A 40% increase of the Norwegian apple production is anticipated over the coming five years. This will require optimal fruit quality and careful treatment at harvest, improved environmental conditions for short- and long-term cold storage, and a better communication within the apple industry. The project Eple-Handling will facilitate collaboration in the whole value chain of the apple production, with focus on reducing the incidence of physiological disorders and fungal decay of the fruit.
The project includes education of a PhD as well as MSc students in Norway and to form a network of research and educational activities with PhD-students and scientists in Sweden and Germany.
Experimental work for the PhD included connections between calcium, ethylene and maturity. Use of an ethylene receptor blocker was tested in experiments with fruits of different maturity. Fruit from a field at Esteburg in Northern Germany with cultivars also commonly used in Norway were stored with similar cooling down strategies in both countries in 2021. More in-depth and experiments with molecular methods will be performed in the upcoming years.
Major diseases were focused and experiments concerning the removal of inoculum sources of Monilinia fructigena, the causal agent of brown rot, were initiated in 2021 both in Northern Germany and Norway. Rotten fruit were removed repeatedly during the growing season, and visually healthy fruit were harvested and placed in cold-room storage. Botrytis isolates from Norwegian apple fruit (blossom-end rot and storage rot) were sampled and are currently being assessed for fungicide resistance. A monitoring of fungi associated with core rot and mouldy core was initiated. The isolation and identification of fungi is still ongoing. A method for detecting a range of mycotoxins in apple juice was developed and samples from 2020 were analyzed. In juice made of about 10% fruit with core rot a mycotoxin presumably produced by Fusarium sp. were detected. In 2021 fruit were inoculated and juice from them will be analysed. The information will be used to estimate risk for mycotoxins in juice.
Temperature, relative humidity and ethylene concentrations in storage rooms at packinghouses were measured in 2020 together with fruit quality. Due to a low yield level of apples in 2020, new measurements were performed in 2021 as part of the associated project Fruktklima (NFR 317763).
The low volume of fruit in western Norway in 2020 caused relatively small problems with capacity of the cooling machines. Improvements were suggested at each packinghouse, especially for better air distribution and defrosting. They were implemented before the 2021 season. The relatively low in the storage rooms at the packinghouses in western Norway caused low levels of ethylene. Higher levels were detected in the packinghouse in the south-eastern region, especially in full rooms with cultivar Aroma fruit. In 2021, higher levels of ethylene were also measured in the rooms in the packinghouses in the western region due to high volumes of apples. Ethylene production is different for different apple varieties and degrees of maturity. The findings will be used for further studies on how the different ethylene levels influence on the apple quality and suggestions for measures that can be taken on reducing ethylene levels in the storage rooms at the packinghouses.
Preliminary quality assessments of Red Aroma show high difference in ripening of Red Aroma delivered to the packinghouses. Even if most of the fruit were harvested at recommended maturation stages, single overmature fruit could have impact on the entire delivery/storage room. Relationships about ripening, ethylene, temperature and storability for our most important cultivars are investigated.
Fruit quality analysis after longer-term controlled atmosphere at 2.5°C of Rubinstep and Elstar showed promising results for extending the sales period for Norwegian apples. A similar assessment of fruit quality will be evaluated for Rubinstep and Elstar stored under controlled atmosphere and two temperatures during the winter 2022. Long term ULO was also tested at one packinghouse with Rubinstep. Shorter term ULO of Aroma was tested at two packinghouses in 2021. Results will come after the 2021 season. Whole value chain communication was initiated by meetings and an online packinghouse school in spring 2021. In total 11 seminars were held with a range of topics.
A 40% increase of the Norwegian apple production is anticipated over the coming five years. This will require optimal quality fruit and careful treatment at harvest, improved environmental conditions for short- and long-term cold storage, and a better communication within the apple industry. Eple-Handling will facilitate collaboration in the whole value chain of the apple production, with focus on reducing the incidence of physiological disorders and fungal decay of the fruit. Physiological disorders will be reduced by increasing the awareness and competence about their causes, optimize orchard conditions, and combine technological, physical, biological and economic knowledge to improve storage management. There will be a special emphasis on fruit calcium content, optimized harvest time and cooling in the early storage phase, with an overall aim to slow the fruit maturation processes. Fruit decay in Norway are caused by numerous fungal pathogens, and Eple-Handling will improve our understanding of pathogen biology, reveal pre- and postharvest sources of inoculum and environmental conditions that cause infection and disease development. Furthermore, Eple-Handling will investigate the postharvest stimulation of pathogens on formation of ethylene and mycotoxins, with subsequent adverse effects on fruit maturation and juice contamination, respectively. The project will be devoted to improving both short- and longer-term storage conditions. An existing or new software program will be adapted to follow the fruit from the orchard via storage to the market, and thus contribute in revealing fruit qualities and critical points of improvement at individual farms and the packinghouses. The project will include education of a PhD as well as MSc students in Norway and form a network of research and educational activities with PhD-students and scientists in Sweden and Germany.