Effect of the increase of UV-B radiation on strawberry fruit quality

The effect of the UV-B radiation on the latent fungi infection in strawberry fruit, on plant production and on physico-chemical quality parameters of strawberry fruits during postharvest preservation was investigated. The experiments were conducted under field conditions in two seasons during 2012. The different UV-B treatments were: Ambient solar UV-B; Ambient solar UV-B reduced by 80% [UV-B(−)] and Ambient solar UV-B supplemented with UV-B lamps [UV-B(+)]. An electronic modulation system was used to keep the increase on UV-B rate at constant levels throughout the day. The parameters evaluated were latent infection of fungi, dry matter of plants, physico-chemical attributes, color of the peel and fruit production. There was no significant difference among the irradiation treatments regarding the incidence of Rhizopus nigricans and Botrytis cinerea at both seasons. Independently on the season and the irradiation treatment, the incidence of R. nigricans was higher than the B. cinerea and this was considered the main postharvest fungi in the experiment. The incidence of Colletotrichum acutatum was limited to second season and it was higher on UV-B(+) treatment. The irradiation treatments had no influence on the dry matter, fruit production, the physico-chemical parameters and color. A strong correlation of both average temperature and precipitation on the incidence of R. nigricans and B. cinerea three weeks before harvesting was detected on both seasons using the Pearson correlation coefficients. The incidence of R. nigricans was positively correlated with precipitation and negatively correlated with average temperature. The inverse has been observed for B. cinerea. The results indicate that, on environmental conditions of a higher UV-B radiation, the probability of spoilage of strawberry fruit would be increased only by C. acutatum incidence.