Predawn leaf water potential over the two growing seasons studied (2008 and 2009). Dotted and solid lines represent the non-irrigated and irrigated treatments, respectively. Triangles and squares represent the “V-” and “V+” families, respectively. Standard deviations were obtained from 6 independent measurements. Abbreviations: T: treatment effect. ** P value < 0.01, ***P value < 0.001 and ****P value < 0.0001.