**3. Effect of abiotic stresses on plants**

Abiotic stresses alone or in combination influence negatively on plants (**Figure 2**). It has been observed in various regions and crops that there is generation of H2O2 under abiotic stress. Closure of stomata partially or completely under abiotic stress such as drought stress reduces photosynthesis by restricting entry of CO2 and hampering electron flow through electron transport chain. Under abiotic stress, further, hydroxyl radicals, superoxide radicals and singlet oxygen are formed. These altogether adversely affect lipid (lipid peroxidation), protein (oxidation), nucleic acids and enzyme activity leading to cell death. Some adverse effects of different abiotic stresses on plant are briefly discussed below.
