Modified atmosphere in the control of Alternaria rot on postharvest grapes


Tema: Fitopatologia

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Ana Rosa Peixoto , Elizabeth Orika Ono , Daniel Terao , Rubia Camargo Inoue , Matheus Silva E Silva , Andrew Kim Lopes Ferraz

The aim of this study was to evaluate the control of Alternaria rot in 'Thompson Seedless' grapes by means of modified atmosphere. Polyamide bags were compared to high density polyethylene bags, combined or not with sodium metabisulphite (SO2). Fruit from a commercial farm were selected and disinfested; then, they were injured with an entomological pin, inoculated with a suspension of Alternaria alternate at a concentration of 105 conidiam  L-1 and kept in a wet chamber for 24 hours. Subsequently, grape boxes were placed inside specific bags according to the treatment and stored in a cold chamber at 2°C and 75% relative humidity during 40 days. From the 12th day of storage, the disease incidence and the following physic chemical varieties were weekly evaluated until the 40th day: weight loss, soluble solids content (SS), pH, titrable acidity (TA), SS/TA ratio, peroxidase activity, and CO2 and O2 concentrations. A completely randomized split-plot design was adopted with five replicates. Covering grape boxes with polyamide bags, even when sodium metabisulphite was not used, showed to be a feasible alternative to maintain the postharvest quality of ‘Thompson Seedless’ grapes, as well as to reduce rot caused by A. alternata.

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Foto do Usuário Alisson Marcos Fogaça 09-02-2021 12:50:35

The manuscript present significant research on the topic of postharvest grape root caused by Alternaria. -The introduction is consistent but could be supported with numerical data of production and consumption. -Material and methods are clear and well established to reach the objectives, covering fruit mass and quality, and Alternaria incidence. -The authors used completely randomized design in subdivided plots. I understand that there is no physical division for subdivided or split plots. Also, there is a statistical method of Scott-Knott test concerning POD, which I could not find in Figure 4. -Results are presented and authors tried to understand how traits analysis leads to conclusions. Figure 1 had the same color for different treatments. - titrable acidity (TA) is missing of the results. - Figures 2 and 3 were used to understand gas dynamics in the bags, however, it is missing the HDPE bags, that could support the investigation. - It could be added to the conclusion the main reason that leads to suggesting that polyamide film can be a feasible alternative to use over sodium metabisulphite to maintain postharvest quality. Figure 1 and Table 1 led me to conclude that bag PA with SO2 showed minor incidence of the root while resulted in a reduced mass loss in relation to HDPE treatments. It also had the same fruit quality (pH and SS).

Foto do Usuário Ana Patricia Lima Sampaio 09-02-2021 12:50:35

Excelente! Um tema muito importante para o momento atual. Parabéns a todos envolvidos.

Foto do Usuário Ingrid Gomes Duarte 09-02-2021 12:50:35

Trabalho com resultados muito interessantes e promissores para a manutenção de qualidade pós-colheita dos frutos. Acredito que na introdução seria interessante apresentar alguns dados de produção e/ou de perdas pós-colheita devido a incidência da Alternaria ou de demais fitopatógenos. Sobre as leituras de concentração de gases, foi utilizado apenas os sacos do tipo PA. Não seria interessante realizar estas leituras também para sacos do tipo HDPE, já que foram utilizados em dois dos tratamentos na avaliação de incidência de Alternaria? Assim poderia obter-se mais dados para comparação.