Antioxidant activity and physiological performance of popcorn seed after saline stress and analysis of seedling images

Atividade antioxidante e desempenho fisiológico de semente de milho pipoca após o estresse salino e análise de imagens de plântulas

ABSTRACT

Salinity influences all germination stages and may adversely affect seedling establishment in the field. The objective of this research was to determine the relationship between the antioxidant activity and the physiological performance of seeds and to verify the efficacy of the imaging analysis of popcorn seedlings after seed exposure to saline stress. A completely randomized design was used that consisted of four replicates in a factorial scheme. This scheme comprised three popcorn hybrids (P618, AP6002, and AP8203) and five saline potential levels (0.0; -0.1; -0.3; -0.6, and -0.9 MPa) that were obtained from KCl solutions of different concentrations. First count germination, germination and seedling vigor classification (strong normal seedlings), and dry mass of seedlings were evaluated to determine the physiological quality of the seed. The images of seedlings were used to evaluate the coleoptile and root lengths, indices of vigor, uniformity, and growth using the Groundeye^® software. The activities of the antioxidant enzymes superoxide dismutase (SOD), ascorbate peroxidase (APX), and catalase (CAT) were also determined. Saline stress compromises the physiological quality and antioxidant activity of seeds and the performance of popcorn seedlings. Computerized image analysis using Groundeye^® was efficient in evaluating the popcorn seedlings after being subjected to salt stress. Hybrids AP6002 and AP8203 were more tolerant to salt stress than hybrid P618.

Index terms:
Zea mays var. everta; physiological quality; seed vigor; image processing; salinity.