Sulfate-Based Fertilizers Regulate Nutrient Uptake, Photosynthetic Gas Exchange, and Enzymatic Antioxidants to Increase Sunflower Growth and Yield Under Drought Stress

Abstract

The challenging impact of drought to agricultural productivity requires the adoption of mitigation strategies with a better understanding of underlying mechanisms responsible for drought tolerance. The present study aimed at investigating the effects of sulfur-based fertilizers on mitigation of drought stress in sunflower. Sulfate-containing fertilizers, viz., ammonium sulfate, zinc sulfate, magnesium sulfate, potassium sulfate, and gypsum, were initially evaluated at two different rates (10 and 20 mg kg−1 soil equivalent to 20 and 40 kg ha−1, respectively) for nutrient uptake and growth-promoting traits in sunflower seedlings (cv. Hysun-33). The best performing fertilizer (gypsum) was then selected to evaluate the response of sunflower under drought stress imposed at flowering stage for three weeks (25–30% water holding capacity). Results indicated significant amelioration of drought stress with higher activity of photosynthetic apparatus, upregulation of antioxidative enzymes, and increased achene yield by gypsum application. In comparison to control, gypsum-treated plants (20 mg kg−1 soil) exhibited higher water status (32%), leaf photosynthetic rate (29%), transpiration rate (67%), and stomatal conductance (118%) under drought stress. The antioxidant enzyme activities of catalase, guaiacol peroxidase, and superoxide dismutase were also increased by 67%, 62%, and 126%, respectively, resulting in higher achene yield (19%) under water-deficit conditions. This study indicates that the application of sulfur-based fertilizers (gypsum) can be used to induce drought tolerance and obtain high sunflower yields under drought stress, and furthermore, it is a cost-effective strategy resulting in high benefit–cost ratio with respect to no gypsum application.

Plant growth and nutrient uptake of Green gram (Vigna radiata. L) under marine gypsum reclaimed sodic soil as influenced by foliar nutrition

“…Hence, combination of marine gypsum with foliar application of 1 % MKP along with 100 ppm Salicylic acid and 0.5 ppm of Brassinosteroid improved soil structure and increased translocation of assimilated products from source to sink resulted in a higher amount of dry matter production. Similar results were reported by Ashraf et al (2010), Sajyan et al (2018) and Shafiq et al (2021).…”

Monitoring of Salinity, Temperature, and Drought Stress in Grafted Watermelon Seedlings Using Chlorophyll Fluorescence

“…Furthermore, plants also undergo various in vitro phenotypic and in vivo physiological changes both internally and externally when subjected to drought stress, and activate multiple defense mechanisms for protection and survival ( Yordanov et al, 2000 ; Kapoor et al, 2020 ; Tabassum et al, 2021 ). In addition, drought stress is known to limit photosynthetic activity ( Shafiq et al, 2021 ). Drought stress caused by inadequate watering induces physiological changes in plants, such as cell dehydration, osmotic pressure imbalance, and plant growth retardation ( Jia et al, 2021 ).…”

Activating stress memory: eustressors as potential tools for plant breeding

“…Between these, the reactive oxygen–nitrogen–sulphur species (RONSS) stand out as a key priming agent because of their role as a key messenger in the physiology, metabolism, and responses to stress, and the crosstalk tolerance they could induce in plants (Locato et al 2018 ). By mention, recent studies have highlighted the use of sulfur fertilization to enhance drought tolerance (Chowdhury et al 2020 ; Farman et al 2021 ; Shafiq et al 2021 ) and heavy metal exposure (Ragab and Saad-Allah 2021 ) in crops through the regulation of the enzymatic antioxidant system and photosynthetic efficiency. These suggest a degree of priming additional to the biostimulants effect in the yield.…”