Multiple Adaptation Strategies of Plants to Mitigate the Phytotoxic Effects of Diverse Pesticides and Herbicides

The increase in the world’s population in the twentieth century resulted in the subsequent increase in the demand for food. To enhance the constant supply of food for this large population and sustainable crop production, different types of agrochemicals such as fertilizers, pesticides, fungicides, and herbicides were used by farmers for decades. Pesticides are mainly categorized as herbicides, fungicides, and insecticides based on the target they killed. Pesticides and herbicides are designed to kill and prevent pests and unwanted weeds respectively. As their mode of action is not species specific, they often harm other organisms including crops in the agricultural field when used in excess amounts. Over time, insects and weeds become adapted and develop resistance to such chemicals, which necessitates the excessive amount of usage and development of new chemical compounds to protect crops. In many developing countries cheap compounds, such as dichloro-diphenyl-trichloroethane (DDT), hexachlorocyclohexane (HCH), and lindane are popular among farmers, even though they are environmentally persistent and have a toxic effect on soil flora and fauna. Thus, the pesticide and herbicide compounds have emerged as a new global concern owing to their several phytotoxic effects. Moreover, the development of leaf and crop growth rate, and the nutritive composition of seeds, specifically the content of proteins, fall sharply following pesticide treatment. The herbicides and pesticides cause several cytotoxic and genotoxic effects which ultimately challenge the stability of the plant genome through the production of reactive oxygen compounds. To combat these stress conditions, plants have evolved several biochemical, physiological, transcriptional, and epigenetic strategies that together help to maintain the growth and development of plants. In this present book chapter, we summarize the harmful effects of pesticides and herbicides on crop plants and the different strategies evolved by plants to combat these emerging stress compounds to sustain growth and eventually survivability.