Abstract: This study was performed in two stages in 1975-1979 and 1987-1988. There were 295 materials for test during 7 years. The results were as follows: The first and second vegetative generations were positively and significantly correlated with each other in length of longest viticula, weight of viticula and leaf, viticula diameter, tuber number per plant and number of proximal branches. The variation coefficient was lower and the characters were stable. The tuber weight per plant in the first generation was unsignificantly correlated with the yield in the second generation, and the variation coefficient was great (50.69). But the lines with higher and middle tuber weight per plant in the first generation appeared high percentage of supercontrol line in the seoond generation, and the lines with low tuber weight appeared few or no supercontrol line in the second generation. Therefore the authors held that the yield in first vegetative generation should be as a selective character. This position differs from that of others. When the lines have the longest viticula (100-300cm), 11-13 branches, 5-6 tubers per plant in the first vegetative generation, the tuber weight in the first generation is positively and significantly correlated with the yield in the second vegetative generation. This conclusion has provided a basis for improvement of selective accuracy lor the first vegetative generation of sweet potato.

Key words: Sweet potato, First vegetative generation, Selective character, Selective type