Does rootstock-scion relationships affect plant nutrition, root architecture and root exudates in grafted Cucurbitaceae vegetable crops?

Though the use of grafted seedlings has been increasingly popular in the production of many fruit-bearing vegetables such as watermelon, cucumber, oriental melon, muskmelon, tomato, eggplant, and red pepper, little is known about enzymatic activity of the rootstock on enhanced macro and micronutrient capabilities of grafted plants. Even less is known about possible influences of the scions on the development and architecture of rootstocks and their physiological parameters including the excretion of extracellular enzymes and organic acids. This information will be key to develop tailor-made fertilization programmes, especially in regard to P, specific to particular rootstock-scion combinations, and consequently to provide additional tools to maintain the soil health. This proposal will study melon and cucumber on a commercial rootstock (Cucurbita maxima and Cucurbita maxima x C. moschata) to (1) provide novel insights regarding the root exudation profile of common and grafted cucurbit seedlings, (2) insight into some non-explored aspects of rootstock-scion relationships (the influence of scion on root morphology of rootstock and the profile of rootstock root exudates, carbon cost related trade-off between higher root production or high exudates excretion rate), and (3) to explore better matching rootstock – scion combination in grafted cucurbits to maximise P mobilization in low P soils due to raised root exudates activity.