Procedures for evaluating the tolerance of cassava genotypes to postharvest physiological deterioration

Abstract

-The objective of this work was to define procedures to assess the tolerance of cassava genotypes to postharvest physiological deterioration (PPD) and to microbial deterioration (MD). Roots of six cassava genotypes were evaluated in two experiments, during storage under different environmental conditions: high temperature and low soil moisture; or low temperature and high soil moisture. Roots were treated or not with fungicide (carbendazim) before storage. Genotype reactions to MD and PPD were evaluated at 0, 2, 5, 10, 15, 20, and 30 days after harvest (DAH), in the proximal, medial, and distal parts of the roots. A diagrammatic scale was proposed to evaluate nonperipheral symptoms of PPD. Fungicide treatment and root position did not influence PPD expression; however, all factors had significant effect on MD severity. Genotypes differed as to their tolerance to PPD and MD. Both deterioration types were more pronounced during periods of higher humidity and lower temperatures. The fungicide treatment increased root shelf life by reducing MD severity up to 10 DAH. Whole roots showed low MD severity and high PPD expression up to 10 DAH, which enabled the assessment of PPD without significant interference of MD symptoms during this period.Index terms: Manihot esculenta, genotype screening, microbial deterioration, procedure standardization, shelf life, storage conditions. Procedimentos para avaliar a tolerância de genótipos de mandioca à deterioração fisiológica pós-colheitaResumo -O objetivo deste trabalho foi definir procedimentos para a avaliação da tolerância de genótipos de mandioca à deterioração fisiológica pós-colheita (DFPC) e à deterioração microbiana (DM). Raízes de seis genótipos de mandioca foram avaliadas em dois experimentos, durante armazenamento em diferentes condições ambientais: alta temperatura e baixa umidade do solo; ou baixa temperatura e alta umidade do solo. As raízes foram tratadas ou não com fungicida (carbendazim) antes do armazenamento. As reações dos genótipos à DM e à DFPC foram avaliadas aos 0, 2, 5, 10, 15, 20 e 30 dias após a colheita (DAC), nas partes proximal, medial e distal das raízes. Uma escala diagramática foi proposta para avaliar sintomas não periféricos da DFPC. O tratamento com fungicida e a posição das raízes não influenciaram a expressão da DFPC; no entanto, todos os fatores apresentaram efeito significativo sobre a severidade da DM. Os genótipos diferiram quanto à tolerância à DFPC e à DM. Ambos os tipos de deterioração foram mais pronunciados durante os períodos de maior umidade e de temperaturas mais baixas. O tratamento com fungicida proporcionou maior vida de prateleira às raízes, por reduzir a severidade da DM até 10 DAC. As raízes inteiras apresentaram baixa severidade da DM e alta expressão da DFPC até 10 DAC, o que possibilitou a avaliação da DFPC sem interferência significativa dos sintomas da DM nesse período.Termos para indexação: Manihot esculenta, triagem de genótipos, deterioração microbiana, padronização de procedimentos, vida de prateleira, con...

Variation in cassava germplasm for tolerance to post-harvest physiological deterioration

“…The thickness of the cut slices was about 1 cm at 25, 50, and 75% of the total root length, referred to as proximal, medial, and distal, respectively. Next, the severity of PPD was evaluated according to two diagrammatic scales, one proposed by Wheatley and Schwabe (1985) for peripheral symptoms, and the second proposed by Venturini et al (2015) for symptoms distributed throughout the root, both with variation in scores from 0 to 100%. The PPD values for each root were calculated by averaging the scores of the three transverse slices.…”

Effects of harvest period, storage, and genotype on postharvest physiological deterioration responses in cassava

“…Moreover, the analysis results for PPD responses using the available methods are also contained a high experimental error (Morante et al 2010;Gracia et al 2013;Mahmod and Beching 2018). According to Morante et al (2010), Tumuhimbise et al (2015), and Verturini et al (2015), the PPD response trait is controlled genetically. However, environmental factors also played an essential role in PPD response, especially to the onset of the PPD responses (Zainuddin et al 2018).…”

Influence of Coating Application Methods on the Postharvest Quality of Cassava

“…Injuring of the cassava root crop during harvest triggers the contact of linamarin and linamarase enzyme which leads to an eventual production of hydrogen cyanide [36]. This process requires the presence of oxygen [37]. The coating process prevents oxygen access to the root hence it may have prevented the production of reactive oxygen species (ROS) that accelerate production of cyanide [25].…”