Indian Journal of Biochemistry & Biophysics Vol. 49, February 2012, pp 63-70 Pre-treatment of seeds with static magnetic field ameliorates soil water stress in seedlings of maize (Zea mays L.) Anjali Anand 1 *, Shantha Nagarajan 2 , A P S Verma 3 , D K Joshi 4 , P C Pathak 5 and Jyotsna Bhardwaj 6 1,5,6 Division of Plant Physiology, 2 Nuclear Research Laboratory, 3,4 Division of Agricultural Physics, Indian Agricultural Research Institute, New Delhi 110012, India Received 25 June 2011; revised 12 October 2011 The effect of magnetic field (MF) treatments of maize (Zea mays L.) var. Ganga Safed 2 seeds on the growth, leaf water status, photosynthesis and antioxidant enzyme system under soil water stress was investigated under greenhouse conditions. The seeds were exposed to static MFs of 100 and 200 mT for 2 and 1 h, respectively. The treated seeds were sown in sand beds for seven days and transplanted in pots that were maintained at -0.03, -0.2 and -0.4 MPa soil water potentials under greenhouse conditions. MF exposure of seeds significantly enhanced all growth parameters, compared to the control seedlings. The significant increase in root parameters in seedlings from magnetically-exposed seeds resulted in maintenance of better leaf water status in terms of increase in leaf water potential, turgor potential and relative water content. Photosynthesis, stomatal conductance and chlorophyll content increased in plants from treated seeds, compared to control under irrigated and mild stress condition. Leaves from plants of magnetically-treated seeds showed decreased levels of hydrogen peroxide and antioxidant defense system enzymes (peroxidases, catalase and superoxide dismutase) under moisture stress conditions, when compared with untreated controls. Mild stress of -0.2 MPa induced a stimulating effect on functional root parameters, especially in 200 mT treated seedlings which can be exploited profitably for rain fed conditions. Our results suggested that MF treatment (100 mT for 2 h and 200 for 1 h) of maize seeds enhanced the seedling growth, leaf water status, photosynthesis rate and lowered the antioxidant defense system of seedlings under soil water stress. Thus, pre sowing static magnetic field treatment of seeds can be effectively used for improving growth under water stress. Keywords: Static magnetic field, Soil moisture stress, Leaf water relations, Antioxidant enzymes The beneficial effect of both static and oscillating magnetic fields (MFs) of very low to high field intensity has been reported in different plant species. Studies have shown that germination characteristics of the maize seeds exposed to MF are enhanced 1-3 . Wheat seeds exposed to MFs of 50 to 300 mT increase seedling vigor, respiratory quotient and -amylase activity as compared to control seeds 4 . Growth of the germinated Vicia faba seedlings is found to be enhanced by the application of power frequency MFs (100  T), as evidenced by mitotic index and 3 H-thymidine uptake 5 . A review article on currently accepted mechanisms of magnetoreception has reported that the research on magetoresponse in biology has been carried out in an unsystematic manner in the past 6 . Preliminary experiments in our laboratory have reported best combination of magnetic field strength and duration of exposure to get maximum enhancement in germination and field emergence characteristics in maize 7 . From these results, two treatments, namely 100 and 200 mT fields for 2 and 1 h exposure time respectively have been selected for further study. The dramatic two-fold increase in root length and root surface area in one month old plants from treated seeds has prompted us to test the performance of the maize plants raised from magnetically-exposed seeds under controlled moisture stress conditions. In an earlier report, differential response in maize roots and shoots is reported in plants exposed to low  (-1.6 MPa). The growth of leaves and stems is found to be rapidly inhibited, but roots continued to elongate to facilitate water uptake from the soil 8 . Abiotic stress also leads to production of reactive oxygen species (ROS) that may cause membrane lipid peroxidation, inactivation of -SH containing enzymes and RNA and DNA damage 9 . Plants have evolved specific protective mechanisms to defend themselves against the overproduction of ROS. The primary scavenger is superoxide dismutase (SOD) which ____________ *Corresponding author. Phone: 91-011-25842815 Fax: 91-011-25846107 E-mail: anjuanand2003@yahoo.com shantha@nagarajans.net