No abstract

Pesticides are a group of chemical substances which are widely used to improve agricultural production. However, these substances could be persistent in soil and water, accumulative in sediment or bio-accumulative in biota depending on their solubility, leading to different types of environmental pollution. The present study was done to assess the impact of pesticides-mancozeb and chlorpyrifos, via morphological and physiological parameters using test system. Phytotoxic effects of pesticides were examined via germination percentage, survival percentage, root and shoot length, root shoot length ratio, seedling vigor index, percentage of phytotoxicity and tolerance index. Oxidative stress on seedlings caused by pesticides was also assessed by investigating the activity of antioxidative enzymes viz. catalase, peroxidase and superoxide dismutase. Correlation was worked out between morphological parameters and antioxidative enzymes to bring out the alliance between them. Mancozeb and chlorpyrifos concentrations were significantly and positively correlated with the activity of antioxidative enzymes and negatively correlated with morphological parameters. Significant positive correlation between various morphological parameters showed their interdependency. However, negative correlation was obtained between activity of antioxidative enzymes and morphological parameters. The enzymes however, showed positive correlation with each other. Based on our result we can conclude that all morphological parameters were adversely affected by the two pesticides as reflected by phytotoxicity in . Their negative correlation with activity of antioxidative enzymes indicates that upregulation of antioxidative enzymes is not sufficient to overcome the toxic effect, thereby signifying the threat being caused by the regular use of these pesticides.

No abstract

Ideal herbicides are used to shield crop plants from weed competition without harming the non-target plants. Metribuzin is a selective triazinone herbicide applied to control broadleaf weeds, grasses, sedges. But application of metribuzin is reported to damage non-target plants besides controlling the weed emergence. The present study investigated the possible ameliorative role of salicylic acid in protecting plants from herbicide toxicity. Metribuzin treatment caused a significant decrease in root length, number of root tips and ultimately in mitotic index along with induction of different types of chromosomal abnormalities in the meristematic cells of Allium cepa roots. Exogenously salicylic acid treatment resulted in significant increase in root length, number of root tips and mitotic index and also resulted in significant reduction in chromosomal abnormalities. These results exemplify the ameliorative effect of salicylic acid under stress conditions and reveal that it is effective in alleviating the toxic stress of herbicide metribuzin at different concentrations.