The use of organic biostimulants in hot pepper plants to help low input sustainable agriculture
World demand for agricultural products is increasing. New insights are required in order to achieve sufficient and sustainable yields to meet global food request. Chemical fertilizers have been studied for almost 200 years, and it is unlikely that they could be improved. However, to produce food for a growing world population, various methods to increase the efficiency of chemical fertilizers are investigated. One approach to increasing crop productivity is the development of environment-friendly organic products named biostimulants which stimulate plant growth by enhancing the efficiency of chemical fertilizers. Most studies have tested these products in short-term experiments, but little information is available on their effect on plants at the maturity stage of growth. On this account, this paper focuses on the effects of two biostimulants, red grape skin extract (RG) and alfalfa hydrolyzate (AH), throughout the entire plant development. The findings obtained in the present investigation demonstrate the effectiveness of RG and AH in improving growth and the nutritional value of peppers. Specifically, the two biostimulants increased the phenol concentration, antioxidant activity, and ascorbic acid concentration in fruits, as well as the capsaicin concentration in plants. Differences in effectiveness between RG and AH were likely related to the characteristics of the starting matrixes as well as to the industrial processes used for their production. The efficiency of RG and AH in promoting plant growth and yield could also be due to their content in indole-3-acetic acid (IAA), isopentenyladenosine (IPA), phenols, and amino acids. In the light of these results, the application of biostimulants could be considered as a good strategy for obtaining high yields of nutritionally valuable vegetables with lower environmental impact.