EVALUATION OF THE WATER STRESS EFFECT ON THE GROWTH OF SUGARCANE CULTIVARS USING AN AUTOMATIC FERTIGATION SYSTEM

摘要

The objective of this research was to identify the effect of different water stress levels on crop growth of RB92579, RB855453, RB867515 and RB928064 cultivars, by using an automatic system to control fertigation events, during the sugarcane formative phase. In the experimental period, plants were subjected to alternate periods of stress and water supply, by means of periodic fertigations, whose limits of the water matric potential (Psi) were denoted, for comparison purposes, as absence of water stress and mild, moderate and severe water stress, respectively for critical Psi values of -10, -60, -90 and -120 kPa. For evaluation of the water stress effect on the sugarcane growth, it was utilized the sigmoid model with three parameters and degree-days as independent variable, which demonstrated excellent adjust to stalk length (R-aj(2) > 0.95). Under the absence of water stress, the maximum values of the stalk elongation rate (SER) ranged from 0.23 to 0.26 cm degrees Cd-1, regardless of the cultivar. In contrast, under severe water stress, the maximum SER values were between 0.07 and 0.09 cm degrees Cd-1, also regardless of the evaluated cultivar.