Abstract:The effects of five ways of calcium (Ca) application to tomato plants (lycopersicon esculentum Mill., cv. 21shijibaofen) on the concentration of Ca, magnesium (Mg), potassium (K), phosphorus (P), boron (B), copper (Cu), iron (Fe), manganese (Mn), molybdenum (Mo), zinc (Zn) and a variety of Ca compounds in mature fruit were studied in this paper. Calcium was applied by increasing Ca concentration in nutrient solution (10mmol/L Ca), spraying the mixture solution of 20mg/L NAA (methyl α-naphthyl acetate)+0.5%CaCl2 on the first inflorescence and the two leaves upper and lower the first inflorescence during anthesis, and on the fruits of 1-week and 3-week old. Results showed that calcium content in the fruit increased significantly in all Ca treatments except spraying Ca on the 3-week old fruit, while the uptake of K, Mg and P were depressed in the treatments mainly due to anionic antagonism and interactions with increased Ca in fruit. Fruit micronutrients were affected not regularly except B and Mn were consistently declined in all treatments. The concentration of Ca and percentage of Ca pectate in total Ca of the tomato fruit increased significantly in effective Ca treatments. At the same time, Vc content and the percentage of titrable acidity in the fruits were also positively affected greatly, indicating that the fruit quality was improved. By the way, the possible mechanism of increasing the fruit Ca was discussed. Comparison of the effects of the five ways of external Ca application to tomato plants demonstrated that spraying Ca on the leaves during anthesis was the best way to increase Ca content and improve the fruit quality and spraying the Ca solution on the young fruits was also effective.