Quality Analysis and Evaluation of Fleshy Stems and Leaves of 10 Lettuce Varieties

Ten lettuce varieties (lines) grown in Chengdu Plain were used as test materials, and 8 post-harvest appearance quality indexes (single plant weight, single plant stem weight, single plant length, stem length, stem thickness, stem skin hardness, stem flesh hardness, and stem edible rate), as well as 7 nutrient quality indexes (water content, chlorophyll, vitamin C, reducing sugars, soluble proteins, cellulose, and free amino acids) were tested and statistically analyzed. The aim of this study was to compare and evaluate the postharvest quality of the tested varieties and select the excellent varieties. The results showed that the values of coefficient of variation among the tested varieties ranged from 0.45% to 50.64%, among which the coefficient of variation of lettuce variation (lines) of free amino acid content in fleshy stems was the largest, reaching 50.64%. The content of stem chlorophyll and soluble protein, leaf reducing sugar showed great differences with the values of coefficient of variation all greater than 30%. The appearance quality, commerciality, and nutrition quality all showed strong correlation among several indicators. The excellent fresh varieties for 3 stem ('Zuhe 2019135' 'Chuanlüxiang 1' and 'Hongjiansun 2') and 3 leaf ('Zhutongqing' 'Xincuizhu' and 'Zuhe 2019135') were selected, respectively. The postharvest quality characteristics of some main lettuce varieties cultivated in winter and spring in the vegetable production area of Chengdu Plain were further clarified in this study, which could provide reference for the selection of excellent fresh lettuce varieties in production.