Classification and screening of baby-leaf vegetables on the basis of their yield, external appearance and internal quality

“Baby-leaf vegetables” is a new category of leafy vegetables that are used in juvenile stage mixtures of different types of leafy vegetables. They include Brassicaceae, Asteraceae, Amaranthaceae, and other crops. The emergence periods, growing periods, total cultivation periods, from sowing to harvest, as well as the yields, SPAD values, ascorbic acid and nitrate concentrations, leaf characteristics and post-harvest shelf lives of 22 baby-leaf crops were investigated in April 2010 and April 2011. A principal component analysis, based on the total cultivation periods, yields, SPAD values, as well as the ascorbic acid and nitrate concentrations, indicated three main groups: Brassicaceae crops, which had short total cultivation periods and high ascorbic acid concentrations; Asteraceae crops (except for ‘Italian Red’ chicory), which had long total cultivation periods and low ascorbic acid concentrations; Amaranthaceae crops, which had comparatively high yields and low nitrate concentrations. ‘Italian Red’ chicory did not fall into any of these three groups. The yield had very limited effects on the grouping. The higher-yield crops tended to have more leaves and lower dry matter ratios, and the crops with higher SPAD values tended to have thicker leaves. An ideal assortment of baby-leaf crops was proposed based on an evaluation of the yield, external appearance and internal quality of each crop.