African Journal of Basic & Applied Sciences 1 (5-6): 105-109, 2009 ISSN 2079-2034 © IDOSI Publications, 2009 Corresponding Author: Dr. Parmanand Sharma, Scientist B, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India-110067 105 Morphological and Biochemical Response of Cicer arietinum Var.-Pusa-256 Towards an Excess Zinc Concentration Sudarshana Sharma, Parmanand Sharma, Shankari P. Datta and Varsha Gupta 1 2 1 1 Department of Biochemistry, Bundelkahnd University Jhansi, India-284128 1 School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India-110067 2 Abstract: The toxic effects of zinc (Zn) at increasing concentrations were studied with special attention being given to the morphological and biochemical response of Cicer arietinum. Seeds were grown in different concentration of ZnSO (0, 10, 25, 50, 75 and 100µM) for 15 days. In respective to their controls, low 4 concentration (10 and 25µM) of Zn greatly stimulated the seed germination, while it was inhibited at maximum concentration (100µM). Radical, hypocotyls length and root length (TI) and plant height (TI) were also augmented up to 25 µM of Zn addition and after that a significant reduction were noticed at 75 and 100µM. The effects of toxicity of Zn on chlorophyll content and antioxidant enzymes activity include CAT, APX and GPX were also investigated. The data showed that the low concentration of Zn (25µM) addition induced chlorophyll content and high doses of Zn reduced the chlorophyll synthesis. Maximum and minimum chlorophyll content were observed at 25 and 100 µM of Zn addition respectively. Activities of antioxidant enzymes were indicated close relationship with increase in Zn concentration and shoots showed higher activity of antioxidant enzymes than roots. The activity of APX in shoot and root were higher than CAT and GPX. Key words: Cicer arietinum Tolerance Indices Antioxidant enzymes Hypocotyls Length Seed Germination INTRODUCTION with DNA and RNA it might also influence DNA and With the development of industries, mining activities, concentration of Zn in the plant tissue seriously affects application of waste water and sewage sludge on land, activity of several enzymes and other fundamental phytotoxicity of the heavy metals pollution has serious metabolic processes. An excess of Zn also reduced implications in soil degradation and it may reduce photosynthetic rate as a part of enzymes concerned in the both the quality and efficiency of plants [1]. Although photosynthesis [2]. Nitrogen metabolism is also affected certain metals like Cu, Mn, Fe and Zn are crucial for plants in diverse ways by an excess of Zn [14]. The protein and are used as micronutrients, however, at higher content was found to be reduced; nitrogen-fixation and concentrations they may reveal strong toxicity. nitrate reductase activities were also concealed by Zn They obstruct plant growth as do the other heavy toxicity. metals like Cd, Hg, or Pb, which have no function in plant An overindulgence of both essential and toxic heavy metabolism [2]. metals has been found to be allied with generation of free Zn is a microelement with important physiological radicals. Free radicals or ROS are toxic by-products, functions in plants, however, at higher concentrations it generated at low levels in non-stressed plant cells in can become toxic, thus leading to physiological and chloroplasts and mitochondria and also by cytoplasmic, morphological disturbances and, eventually to decreased membrane-bound or exocellular enzymes concerned in yield. It triggers enzymes by incorporating themselves redox reactions (especially photosynthetic electron into metalloenzymes of the electron transport system. Zn transport processes and respiration). An extra amount plays a vital role in the cell division, cell expansion, of ROS occur under stressful conditions and over proteins synthesis and also in carbohydrate, nucleic acid production of these ROS such as superoxide, H O and and lipid metabolism [8]. As Zn forms stable complexes OH exhibited that plants exposed to stress conditions RNA stability. But on the other hand a higher 2 2 .