Abstract: Calcium, associated with the yield formation and quality improvement in peanut, is one of the important nutrient elements in peanut growth and development. To investigate the proper calcium applying amount and the effects on physiological characteristics, yield and quality in peanut (Arachis hypogea), four treatments of 0 (CK), 150, 300, and 450 kg ha^-1 of CaO were set by top dressing at seedling stage using peanut cultivar Fenghua 1 in the Experimental Station of Shandong Agricultural University in 2004 and 2005 with randomized complete block design and three replications. The results showed the main stem height and branch length were shortened, chlorophyll content and leaf photosynthetic rate raised, the activities of superoxide dismutase (SOD), peroxi-dase (POD), and catlase (CAT), and the soluble protein content increased but the content of a lipid peroxidation product, malondialdeyde (MDA) content decreased with the Ca application. The Ca treatment significantly increased total pod and kernel weight because of the increase of pod weight, kernel rate and pod number per plant. The Ca treatment increased not only the content of fat and protein in peanut kernel, but also the ratio of oleic acid to linoleic acid (O/L), and the contents of lysine and methionine. It was suggested that 300 kg ha^-1 Ca application gave the highest yield and the good quality in the peanut seed.

Key words: Peanut, Ca fertilizer, Physiological characteristics, Yield and quality