Indicadores fisiológicos, fitotécnicos e agroindustriais de variedades de cana-de-açúcar cultivadas sob duas condições hídricas

Abstract

Sugarcane is an important crop for Brazil, but in regions where there is the limitation of water availability as the North of Minas Gerais, growth and development of the plant are damaged, causing socioeconomic losses. Water restriction is a problem that affects most of the cropland in the world, mainly those located in semiarid regions. Thus, the purpose of this study was to evaluate the sensitivity of physiological, phytotechnical and agroindustrial indicators in three sugarcane varieties, cultivated with and without irrigation. That information could be used for advise farmers to choose the varieties to be cultivated under restrictive water conditions, and also for future breeding programs of the culture. For that, the plants were grown on field at Experimental Farm of the UNIMONTES in the Gorutuba Irrigation District in Janaúba-MG. The study was in split-plots with six treatments (three varieties x two water conditions) in a randomized block design with four replications. The water conditions of cultivation were: with and without irrigation. The evaluated variables were: SPAD index, leaf temperature, plant height, stem diameter, total yield, ºbrix and percentage of fiber. The data were submitted to variance analysis and means were compared among themselves by Tukey test, with P < 0.05. The condition without irrigation provided significant reductions in the SPAD index, plant height and total yield and increased significantly the leaf temperature, ºbrix and percentage of fiber. The SP 79-1011 and RB 72-454 varieties presented higher SPAD index, even without irrigation. The condition without irrigation also increased significantly the leaf temperature of 3,35 °C in relation to irrigated one. For plants height variable, the RB 72-454 and SP 80-1842 varieties presented the highest averages. The stems diameter was not influenced by the water conditions of cultivation, but the SP 79-101 was stood out with larger average diameter. The RB 72-454 e SP 80-1842 varieties gotten good yield indexes. The SP 79-101 variety presented the highest °brix, differing from the other varieties, and with the RB 72-454 showed the ideal percentage of fiber for sugar and alcohol industry. Finally, the RB 72-454 and SP 79-101 varieties demonstrated, in a general way, regular performance for evaluated indicators, being possible infer that those studied varieties could present good adaptability to semiarid region form Minas Gerais.