Radish (Raphanus sativus L.) morphophysiology under salinity stress and ascorbic acid treatments

Abstract

The use of saline or low-quality water in agriculture is an alternative to increasing water demand, especially in arid or semi-arid regions. However, the use of water with high levels of salts causes disturbances in plants, which can lead to their death; thus, alternatives to mitigate these effects are relevant in current agriculture. Currently, antioxidants are used to mitigate the effects of salts in plants, and among them ascorbic acid has been frequently mentioned. Therefore, the aim of this study was to evaluate the effect of irrigation with saline water combined with applications of ascorbic acid on the development and photosynthetic activity of radish (Raphanus sativus L.) plants. This experiment was carried out in a greenhouse with a randomized block design, with the treatments distributed in a 5.5 incomplete factorial scheme, composed of five electrical conductivities of the irrigation water (ECw): 0.50, 1.30, 3.25, 5.20 and 6.00 dS m-1, and five ascorbic acid (AA) doses: 0.00, 0.29, 1.00, 1.71, and 2.00 mM. The evaluated variables were: shoot height, leaf number, tuberous root diameter, chlorophyll a, b and total content, chlorophyll a/b ratio, initial fluorescence, maximum fluorescence, variable fluorescence and quantum yield of photosystem II. The saline water influenced the analyzed variables in the radish crop regardless of the ascorbic acid application. The ascorbic acid was not efficient in attenuating the deleterious effect of salinity in the irrigation water on the development and fluorescence of the radish. However, it was observed that the concentration of 1.00 mM of ascorbic acid promoted an increase in chlorophyll a, b and total in the saltstressed radish plants.