（1Vegetable Institute，Guangxi Academy of Agricultural Sciences，Nanning 530007，Guangxi，China；2Guangxi Key Laboratory of Vegetable Breeding and New Technology Development，Nanning 530007，Guangxi，China；3Achievement Transformation Office，Guangxi Academy of Agricultural Sciences，Nanning 530007，Guangxi，China ）
Abstract：In order to identify and evaluate the agronomic traits and heat tolerance of over summer chives （Allium fistulosum L. var. caespitosum Makino）germplasm resources from Guangxi，and to screen out potential chives germplasm resources being suitable for cultivation in summer and autumn in Guangxi，this experiment took 11 accessions of chives germplasm resources collected from various main chives producing areas of Guangxi as research object；and carried out field comparison，identification and screening tests in summer．At the same time，this experiment also conducted comprehensive evaluation on chives germplasm agronomic traits and heat tolerance by principal component analysis，clustering analysis and regression analysis．The results showed that through contrastive analysis on agronomic traits，‘Lingxiang .2’ AF90，‘Baitoucong’AF131 and ‘Hezhouzhongshansazicong’ AF65 were screened out for their better expression in over summer yield performance．Among chives agronomic traits indexes，the variation coefficient analysis of quantitative traits showed that the variation in single plant weight and tiller number were richer．The distribution frequency of quality traits showed that the 11 accessions of chives had a wider quality traits distribution．Principal component analysis transformed the original 19 agronomic traits into 6 comprehensive factor indexes，and the cumulative contribution rate reached 84.754%．Clustering analysis divided chives germplasm into 3 types： strong heat tolerant，medium heat tolerant and weak heat tolerant．Both ‘Lingxiang No.2’ AF90 and ‘Baitoucong’ AF131 were strong heat tolerant germplasm，and suitable for spreading in Guangxi for over summer cultivation．The mathematical model Y（heat tolerance）= 7.376 - 0.001X1（yield） for chives heat tolerance evaluation was established by stepwise regression analysis，which could be used for identification of successive heat tolerant breeding material．
