Effects of drought stress on the phenol, flavonoid and cyanidin 3-glocoside content of juice and fruit yield in native pomegranate genotypes (Punica granatum L.)

In order to study the effects of drought stress on polyphenolic compounds of pomegranate juice (Punica granatum L.) (total phenol, total flavonoid and cyanidin 3-glocoside content) as well as  fruit yield, an experiment was carried out as split plot based on a randomized complete block design with three replications (irrigation levels in main plots and pomegranate genotypes in subplots). Results showed that drought stress increased the content of juice polyphenolic compounds (P <0.05) and decreased fruit yield (P <0.05) in comparison with non-stress conditions (75±5% FC). However, mild stress (55±5% FC) caused a lower yield loss (P <0.05) compared to severe stress (35±5% FC). The results also showed that the genotypes studied could be considered as a rich source of phenolic compounds; however, the highest difference among the genotypes was found for cyanidin 3-glocoside content at different irrigation levels. On the other hand, based on the principal component analysis, under non-stress and mild stress conditions, genotypes Agha Mohamad Ali (AMA), Pust Sefid Torsh (PST), Malas Torshe Saveh (MTS), and Malas Shirine Saveh (MSS) could be recommended in food and pharmaceutical industries as superior and natural antioxidant-rich genotypes due to the high fruit yield and polyphenolic compounds. Generally, because of the importance of yield potential under drought stress, the mild drought stress treatment (55±5% FC) could be introduced as the optimum condition to obtain acceptable level of secondary metabolites, particularly cyanidin 3-glocoside, and fruit yield in Saveh region.