Lixiviação de potássio na avaliação da qualidade fisiológica de sementes de amendoim

Abstract

O presente trabalho teve como objetivo investigar a possibilidade de se obter indicações sobre a qualidade fisiológica de sementes de amendoim através do teste de lixiviação de potássio, cuja eficiência foi avaliada comparativamente às informações fornecidas por outros testes de vigor e à emergência de plântulas em campo. Para tanto, utilizou-se dois lotes de sementes de amendoim da cultivar Tatu (peneira 20/64") que foram submetidos aos testes de germinação, primeira contagem de germinação, envelhecimento acelerado, condutividade elétrica (3 e 24 horas), emergência de plântulas em campo, índice de velocidade de emergência de plântulas, peso de matéria seca de plântulas e determinação do grau de umidade. Além destes, foram conduzidos estudos de lixiviação de potássio, cálcio e magnésio utilizando-se amostras de sementes fisicamente puras. A quantificação de potássio foi conduzida em fotômetro de chama e as de cálcio e magnésio em espectrofotometro de absorção atômica após 3, 6, 9, 12, 15, 18, 21, 24, 27 e 30 horas de embebição a 20ºC. As avaliações da lixiviação de potássio mostraram-se promissoras para a identificação de lotes com diferentes níveis de qualidade.

Biochemical behavior of bean seeds and grains during storage

“…In the meantime Fessel et al (2006) noticed that the decrease in the corn seeds vigor was directly proportional to the loss of potassium through the damaged membrane, corroborating Vanzolini & Nakagawa (2003) for peanut seeds, Costa et al (2008) for pea seeds, Fessel et al (2010) for soy seeds and Silva et al (2012) for bean seeds.…”

“…Kikuti et al (2008) and Binotti et al (2008) found a strong correlation between great release of K + and lower physiological quality of beans and peanut seeds. Different authors have been stated that potassium is the most released ion by seeds (VANZOLINI;NAKAGAWA, 2003;MARCOS FILHO, 2005;FESSEL et al, 2006;COSTA et al, 2008;FESSEL et al, 2010;SILVA et al, 2012). The results were higher than the ones observed by Binotti et al (2008), for pearl beans (0.17 mg g -1 ), and by Pereira et al (2011), for creole beans in two years of cultivation (10.92 to 20.21 mg kg -1 ).…”

“…Nevertheless, Vanzolini and Nakagawa (2003), analyzing the same test for peanut seeds were not able to distinguish amounts of Mg 2+ of their lots, while Costa et al (2007), studying the relationship between magnesium and physiological potential in onion seeds, noticed a downfall of this parameter during their work.…”

Temperature during soybean seed storage and the amount of electrolytes of soaked seeds solution

“…At three months interval, from January to October 1998, the seeds were sampled and tested for the electrical conductivity (Vieira et al, 2001) until the end of the storage period and at each sampling the chemical composition of the soak water was determined. The procedure for electrical conductivity consisted of imbibing four replicates of 50 seeds in 75 mL of deionised water for 24 hours at a constant temperature of 25°C and the bulk electrical conductivity was measured using a conductivity meter as described by Hampton & TeKrony (1995) and Vieira & Krzyzanowski (1999). After that, the soak water was filtered and the following chemical elements measured: K and Na by means of the flame photometry process, Ca, Mg and Fe by the atomic absorption spectrophotometry method (Bataglia et al, 1983;Tomé Júnior, 1997).…”

“…That is one of the reasons why the determination of the amount of K in the soak water has been proposed as a vigor test for soybean (Dias et al, 1997) and peanut (Vanzolini & Nakagawa, 2003) seeds.…”