1405 Effect of iron stress on selected physiological and spectral parameter on four rice varieties (Oryza sativa L.) Banhishikha Singh 1 , Rajeshwari Chatterjee 2 , Niniva Datta 1 , Soma Banerjee 1 1. Department of Biotechnology, Heritage Institute of Technology, Kolkata 700107, India 2. Department of Hotel Management and Catering Technology, Birla Institute of Technology, Mesra, Ranchi. Jharkhand 835215, India _______________________________________________________________________________ Abstract Iron toxicity is an abiotic stress coming with high concentrations of Fe 2+ in the soil solution which is a well- recognized problem of rice (Oryza sativa L.) cultivation in lowland. Rice varieties differ widely in their ability to tolerate excess iron. The present study was undertaken with four rice varieties viz. Dhruba, Sampriti, Dhiren, and Puspa. The objective is to study the influence of high applied Fe 2+ concentrations on the growth, chlorophyll content, and antioxidant enzyme activities. The spectral reflectivity and absorption of different chemical bonding through Fourier transform infrared spectroscopy (FTIR) of four rice varieties was also analyzed. Seven-day-old rice seedlings treated with Ferrous sulphate and subjected to 100 ppm to 750 ppm for further 14-day iron stress were used to analyze their morphological and biochemical responses. Besides, Fourier transform infrared spectral reflection was attributed in root and shoot part. Results indicated shoot growth and chlorophyll content decreased in 750 ppm in all the selected rice varieties of interest. On the contrary, the catalase activity, protein content, and lipid peroxidation increased in these varieties. However, the expression of high amount of CAT activity in Sampriti variety and high amount of SOD activity in Dhruba variety led to tolerance in iron stress in comparison to other two varieties of interest. FTIR revealed steep band stretching of various functional groups of different compounds in both the root and shoot parts of all the varieties. Results revealed that the change of antioxidant expression and FTIR spectra were attributed to the effect of iron toxicity on rice plants. Keywords: rice, iron stress, chlorophyll, antioxidant, Fourier transform infrared spectroscopy Singh, B., R. Chatterjee, N. Datta and S. Banerjee. 2021. Effect of iron stress on selected physiological and spectral parameter on four rice varieties (Oryza sativa L.)'. Iranian Journal of Plant Physiology, 11 (3),3709- 3718. ________________________________________________________________________________ Introduction Iron (Fe) is one of the essential micro elements which involves in several biological processes of the plant cells throughout their life. Due to the redox status change between two states of iron, i.e. the ferrous (Fe-II) and ferric (Fe-III), Fe acts as an electron donor or acceptor, which is vital in photosynthesis and respiration (Kobayashi and Nishizawa, 2012; Zhai et al., 2014). Moreover, in plant growth Fe enhances enzymatic redox reaction (Gill and Tuteja, 2010). It also serves as a co-factor of several enzymes and it is the major ingredient of the cell redox systems like heme ____________________________________ * Corresponding Author E-mail Address: soma.banerjee@heritageit.edu Received: May, 202 Accepted: March, 2021