Abstract: 【Objective】 Sweetpotato vine is composed of 3 parts, namely leaf, petiole and stem. It has received more and more attentions from the researchers, consumers, and are popular in vegetable market because sweetpotato vine is an excellent source of antioxidative polyphenolics which have anthocyanins and phenolic acids such as chlorogenic acid, and is superior in this regard to other commercial vegetables. So, the differences in chlorogenic acid contents in shoot-tips among varieties, parts and topping times of vegetable-use sweetpotato and their DPPH-scavenging capacities were studied in present paper. 【Method】 The contents and DPPH-scavenging capacities of chlorogenic acid in leaves, petioles and stems of shoot tips of 3 vegetable-use sweetpotato varieties Guangcaishu No.2, Pushu 53 and Fushu 7-6 at 6 topping times after transplanting were determined and the correlationship between the chlorogenic acid content and its DPPH-scavenging capacity was analyzed. 【Result】 The order of 3 varieties about their average chlorogenic acid contents in shoot tips during 6 topping times was Guangcaishu No.2 (0.2920%fb)＞Pushu 53 (0.2750%fb)＞Fushu 7-6(0.1638%fb), and the order of 3 parts of shoot tips was leaf (0.3539%fb)＞stem (0.1444%fb)＞petioles (0.1173%fb) and the average chlorogenic acid content in leaves was 2.70 times the average of chlorogenic acid contents in petioles and stems. The average chlorogenic acid contents during the former 3 topping times in shoot tips of Guangcaishu No.2, Pushu 53 and Fushu 7-6 were 2.22, 2.68 and 2.41 times those during the latter 3 topping times, respectively. And the average chlorogenic acid contents during the former 3 topping times in leaf, petiole and stem of shoot tips were 2.49, 2.53 and 2.20 times those during the latter 3 topping times, respectively. The above differences in chlorogenic acid content were all significant. The significant variations of chlorogenic acid contents among varieties, parts and topping times were derived partly from the variety, and the effect of part, topping time and their interactions were also significant. 73.64% of chlorogenic acid in shoot tips was distributed in leaves, 11.96% in petioles and 14.41% in stems. The order of average DPPH-scavenging capacities of shoot tips of the 3 varieties during 6 topping times was Guangcaishu No.2 (34.99%)＞Pushu 53 (31.05%)＞Fushu 7-6 (18.83%), and the order of 3 parts was leaf (32.52%)＞stem (23.64%)＞petioles (17.91%). The average DPPH-scavenging capacities during the former 3 topping times in shoot tips, leaf, stem and petiole were 1.91, 2.02, 1.69 and 1.99 times those during the latter 3 topping times, respectively. The DPPH-scavenging capacities of shoot tips, leaf, stem and petiole were all significant positively correlated with their chlorogenic acid contents. 【Conclusion】 There were significant differences in chlorogenic acid contents among different varieties, parts and topping times of vegetable-use sweetpotato and these differences had significant effects on the shoot tips DPPH-scavenging capacities. The behavior of chlorogenic acid content variation should be taken into account in the breeding, cultivation and industrialization of vegetable-use sweetpotato.

Key words: vegetable-use sweetpotato, chlorogenic acid content, variety, part, topping time, DPPH-scavenging capacity