 t/ha) was obtained at 35 kPa the tension and the maximum N level (360 kg/ha of N), while the smallest productivity (17.3 t/ha), at 100 kPa the tension without N addition. At the tensions of 60, 100 and 500 kPa there was limitation in the use of N at the highest doses, due to the deficit water. Higher DMAR were observed from 09/21 to 11/29, and the averages ranged from 73.4 to 194.6 kg/ha/day of DM, while from 05/26 to 08/09 the smallest averages were observed, that ranged from 44.9 to 55.2 kg/ha/day of DM. No effect of N levels was observed from 03/16 to 08/09. In the other periods, DMYR increased as N levels increased. There was no effect of the different water tensions on DMYR. LAI increased as N levels increased, from 09/21 to 01/10, with averages from 3.07 to 9.64. In the periods with low temperatures, N levels and did not affect LAI. Water tension did not affect LAI in all evaluated periods.