The plants grown without B for 9 weeks had smaller roots thanthose grown in a complete nutrient solution (Fig. 1a). No new root initiation was observed in B-deficient plants. The symptoms ofcurling of the leaves, corking of the veins, and leaf chlorosis wereobserved only in the upper leaves of B-deficient plants (Fig. 1b). Thelower leaves did not show any visible symptoms