Posležetvene promene u sadržaju šećera i organskih kiselina u sortama trešnje pod uticajem Monilinia laxa

Abstract

Cilj rada je bio evaluacija uticaja posležetvene, veštačke inokulacije fitopatogenom gljivom Monilinia laxa na sadržaj šećera i organskih kiselina u plodovima devet sorti trešnje (Prunus avium).

The aim of the study was to evaluate impact of postharvest, artificial inoculation with Monilinia laxa pathogenic fungus on sugars and organic acids contents in fruits of nine sweet cherry (Prunus avium) cultivars: ‘Burlat’, ‘Priusadebnaja’, ‘Asenova rana’, ‘Lionska’, ‘Sue’, ‘Junska rana’, ‘Merchant’, ‘Summit’ and ‘3/VAL'. M. laxa represents one of the major pre- and postharvest pathogens of fresh fruits, causing significant economic losses. Due to different possibility of disease incidence in tested cultivars, artificial inoculation would explain how this pathogen affects quality of tested fruits. Determination of individual sugars and organic acids was performed by HPLC methods. For sugars, mobile phase was twice distilled water (0.6 mL/min); Rezex RCMmonosaccharide Ca+ (2%) column (300mmx7.8 mm, Phenomenex) operated at 65 °C, 30 min the total run time. Organic acids were analyzed as follows: 4 mM sulphuric acid in twice distilled water 30 min, Rezex ROA-organic acid H+ (8%) column operated at 65 °C, UV detector 210 nm. Contents of sugars in this study were (in g/kg dry weight): glucose 205-439 and 268-443, fructose 175-398.9 and 208.6-365.8 and sucrose 20-47.6 and 19.2-38.6, in healthy and infected fruits, respectively. Organic acids detected in sweet cherry cultivars were citric, malic, quinic, shikimic and fumaric acid, and their content varied depending on cultivar and treatment. Only ‘Burlat’ accumulated tartaric acid after the infection. ‘Junska rana’ and ‘Merchant’ had significantly decreased organic acids content after the infection, while ‘Sue’ and 3/VAL reacted to the infection by accumulation, especially of fumaric acid.