Estado nutricional, qualidade industrial e produtividade de variedades de cana-de-açúcar nos ciclos de cana-planta, primeira e segunda rebrotas

Abstract

Nutritional status, nutrient accumulation, juice quality and cane yield of four sugar cane varieties: RB867515, RB92579, SP813250 and VAT90212 were evaluated in three cycles: plant cane, first and second ratoon. This study was carried out in Anadia, Agreste region of Alagoas, on an oxisol. Before the implementation of this study, the soil in the experimental area was analyzed, in order to apply the correct amount of limestone and gypsum, aiming to raise the percent base saturation to 60%. The experiment was implemented 60 days after the application of limestone and gypsum, on September 2009. The experimental design used was a randomized block design with four treatments and five replications. The experimental area underwent a chemical control for weeds and ants plus a biological control for the sugarcane borer and leafhopper. Plant nutritional status was evaluated in the phase of maximum plant growth, in the cycle of plant cane eight months after the planting, in the first and second ratoon at six months after the plant cane harvest and in the first ratoon, respectively. Fourteen months after the planting, the following evaluations were made: nutrient accumulation, sugar production, stalk production and juice quality. In the first and second ratoon cycles, these evaluations were made 12 months after the harvest of plant cane and first ratoon, respectively. Statistical differences were found in varieties regarding the nutrient content, but there were not any varieties with maximum leaf nutrient content for all nutrients simultaneously. The nutrient accumulation showed a similar pattern for the four varieties in the cycle of plant cane and first ratoon, while the second ratoon showed statistical differences in the accumulation zinc and iron in the aboveground biomass. Regarding juice quality evaluation, only the amount of inorganic phosphorus showed statistical difference in the cycle of plant cane. On first and second ratoon, fiber content was the only variable with no statistical difference between varieties. VAT90212 showed the highest content of inorganic phosphorus in the three crop cycles, with 89, 73 and 111 mg dm-3 in plant cane, first and second ratoons, respectively. The varieties did not differ statistically regarding the productivity of industrialized stalks and sugar, with 126, 102 and 86 t ha-1 of stalk production in plant cane, first and second ratoons, respectively.