Abstract: ‘L iaoyuan Duoli’ tomato was cultivated in solar greenhouse. Different fruit parts namely peduncle vascular bundle, sepal, pericarp, pectinic, dissepiment and fruit vascular bundle were taken in order to determine carbohydrate composition and content and sucrose2metabolizing enzymes activities of each part during tomato fruit development. The results indicated that a negative correlation was found between glucose and fructose contents and sucrose synthase ( SS) activity during fruit development. The correlation coefficients
were - 0.9497^* and - 0.9598^** 〔r_{(0.05, 3)} = 0.8783, r_{(0.01, 3)} = 0.9587〕, respectively. A positive correlation was found between invertase activity and glucose and fructose contents, while there was a significant negative correlation between the invertase activity and the sucrose content. The correlation coefficients were - 0.9706^** and - 0.9669^**〔r_{(0.01, 3)} = 0.9587〕, respectively. There was a significant positive correlation between sucrose accumulation and SS activity, with the correlation coefficient being 0.8886^*〔r_{(0. 05, 3)} =0.8783〕. Throughout the whole fruit development, no significant correlation existed among the contents of three kinds of sugar and sucrose phosphate synthase ( SPS) activity, suggesting that the accumulation and metabolism of sugar in the tomato fruitwere controlled by the SS and invertase activity mainly, not by SPS activity. Starch accumulation in the fruit was correlated significantly positive with SS and had little to do with other
enzymes. Therefore, the combined action of invertase and SS was the key factor affecting sugar accumulation in tomato (Lycopersicon esculentum Mill. ) fruit.

Key words: Tomato, Carbohydrate, Sucrose metabolism, Sucrose-metabolizing enzymes