Abstract：Taking 28 different types germplasm resources of welsh onion as research objects，this paper
selected 9 major traits at bolting and flowering stages of welsh onion as evaluation indexes on bolting nature，
and conducted comprehensive evaluation on welsh onion bolting nature by principal component clustering
analysis，average membership degree and bolting index methods．The results showed that the factors with
bigger contribution to principal component of welsh onion bolting nature were initial bolting date，early
flowering date，number of leaves and bolting speed．Their cumulative contribution rate reached 58.93%．
Specially，initial bolting date had higher correlation with the other indexes，which could be the leading
indicators for bolting nature evaluation．The bolting nature of different welsh onion germplasm resources could
be distinguished effectively by principal component clustering analysis，average membership degree and bolting
index methods．Among them，the average membership degree and bolting index methods could provide more
visual and clear partition on bolting nature of welsh onion germplasm resources．These 2 methods had similar
results．But the former’s merit was comprehensive，and the latter’s merit was simple and convenient．
