Valorization of bio-refinery by-products in potted ornamental shrub cultivation: effects on growth, water relation and leaf gas exchange

In the coming few years new research trends such as the production of green chemicals (e.g. biorefineries) will continue to gain more importance, in order to minimize the dependence on fossil-based resources. Furthermore, this exponential growth of biorefinery concept will contribute to the development of a circular economy model, where lignocellulosic materials, used to generate bio-based products, are recovered and recycled. The possibility of an agrochemical use of bio-refinery by-products is an important tool of innovation in horticulture in terms of sustainability and safety of the crops. By-products residuals often contain bio-molecules able to stimulate the plant performance. The aim of the current research was to assess the effects of a lignocellulosic by-product of the industrial process of extraction of succinic acid by Arundo donax biomass, on plant growth parameters, water relations, gas exchange and mineral composition of two potted grown ornamental shrubs: Bougainvillea spectabilis Willd and Viburnum lucidum L. The treatments consisted of a control (no residual addition) and the addition to the substrate of 40 or 80 g l-1 of residual. Our results clearly demonstrated that the addition of the residual significantly improved the crop performance of both ornamental shrubs. The addition of 80 g l-1 one time per month increased plant growth parameters such as plant height and shoot length and this was attributed to a better leaf gas exchange status.