Physiological changes in seeds and seedlings of pumpkins submitted to salt stress

Abstract

Salinity is one of the most limiting environmental factors for plant growth in semi-arid regions. Excess of salts reduces water potential, causes physiological drought and can influence germination and initial growth of plants. The objective of this work was to study physiological and metabolic changes in seeds and seedlings of pumpkin (Cucurbita pepo cultivars Caserta and Redonda and C. maxima cv. Coroa) in a saline condition of salt stress. Thus, we it was quantified germination parameters; seedlings growth; seeds and seedlings respiration; degradation of total soluble sugars, reducing sugars and total proteins in cotyledons and the activity ascorbate peroxidase (APX), glutathione-S-transferase (GST) and catalase (CAT) during germination and initial growth of the pumpkin species studied in saline conditions. The experimental design was totally randomized in a factorial scheme 6x3, with six electrical conductivities (0; 2; 4; 6; 8 e 10 dS.m-1) and three cultivars (Redonda, Caserta and Coroa). Salinity did not influence the rate of seed respiration during the germination, although seedlings respiration decreased, as well as its vigour. Total sugars were degraded, while there was accumulation of reducing sugars and proteins in cotyledons of germinating seeds in salt solutions. Increased electrical conductivity reduced APX activity in the embryo and CAT in cotyledons, but did not influence GST. Pumpkin seedlings showed low tolerance to salt stress.

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“…Biotic and abiotic stressors in the environment have become major factors limiting global crop growth and production and increased soil salinization has become a primary factor that decreases growth and production (Tavakkoli et al, 2011;Abideen et al, 2020). Saline environments harm plants through physiological drought (Dantas et al, 2019), ion dysregulation (Habib et al, 2016) and, oxidative stress (Yang and Guo, 2018) and leads to a generated metabolic disorder (Zhang et al, 2021). Seed germination and seedling growth are the most vulnerable periods in the seed life process and germination is easily disturbed by numerous stressors that in turn, affect seedling growth and final yield and quality (Smolikova and Medvedev, 2022).…”