Responses of different varieties of sugarcane to irrigation levels in the Cerrado

Abstract

The Cerrado is under full expansion of sugarcane cultivation. However, the climate of this biome limits the production of sugarcane due to a marked water deficit. Therefore, the objective of this study is to evaluate different varieties of sugarcane in two cultivation cycles in response to irrigation levels in the Cerrado. The experiment was conducted in Goiânia-GO, Brazil, from March 2016 to March 2018, during the cycles of plant-cane and ratoon cane in pots. The experiment was completely randomized in a 5 x 6 factorial design. The treatments were five varieties of sugarcane (RB867515, CTC11, SP860042, IAC873396, and IAC911099) and six levels of supplementary irrigation (100, 80, 60, 40, 20 and 0% of the ETc determined by weighing lysimeter), and four replications. Eight biometric analyses were performed 45 days apart. At the end of each cycle, the quality of the raw material was determined through technological analysis. At the initial development phase (between March and August), when growth is low, we found that it is better to use an irrigation level that provides at least 40% of ETc, since the Cerrado environment does not increase sugarcane height. At the growth phase (between September and March), there is active growth corresponding to 74% of the cane's height. Therefore, the ideal irrigation is that at least 80% of the ETc be provided at the growth stage to support the sugarcane to reach a maximum growth and consequently favorable technological indexes. The supplementary irrigation level of 60% of ETc accelearted the process of maturation of sugarcane for a 12-month cycle. We conclude that the level of supplementary irrigation using greater technical viability for the cultivation of sugarcane in the Cerrado is 60% of the ETc. The varieties most adapted to this production environment are RB867515 and IAC873396.