High gamma irradiation doses and long storage times reduce soybean seed quality

Abstract

High quality seeds are required for soybean production. This study evaluated the effect of gamma irradiation and storage time on seed quality in soybean lines VX04-6828 and VX04-5692. Seeds were gamma irradiated ( 60 Co) with 0, 50, 150, and 250 Gy. After the first seed production cycle (M1), the harvested seeds were stored in the laboratory for 0, 2, 4, and 6 months. Moisture content, seed quality (germination rate, dead seeds, and normal and abnormal seedlings), and seed vigor (first germination count, germination index, and seedling length) were determined. Data were submitted to analysis of variance for each soybean line using a 4 x 4 factorial design (four storage times x four gamma irradiation doses). Response surfaces were constructed based on the F test significance (p ≤ 0.05). VX04-5692 seeds were more sensitive to gamma radiation than were VX04-6828 seeds. Soybean seed quality was highest in M2 seeds derived from seeds irradiated with less than 100 Gy and stored for up to two months. High gamma irradiation doses and long storage times reduced soybean seed quality. Key words: Germination. Glycine max. Gamma radiation. Vigor. ResumoSementes de elevada qualidade fisiológica são necessárias à produção e à comercialização da soja. Portanto, avaliaram-se os efeitos da radiação gama e do armazenamento na qualidade fisiológica de sementes das linhagens de soja VX04-6828 e VX04-5692. As sementes dessas linhagens foram irradiadas com 0, 50, 150 e 250 Gy de radiação gama ( 60 Co). Após o primeiro ciclo de produção (M1), as sementes foram armazenadas em condições laboratoriais e avaliadas aos 0, 2, 4 e 6 meses, quanto ao teor de água das sementes e à qualidade fisiológica, por meio dos testes de germinação (plântulas normais, anormais e sementes mortas) e de vigor (primeira contagem de germinação, índice de velocidade de germinação e comprimento das plântulas). Os resultados foram submetidos à análise de variância para cada linhagem, utilizando-se o modelo fatorial 4 x 4 (quatro tempos de armazenamento x quatro doses de radiação gama). Com base no teste F (p < 0,05), foi realizado o ajuste de superfícies de resposta. As sementes da linhagem VX04-5692 são mais sensíveis à radiação gama que da linhagem Vx04-6828. Melhor qualidade fisiológica das sementes M2 de soja é expressa em doses inferiores a 100 Gy e armazenadas até 2 meses. Doses elevadas de radiação gama e longo período de armazenamento reduzem a qualidade fisiológica das sementes de soja. Palavras-chave: Germinação. Glycine max. Radiação gama. Vigor.

Soybean Generations Under Gamma Rays and Effects on Seed Quality

“…For abnormality of seedlings and dead seeds, responses of possible mutations observed by the soybean lines were evident and when they presented similar behaviors in the M2 generation for the different doses evaluated. These results can be elucidated by the radiosensitivity of soybean seeds to plant segregation after cultivation and at doses greater than 150 Gy, which results in modified plants that produce seeds of low physiological quality (Nobre et al, 2016). In the present study, however, the characteristics set for the M2 generation showed low percentages of abnormal seedlings and dead seeds.…”