Thermal time in nitrogen and boron application on irrigated Mombaça grass "Guinea grass".

This study aims to evaluate the correlation among growing degree-days (GDD), canopy height (CH), and leaf area index (LAI) for Guinea grass irrigated, considering the different combinations of the nitrogen and boron rates and cycles of regrowth. The experiment was carried out from August/2017 to August/2018 in a field experiment, and the climate of the region is classified as subtropical. A randomized block design arranged in a factorial scheme (4x3x11) with four replications was used. The treatment was (i) boron fertilization: 0, 1, and 2 kg ha-1; and (ii) nitrogen fertilization: 250, 500, 750, and 1,000 kg ha-1 distributing to 11 growth/cutting cycles. We observed the high correlation between GDD and the parameters evaluated of CH and LAI. The nitrogen results showed a low influence on canopy height and the leaf area index, and boron results did not influence these parameters. [ABSTRACT FROM AUTHOR]