Exogenous application of humic acid mitigates salinity stress in maize (Zea mays L.) plants by improving some key physico-biochemical attributes

Abstract

Application of salt stress (100 mM) through root growing medium caused a considerable decrease in plant fresh and dry biomass, maximum quantum yield (F v /F m), chlorophyll contents, leaf water potential, and leaf Ca, K, P and N concentrations of two maize cultivars (Apex 836 and DK 5783). However, salt-induced increase was observed in leaf osmolality (LO), proline, hydrogen peroxide (H 2 O 2), malondialdehyde (MDA), Na + concentration and activities of enzymatic antioxidants, such as catalase (CAT), peroxidase (POD) and superoxide dismutase (SOD). Of five humic acid (HA) levels used under non-stress and stress conditions in an initial experiment, 100 mg L-1 was chosen for subsequent studies. Exogenous application of humic acid (HA) at the rate of 100 mM as a foliar or pre-sowing seed treatment significantly increased the plant biomass, F v /F m , chlorophyll pigments and proline contents, while it considerably reduced the leaf water potential, H 2 O 2 and MDA contents as well as the activities of all the afore-mentioned enzymatic antioxidants. Of both modes of exogenous treatment, foliar spray was better in improving plant biomass, chlorophyll contents, LO, leaf Na + as well as the accumulation of all nutrients measured, however, in contrast, seed pre-treatment was more effective in altering leaf proline, H 2 O 2 and MDA contents. Of both maize cultivars, cv. DK 5783 excelled in plant biomass, chlorophyll contents and leaf N, Ca and K concentrations as well as in the activities of all three antioxidant enzymes, whereas cv. Apex 836 was superior in leaf Na + and P concentrations, H 2 O 2 and MDA contents. Cv. DK 5783 was comparatively better in salt tolerance as compared to cv. Apex 836. Overall, exogenous application of HA was effective in improving salinity tolerance of maize plants which can be attributed to HA-induced increase in plant biomass, chlorophyll contents, mineral nutrients and activities of key antioxidant enzymes.

Exogenous jasmonic acid and humic acid increased salinity tolerance of sorghum

“…These results confirm by Akladious and Mohamed () and Kaya et al. (). The foliar application of HA can enhance photosynthesis activity and increase tolerance in stresses conditions by increased the activity of the enzyme rubisco (Latif & Mohamed, ).…”

“…In our results, HA was positive effective on APX activity. Increased APX activity under HA application has been reported in maize plant exposed to salinity (Kaya et al., ). El‐Beltagi, Salama, and El Hariri () and Kesba and El‐Beltagi () reported that HA was improved the APX activity in response to salinity stress.…”

“…Humic acid (HA) is one of the frequently used organic fertilizer that can significantly influence the growth stage of crops and increase N, K, Ca, Mg, and P absorption (Elmongy, Zhou, Cao, Liu, & Xia, ). Notably, humic substances can alleviate stresses by increasing shoot and root dry weight and promoting plant growth (Kaya, Akram, Ashraf, & Sonmez, ). Under salt stress, humic substances can decrease the uptake of toxic elements and improve the uptake of essential nutrients in garden cress ( Lepidium sativum L) and maize ( Zea mays L.).…”

“…Under salt stress, humic substances can decrease the uptake of toxic elements and improve the uptake of essential nutrients in garden cress ( Lepidium sativum L) and maize ( Zea mays L.). The application of HA also improved maize crop under salt stress, which was attributed to a good accumulation of essential nutrients including N, P, and K (Kaya et al., ).…”

Ameliorative Effects of Jasmonic Acid and Humic Acid on Antioxidant Enzymes and Salt Tolerance of Forage Sorghum under Salinity Conditions

“…In the present study, MDA content increased with increased salinity and JA. In other studies, MDA content increased under salinity in sweet sorghum (Nimir et al, 2015) and wheat (Kaya et al, 2018; Qiu et al, 2014). When NaCl was applied, the MDA content was substantially higher than in the control in wheat (Qiu et al, 2014).…”