Effect of Heavy Metal Stress (Cadmium) on Morphological Physiological Activity and Anatomy of Cow Pea Plant (Vigna Uncuigulata)

Abstract

This study was done to examine the effect of heavy metal on the growth, lipid peroxidation, antioxidant enzyme activity and some key physio-biochemical attributes in cowpea (Vigna unguiculata [L]. In this study 21 days old seedlings of Cow pea plant (Vigna unguiculata L) were subject to different heavy metal stress levels (0g, 0.1g and 0.2g Cd) at germination and early seedling growth stage of plant development. Data were analyzed for growth parameters such as plant height, fresh and dry weight, leaf water content (LWC), and length of radicle and plumule during germination period, and biochemical parameters such as proline content, membrane stability index (MSI), malondealdehyde (MDA) content, chlorophyll content, and antioxidant enzyme activity Catalase (CAT) and Peroxidase (POD). It was seen that the effect of heavy metal stress reduced plant height, fresh and dry weight, LWC, radical and plumule length. I. INTRODUCTIONEnvironmental abiotic stresses, such as presence of heavy metals have been found to a stress factor for plants throughout the world. Many experiments described that cadmium (Cd) known as a non-essential toxic heavy metal produces physiological and morphological alterations in plants such as reduction in photosynthesis or growth as well as results in chlorosis in leaves. These indicators results in oxidative stress which is expressed as increase of lipid peroxidation (LP), formation of reactive oxygen species (ROS) and decrease in the activity of enzymatic and non-enzymatic antioxidants. Worldwide agricultural soils are slightly to considerably contaminated from heavy metals that limit the crop plants to achieve their full genetic potential and also reduce their productivity. Soil pollution by heavy metals has reasonably increased in last few decades due to discharge of wastewater and waste from anthropogenic sources. There are many illustrations which show that some aspects of Cd stress that make changes in morphological, physiological and biochemical changes of plants. Cd stress declines photosynthetic rate. This is due to limited access of CO 2 which results in a decrease in the gas exchange process and the results triggers reduction in the growth and productivity of the plant. It also reduce leaf size, stems extension and root proliferation and decrease water absorption and transportation by causing turgor loss through decreasing the cell wall elasticity. Cd stress increases reactive oxygen species (ROS) production. ROS is harmful for the cell components. Cadmium toxicity also results in alterations in the antioxidant systems. This research focuses on the ability and strategies of higher plants to respond adapt and overcome the Cd stress. In this study the 21 days old seedings of Cow pea plant (Vigna unguiculata L) were subject to different Cadmium levels (0g, 0.1g and 0.2g NaCl) at germination and early seedling growth stage of plant development. Data were analyzed for growth parameters such as plant height, fresh and dry weight, leaf water content (LWC), and length of radicle and...