Defective Coffee Bean Extract Enhances Coffee Tree Growth and Physiological, Biochemical, and Nutritional Responses in the Presence of Meloidogyne paranaensis

Meloidogyne paranaensis is widespread in Brazil’s main coffee-growing regions, reducing productivity and potentially causing plant death. Defective black-green-sour (BGS) coffee beans are an abundant source of bioactive compounds capable of activating plant defense mechanisms. This study evaluated the potential of aqueous BGS-bean extracts for their ability to induce physiological and biochemical defenses in susceptible Coffea arabica cv. ‘Catuaí Vermelho IAC 144’. Plants were inoculated with 5000 M. paranaensis eggs, and BGS-bean extracts diluted to different chlorogenic acid (CGA) concentrations (0.075, 0.150, 0.250, and 0.300 mg mL−1) were applied one day before inoculation, 45 days after, and 15 days before harvest. We assessed nematode population density, shoot biomass, bioactive compounds, foliar nutrients, antioxidant enzyme activities (Superoxide dismutase (SOD), catalase (CAT)), lipid peroxidation (MDA), and photosynthetic pigments. BGS-bean extracts containing 0.25 and 0.30 mg mL−1 CGA increased root CGA content and preserved chlorophyll a and carotenoids under nematode challenge. Treatments reduced lipid peroxidation through enhanced CAT activity in roots and SOD activity in leaves, while increasing foliar concentrations of potassium (K), magnesium (Mg), nitrogen (N), and manganese (Mn). Shoot dry mass increased regardless of nematode presence. Overall, BGS bean extracts enhanced coffee tree growth and induced physiological, biochemical, and nutritional responses commonly associated with plant defense mechanisms in the presence of Meloidogyne paranaensis.