Study of nickel pretreatment on some physiologic traits and growth of the serpintine plant, Cleome heratensis and non-serpertine plant, Cleome foliolosa under PEG-induced drought stress

Plants grown in serpentine soils, in addition to heavy metals which their indicators is nickel (Ni) are encountered with a lot of edaphically stress such as drought stress. At the present study, we investigated the effect of pretreatment Ni and PEG-simulated drought stress on some physiological parameters and Ni accumulation of the serpintine plant, Cleome heratensis and related non-serpertine plant, Cleome foliolosa. After 75 days, half number of vessels with grown plants in hydroponic condition, received 20 µM Ni for 7 days, and then plants ± Ni were exposed to drought stress which simulated by PEG in three levels (0, -0.3, or −0.9MPa ) for 7 days. Results showed that serpentine plant populations were pretreated with Ni, shoot to root ratio significantly decreased and relative water content improved and these plants accumulate most of Ni in the root and with drought stress, accumulation Ni in the root increased and translocation it to shoot reduced, Serpentine plant in the highest level of water stress and total phenol amount was enhanced which agreement Phenyle alanin ammonia lyase (PAL) activity in the highest drought stress in C. heratensis, but deleterious effect on same parameters in C. foliolosa. Thus, it can be suggested that serpentine plants use nickel to increase drought resistance which represent the genotypic dependence of serpentine plants to nickel in order to improve drought stress resistance.