Biostimulant effect of apple and potato by-product extracts on viability and germinability of fresh and stored pollen in several fruit species

The recovery of waste from agri-food industry, representing a valuable source of bioactive compounds, intends to promote a circular economy, fostering more sustainable development and reducing environmental impact. In this context, application of biostimulants based on natural materials has proved to have a positive impact on plant growth parameters. This study aimed to evaluate the potential biostimulant impact of aqueous extracts derived from apple and potato by-products on the in vitrogermination of fresh and stored pollen from six fruit species (almond, apricot, hazelnut, olive, pear, and pomegranate). Thus, potato and apple extracts (PE and AE), firstly characterized for mineral composition, total antioxidant capacity and total phenols, were added to the basic germination medium at 1 mgL^-1 and 10 mgL^-1 concentrations. Results showed that, while the AE did not give positive effect in most genotypes, the PE at the lowest concentration improved the pollen performance. In particular, the PE was able to restore pollen germination ability in cultivars that did not retain a good viability after storage. This booster effectiveness could represent a promising tool to develop new biostimulants for improving the fertilization process, offering an opportunity to enhance the utilization of byproducts, leading to a reduction in the environmental impact of potato processing industries.