Evapotranspiration of ‘‘Superior’’ grapevines under intermittent irrigation Pedro Vieira de Azevedo a, *, Jose Monteiro Soares b , Vicente de Paulo Rodrigues da Silva a , Bernardo Barbosa da Silva a , Tarcizio Nascimento b a Atmospheric Sciences Academic Unity, Federal University of Campina Grande, Av. Aprı ´gio Veloso, 882, Bodocongo ´, 58109-970 Campina Grande, PB, Brazil b Brazilian Company for Agricultural and Animal Research, BR 423, Km 152, CX 23 Petrolina, PE, Brazil 1. Introduction The efficient use of irrigation-water has become very important to face the lack of water resources and the high cost of fertilizers and other agricultural expenses. Such evidence has makes the adequate irrigation-water application imperative in the world. The production of grapevines (Vitis vinifera L.) has reached economic relevance in the San Francisco River Valley (northeastern Brazil). The application of advanced production technology allows a high fruit quality to different consumer markets. Several studies have been conducted on vineyards all over the world (Daudet et al., 1998; Tonietto and Carbonneau, 2004; Arte ´ s-Herna ´ ndez et al., 2006; Ramos and Martinez-Casasno- vas, 2006; Monteiro and Lopes, 2007). Evans et al. (1993) observed that the soil–crop foliage cover of an adult vineyard is greatly affected by variety, soil structure and depth, crop spacing, crop practices, as well as by climate and soil water management. The authors also found that the most critical factors are spacing, training system and management practices, such as irrigation and thinning. Despite the fact that local growers have been using site–irrigation systems agricultural water management 95 (2008) 301–308 article info Article history: Received 11 July 2007 Accepted 7 October 2007 Published on line 4 December 2007 Keywords: Soil drainage Lysimeter Soil water balance Vitis vinifera Water requirements abstract This study deals with the effects of intermittent irrigation on actual evapotranspiration (ET) and leaf area index (LAI) of ‘‘Superior’’ grapevines grown in a semiarid environment in northeastern Brazil. The field experiments were carried out during two consecutive fruiting cycles (dry season and rainy season) of grapevines (Vitis vinifera, L) irrigated by drip at a rate of 2.3 L h 1 . Four irrigation time intervals were used as follow: one turn irrigation-time (I-1), two turn irrigation-time (I-2), three turn irrigation-time (I-3), and four turn irrigation-time (I- 4). The growing cycles received different amounts of water by irrigation, which for dry and rainy seasons were 470.5 and 243.5 mm, respectively. The ET increased from 5.7 to 7.5 mm day 1 when the irrigation time interval changed from I-1 to I-4 and resulted in a higher value of LAI. The values of ET during the rainy-season growing cycle were much lower throughout the phenological stages, reaching a maximum of 6.4 mm day 1 for I-4 in the maturation stage. For both growing cycles, an increase in the cumulated vineyard evapotranspiration was observed when changing the irrigation time interval from I-1 to I-4, except I-2, which was slightly greater than I-3. Soil water drainage had a very gradual exponential decrease from I-1 to I-4 in both fruiting cycles. The grapevine coefficient under intermittent irrigation can be described as function of days after pruning by polynomial models. # 2007 Published by Elsevier B.V. * Corresponding author. Tel.: +55 83 3310 11199; fax: +55 83 3310 1202. E-mail address: pvieira@dca.ufcg.edu.br (P.V.d. Azevedo). available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/agwat 0378-3774/$ – see front matter # 2007 Published by Elsevier B.V. doi:10.1016/j.agwat.2007.10.011