Plants growth was strongly inhibited under B deficiency conditions. Growth impairment was higher for root compared with that for shoot leading to an increase in the shoot/root dry weight ratio in studied species except for red cabbage. Higher susceptibility of root growth as compared with shoot growth has also been reported by other authors (Camacho-Cristóbal & González-Fontes 1999). Inhibition of root elongation is the most rapid response to B deficiency that occurs as soon as three hours after the B supply is interrupted (Marschner 1995). Root elongation is the result of various processes including cell division and cell elongation, the latter is associated with loosening and reforming of cross-links in the cell wall (Wolf et al. 2012). Considering B as a structural component required for the stability of rhamnogalacturonan-II cross-links in the pectin matrix of the cell wall (O’Neill et al. 2001, 2004), cessation of cell elongation is expected under B deficiency conditions. Boron deficiency alters the physical properties (extensibility and plasticity) of the cell wall and, therefore, impairs cellular elongation (Broadley et al. 2012). The expression of several genes coding for cell wall-modifying enzymes is downregulated under B deficiency, which could alter the cell wall loosening required for cell elongation (CamachoCristóbal et al. 2008). It has also been proposed that B deficiency decreases cell division in root meristematic regions (Dell & Huang 1997), although this effect has not been observed by other authors (Martín-Rejano et al. 2011) and is probably a secondary effect of this mineral deficiency (Dell & Huang 1997). It has been proposed that, changes in the cell wall structure and functions are the primary effects of B deficiency leading to a cascade of secondary effects in growth and metabolism of plants (Broadley et al. 2012).