Study on Quality Grading Standard of Marsdenia tenacissima Seedlings

To establish the quality grading standard of Marsdenia tenacissima seedlings,Seedling height,ground diameter,leaf number,leaf width,leaf length,root diameter and root length of2-month-old seedlings were observed and measured.The seedling grading indexes were determined by correlation analysis and principal component analysis,and k-mean clustering analysis was used for grading study.The results showed that the Marsdenia tenacissima seedlings were divided into three grades:grade I:seedling height≥37.00 cm,ground diameter≥4,00 mm,root length≥15.00 cm,rootdiameter≥ 3.8 0 mm;Grade Ⅱ:2 4.0 0 cm≤seedling height ＜3 7.0 0 cm,3.3 0 mm≤ground diameter ＜4.00 mm,12.00 cm≤root length ＜15.00 cm,3.00 root diameter ＜3.80 mm;Grade Ⅲ:13.00 cm≤seedling height＜24.00 cm,3.00 mm≤ground diameter ＜3.30 mm, 6.00 cm≤root length ＜12.00 cm,2.50 mm≤root diameter ＜3.00 mm.