Yuchuan Ding;Chiung Chih Chang;Wen Luo;Yi Wu;Xiaoyong Ren;Ping Wang;Guohua X

State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China); State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China);Institute of Soil and Fertilizer, Shanxi Academy of Agricultural Sciences, Taiyuan 030031 (China);State Key Laboratory of Crop Genetics and Germplasm Enhancement, College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China;Agronomy College, South China University of Tropical Agriculture, Danzhou 571737 (China)

deflciency;leaves;activities;sod;supply;high

Magnesium (Mg) deficiency in plant affects photosynthesis and many other metabolic processes. Rice (Oryza sativa L. cv. 'Wuyunjing 7') plants were grown in hydroponics culture at three Mg and two potassium (K) levels under greenhouse conditions to examine the induction of oxidative stress and consequent antioxidant responses in rice leaves due to Mg deficiency. At low Mg (0.2 mmol L-1 Mg supply for two weeks after transplanting) and high K (6 mmol L-1) for 21 days, the rice plants showed severe Mg deficiency and a significant decreases in the dry matter production. The Mg deficiency in leaves decreased chlorophyll concentrations, photosynthetic activity, and soluble protein, but significantly increased the concentrations of soluble sugars and malondialdehyde (MDA) and the activities of superoxide dismutase (SOD, EC 1.15.1.1), catalase (CAT, EC 1.11.1.6) and peroxidase (POD, EC 1.11.1.7). In addition, Mg concentrations in the leaves and in the shoot biomass were negatively related to the activities of the three antioxidative enzymes and the concentration of MDA in leaves. There were very significant interactive effects between Mg and K supplied in the culture solution on shoot biomass yield, chlorophyll content, photosynthesis rate, the activities of SOD, CAT and POD, and MDA content in the leaves of rice. It is suggested that the high K level in the nutrient solution aggravated the effect of low Mg supply-induced Mg deficiency and created the oxidative damage in rice plants.