Agro-morphological, biochemical and antioxidant characterization of a Tunisian chili pepper germplasm collection

Pepper species have been described as being highly sensitive to climate change. Here, we discuss the variability of the agro-morphological and phytochemical responses of pepper cultivars in the context of ongoing climate changes during seven stages of maturity, including heat stress. The effects and interactions were calculated to determine the source of variation according to rising temperature. Capsaicin content (CAP), total phenolic (TPC) and flavonoid (TFC) levels and antioxidant activity (AA) were also determined at different harvest times (at 10, 25, 40, 55, 70, 85 and 100 days after anthesis, DAA). Agro-morphological data showed that the highest variation was recorded for fruit traits compared to flower and plant ones. In particular, calyx shape margin, calyx annular constriction, fruit shape at blossom end and fruit size had a significant impact on the morphologic diversity among accessions. Levels of bioactive compounds and antioxidant activity depended on the genotype and the harvest time. TPC and AA increased at 100 DAA, while TFC were highly detected at the early harvest. Principal component analysis (PCA) allowed us to separate three clusters with well-defined biochemical traits. In particular, regardless of harvest time, Baklouti Chébika, Baklouti Sbikha and Chaabani accessions presented higher levels of TPC, TFC and AA regardless of the considered harvest time. In conclusion, high genetic variability was noted within the analyzed pepper germplasm, thus suggesting the need for major consideration of both agro-morphological and biochemical traits for pepper breeding programs. The current research was conducted to facilitate better management under high-stress conditions due to global warming