Physiological mechanisms of exogenous calcium on alleviating salinity-induced stress in rice (Oryza sativa L.)

Abstract

Being more sensitive to salt stress among the cereals, growth of rice (Oryza sativa L.) has been habitually affected by salinity. Although, several practices have evolved to sustain the growth of rice under salinity, the enormous role of calcium (Ca 2?) as a signalling molecule in salt stress mitigation is still arcane. Considering this fact, an experiment was performed aiming to explicate the mechanism of salt-induced growth inhibition in rice and its alleviation by exogenous Ca 2?. At germination stage, 10 mM and 15 mM CaCl 2 primed rice (cv. Binadhan-10 & Binadhan-7) seeds were grown in petri dishes for 9 days under 100 mM NaCl stress. At seedling stage, 9-day-old rice seedlings grown on sand were exposed to 100 mM NaCl alone and combined with 10 mM and 15 mM CaCl 2 for 15 days. This research revealed that salinity radically slowed down growth of rice seedlings and Ca 2? treatment noticeably improved growth performances. At germination stage, 10 mM CaCl 2 treatment significantly increased the final germination percentage, germination rate index (in Binadhan-7), shoot, root length (89.20, 67.58% in Bindhan-10 & 84.72, 31.15% in Bindhan-7) and biomass production under salinity. Similarly, at seedling stage, 10 mM CaCl 2 supplementation in salt-stressed plants enhanced shoot length (42.17, 28.76%) and shoot dry weight (339.52, 396.20%) significantly in Binadhan-10 & Binadhan-7, respectively, but enhanced root dry weight (36.76%) only in Binadhan-10. In addition, 10 mM CaCl 2 supplementation on salt-stressed seedlings increased the chlorophyll and proline content, and oppressed the accretion of reactive oxygen species thus protecting from oxidative damage more pronouncedly in Binadhan-10 than Binadhan-7 as reflected by the elevated levels of catalase and ascorbate peroxidase activity. The 15 mM CaCl 2 somehow also enhanced some growth parameters but overall was less effective than 10 mM CaCl 2 to alleviate salt stress, and sometimes showed negative effect. Therefore, supplementary application of calcium-rich fertilizers in saline prone soils can be an effective approach to acclimatize salt stress and cultivate rice successfully.

Mitigation of salinity stress by exogenous application of cytokinin in faba bean (Vicia faba L.)

“…In our current investigation, we observed that the enzymatic activity of all antioxidants (namely SOD, CAT, POD and APX) was enhanced in both salt-treated plants (Figure 5B-E). Our result was supported by experiments on soybean (Weisany et al, 2012), maize (Tahjib-Ul-Arif et al, 2018b) and rice (Roy et al, 2019), whereas opposite findings were reported in Pisum sativum (Öztürk, 2012) and rice (Tahjib-Ul-Arif et al, 2018a). However, foliar spraying BA to both stresstreated plant leaves, further accelerated the activities of all studied antioxidant enzymes (Figure 5B-E), suggesting an advanced antioxidant capacity of the broad bean plants in response to 'B+S1' and 'B+S2' treatment to detoxify salt-induced ROS.…”

“…On the contrary, exogenous BA treatment to broad bean leaves alleviated salt-mediated oxidative injury, as strongly supported by the reduced MDA content in the of 'B+S1' and 'B+S2' plants leaves (Figure 5A), which was similar to the findings in maize under salinity and submerge conditions and faba bean under salt stress (Shah, 2011;Ren et al, 2018;Tahjib-Ul-Arif et al, 2018b;. When the plants are exposed to salt stress, it produces toxic ROS which resulted in oxidative damage and retard the growth of the plant (Tang et al, 2015;Roy et al, 2019). However, the increased activities of some antioxidants showed an efficient and effective remedy against ROS toxicity and oxidative damage (Hanin et al, 2016;Engwa, 2018).…”

“…The enhanced activity of SOD was correlated with the salinity tolerance in plants (Ma et al, 2012). Besides, POD, CAT and APX are work as H2O2 scavenging enzymes in cells (Mittler, 2002;Roy et al, 2019).…”

Growth Characteristics and Fruit Quality of Chili Pepper under Higher Electrical Conductivity of Nutrient Solution Induced by Various Salts

“…A similar response but to lesser extent was observed in K₂SO₄ treated plants. Application of calcium in different chemical forms has been shown to mitigate salinity effects on plant growth (Methenni et al, 2018;Roy, Tahjib-Ul-Arif, Polash, Hossen, & Hossain, 2019), while the calcium source still play a critical role in this aspect . Nevertheless, it seems that addition of other nutrients to saline medium induced by NaCl, could have beneficial consequences for plant growth, indicating the ameliorating effect of some ions on negative effects of other ions.…”

Differential Response of Sugar Beet to Long-Term Mild to Severe Salinity in a Soil–Pot Culture

“…In plants, ROS generates in the process of photorespiration and β-oxidation of fatty acids which is considered as a normal metabolic phenomenon. On the contrary, extreme salinity triggers the production of a lethal amount of ROS which can affect the structural integrity of the plasma membrane, functions of enzymes, and the CO 2 assimilation apparatus of plants [23,24,64,75,76]. Plant cells possess an array of enzymatic and non-enzymatic antioxidants that protects plant cells from the adverse effects of excessive ROS by scavenging it in different steps [77].…”