Exogenous jasmonic acid and humic acid increased salinity tolerance of sorghum

Abstract

Salinity limits germination and plant growth and development in 45 million ha worldwide. Techniques to overcome this problem are needed. This project investigated the effects of jasmonic acid (JA) (0, 5, and 10 mM JA) and humic acid (HA) (0, 3, and 6 g HA kg −1 soil) on growth and physiological parameters of forage sorghum (Sorghum bicolor L. Moench) under different NaCl salinity levels (0, 100, and 200 mM NaCl, with an equivalent electrical conductivity (EC) of 0.12 dSm −1 as control treatment, 3.22, and 5.78 dSm −1 , respectively). NaCl salinity reduced emergence percentage, emergence rate, salt tolerance index and seedling vigor index, all seedling growth parameters, ascorbate peroxidase (APX) activity, chlorophyll a, b and total chlorophyll content. Proline content and soluble protein content were increased with salinity. At the 200 mM salinity level, seeds treated with 10 mM JA had a positive effect on emergence percentage, emergence rate, shoot length, total fresh weight, salt tolerance index, seedling vigor index, chlorophyll a and total chlorophyll content. At 200 mM NaCl salinity level, seeds treated with 6 g HA kg −1 soil had increased root length, total dry weight, salt tolerance index, seedling vigor index, shoot length, protein content, APX, chlorophyll b, and total chlorophyll in seedlings. The application of 5 mM JA combined with 6 g HA kg −1 soil was most effective in minimizing salinity stress. Our study suggested that the appropriate combined application of HA and JA could efficiently protect early seedlings from salt stress damage and alleviate abiotic stress.Abbreviations: APX, ascorbate peroxidase; HA, humic acid; JA, jasmonic acid; ROS, reactive oxygen species.

Reactive Oxygen Species and Antioxidant Defense in Plants under Abiotic Stress: Revisiting the Crucial Role of a Universal Defense Regulator

“…For instance, Alsahli et al [ 179 ] found that a 2-fold increase in SOD, CAT, and APX activity decreased 3-fold H 2 O 2 in salt-stressed wheat by salicylic acid (SA) application compared with untreated control plants. Similarly, the combined application of jasmonic acid (JA) and humic acid also increased APX activity, resulting in salinity tolerance in sorghum [ 180 ], while exogenous application of polyamines regulated sour orange antioxidant responses under salinity stress conditions [ 181 ]. Nitrogen supplementation is also reported to increase the antioxidant (SOD, CAT, APX, GR, MDHAR, DHAR activities and the biosynthesis of AsA and GSH) levels with declining 2.5-fold H 2 O 2 and 1.7-fold O 2 •− generation in wheat under 100 mM NaCl stress [ 182 ].…”

From Lab to Field: Role of Humic Substances Under Open-Field and Greenhouse Conditions as Biostimulant and Biocontrol Agent

“…Plant secondary metabolism produces a large number of specialized compounds that do not directly aid in the growth and development of plants but are required for the plant to survive in its environment and under biotic and abiotic stress. Salinity and drought are the most frequent stresses studied in fields and under greenhouse conditions (Ali et al, 2020). Several reports have been published on the impact of HS on the growth of pepper, common beans, rice, tomato, corn, sorghum, and cucumber under these stress conditions (Demir et al, 1999;García et al, 2012;Berbara and García, 2014;Rose et al, 2014;Prado et al, 2016;Van Oosten et al, 2017;Bulgari et al, 2019;Pinos et al, 2019;Ali et al, 2020).…”

“…Several reports have been published on the impact of HS on the growth of pepper, common beans, rice, tomato, corn, sorghum, and cucumber under these stress conditions (Demir et al, 1999;García et al, 2012;Berbara and García, 2014;Rose et al, 2014;Prado et al, 2016;Van Oosten et al, 2017;Bulgari et al, 2019;Pinos et al, 2019;Ali et al, 2020). One of the underlying mechanisms of the impact of the HS is the interaction with auxin, jasmonic acid and abscisic acid by phytohormonal regulation in the root, which are well-known plant hormones for the stress of drought and salinity (De Hita et al, 2019;Ali et al, 2020). Another example is the synthesis of flavonoids, which are involved in the interception of ultraviolet (UV) as an adaptive mechanism preventing UV in plant physiology (Hollósy, 2002).…”

Gibberellic acid and nitrogen efficiently protect early seedlings growth stage from salt stress damage in Sorghum

“…Salinity stress can significantly inhibit germination and seedling growth, decrease many physiological processes and ultimately reduce crop productivity by causing osmotic stress and/or toxicity of ions as well as by reducing the uptake of important ions such as calcium and potassium 6 . Crop plants can suffer from salinity stress at all growth stages, but germination and early plant stage are known to be more sensitive for most plant species 7 , 8 . Salinity stress affect all growth stages, but germination and early seedling stage are known to be more sensitive to salinity, causing significantly inhibited germination and seedling growth and ultimately decreased crop productivity through osmotic stress and ion toxicity such as Na + and Cl − , as well as throught reduced absorption of important nutrients such as Ca +2 and K + 6 , 9 .…”