Yield and quality of lettuce and rocket grown in floating culture system

Abstract

In recent years, there has been a growing trend towards cultivating leafy vegetables in hydroponic systems. Floating system is an alternative hydroponic system suitable for the production of baby vegetable products, ready-to eat salads and minimally processed leafy vegetables. However, the implementation of this system for the production of fully grown leafy vegetables is not sufficiently studied. The aim of the present study was to examine the potential of floating system as an alternative growing technique of lettuce and rocket plants, as well as the effect of nitrogen (N) application rate (three treatments 100, 150 and 200 mg L-1 of N) on plant physiology, quality and yield during three growing periods. The results showed that increasing the N application rate resulted in an increase of fresh weight of the aerial parts of both lettuce and rocket, while total yield ranged between 12.0 to 41.9 and 8.0 to 30.2 kg m-2 of fresh leaves, for lettuce and rocket, respectively. In addition, increasing the nitrogen rate resulted in higher number of leaves for lettuce and rocket, as well as in a significant increase in the rate of photosynthesis. A similar increase was observed in nitrate, K, Mg and Mn content in the leaves, without however exceeding the permissible limits for nitrates in any case. In conclusion, the use of floating raft technique for lettuce and rocket cultivation in order to produce not only seedlings production or baby products, but also fully grown plants of high quality is highly recommended.