Effect of Cadmium and Phosphorus Interaction on Tomato: Chlorophyll a Fluorescence, Plant Growth, and Cadmium Translocation

摘要

Cadmium (Cd) is considered one of the heavy metals disturbing plant biophysiological functions. The potential role of phosphorus (P) nutrition in the attenuation of Cd effects on photosynthetic efficiency, plant growth, and cadmium uptake has been investigated in hydroponically grown tomato. Two P nutrition regimes (P15: 15 mg l(-1); P30: 30 mg l(-1)) were assessed in the presence or absence of Cd (Cd0: 0 mu M; Cd25: 25 mu M of CdCl2). The results showed a positive effect of P30 concentration on leaf chlorophyll content and chlorophyll a fluorescence compared to P15 treatment under Cd stress (Cd25). The disturbance of electron transfer caused by Cd at K and I-steps of OJIP transient was attenuated with sufficient P supply. P30 enhanced the performance index of photosystem II and the efficiency of electron transfer to electron acceptor at PSI acceptor side. Besides, increased P concentration improved root growth parameters and biomass accumulation in the presence of Cd. It was found that root tissues accumulated more Cd than shoots and Cd translocation was reduced with increasing P concentration. Our results reveal that Cd-P interaction induced a cascade of physiological and chemical changes in plants. An optimal P nutrition can attenuate Cd stress on plant by the promotion of nitrogen and potassium uptake, which in return improved photosynthesis efficiency, enhanced biomass accumulation and distribution, and minimized Cd accumulation and translocation in plant tissues.