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ABSTRACTAbiotic factors such as light influence the physicochemical properties of fruit and may alter the response of the fruit to the environment. The aim of this study was to investigate the effect of two postharvest storage conditions on the overall quality and natural fungal disease incidence (fruit decay) of organic nectarines. Experiments were conducted with four organically grown nectarine cultivars (two early-mid season and two late-season) that were unbagged or bagged during preharvest. After harvest, they were stored for 7–9 days in darkness or under a treatment with lighting. Quality parameters (weight, diameter, firmness, soluble solids content, titratable acidity, and single index of absorbance difference), ethylene production, and fruit decay (% incidence of decay) were evaluated. Preharvest bagging reduced fruit decay in the late-season cultivars, for which storage under darkness reduced fungal decay (up to 100%) more than storage under lighting treatment (47% reduction). Bagging altered the initial fruit quality, but values were within official recommendations. Storage conditions reduced differences attributed to bagging, especially under storage with lighting. This work highlighted the importance of modulating the light, both in the field by fruit bagging and during postharvest, to reduce fruit decay and improve fruit quality. These results may serve as a tool for both farmers and postharvest chain managers.

•The commercial application of biocontrol agents is very limited in postharvest.•Consistent efficacy is not enough to be successful in the postharvest market.•Postharvest market is very small and is necessary to broad the spectrum of action.•Integration with other strategies as natural substances or physical methods.•Is necessary to increase bridge between researchers and private companies.

The effectiveness of Candida sake(CPA-1) in combination with Pantoea agglomerans(CPA-2) for controlling Penicillium expansumand Botrytis cinereaon pears and apples was determined. The concentrations tested were 2 × 106and 2 × 107CFU/ml for C. sakeand 2 × 107and 8 × 107CFU/ml for P. agglomerans. At room temperature, the two antagonists were combined in proportions of 0 to 100% in 25% increments. At the proportion of 50:50, no rot development was observed in pears, and the greatest control of blue mold in apples was observed at this proportion for all the tested concentrations. Under cold temperature on pears, the highest effectiveness of the mixture was observed when C. sakeat 2 × 107CFU/ml was combined with P. agglomeransat 2 × 107or at 8 × 107CFU/ml at the proportion 50:50. Under these conditions, no rot development of blue mold was reported, and gray mold lesion size was reduced by more than 95%. On apples, the mixture of C. sakeat 2 × 107CFU/ml and P. agglomeransat 8 × 107CFU/ml at the proportion 50:50 reduced blue and gray mold incidence by 90%. Populations of the two antagonists had the same growth pattern at 20°C when they were applied individually or in combination, but the population level was always higher when they grew alone. In contrast, at 1°C, the population of both antagonists in combination formed a stable community with the same levels as individual application during the first 30 days; after that, C. sakedominated, and P. agglomeransdecreased on apples and pears. At both temperatures, the maximum population level of C. sakewas observed in apples, and the maximum population level of P. agglomeranswas observed in pears.

Pome fruits are poor in nitrogenous compounds and the addition of nitrogen can improve colonisation of the fruits by antagonists. Twenty-two nitrogenous compounds were evaluated for their effect on Candida sake(CPA-1) growth in vitro. Ten compounds that induced greater growth were applied with the antagonist to wounded fruits to evaluate their effect on enhancing control of Penicillium expansum. Calcium chloride and 2-deoxy-D-glucose were also tested. L-serine and L-aspartic acid enhanced biocontrol by C. sakeagainst P. expansumon apples. On apples and pears, ammonium molybdate, calcium chloride and 2-deoxy-D-glucose improved the capacity of the antagonist to control P. expansum. The addition of ammonium molybdate at 1 mM allowed C. saketo be used on apples and pears at a lower concentration without diminishing control. Similar results were observed with the addition of calcium chloride to the antagonist. 2-deoxy-D-glucose at 6 and 18 mM enhanced biocontrol on pears by over 81%, but on apples the improvement of biocontrol was observed only at 6 mM. In cold storage, the combination of ammonium molybdate and C. sakecompletely eliminated the incidence of blue mould on pears, and reduced its severity and incidence by more than 80% on apples.

This study examined the impact of the application of a biocontrol yeast, Candida sake CPA-1 (3 × 106colony forming units (cfu) ml-1) on the resident microbial populations just prior to harvest, during 7 months cold storage and subsequent ambient shelf-life in two seasons on apples untreated or treated with a preharvest pesticide programme. The changes in populations of the antagonistic yeast ( C. sake) were also monitored. Generally, application of the antagonist had little effect on the total bacterial populations which remained very low both prior to harvest and subsequently during cold storage. White yeasts were predominant on the apples during the experimental period, with lower populations of pink yeasts. When apples were removed after 7 months to ambient conditions the yeast populations increased quickly but those apples treated with C. sake had significantly less white yeasts than untreated controls. The dominant filamentous fungi isolated were Cladosporium, Alternaria and Penicillium spp. Penicillium spp. which is responsible for major postharvest diseases was seldom isolated at preharvest but it became important during later cold storage and shelf life period. Populations of Cladosporium and Penicillium were significantly reduced by the C. sake treatment when removed from cold storage during the ambient shelf-life. In contrast, the Alternaria spp. were unaffected by the antagonist. The actual populations of C. sake applied decreased significantly immediately after application (24 h). However, they subsequently increased to a maximum after one month cold storage (103cfu g-1), and populations increased again under ambient shelf-life conditions. The C. sake populations, and the resident microbial populations, were unaffected by preharvest fungicide applications. This study demonstrates that preharvest application of an antagonistic yeast such as C. sake has an impact on the resident mycoflora both during 7 months cold storage and during ambient shelf-life storage.