| Resumo: | The cultivation of peppers (Capsicum annuum L.) is of significant economic importance worldwide, due to their high nutritional value and culinary applications. Notwithstanding, considerable economic losses were incurred due to spoilage and deterioration during storage. Moreover, there is an increasing consumer demand for high-quality produce with enhanced nutritional value and treated throughout eco-friendly preharvest strategies. This is due to consumers' concerns and legal restrictions regarding the use of postharvest chemical treatments. The present PhD thesis explores the postharvest loses in Lamuyo-type green peppers and the increasing consumer demand for high-quality produce through preharvest strategies. The research focuses on the application of salicylic acid (SA) and methyl jasmonate (MeJA) as plant elicitors to enhance the quality and shelf-life of peppers, as well as on the integral valorisation of pepper seeds. The PhD thesis, which comprises six publications, was the first to identify the optimal phenological stage S12 and harvest time (April) for maximum bioactive compound accumulation, thereby establishing a basis for subsequent studies. The findings from the second and third studies demonstrated that 0.5mM SA application, via foliar and irrigation, improved crop yield, maintained quality up to 28 days at 7 °C, and upregulated the relative response of antioxidant-related genes, with irrigation being more practical. The fourth publication revealed that foliar application of 0.1mM MeJA increased crop yield, delayed senescence, maintained quality attributes, and enhanced the total phenolic content, total antioxidant activity and the activity of antioxidant enzymes after 28 days at 7°C. The fifth study showed that both 0.5 mM SA and 0.1 mM MeJA, applied via foliar or irrigation, induced chilling tolerance and maintained the postharvest quality of green bell peppers stored at 2 °C for 28 days plus 2 days at 20 °C, with SA irrigation being the most effective. The final publication took the form of a review article, the purpose of which was to emphasise the nutritional and funconal value of pepper seeds as a sustainable alternative in agrifood, with the objective of promoting a circular bioeconomy. In conclusion, recent advancements in understanding green bell pepper have encompassed two primary domains. Firstly, significant progress has been made in the optimisation of the physiological development stage. Secondly, there has been considerable progress in the application of SA and MeJA as preharvest strategies in green pepper fruit. These developments have the potential to assist horticultural companies in enhancing crop yield, ensuring the provision of green pepper fruits that meet higher quality standards at harvest, and extending shelf-life. Furthermore, a comprehensive review of bell pepper seeds as a by-product within the industry underscores their potential value for diverse agrifood applications. Subsequent research would likely concentrate on investigating: 1) the effects of elicitors on resistance to rotting, as this is one of the major problems facing the marketing of peppers, 2) the development of pre- and postharvest strategies to extend the shelf-life of fresh-cut pepper fruits, which are a popular choice for salads and various dishes due to the exponential growth of the processing industry, and 3) the potential use of seeds as a food ingredient and plant biostimulants.
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