1. Department of Agronomy, Federal Rural University of Pernambuco, Recife, Brazil
2. Department of Educational Development, Federal Institute of Education, Science and Technology of Pernambuco, Vitória de Santo Antão, Brazil
3. Academic Unit of Serra Talhada, Federal Rural University of Pernambuco, Serra Talhada, Brazil
4. Department of Agronomy, Sugarcane Experimental Station, Carpina, Brazil