Envelhecimento acelerado e ocorrência de fungos para avaliação do potencial fisiológico de sementes de arroz

Abstract

R E S U M OO teste de envelhecimento acelerado é um dos mais difundidos para a avaliação do vigor das sementes de várias espé-cies cultivadas, sendo capaz de proporcionar informações com alto grau de consistência. No entanto, o desempenho das sementes envelhecidas artificialmente pode ser influenciado, de modo negativo, pela presença de fungos. Diante disso, o presente trabalho teve por objetivo estudar o teste de envelhecimento acelerado em diferentes concentrações salinas para determinar o potencial fisiológico e sanitário de cultivares de arroz. Foram utilizadas sementes de arroz das cultivares Irga 409, Irga 424 e Epagri 144. O teste de envelhecimento acelerado foi conduzido em três etapas: teste tradicional com uso de água; teste com uso de soluçõesde NaCl saturada (SS) e super saturada (SSS) durante os períodos de 24, 48, 72 e 96 horas a 42 °C. Após, foi avaliado o grau de humidade, a germinação e a sanidade das sementes. Os efeitos deletérios do teste de envelhecimento acelerado foram atenuados com o incremento de concentrações salinas. O teste de envelhecimento acelerado em SS às 48 h e em SSS às 48, 72 e 96 h permite classificar as cultivares de arroz em diferentes níveis de vigor. Sementes contaminadas por agentes fúngicos tiveram resposta positiva na germinação com o uso dos métodos com solução salina. Palavras-chave: cloreto de sódio, cultivares, Oryza sativa L., teste de vigor. A B S T R A C TThe accelerated aging test is one of the most widespread for the vigor of the seeds of various cultivated species, being able to provide information with a high degree of consistency. However, the performance of the artificially aged seeds can be influenced negatively by the presence of fungi. Thus, the present work aimed to study the accelerated aging test at different salt concentrations to determine the physiological and health potential of rice cultivars. Were used seeds of rice cultivars Irga 409, Irga 424 and Epagri 144. The accelerated aging test was conducted in three stages: traditional test with water; test using saturated NaCl solution (SS) and supersaturated NaCl solution (SSS), during periods of 24, 48, 72 and 96 hours at 42 °C. After, we evaluated the degree of moisture, germination and seed health. The deleterious effects of accelerated aging test were attenuated with the increase of salt concentrations. The accelerated aging test in saturated solution (SS) for 48 h and super saturated solution (SSS) at 48, 72 and 96 hours allows classifying rice cultivars at different levels of force. Seeds contaminated by fungal agents had a positive response in germination when treated with saline solutions

Improving the method for determining the physiological and sanitary potential of Gherkin seeds

“…Higher incidence of fungi from the genus Aspergillus was observed in gherkin seeds, considered toxic and causing seed decay. It is a saprophytic fungus of easy dissemination, once the spores are light and dry (Monteiro et al 2017). This fungus may growth under low water potential, commonly being the first one to develop under low humidity conditions and disturbing the development of other genera which require higher humidity (Monteiro et al 2017).…”

“…Small seeds such as vegetables seeds absorb water in uneven and fast manner at the end of the accelerated aging period, due to the high humid atmosphere, resulting in an accentuated variation in the degree of seed humidity and promoting inconsistent test results, due to the different degrees of seed deterioration (Radke et al 2016;Duarte et al 2017). In addition, the performance of seeds may be influenced by the presence of saprophytic fungi and its high incidence may limit the estimative of seed vigor, once they influence the deterioration interfering in the interpretation of data (Monteiro et al 2017).…”

Seed priming with copper‐loaded chitosan nanoparticles promotes early growth and enzymatic antioxidant defense of maize (Zea mays L.) seedlings

“…22 During this process, seeds are exposed to a high temperature (42°C) and relative air humidity (close to 100%), which considerably increases the rate of deterioration. 23,24 The seeds were distributed in a single layer using the plastic box method (11 × 11 × 3 cm). We added distilled water (40 mL) to the bottom of the plastic boxes, which were kept in an accelerated aging chamber at 42°C for 72 h. Four replicates of 25 aged seeds were then distributed on Germitest germination papers moistened with distilled water (2.5 × the dry paper mass).…”

Physiological potential of chickpea seeds

“…Este método tem o objetivo de reduzir a umidade relativa do ar durante a exposição das sementes às altas temperaturas. Alternativa que tem sido recomendada para avaliação de várias espécies como o tomate (Panobianco & Marcos-Filho, 2001), coentro (Radke et al, 2016), arroz (Monteiro et al, 2017) e soja (Marcos-Filho et al, 2000). O resultado da redução de umidade é a menor velocidade de captação de água e consequentemente redução da deterioração das sementes (Jianhua & McDonald, 1996;Panobianco & Marcos-Filho, 2001), com possíveis reflexos na melhoria do ranqueamento dos lotes em níveis de vigor.…”