Emily Follett
Forsker
(+47) 950 05 357
emily.follett@nibio.no
Sted
Ullensvang
Besøksadresse
Ullensvangvegen 1005, 5781 Lofthus
Sammendrag
The positive effects of the commonly used commercial treatments of 1-MCP and CA storage on apple are well known and implemented for a range of cultivars in many countries. However, as both technologies demand investments and require additional annual user costs, the decision of implementation must be taken based on the predicted benefit obtained in the specific conditions. The main cultivar in volume in Norway, ‘Red Aroma’, commonly has a main sale period from about two to maximum eight weeks after harvest, in part due to market preferences. However, without additional treatments, the cultivar is often unmarketable after eight weeks due to a combination of firmness loss regardless of storage temperature and soft scald development, with further impacts of variation in ripening at harvest and decay development during storage. Possible improvement in shelf-life quality of fruit stored for about eight to 10 weeks either in CA, or in combination with 1-MCP, were explored through a holistic perspective in industrial scale experiments. Differences in effects of the treatments on multiple commercial deliveries, between seasons, packinghouses, and varying fruit sizes were found. Possible reasons for these differences as well as opportunities for improvements at the packinghouse level will be discussed.
Forfattere
Theresa Weigl Jorunn Børve Emily Follett Ingunn Øvsthus Carl Gunnar Fossdal Hanne Larsen Siv Fagertun RembergSammendrag
The mid-early-ripening cultivar ‘Summerred’ is popular among consumers and widely grown in Norway. However, ‘Summerred’ fruit is prone to rapid softening and development of senescence-related disorders, especially senescent breakdown. Calcium can have a significant role in maintaining firmness and delaying senescence of fruits. In a two-year study, foliar application of calcium chloride (CaCl2) was conducted six times, with varying weather conditions between the growing seasons. Fruit was harvested at optimal commercial maturity and stored at 4°C for either 6 or 9 weeks, followed by simulated shelf-life conditions at 20°C. Ethylene levels were monitored during storage to detect ripening discrepancies. At harvest, CaCl2-treated fruit exhibited significantly lower ethylene production compared to untreated fruit, although no differences were observed at the end of the storage period. Senescent breakdown showed significant variability between the two seasons, with an incidence of up to 15% in the first season and nearly no incidence in the second. Senescent breakdown increased with storage duration but was unaffected by foliar CaCl2 application. Real-time PCR analysis of fruit flesh samples revealed increased expression of polygalacturonase and β-galactosidases genes after storage, indicating their involvement in apple softening. Notably, there were no differences in gene expression between CaCl2-treated and untreated fruit after storage. Expression patterns of genes involved in ethylene biosynthesis at harvest were different between the two seasons. Higher expression was observed in the year with greater disorder development, indicating greater maturity at harvest. There were no significant differences in the Streif index between the two years.
Forfattere
Jorunn Børve Theresa Weigl Emily Follett Ingunn Øvsthus H. Larsen Torbjørn Haukås E. Indergård S.F. Remberg Dalphy Ondine Camira Harteveld Arne StensvandSammendrag
Evaluating the effect of different treatments after a simulated shelf life is common in postharvest industry experiments. As fungal fruit decay development is closely linked to preharvest factors, fruit quality, and postharvest treatments two other time points were added in recent experiments. When commercial packinghouses graded the different experimental units (from 1 to 4 bins) they made three different samples; 1) all the fruit manually discarded before size grading (mostly external symptoms of fungal fruit decay and physiological disorders), 2) a 100-fruit sample of the fruit not regarded as first class by the grading machine at size grading (fruit that could be used for industry purpose, processing fruit), and 3) packed fruit for shelf life testing. As expected, differences in pathogen presence were found varying with storage time, cultivar, season, treatments, etc., but overall, some important factors could be pointed at: up to 70% of the processing fruit had damages (caused by insects, weather or mechanical damage) that could be an entry point of fungal pathogens in storage. Apple scab was found on up to 60% of that fruit and up to 12% of the graded fruit in shelf-life tests, indicating a less effective fungicide strategy in some of the commercial orchards. The additional knowledge gained by having three sample types in the experiments is discussed.
