Effect of Cd on Photosynthesis and Transpiration of Excised Leaves of Corn and Sunflower

Abstract

Detached corn and sunflower leaves exposed to various concentrations of Cd, supplied as CdCU, exhibit reduced photosynthesis and transpiration. The reduction is dependent on the concentration of CdCU solution and generally becomes more pronounced with time. In sunflower, net photosynthesis and transpiration are completely inhibited within 45 min after the introduction of 18 mM Cd. Within two hours net photosynthesis is reduced to 40% and 70% of maximum after the introduction of 9 and 4.5 mM Cd respectively. In corn the trend of photosynthetic response to Cd is similar to that in sunflower except that the inhibition in corn is more pronounced at all treatment levels. A strong linear relationship between photosynthesis and transpiration inhibition is obtained in both species suggesting that Cd contamination induces stomatal closure.

Antioxidative parameters in the opposite-leaved pondweed (Gronlendia densa) in response to nickel stress

“…In this study, the contents of chlorophylls in the plants were significantly affected by nickel treatment (Figure 1). The reduced chlorophyll accumulation in plants could be explained by the inhibition of chlorophyll biosynthesis (Bazzaz et al, 1992). Accordingly, there were significant decreases in chlorophyll a and b for the plants exposed to 20 mg L À 1 Ni compared with the control (Figure 1).…”

Ultrastructural and Photosynthetic Response of Populus 107 Leaves to Cadmium Stress

“…Cd convincingly resulted in marked distortion of chloroplast ultrastructure leading to disturbed shape and inflated thylakoids [14]. Once Cd enters chloroplasts, it can disturb chloroplast function by inhibiting the enzymatic activities of chlorophyll biosynthesis, pigment -protein complexes, O 2 -evolving reactions of photosystem II (PSII), electron flow around photosystem I (PSI), and chloroplast structure [15][16][17][18].…”

Subcellular Distribution and Chemical Form of Cadmium in Bean Plants

“…The molecular basis for this toxicity remains largely unknown. Interest has focussed primarily on the relationship between substrate parameters and plant concentration (12,20), the general toxicity symptoms (10,26), and specific effects on transpiration and photosynthesis (1,2). Numerous in vitro and in vivo studies on the effects of Cd revealed that it is either an inhibitor or activator of enzymes, such as nitrate reductase, malate dehydrogenase, and peroxidase (16,17).…”