Abstract
Selenium (Se) has been recently reported to play a crucial role in ameliorating the negative impact of abiotic stress, including salinity, on several plant species. Two field experiments (2016/17 and 2017/18) were carried out to investigate the possible effect of exogenous Se application at two levels (25, 50 mg L−1) on growth, bulb yield, physio-biochemical attributes, and antioxidant activities of onion grown under saline (5.25 dS m−1) soil condition. Se (25 or 50 mg L−1) foliar application enhanced growth characteristics, as well as membrane stability index (MSI) and relative water content (RWC) as a result of the osmotic adjustment by accumulating more osmoprotectants and enhancing the activity of antioxidants defense system, thus improving photosynthetic efficiency and bulb yield. Proline, glycine betaine, choline, and total soluble sugars content were higher in leaves and bulbs of Se-treated plants under salt stress. Se (25 or 50 mg L−1) significantly increased the activities of enzymatic (ascorbate peroxidase, superoxide dismutase, and catalase) and non-enzymatic (ascorbic acid and glutathione) antioxidants in both leaves and bulbs of salt-stressed onion. Se application at 25–50 mg L−1 may find, in the future, a potential application as anti-abiotic stresses for improving plant growth and productivity under saline soil condition.
Highlights
Onion (Allium cepa L.) is the second most broadly cultivated vegetable crop in the world for their economic importance, nutritional value, flavor, and medicinal properties [1].In 2019, worldwide bulb onion production was approximately 100 million tons harvested from an area of approximately 5.2 million ha
Se-treated onions with 25 mg L−1 or 50 mg L−1 showed enhanced growth and biomass compared to the nontreated plants. These improvements were more pronounced at 50 mg L−1 Se, which caused an increase of shoot length by 20% and 39%, the number of leaves by 45% and 30%, leaf area by 134% and 184%, shoot fresh weight by 165% and 134%, and shoot dry weight by
Our study exhibited that the negative effects on growth traits of salt-stressed onion were alleviated by foliar-applied Se in particular, 50 mg L−1, thereby enhanced shoot length, leaf area, and number of leaves per plant; Se increased onion biomass production grown under salinity stress
Summary
Onion (Allium cepa L.) is the second most broadly cultivated vegetable crop in the world for their economic importance, nutritional value, flavor, and medicinal properties [1]. In 2019, worldwide bulb onion production was approximately 100 million tons harvested from an area of approximately 5.2 million ha. Onion cultivated area in Egypt was 87,948 ha and produced 3.08 million tons. Among the main countries exporting onion, Egypt ranked fourth after China, India, and United States of America [2]. Onion is deemed to be a salt-sensitive crop, with a salinity threshold level of around 1.2 dS m−1 for bulb yield [3]. For every increase in ECe unit, onion bulb yield proportionally reduces [4,5]
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