Among the leafy vegetables, lettuce (Lactuca sativa L.) is the most widely grown species
in the world. Wide ranges of physical properties of the products are used to assess
the degree of maturity. In this study, different lettuce varieties were grown under
an unheated plastic tunnel in springtime. We evaluated the agronomic properties of
different lettuce varieties, evaluated the condition of the plants, and determined
the bioactive substances. Larger head weight can be achieved by the ‘King of May’
butterhead (259.31 g) and ‘Great Lakes 659’crisphead (220.40 g) genotypes. A very
strong correlation (r = 0.995) was observed between the lettuce head index, and leaf
index and both had a strong positive correlation (r = 0.828 and 0.760) with NDVI.
The highest SPAD values were measured for cos lettuce ‘Romaine lettuce’ (44.01) and
iceberg lettuce ‘Great Lakes 659’ (42.71). However, these genotypes showed the highest
(9.52%; 8.74%) dry matter content, too. The red leaf variety 'Lollo Rosso' had the
highest total polyphenol content (181.53 GAE/100 g FW). Among the evaluated properties,
iceberg lettuce showed favorable morphology, plant condition, and good dry matter
content. In addition, between the loose-leaf lettuces, the red leaf lollo type was
outstanding with bioactive content.
