Modificações fisiológicas e bioquímicas em sementes de feijão no armazenamento

Abstract

RESUMO -Para avaliar alterações fisiológicas e bioquímicas em sementes de feijoeiro durante o armazenamento em condições ambientais não controladas de temperatura e umidade relativa do ar, foi realizado o presente trabalho. Foram utilizadas as cultivares Iapar 44, Macotaço, TPS Bonito, TPS Bionobre e TPS Nobre. As sementes foram avaliadas durante o armazenamento, em condições ambientais não controladas, no município de Santa Maria-RS, pelo período de oito meses. As avaliações fisiológicas constaram do teste de germinação, primeira contagem de germinação, comprimento de hipocótilo e de raízes, condutividade elétrica e emergência em campo. As avaliações bioquímicas das sementes foram obtidas pela técnica de eletroforese de sistemas enzimáticos, avaliando-se a atividade das enzimas fosfatase ácida, malato desidrogenase, glutamato desidrogenase e esterase. Todas as avaliações foram realizadas antes e a cada dois meses durante o armazenamento. Os resultados permitem concluir que a atividade das enzimas malato e glutamato desidrogenase é estável durante o armazenamento em condições ambientais não controladas nos cultivares vigorosos (TPS Bionobre, TPS Nobre e Iapar 44); a enzima esterase tem sua atividade incrementada durante o armazenamento não controlado, independentemente da qualidade fisiológica das sementes de feijão; potenciais de armazenamento sob condições ambientais não controladas são diferentes nos cultivares TPS Bionobre, TPS Nobre, TPS Bonito, Macotaço e Iapar 44.Termos para indexação: Phaseolus vulgaris, enzimas, deterioração. PHYSIOLOGIC AND BIOCHEMICAL MODIFICATIONS DURING STORAGE OF BEAN SEEDSABSTRACT -To evaluate physiologic and biochemical alterations in bean seeds during storage in environmental conditions not controlled of temperature and relative humidity of the air, the present work was accomplished. It were used the cultivars: Iapar 44, Macotaço, TPS Bonito, TPS Bionobre and TPS Nobre. The seeds were stored in not controlled environmental conditions in Santa Maria -RS, for eight months. The physiologic evaluations consisted of the germination test, first germination count, electric conductivity, seedling and root length, electric conductivity and emergency in field. The biochemical evaluations of the seeds were obtained by the technique of electrophoresis of enzymatic systems, being evaluated the activity of the enzymes acid fosfatase, malate dehydrogenase, glutamate dehydrogenase and esterase. All the evaluations were accomplished before and each two months during the storage. The results allow to conclude the activity of the enzymes malate and glutamate dehydrogenase are stable during the storage in not controlled environmental conditions in cultivars vigorous (TPS Bionobre, TPS Nobre and Iapar 44); the esterase enzyme has its activity increased during storage in not controlled environmental Federal de Santa

Activity of some isoenzymatic systems in stored coffee grains

“…Probably the temperature used to reduce the water content imposed a greater stress condition and accelerated the metabolism of these grains, thus reducing the efficiency of defense mechanisms and prevention against loss of quality. This observation corroborates the information provided by researchers who reported the role of the enzyme PO in the metabolism of seeds as mechanism of defense and prevention of quality loss due to the fact that it uses peroxides as acceptor of hydrogen (Brandão Júnior, Vieira;Hilhost, 2002;Rosa et al, 2005;Santos, Menezes;Villela, 2005;Beltrã;Oliveira, 2007;Veiga et al, 2010;Taveira et al, 2012). PPO and PO are correlated to the seed quality, considering they are directly present in the cell membrane complex.…”

“…The conditions of temperature and relative humidity of air are extremely important for the evolution of grain deterioration, which is a continuous process and may be avoided (Santos, Menezes;Villela, 2005;Santos, Chalfoun;Pimenta, 2009). The extent of changes that occur in this process depends mainly of the period and the environmental conditions of storage, which may result on alterations that may be characterized by the activity of enzymatic complexes, such as the enzyme esterase (EST), since it acts on the hydrolysis of esters and on the metabolism of lipids (Brandão Júnior, Vieira;Hilhost, 2002;Santos, Menezes;Villela, 2005).…”

“…This increased activity is associated to the oxidation of lipids, characterizing the degenerative process of cell membranes of stored coffee. This occurs because, according to Santos, Menezes and Villela (2005), Malone et al (2006) and Nakada et al (2010), EST is involved both on hydrolysis of esters and on lipids metabolism, like the total phospholipids of membrane.…”

“…Thus, it is important to highlight that only the joint action of the protein system and the isoenzymatic complex protect the membranes from peroxidative damages (Taiz;Zeiger, 2004), neutralizing the effects of oxygen (O 2 ), thus avoiding excessive oxidations (Faria et al, 2003;Freitas et al, 2006;Santos, Menezes;Villela, 2005;Veiga et al, 2010). Considering the hypothesis that due to the damage level of membranes the oxygen acts more intensively promoting the oxidation of compounds, affecting the bioavailability of the chemical content of the grains, and that these oxidative processes may be intensified under stress conditions, the current work aimed to evaluate the biochemical performance of arabica coffee grains during storage after different post-harvest processes.…”

Qualidade fisiológica, sanitária e análise de isoenzimas de sementes de aveia-preta tratadas com diferentes fungicidas

“…Segundo Roberts (1973), enzimas hidrolíticas têm sua atividade incrementada com a perda da viabilidade das sementes. Em estudos conduzidos por Santos et al (2005), observou-se aumento na atividade da enzima esterase nas sementes de feijão durante o armazenamento. Estes mesmos pesquisadores verificaram nas sementes de feijão uma redução acentuada na germinação, primeira contagem de germinação, emergência em campo, pois alterações nos padrões desta enzima evidenciam a ocorrência de eventos deteriorativos.…”