Preharvest foliar salicylic acid sprays reduce cracking of fig fruit at harvest

Authors: KARANTZI, ATHANASIS - Agricultural University Of Athens; KAFKALETOU, MINA - Agricultural University Of Athens; TSANIKLIDIS, GEOGIOS - University Of The Mediterranean; Bai, Jinhe; CHRISTOPOULOS, MILTIADIS - University Of The Mediterranean; FANOURAKIS, DIMITRIOS - University Of The Mediterranean; TSANTILI, ELENI - Agricultural University Of Athens

Submitted to: Applied Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/28/2021
Publication Date: 12/1/2021
Citation: Karantzi, A., Kafkaletou, M., Tsaniklidis, G., Bai, J., Christopoulos, M., Fanourakis, D., Tsantili, E. 2021. Preharvest foliar salicylic acid sprays reduce cracking of fig fruit at harvest. Applied Sciences. https://doi.org/10.3390/app112311374.
DOI: https://doi.org/10.3390/app112311374

Interpretive Summary: Cracking incidence is a common, but serous disorder for the fig marketability. Cracking limits the storage period and shelf life due to enhanced water loss and increased pathogen infections. In this two-year field study, the potential of spraying salicylic acid (SA) during cultivation to decrease fig fruit cracking incidence and severity was investigated. Other critical external (peel color) and internal (flesh total soluble solids, titratable acidity, and pH) quality features were also assessed. A more fundamental basis for the potentially positive role of SA was sought by assessing the contents of total anthocyanins and cya-nidin-3-rutinoside in fig fruit, as well as the expression of four genes coding for regulatory enzymes of the phenylpropanoid biosynthetic pathway. The results shown that preharvest foliar SA sprays substantially suppressed fruit crackings, and doubled the fruit marketability.

Technical Abstract: Peel cracking and ostiole-end splitting (collectively termed cracking) are common disorders in ripe fig fruit, downgrading fruit quality and thus limiting marketability. This two-year field study addressed the possibility of alleviating cracking at harvest by two foliar salicylic acid (SA) sprays prior to harvest (8 and 5 d). Three SA concentrations (0, 1, and 2 mM) were employed in the first year, and based on the obtained results two (0, and 2 mM) in the second year. A local variety (‘Vasilika’) with excellent organoleptic profile, and high sensitivity to cracking was evaluated. Fruit was harvested at commercial maturity. Fruit marketability was assessed based on the incidence and severity of cracking, peel color, as well as flesh total soluble solids (TSS), titratable acidity (TA), and pH were assessed. The contents of total anthocyanins (TAN), and cya-nidin-3-rutinoside (c-3-rut; the major anthocyanin in fig), and the expression of four genes cod-ing for regulatory enzymes (phenylalanine ammonia lyase, anthocyanidin synthase, UDP-flavonoid glucosyl transferase 1, and UDP-flavonoid glucosyl transferase 2) of the phe-nylpropanoid biosynthetic pathway were also determined in the peel. Preharvest SA application (2 mM) increased the percentage of fruit not showing cracking (the so-called sound) by 1.4–2.6-fold, and of marketable fruit (sound and slightly cracked) by 2-fold. SA application (2 mM) was associated with increased flesh TSS and TA, as well as with decreased flesh pH and red col-oration in the peel stripe. The treatment (2 mM SA) decreased both TAN and c-3-rut contents, which were highly associated (r = 0.978). Responses of transcription level of the four genes to SA application varied, and did not correlate with the other variables in the study. In conclusion, SA appears as a low-cost and environmentally-safe agent of improving fig fruit quality and mar-ketability and facilitates harvesting and postharvest management of figs.