Reactive oxygen species (ROS) are accumulated in cell because of imbalance in production. ROS can cause severe damage to cell which sometimes leads to the death of the cell. Antioxidants which present in different fruits and vegetables have capacity to fight against these ROS. They improve immune function and lower the risk for infection, cardiovascular disease, and cancer. The colours of fruits and vegetables are clues about the types of nutrients they provide. To get a variety of nutrients, eat a variety of colours. Fruits and vegetables contain antioxidants like Vitamin A, Vitamin C, Vitamin E, Anthocyanins, Beta-carotene, Catechins, Ellagic acid, Lutein, Lycopene, Resveratrol.
Stress is a negative factor for normal growth of plant. Abiotic stresses like into temperature, water, oxidative (nutrient deficiency or presence heavy metals) and salinity stress lead to damage the plant and reduce productivity. Heavy metals lead oxidative stress, react with sulfhydryl group, cause displacement of essential cationic, production of reactive oxygen species (ROS). Plants protect themselves by reducing uptake and translocation of metal ion, producing hormones (Brassinosteroids) lead to production of antioxidant enzymes and non-enzymatic antioxidants.
Stress is external condition that adversely affect on plant growth, development and productivity. The negative impact of living factors and non-living factors on the living organisms in a specific environment is known as Biotic stress and Abiotic stress respectively. The major factors of abiotic stress are high temperature, low temperature, water stress, water lodging, various salt, oxidative, deficiency of nutrients, excess of heavy metals etc.