Desempenho agronômico e tecnológico de variedades de cana-de-açúcar submetidas a diferentes lâminas de irrigação no Norte de Minas Gerais

Abstract

The semi-arid region of the North of Minas Gerais has emerged as promising for the cultivation of sugarcane. Even though important in the local economy, the region still grows old varieties of sugarcane genetically degenerate, with low productivity and inferior quality. Among the technologies necessary for the region is the irrigation. In semi-arid conditions in which is that region, the practice of irrigation is essential. The objective of this study is to evaluate the performance of improved varieties of sugarcane under different irrigation depth, as for the agronomic and technological traits in the soil-climate conditions of the North of Minas Gerais. The experiment was conducted in the semiarid region of Minas Gerais, with essays at EPAMIG - Experimental Farm Mocambinho (FeMo) in the municipality from Jaíba - MG, situated in the Irrigation District from Jaíba (DIJ). The experimental design was in randomized blocks (RBD), in à split-plot scheme (6 x 5), being used in the plots six varieties RB76-S418, SPSO-1816, SP80-1842, RB$3-5486, RB S5-5536 and IAC 86-2480, and the subplots five irrigation blade 125%, 100%, 75%, 50%, 25% ETs, with four replications. The irrigation was by the line Source system. Irrigation management was monitored based on the reference potential evapotranspiration calculated using the method of Hargreaves. The harvest was carried out at 11 months in the cane plant. The agronomic analyzed variables were: number of stems (ha"), plant height, stem diameter and yield (t ha), and technological analyses: º Brix, Cane and Juice Pol%, fiber, moisture, RS, TRS and STR. The data were subjected to analysis of variance and means were compared among themselves by Tukey test, with P < 0.05 for varíeties, and regression for irrigation blade. As for agronomic evaluation, SP80-842 variety showed higher plant height at the blade of 1351 mm. The variety IACS62480 showed the highest number of stems at the blade of 1351 mm. The variety SP8O-I816 showed greater stem diameter at 811 mm blade and variety IAC86-2480, RB83- 5486 and the lowest blade 271 mm. The varieties SP80-1842, SP80-1816 and RB85-5536 showed higher yields on the blade of 1351 mm and the varieties RB83-5486, RB76-5418 IACS6-2480 and the blade of 1081 mm. For technology appraisals, the variety RB83-5486 showed the best percentage of Pol% cane, pol% juice, purity, and RTS at the blade of 1080 mm. The variety presented SP80-1816 ideal percentage of fiber in blade of 811 mm. In the varieties IACS 6-2480 and RB85-5536 the lowest blade (270 mm) provides the greatest percentage of fiber, RS and humidity.