Diversity evaluation of morphological traits and allicin content in garlic (Allium sativum L.) from China

China has a long history in garlic cultivation and is the biggest country of garlic production in the world. 375 accessions of garlic from 23 provinces and areas in China has been collected and preserved in national germplasm repository for vegetatively propagated vegetables in Beijing since 2002. However, the genetic background and diversity of garlic from China has not been well characterized. In this study, 212 of 375 accessions of garlic were evaluated based on 29 morphological traits and allicin content. Cluster, principal compound, principal ordinates, Shannon diversity index and Pearson correlation analysis were used. The results showed that the garlic clones from China had a widely diversity among all traits. Principal component analysis showed the cumulative proportion of the first eight components explained 71.35 % of total morphological variation in all accessions. Germplasm cluster analysis whether based on 29 morphological traits or bulb yield-related traits could distinguish all germplasm. All accessions were divided into two groups with bolting and non-bolting respectively, or into five subgroups with different traits based on 29 morphological traits. Principal coordinate analysis based on eight bulb related traits divided all accessions into 6 groups. Yield among the accessions ranged from 1.60 to 16.78 t/ha, and three accessions yielded above 15 t/ha. Pearson analysis suggested bulb yield was significantly positively correlated with bulb weight (r = 0.99), bulb diameter (r = 0.73), bulb height (r = 0.53), clove number (r = 0.52), leaf width (r = 0.52). Allicin content ranged from 0.81 to 3.01 %. Pseudostem diameter was found to be significantly positively correlated with allicin content but with the low correlation coefficient (r = 0.23). The result will obviously be helpful for breeder and researchers to comprehensively understand the genetic background of the collection and more easily select the target accessions, especially those with high yield and allicin content.