Aroma compounds in mini-watermelon fruits from different grafting combinations

BACKGROUND: In recent years, mini-watermelons have increased in popularity. To maintain production and quality standards, various agronomic techniques have been applied. For the Cucurbitaceae family, grafting technique has been used to improve resistance to abiotic stresses, crop productivity and fruit qualitative characteristics. There is some previous literature on this matter, but no information on the influence of grafting on the aroma compounds of mini-watermelons is available. Hence, our research aimed to evaluate the effect of some rootstocks, which were selected on the basis of their tolerance to pathogens, on the quality of mini-watermelons, with particular attention to the volatile aroma compounds. RESULTS: Volatile aroma compounds were analysed using solid-phase microextraction–gas chromatography–mass spectrometry. The most represented compounds were C₆ and C₉ aldehydes and alcohols, which characterize the fruit aroma of the Cucurbitaceae family: (Z)-2-nonenal, (E,Z)-2,6-nonadienal, (Z)-3-nonen-1-ol and (Z,Z)-3,6-nonadien-1-ol were prevalent. Quantitative differences resulted in relation to the various selected rootstocks. Among these, the RS841 rootstock was found to be the most suitable for maintaining yield, quality parameters, sensory characteristics and volatile aroma compounds of mini-watermelon fruits. CONCLUSIONS: The results highlighted that the rootstock, as for other Cucurbitaceae varieties, influences fruit quality and plant yield also for the mini-water melon; the results show the importance of screening for rootstock/scion combinations in order to select a graft able to provide resistance to abiotic stresses, and at the same time improve yield and fruit quality.