Priming for Saline-Alkaline Tolerance in Rice: Current Knowledge and Future Challenges

doi:10.1016/j.rsci.2023.05.003

Abstract

Abstract:

Soil salinization and/or alkalization is a major constraint to crop production worldwide. Approximately 60% of the cultivated land is affected by salt, over half of which is alkalized. Alkaline soils are characterized by high alkalinity and typically high salinity, which creates a complex saline-alkaline (SA) stress that affects plant growth. Rice cultivation has been accepted as an important strategy for effective utilization of SA land if water is available for irrigation. Nevertheless, as a salt-sensitive plant, rice plants suffer severe SA-induced damage, which results in poor plant growth and grain yield. Various approaches have been employed to improve rice productivity in SA land. Among them, the priming technique has emerged as a powerful method for enhancing SA tolerance in rice plants. In this review, we summarized how SA stress damages rice plants, and then presented how priming treatment can mitigate such damage.

Key words: saline-alkaline stress, plant hormone, abscisic acid, reactive oxygen species, antioxidant, stress tolerance

Jiang Changjie, Liang Zhengwei, Xie Xianzhi. Priming for Saline-Alkaline Tolerance in Rice: Current Knowledge and Future Challenges[J]. Rice Science, 2023, 30(5): 417-425.

Figures/Tables 2

References 92

[1]	Abdel Latef A A, Tran L S P. 2016. Impacts of priming with silicon on the growth and tolerance of maize plants to alkaline stress. Front Plant Sci, 7: 243. PMID
[2]	Aranega-Bou P, de la O Leyva M, Finiti I, García-Agustín P, González-Bosch C. 2014. Priming of plant resistance by natural compounds: Hexanoic acid as a model. Front Plant Sci, 5: 488. PMID
[3]	Baxter A, Mittler R, Suzuki N. 2014. ROS as key players in plant stress signalling. J Exp Bot, 65(5): 1229-1240. PMID
[4]	Beckers G J M, Conrath U. 2007. Priming for stress resistance: From the lab to the field. Curr Opin Plant Biol, 10(4): 425-431. PMID
[5]	Bektas Y, Eulgem T. 2015. Synthetic plant defense elicitors. Front Plant Sci, 5: 804.
[6]	Campbell S A, Nishio J N. 2000. Iron deficiency studies of sugar beet using an improved sodium bicarbonate-buffered hydroponic growth system. J Plant Nutr, 23(6): 741-757.
[7]	Cao X F, Sun B, Chen H B, Zhou J M, Song X W, Liu X J, Deng X D, Li X J, Zhao Y G, Zhang J B, Li J Y. 2021. Approaches and research progresses of marginal land productivity expansion and ecological benefit improvement in China. Bull Chin Acad Sci, 36(3): 336-348. (in Chinese with English abstract)
[8]	Chen S S, Xing J J, Lan H Y. 2012. Comparative effects of neutral salt and alkaline salt stress on seed germination, early seedling growth and physiological response of a halophyte species Chenopodium glaucum. Afr J Biotechnol, 11(40): 9572-9581.
[9]	Choudhury F K, Rivero R M, Blumwald E, Mittler R. 2017. Reactive oxygen species, abiotic stress and stress combination. Plant J, 90(5): 856-867.
[10]	Dejonghe W, Okamoto M, Cutler S R. 2018. Small molecule probes of ABA biosynthesis and signaling. Plant Cell Physiol, 59(8): 1490-1499. PMID
[11]	Dietz K J, Turkan I, Krieger-Liszkay A. 2016. Redox- and reactive oxygen species-dependent signaling into and out of the photo- synthesizing chloroplast. Plant Physiol, 171(3): 1541-1550.
[12]	FAO (Food and Agriculture Organization). 2022. How to feed the World in 2050. [2023-01-01]. https://www.fao.org/fileadmin/templates/wsfs/docs/expert_paper/How_to_Feed_the_World_in_2050.pdf.
[13]	Ganapati R K, Naveed S A, Zafar S, Wang W S, Xu J L. 2022. Saline-alkali tolerance in rice: Physiological response, molecular mechanism, and QTL identification and application to breeding. Rice Sci, 29(5): 412-434.
[14]	Goellner K, Conrath U. 2008. Priming: It’s all the world to induced disease resistance. Eur J Plant Pathol, 121(3): 233-242.
[15]	Grattan S R, Zeng L H, Shannon M C, Roberts S R. 2002. Rice is more sensitive to salinity than previously thought. Calif Agric, 56(6): 189-195.
[16]	Gregory P J, Ingram J S I, Andersson R, Betts R A, Brovkin V, Chase T N, Grace P R, Gray A J, Hamilton N, Hardy T B, Howden S M, Jenkins A, Meybeck M, Olsson M, Ortiz- Monasterio I, Palm C A, Payn T W, Rummukainen M, Schulze R E, Thiem M, Valentin C, Wilkinson M J. 2002. Environmental consequences of alternative practices for intensifying crop production. Agric Ecosyst Environ, 88(3): 279-290.
