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.

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