Effect of Cadmium and Kinetin on Transpiration Rate, Stomatal Opening and Leaf Relative Water Content in Safflower Plants

The effects of cadmium and kinetin on transpiration rate, stomatal opening and leaf relative water content were studied in safflower (Carthamus tinctorius) plants. Pollution of the root environment with concentration of cadmium ranging from 3 to 30 M, supplied as CdCI2, reduced leaf area, transpiration rate, stomatal opening and leaf relative water content. Transpiration rates were reduced to 59, 60, 55 and 48% of those in the control plants at 3, 10, 20 and 30 M Cd, respectively. Reduction in transpiration due to higher cadmium contaminators is quite large at noon unlike that in the early morning or late afternoon. Kinetin greatly reduced or reversed the inhibitory effect of cadmium. Kinetin-treated plants generally showed a significantly higher transpiration rate, larger stomatal aperture and higher leaf turgidity than those untreated plants. Kinetin also increased leaf area significantly at higher Cd concentration. The highest kinetin concentration used was most effective in this respect. The results proved that cadmium mediated reduction in transpiration rate, stomatal opening and leaf turgidity are effectively reversed by kinetin.