Salt stress: antioxidant activity as a physiological adaptation of onion cultivars

Abstract

The germination and development of several plant species can be limited when those plants are grown in soils with high salinity, which reduces seedling viability and vigor, as well as activating the antioxidant defense system. The aim of this study was to evaluate germination, initial growth and activity of antioxidant enzymes (superoxide dismutase, catalase and ascorbate peroxidase) in seedlings of three onion cultivars (Madrugada, Fepagro 27 and Petroline) exposed to different concentrations of NaCl (0, 40, 80, 120 and 160 mM). Seedlings were evaluated for viability, vigor and antioxidant enzyme activity. The experimental procedures were completely randomized in 3 × 5 factorial design, with each treatment performed in triplicate, at a significance level of 5%. For all cultivars, viability and vigor decreased in parallel with increasing NaCl concentrations, whereas antioxidant enzyme activity increased, and one cultivar (Madrugada) showed less salt tolerance than did the others. We conclude that high NaCl concentrations have a negative effect in the physiological quality of onion seeds, resulting in lower seedling growth rates and increased antioxidant enzyme activity, where Fepagro 27 and Petroline cultivars were more tolerant to salt stress than 'Madrugada' .

Effects of Sesuvium verrucosum Raf. Compost and vermicompost on the growth and production parameters of the Solanum lycopersicum L. crop

“…Besides, both organic fertilizers are rich in humic substances and growth-regulating hormones, such as zeatin, kinetin, cytokinin, auxin and abscisic acid (in the case of vermicompost), which possibly had a stimulating effect on root development and plant growth (Zhang et al 2015), since the humic substances tend to improve humidity, nutrient holding capacity and levels of microbial activity; while the growth-regulating hormones promote cell division, cell growth and tissue expansion in certain parts of the plant, aspects that in conjunction might have helped the S. lycopersicum crop to better regulate its cellular metabolism, photosynthesis and enzymatic activity (Silveira-Corrêa et al 2013). Moreover, the aforementioned could explain the increases found in its biomass and, consequently, in the obtained yields (Table 4).…”

Tratamento de sementes de milho sobre o desempenho de plântulas em condições de estresse salino

“…A germinação (Figura 1a) e o índice de velocidade de germinação (Figura 1c) das sementes dos híbridos de milho submetidas a estresse salino foram afetados pela diminuição KCl apresentaram redução linear do comprimento da parte aérea e da raiz, assim como da massa seca das plantas. Outros trabalhos também relatam a inibição do crescimento radicular devido ao estresse salino, em espécies cultivadas, como o pinhão-manso (Silva et al, 2009), o feijão-caupi (Maia et al, 2012) e a cebola (Corrêa et al, 2013). As raízes pareceram suportar melhor a salinidade do que a parte aérea, fenômeno que pode estar associado ao ajustamento osmótico mais rápido e à perda de turgor mais lenta das raízes, quando comparadas com a parte aérea (Shalhevet et al, 1995).…”

“…Para as variáveis primeira contagem da germinação (Figura 1b) e comprimento de parte aérea (Figura 1d), o híbrido CD393 apresentou-se superior ao híbrido 30F53H nos diferentes potenciais; contudo, para comprimento de raiz, o híbrido 30F53H apresentou comportamento quadrático e foi superior ao híbrido CD393 (Figura 1e). A diferença entre cultivares quanto à sensibilidade ao estresse salino pode estar relacionada a fatores genéticos e à qualidade de sementes, tendo sido também observada para outras culturas, como para soja (Carvalho et al, 2012), feijão-caupi (Maia et al, 2012) e cebola (Corrêa et al, 2013).…”