Importance of the growing system in the leaf morphology of Diplotaxis erucoides

Abstract

[EN] Worldwide there are around 7,000 edible plant species which are known to have been consumed by humans. Wall rocket (Diplotaxis erucoides) is an herbaceous plant widespread in the Mediterranean region. As a leafy vegetable, this plant can be used as a component of salads, providing a characteristic, mild pungent flavour. Due to the potential interest of this species, we are initiating a breeding program, of which the establishment of a correct growing system is an important part. In this study, two wild, pre-selected populations of wall rocket were analysed and compared with a commercial cultivar. Material was grown in the late autumn-winter season under two different systems, greenhouse and field, and leaf morphological traits were evaluated. Remarkable differences were found among the growing systems in the morphology of the leaves as well as in the leaf colour. Plants growing in greenhouse had larger total leaf area than those growing in the field. The leaf length/width ratio was greater in greenhouse than in the field for the wild populations, while it did not change significantly in the commercial cultivar. Leaf lobation was more marked in the field in all populations assayed. The relative chlorophyll content decreased in the greenhouse system, while both the hue angle and chroma increased compared to the field system. Despite the larger size of the leaves in greenhouse, their lighter colour and few lobation makes them less attractive for the salads market. Therefore, cultivating this species in field seems to offer a better potential for a ready-to-eat product.