Journal of Agricultural Science; Vol. 10, No. 7; 2018 ISSN 1916-9752 E-ISSN 1916-9760 Published by Canadian Center of Science and Education 174 Productivity, Technological Attributes and Water Use Efficiency of Sugarcane Cultivars Under Regulated Deficit Irrigation Anderson P. Coelho 1 , Alexandre B. Dalri 1 , Estêvão P. A. Landell 1 , João A. Fischer Filho 1 , Luís G. P. Libardi 1 , João V. T. Bettiol 1 , Rogério T. Faria 1 & Luiz F. Palaretti 1 1 School of Agricultural and Veterinatian Sciences, São Paulo Satate University, Jaboticabal, São Paulo, Brazil Correspondence: Anderson P. Coelho, School of Agricultural and Veterinatian Sciences, São Paulo Satate University, Jaboticabal, São Paulo, Brazil. Tel: 55-35-99883-0484. E-mail: anderson_100ssp@hotmail.com Received: March 28, 2018 Accepted: May 2, 2018 Online Published: June 15, 2018 doi:10.5539/jas.v10n7p174 URL: https://doi.org/10.5539/jas.v10n7p174 The research is financed by São Paulo Research Foundation (FAPESP)—Process 2014/21433-5. Abstract Irrigation systems with high water application uniformity, adapted cultivars, and management of regulated deficit irrigation (RDI) are some ways to increase water use efficiency in agriculture. RDI is a practice that aims to provide a smaller amount of water than that consumed by crops without significantly affecting agricultural yield. Objectives of this study were to evaluate the technological characteristics (Bx, Juice POL, Fiber, TRS and Cane POL), water use efficiency (WUE), number of stalks, and sugar and stalk yield of five sugarcane cultivars subjected to RDI and non-irrigation. The experiment was conducted at the School of Agricultural and Veterinatian Sciences, São Paulo State, Brazil. The treatments were distributed in a partially balanced incomplete-block design. The RDI provided 50% of the evapotranspiration water by the crop. At each 30 mm water deficit a 15 mm depth was applied. The evaluated sugarcane cultivars were ‘CTC 4’, ‘IACSP 93-3046’, ‘RB 86-7515’, ‘IACSP 95-5000’, and ‘IAC 91-1099’. The total irrigation depth applied during the cycle was 180 mm. The RDI reduced the technological characteristics of sugarcane. However, it increased the productivity of the stalks and sugar, and did not change the number of stalks per hectare, nor the water use efficiency. Among the cultivars, ‘IAC91-1099’ showed the highest sugar yield (21.81 t ha -1 ), stalk yield (146.5 t ha -1 ), and water use efficiency (146.7 kg ha -1 mm -1 ). The cultivar ‘CTC4’ showed little responsiveness to RDI, presenting a lower number of stalks per hectare and water use efficiency in relation to its growth under non-irrigation conditions. Keywords: irrigation management, ripening, stalk yield, sugar yield 1. Introduction In the near future, irrigation management under the condition of water scarcity will be a common practice, being applied to millions of hectares of crops (Fereres & Soriano, 2007). To increase the water use efficiency (WUE) in irrigation, in addition to using efficient irrigation methods and excellent application uniformity, one should maximize the production per unit of water consumed. In this context, the management of regulated deficit irrigation (RDI) is a technique that seeks to both improve the WUE and reduce the production costs (Geerts & Raes, 2009; Garcia et al., 2012). The decreasing water availability for agriculture, and the increase in energy costs, have made the effective use of water increasingly important (López-Mata et al., 2010). However, there is a lack of understanding of the mechanisms with which plants respond to RDI. In particular, little is known about how RDI can increase crop production by reducing the amount of water applied and increasing their efficiency (Chai et al., 2016). The deficit irrigation can be associated with the risk of loss of productivity, impacting upon the yield of agricultural production, once water is applied in a smaller quantity than that of the crop evapotranspiration. Thus, the RDI must result in a higher production per applied water depth. Of the various cultivated species, sugarcane has one of the highest conversions of dry matter per unit of water consumed. However, to obtain a high productivity, there is a need to supply water at a depth of between 1100 and 1800 mm (Carr & Knox, 2011). The supply and uniform distribution of rainfall during the life cycle of the sugarcane is an essential factor for high productivity (Inman-Bamber & Smith, 2005).