Zinc Stress Responses in Cajanus cajan and Sorghum bicolor Stomatal Behavior and Growth Dynamics

In this study we investigated the Zn effect on stomatal behavior and plant growth of Cajanus and Sorghum. The anatomical changes of leaf was observed under Zn effect. Pollution negatively impacts on stomata structure by reducing the size of the stomata. Low concentrations of Zn initially increased the stomatal opening, followed by a closed stomata was found with high Zn concentrations. Tolerance index of Cajanus and Sorghum plants studied increase up to post flowering stage. Sorghum registered greater tolerance index values than Cajanus. The highest decrease in total plant length was noted at 100ppm Zn in both Cajanus and Sorghum. Zn toxicity in plants results in reduced growth of both root and shoot, however end of the research total plant length was decreased with increasing Zn concentration in Cajanus than Sorghum. The growth rate was exhibited slowly in pre flowering stage, followed by a rapid increase until post flowering stage, this growth rate showed a sharp decline in the end of the harvest period in all areas Cajanus and Sorghum plants studied. Flowering stage of Cajanus and Sorghum exhibited nearly one month delay in 50ppm and 100ppm Zn concentrations when compare to the controls. Some plants were not even produce flowers at 100ppm Zn.