Résumé
Objective:To study the quality grading standards of Rheum palmatum seedlings. Method:The quality indicators,such as fresh weight,root length,root diameter,number of lateral roots and seedling lesions,of 80 R. palmatum seedlings from different producing areas in Gansu Provincial Real Estate District were detected,and the K-mean cluster analysis results of each data were used as reference basis for dividing the seedling quality level. Result:The fresh leaf weight,root length and root diameter were used as the main grading indicators to classify the rhubarb seedlings into four grades. Specifically,the extra-large seedlings have a plant weight >30.0 g,the root diameter>2.3 cm,and the root length >30.0 cm,with lateral roots,buds intact,no lesion,wounds. The first grade seedlings have a plant weight ≥ 25.0 g,root diameter ≥ 2.1 cm,root length ≥ 25.0 cm,with no lateral root of more than 3 mm in diameter,bud intact,disease-free spots and wounds. The second grade seedlings have a plant weight ≥ 20.0 g,roots ≥ 1.8 cm,root length ≥ 20.0 cm,with no lateral roots with a basal diameter of more than 4 mm,complete buds,no lesion,wounds. The third grade seedlings have a plant weight ≥ 15.0 g,root thickness ≥ 1.5 cm,root length ≥ 15.0 cm,with a few lateral roots,intact buds,no lesion,wounds. Conclusion:Among the 80 samples of R. palmatum seedlings collected,the second and third grade seedlings accounted for 68.8% . The different grades of R. palmatum seedlings were transplanted as herbs after field processing. In terms of the fresh yield,the first grade > extra-large seedling > the second grade > the third grade seedlings, and in the plant twitch rate,extra-large seedlings > the first grade > the second grade > the third grade seedlings. Therefore,the first and second seedlings are recommended standardized production,rather than extra-large seedlings.