The objective of this study was to analyze the interaction between the sugarcane with the surrounding atmosphere, by means of the decoupling factor (Ω), for five different growth periods and among irrigation events. The study was carried out in an experimental area, located in the region of Lower Middle part of the São Francisco Valley of Brazil. The data used for estimating of Ω were obtained from sensors accommodated on a micrometeorological tower, which was installed inside the experimental area cultivated with sugarcane ratoon crop It was observed that, at the beginning of the crop cycle (70 to 95 days after cutting, DAC), the average value of Ω parameter was 0.74, due to reduced values of plant height and leaf area index, as well as due to the high values of wind speed that reduced the interaction between the sugarcane and the adjacent air. A similar mean value was verified in the period from 309 to 338 DAC, which occurred during the rainy season, due to the evaporation of the water deposited on the canopy. The lodging of the sugarcane plants, which was noticed in the period from 218 and 248 DAC, as well as irrigation suspension at the end of the cycle (339 to 378 DAC), promoted reduction in the mean values of Ω (0.61 and 0.69, respectively).
evapotranspiration; plant-atmosphere interaction; Saccharum spp.; semiarid
