Changes in the Physicochemical Properties Caused by Irrigation at the Pre-Harvest Cluster Drop Period in 'Tombul' Hazelnut Cultivar.

This research was carried out to evaluate the changes of physicochemical contents during storage of 'Tombul' hazelnut cultivar irrigated at the pre-harvest cluster drop period, which is critical for cluster drops, in a conventional rain-fed 'Tombul' hazelnut orchard in Giresun province (Turkey) in 2015 and 2016. The experiment was designed as randomized plots with 3 replications. The plants (multi-stemmed bush) were irrigated with drip irrigation on 16 July (46.08 mm/60 cm), 26 July (44.68 mm/60 cm), 30 July (43.68 mm/60 cm) and 06 August (44.08 mm/60 cm). The dried in-shell hazelnuts were grouped as irrigated and unirrigated (control) samples. 12 kg of in-shell hazelnuts were used in each replication. The hazelnuts were stored in mesh bags under laboratory conditions (20-22 °C and 70-80% relative humidity) for 12 months. The results showed that moisture, ash, oil, and palmitic acid values were significantly affected by the irrigation application. The lowest moisture and ash values, and the highest oil and palmitic acid values were obtained from the samples of irrigated plants. On the other hand, the changes in protein, rancidity, peroxide and vitamin E, and other fatty acids, except for the palmitic acid, were not significant. In conclusion, it can be said that supplementary irrigation in the pre-harvest period has a significant effect on some physicochemical changes during storage in hazelnuts. According to these results, supplementary irrigation can be recommended for hazelnut storage quality in case of insufficient precipitation during the last cluster drop period. [ABSTRACT FROM AUTHOR]