Moderate saline waters are effective to enhance a landrace of unripe melon cultivated in a “water culture system” with high input efficiency

• ‘Scopatizzo’: a landrace of unripe melon ( C. melo L.) to be consumed as alternative to cucumber ( C. sativus L.); • closed cycle soilless system to increase the use efficiency of nutrient solution; • Water culture systems to avoid any stress phenomena due to the use of moderately brackish water; • Enhancement of an Apulian landrace of unripe melon to counteract the loss of agro-biodiversity. The aim of agricultural activity is to produce more, consuming less, focusing on a more efficient use of production inputs and on a reduction of biodiversity loss. Irrigation water salinization is one of the most severe causes of yield reduction in modern agriculture. Basing on this, the aim of the experimental trial was to study if nutrient film technique (NFT) system, with a complete nutrient solution (NS) recirculation, may be an effective system to counteract the negative effects of raising NaCl concentrations in the NS on crops. A landrace of unripe melon (Cucumis melo L.) called ‘Scopatizzo’ was grown in a spring-summer cycle, in the greenhouse, in an NFT system with a closed management of NS and three levels of NaCl (0, 2.5 and 5 mM). ‘Scopatizzo’ plants absorbed an average of 145 L of NS per plant, with daily uptake increasing from 0.5-0.8 L·plant-1 to over 2 L·plant-1, linearly related to total light integral (TLI). Higher NaCl levels raised NS electrical conductivity, with significant differences over time. Water use efficiency (WUE) and average production were 27.6 L·kg-1 and 5.31 kg·plant-1 respectively and fruits with NaCl had higher titratable acidity but lower glucose. NaCl enhanced gas exchange, increasing photosynthetic rate, stomatal conductance, and transpiration, while altering electron transport properties. NFT as a cultivation system has proven to allow the use of moderately saline water without compromising the yield and fruit quality of ‘Scopatizzo’ which represents a valid alternative to the cultivation of cucumber. Further study will be necessary in order to verify up to which concentration of NaCl no significant stress symptoms are identified on the production and growth of the plant.