Foliar fertilization with micronutrients improves Stevia rebaudiana tolerance to salinity stress by improving root characteristics

Abstract

Stevia (Stevia rebaudiana Bertoni), a perennial crop of the family Asteraceae, is one of the most important sources of non-caloric natural sweeteners, but research on the impact of salinity on root parameters and steviol glycoside content is limited or does not exist. The objective of this study was to assess the effect of exogenous application of iron (Fe), boron (B), and selenium (Se) on root characteristics, growth, and yield of stevia under four levels of NaCl salinity (i.e., 0, 30, 60, and 90 mM). Root length (RL), root volume (RV), root area (RA), and root fresh and dry weight (RFW and RDW) were significantly decreased with increasing salinity. The highest values of all the above root traits were observed with foliar spraying B plus Se plus Fe. Foliar spraying B plus Se plus Fe resulted in 2.9 times greater RV and 2.8 times greater RFW than control. Furthermore, salinity significantly decreased plant height, branches number, leaves number, and biomass yield of stevia. However, foliar application of micronutrients, especially B and Se, reduced those adverse effects. Moreover, salinity decreased the relative water content (RWC) and increased relative water loss (RWL) in stevia tissues. The highest RWC and the lowest RWL were observed in foliar application of B plus Se. Foliar spraying of nutrients significantly improved root characteristics and water status of salt-stressed stevia plants, which in turn (i) helped plants to tolerate excessive Na levels and (ii) improved nutrient uptake under salinity stress. In light of the above, foliar treatment of stevia plants with micronutrients for improving growth under saline conditions could be considered, but toward that direction, studies under field conditions would be required to quantify the efficiency of these micronutrients in foliar applications.

Evaluation of metabolites in Iranian Licorice accessions under salinity stress and Azotobacter sp. inoculation

“…It is also known that salt stress reduces Fe availability for plants, as observed in the current study. Similar results have also been stated in previous reports 65 , 66 . Since Fe can increase the uptake of other elements by roots and aerial parts under saline conditions, bacterial inoculation increased the Fe concentration in the leaves and roots of licorice.…”

Selenium-Ethylene Interplay in Postharvest Life of Cut Flowers

“…Selenoamino acids appear to be beneficial to growth in some conditions with an underlying influence on the oxidative protection networks in plants (Pilon-Smits and Quinn, 2010;Feng et al, 2013;Ahmad et al, 2016). Different strategies have been adopted to evaluate the role of Se in response to stress, including the application of Se as a seed priming treatment (Hasanuzzaman and Fujita, 2011;Nawaz et al, 2013;Hussain et al, 2016), soil fertilizer (Kumar et al, 2014;Khan et al, 2015;Atarodi et al, 2018), and foliar drench (Iqbal et al, 2015;Shahverdi et al, 2020). Treatment with Se at low concentrations is known to alleviate several stresses in plants, including those ones caused by drought (Hasanuzzaman and Fujita, 2011;Nawaz et al, 2013), heat (Iqbal et al, 2015), arsenic (Kumar et al, 2014), cadmium (Khan et al, 2015), low phosphorus (Jia et al, 2018), salinity (Shahverdi et al, 2020), as well as lead and aluminum (Feng et al, 2013).…”

“…Different strategies have been adopted to evaluate the role of Se in response to stress, including the application of Se as a seed priming treatment (Hasanuzzaman and Fujita, 2011;Nawaz et al, 2013;Hussain et al, 2016), soil fertilizer (Kumar et al, 2014;Khan et al, 2015;Atarodi et al, 2018), and foliar drench (Iqbal et al, 2015;Shahverdi et al, 2020). Treatment with Se at low concentrations is known to alleviate several stresses in plants, including those ones caused by drought (Hasanuzzaman and Fujita, 2011;Nawaz et al, 2013), heat (Iqbal et al, 2015), arsenic (Kumar et al, 2014), cadmium (Khan et al, 2015), low phosphorus (Jia et al, 2018), salinity (Shahverdi et al, 2020), as well as lead and aluminum (Feng et al, 2013). In addition to positive results in responding to several stresses, low concentrations of Se can also induce plant growth (Lehotai et al, 2012;Boldrin et al, 2016), via an effect on mitochondrial metabolism (Dimkovikj and Van Hoewyk, 2014) and molecular switches (Lehotai et al, 2012;Khan et al, 2015;Jia et al, 2018).…”