Abstract
Applying elicitors and nano-fertilizer has been recommended to enhance the growth and yield of secondary metabolites in herbs and medicinal plants under water-limited stress. However, less information is available on the effects of chitosan and nano-magnesium fertilizers on sesame seed yield, oil content, and physiological traits in the presence of nano-magnesium chelate (nano-Mg) under water-limited supply. In this regard, field experiments as a split-factorial experiment was performed based on randomized blocks in three replicates in Varamin city, south of Tehran, Iran, during 2015-2016 to evaluate the impact of chitosan and nano-Mg on physiological, seed, and oil traits of sesame. Irrigation cut-off based on BBCH scale was considered as the main factor including normal irrigation (I1), irrigation cut-off in 75 (I2), and 65 BBCH (I3) stages. Secondary factors as the subplot included ‘Oltan’ (C1) and ‘Dashtestan-2’ (C2) sesame cultivars, and foliar application of nano-Mg (application and non-application) and chitosan (control (CH1), foliar application of 4.8 g L-1 in 65 BBCH (CH2), and 6.4 g L-1 in 75 BBCH stages (CH3)). Further, free proline content, total sugars, the activity of antioxidant enzymes including catalase (CAT, EC 1.11.1.6), peroxidase (POD, EC 1.11.1), and ascorbate peroxidase (APX, EC 1.11.1.11), photosynthetic pigments content, seed yield, and oil content were evaluated in the next stage. Based on the results, irrigation cut-off in 65 BBCH stage (flowering) significantly increased free proline content, total sugars, and the activity of antioxidant enzymes, CAT, POD, and APX. However, chlorophyll a, b, and total contents, seed yield, oil percentage, and yield decreased under water stress. ‘Dashtestan-2’ cultivar had the highest seed yield and oil content, and more tolerant cultivar under water-limited stress. Interestingly, the production of proline content and total sugars increased while the activity of antioxidant enzymes, CAT, POD, and APX decreased under application of nano-Mg and CH2, which influenced both sesame response and seed attributes. As a result, the production of some physiological traits in sesame cultivars may be regulated by adjusting the irrigating practices. Finally, the co-application of nano-Mg and CH2 increased the seed yield and oil content of sesame under limited water supply in the arid and semi-arid region.
Highlights
Sesame (Sesamum indicum L.) is annual and self-pollinating, which belongs to Pedaliaceae family
The present study aimed to evaluate the effect of magnesium nano-chelate and chitosan elicitor on the activity of antioxidant enzymes, photosynthetic pigments, seed yield, and oil content of sesame under water-limited stress in order to provide a suitable way for reducing drought stresses and achieving sustainable agriculture in arid and semi-arid regions
A set of properties related to sesame medicinal plant including seed yield, oil content, photosynthetic pigments, antioxidant enzyme activities were determined by limited irrigation regimes and application of chitosan and magnesium-nano fertilizers
Summary
Sesame (Sesamum indicum L.) is annual and self-pollinating, which belongs to Pedaliaceae family It is regarded as one of the oldest oysters, which can be adapted to warm and semi-warm regions, known as the queen of oilseed plants. The results of some research indicated that the drought stress generally results in destructing the chloroplasts, and decreasing chlorophyll content and the activity of enzymes in the Calvin cycle during the photosynthesis process (Anaya et al, 2018) In this regard, Mafakheri et al (2010) reported a decrease in leaf chlorophyll content due to drought stress. The first defence line against ROS to enzymatic and non-enzymatic antioxidants increases in plant cells In this regard, the increased activity of antioxidant enzymes due to drought stress was reported by Murshed et al (2013)
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