Abstract
A study was carried out to evaluate the effectiveness of sugar beet extract (SBE) and glycine betaine (GB) in mitigating the adverse effects of drought stress on two maize cultivars. Seeds (caryopses) of two maize cultivars, Sadaf (drought-tolerant) and Sultan (drought-sensitive) were sown in plastic pots. Plants were subjected to different (100%, 75% and 60% field capacity (FC)) water regimes. Then, different levels of SBE (3% and 4%) and GB (3.65 and 3.84 g/L) were applied as a foliar spray after 30 days of water deficit stress. Drought stress significantly decreased plant growth and yield attributes, chlorophyll pigments, while it increased relative membrane permeability (RMP), levels of osmolytes (GB and proline), malondialdehyde (MDA), total phenolics and ascorbic acid as well as the activities of superoxide dismutase (SOD) and peroxidase (POD) enzymes in both maize cultivars. Exogenous application via foliar spray with SBR or GB improved plant growth and yield attributes, chlorophyll pigments, osmolyte concentration, total phenolics, ascorbic acid and the activities of reactive oxygen species (ROS) scavenging enzymes (SOD, POD and catalase; CAT), but reduced leaf RMP and MDA concentration. The results obtained in this study exhibit the role of foliar-applied biostimulants (natural and synthetic compounds) in enhancing the growth and yield of maize cultivars by upregulating the oxidative defense system and osmoprotectant accumulation under water deficit conditions.
Highlights
Crop production and its distribution in the world are being considerably hampered due to drought stress as a consequence of the climatic change and anthropogenic activities [1,2]
Sadaf was better in biomass production than that of cv
Of all the exogenous treatments, sugar beet extract applied at the rate of 4% (40 g/L) was most effective in improving plant growth under drought stress conditions
Summary
Crop production and its distribution in the world are being considerably hampered due to drought stress as a consequence of the climatic change and anthropogenic activities [1,2]. The duration and frequency of drought periods will rise due to the current scenario of climate change resulting in one of the most important threats of the current century [3]. Plants enhance the production of osmolytes or osmoprotectants under stress conditions including drought [6]. Osmoprotectants preserve the cellular apparatus from dehydration-induced injury without interfering with the normal metabolic processes at the cellular level. They comprise a wide variety of compounds/molecules, such as proline, glycine betaine (GB), trehalose, quaternary ammonium compounds, phenolics, sugars, etc. Glycine betaine is a quaternary ammonium compound endogenously synthesized in chloroplasts in response to abiotic stressors, such as drought and salinity [9,10]
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