1110 AJCS 15(08):1110-1118 (2021) ISSN:1835-2707 doi: 10.21475/ajcs.21.15.08.p2978 Responses of different varieties of sugarcane to irrigation levels in the Cerrado Elson de Jesus Antunes Júnior, José Alves Júnior*, Carolina Carvalho Rocha Sena, Derblai Casaroli, Adão Wagner Pêgo Evangelista, Rafael Battisti School of Agronomy, Department of Biosystems Engineering, Federal University of Goiás (UFG), Zip code 74.690.900, Goiânia, Goiás, Brazil *Corresponding author: josealvesufg@ufg.br 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. Keywords: Water deficit; Morphological analysis; Brix. Abbreviation: ETc_culture evapotranspiration, SIL_supplementary irrigation level, DAP_days after plating, DAC_days after cutting, MSD_mean stem diameter, MHS_mean height of the stem, LA_leaf area, NGL_number of green leaves, FC_ fiber. content. Introduction Sugarcane is a crop of great importance to the world. About 75% of the world production of edible sugar (sucrose) comes from it (CRB, 2015). The average Brazilian productivity of sugarcane in the 2018/19 harvest was 72.2 Mg ha -1 . The state of Goiás/Brazil ranks second in national production, which produced 76.3 Mg ha -1 (CONAB, 2019). Sugarcane finds its best growing conditions when there is a hot and humid climate, with high solar radiation during the vegetative growth phase, followed by a dry, sunny, and colder period during the maturation and harvest phases (Machado et al., 2009; Silva et al., 2012; Abreu et al., 2013). Sugarcane development conditions corroborate the prevailing climate in the Cerrado (Cardoso et al., 2014). However, the problem in achieving a high productivity in the Cerrado is linked to the occurrence of water deficit during the vegetative period, coupled with the lack of varieties adapted to such conditions. As semi-perennial crop, the sugarcane may encounter biotic stress and, particularly, abiotic during its growing period. Therefore, it is important to do morphological analysis of plants in different crop cycles (years) to research the effects of water stress in crop, since studies show different response of sugarcane varieties to different soil water availability (Inman-Bamber and Smith, 2005; Smit and Singels, 2006). Sugarcane quality is very importance to industry, and production environment has direct influence on the raw material. On the other hand, there are quality recommended levels for sugarcane. Ripoli and Ripoli (2004), indicated that the sugarcane juice purity must be more than 85%, the HR of 11 to 13% and reducing sugars must be less than 0.80%. Soluble solids content (°Brix) should be at least 13% at harvest, but the optimum level of content is higher than 18% (Orplana, 2013). In an evaluation of 16 varieties of sugarcane under supplementary irrigation in the Cerrado, there was a technical viability of this practice since the average stalk productivity was 147 Mg ha -1 (Campos et al., 2014). Silva et al. (2014) analyzed the response of different varieties of sugarcane under full irrigation in the region of Jaú, SP, and identified that the varieties IAC911099, IACSP96-3060, RB855536, RB867515, and SP851115 had a better agro-industrial productive potential and less relative water consumption. They behaved differently to full irrigation. Thus, this study was carried out to analyze the biometric and technological responses of different varieties of sugarcane in two cultivation cycles under levels of supplementary irrigation in the Cerrado.