Tolerance of sugarcane varieties to different levels of water depletion on soil

Sugarcane is one of the most important crops for Brazilian agribusiness, despite water stress being one of the main limiting factors of growth and productivity. Thus, the objective was to verify if there is variation in the tolerance to water deficit among sugarcane varieties in the soil and climate conditions of Quirinópolis-GO (State of Goiás). The trial was conducted on a Red Latosol, with sugarcane planted in Mar/2019, with 15 buds m-1 in an environment with water deficit of 532 mm during the period from May to September. It used randomized blocks, with four repetitions, in a factorial scheme (3x8), with three varieties: CTC4, RB966928 and RB867515, and eight f factors (soil water depletion factor): 0.36, 0.41, 0.46, 0.55, 0.60, 0.72, 0.84, and 0.87. The data were subjected to mean comparison test and quadratic regression. It was observed that the varieties statistically differed when subjected to the same f factor, regarding stomatal conductance-Gs, leaf transpiration-E, and liquid photosynthesis-Lp, reflecting in a penalty on the productivity of culm and sugar, total recoverable sugar content, juice purity, sucrose content in the culm, fiber and culm moisture. The f factor identified for avoiding water stress was 0.50 for RB867515, 0.49 for RB966928 and 0.47 for CTC4. Key words: Water balance, Saccharum officinarum, depletion, water stress index.