One of the most important problems faced by vegetables in the greenhouse is attacks from nematodes. The chemicals currently used to address this issue have little effectiveness and, in many cases, are toxic to the plants. We examined two new biological products (active flavonoids and extract of vegetable oils) in greenhouse cucumber (Cucumis sativus L.) cultivation in terms of their effectiveness in the soil–plant relationship, measuring how plant and fruit physiology, nutrition, and structure are affected by nematodes, as well as their fertility and mobility.

Application of the bioproducts altered the nematode population, reducing the presence of plant-parasitic species. Treated plants showed fewer root knots, with microscopic analysis revealing a scarcity of giant cells, which are the nematodes' essential feeding sites. The higher efficiency of the oxygen-evolving complex (OEC, Fv/Fo) of cucumber leaves under bioproducts was significantly correlated with the maximum efficiency of PSII photochemistry (Fv/Fm). The decreased non-photochemical quenching (NPQ) in control leaves correlated well with the lower chlorophyll concentration, offering a smaller light-harvesting antennae compared to treated leaves. The increased quantum yield of PSII photochemistry (ΦPSII) and electron transport rate (ETR) under bioproducts can explain the higher net photosynthesis (Pn) and transpiration rate (E). Similarly, chlorophyll fluorescence measurements in fresh mature cucumber fruits under bioproducts revealed a more efficient PSII system compared to the control. Cultivation with these substances had beneficial effects on fruit quality as fresh weight, maintenance of flesh consistency and color, ascorbic acid concentration (which was two times higher than that of control) and sugars.