was maintained at field capacity using a capillary subirrigation system. The leaf water potential maintainedaround _0.9 MPa. Seeds (2 seeds per pot) were planted on a sterile medium contained in plastic pots, 8cm_8cm_7 cm(L_W_H), which were main- tained in closed plastic troughs, 53cm_38 cm_20 cm (L_W_H), with clear glass tops with a provision for active air exchange and circulation so that the seedlings can perform as autotrophs. Seedlings were grown at 22/18 1C (day/night) with a photosynthetic photon flux density (PPFD). of200 mmolm_2 s_1 and a 12 h photoper- iod for 26 d before transferring them to the unprotective environment