[17]	Guan Q J, Liao X, He M L, Li X F, Wang Z Y, Ma H Y, Yu S, Liu S K. 2017. Tolerance analysis of chloroplast OsCu/Zn-SOD overexpressing rice under NaCl and NaHCO₃ stress. PLoS One, 12(10): e0186052.
[18]	Guntzer F, Keller C, Meunier J D. 2012. Benefits of plant silicon for crops: A review. Agron Sustain Dev, 32(1): 201-213.
[19]	Guo M X, Wang R C, Wang J, Hua K, Wang Y M, Liu X Q, Yao S G. 2014. ALT1, a Snf2 family chromatin remodeling ATPase, negatively regulates alkaline tolerance through enhanced defense against oxidative stress in rice. PLoS One, 9(12): e112515.
[20]	Gurmani A R, Bano A, Salim M. 2006. Effect of growth regulators on growth, yield and ions accumulation of rice (Oryza sativa L.) under salt stress. Pak J Bot, 38(5): 1415-1424.
[21]	Gurmani A R, Bano A, Khan S U, Din J, Zhang J L. 2011. Alleviation of salt stress by seed treatment with abscisic acid (ABA), 6-benzylaminopurine (BA) and chlormequat chloride (CCC) optimizes ion and organic matter accumulation and increases yield of rice (Oryza sativa L.). Aust J Crop Sci, 5(10): 1278-1285.
[22]	Gurmani A R, Bano A, Ullah N, Khan H, Jahangir M, Flowers T J. 2013. Exogenous abscisic acid (ABA) and silicon (Si) promote salinity tolerance by reducing sodium (Na⁺) transport and bypass flow in rice (Oryza sativa indica). Aust J Crop Sci, 7: 1219-1226.
[23]	Hartung W, Leport L, Ratcliffe R G, Sauter A, Duda R, Turner N C. 2002. Abscisic acid concentration, root pH and anatomy do not explain growth differences of chickpea (Cicer arietinum L.) and lupin (Lupinus angustifolius L.) on acid and alkaline soils. Plant Soil, 240(1): 191-199.
[24]	Haynes R J. 2017. Significance and role of Si in crop production. Adv Agron, 146: 83-166.
[25]	Hewage K A H, Yang J F, Wang D, Hao G F, Yang G F, Zhu J K. 2020. Chemical manipulation of abscisic acid signaling: A new approach to abiotic and biotic stress management in agriculture. Adv Sci, 7(18): 2001265.
[26]	Hossner L R. 2008. Field pH. In: Chesworth W. Encyclopedia of Soil Science. Dordrecht, the Netherlands: Springer: 271-272.
[27]	Huang L H, Liang Z W, Suarez D L, Wang Z C, Wang M M, Yang H Y, Liu M. 2015. Impact of cultivation year, nitrogen fertilization rate and irrigation water quality on soil salinity and soil nitrogen in saline-sodic paddy fields in Northeast China. J Agric Sci, 154(4): 632-646.
[28]	Islam F, Wang J, Farooq M A, Yang C, Jan M, Mwamba T M, Hannan F, Xu L, Zhou W J. 2019. Rice responses and tolerance to salt stress: Deciphering the physiological and molecular mechanisms of salinity adaptation. In: Hasanuzzaman M, Fujita M, Nahar K, Biswas J K. Advance in Rice Research for Abiotic Stress Tolerance. Cambridge, UK: Woodhead Publishing: 791-819.
[29]	Islam M S, Akhter M, El-Sabagh A, Liu L Y, Nguyen N T, Ueda A, Masaoka Y, Saneoka H. 2011. Comparative studies on growth and physiological responses to saline and alkaline stresses of Foxtail millet (Setaria italica L.) and Proso millet (Panicum miliaceum L.). Aust J Crop Sci, 5(10): 1269-1277.
[30]	Jisha K C, Vijayakumari K, Puthur J T. 2013. Seed priming for abiotic stress tolerance: An overview. Acta Physiol Plant, 35(5): 1381-1396.
[31]	Jones A M. 2016. A new look at stress: Abscisic acid patterns and dynamics at high-resolution. New Phytol, 210(1): 38-44. PMID
[32]	Kamanga R M, Oguro S, Nampei M, Ueda A. 2022. Acclimation to NaCl and H₂O₂ develops cross tolerance to saline-alkaline stress in Rice (Oryza sativa L.) by enhancing fe acquisition and ROS homeostasis. Soil Sci Plant Nutr, 68(3): 342-352.
[33]	Kerchev P, van der Meer T, Sujeeth N, Verlee A, Stevens C V, Van Breusegem F, Gechev T. 2020. Molecular priming as an approach to induce tolerance against abiotic and oxidative stresses in crop plants. Biotechnol Adv, 40: 107503.
[34]	Khan M S A, Hamid A, Karim M A. 1997. Effect of sodium chloride on germination and seedling characters of different types of rice (Oryza sativa L.). J Agron Crop Sci, 179(3): 163-169.
[35]	Khan M A, Abdullah Z. 2003. Salinity-sodicity induced changes in reproductive physiology of rice (Oryza sativa) under dense soil conditions. Environ Exp Bot, 49(2): 145-157.
[36]	Leng C X, Zheng F Y, Zhao B P, Li H Y, Wang Y J. 2020. Advances on alkaline tolerance of rice. Bull Biotechnol, 36(11): 103-111. (in Chinese with English abstract)
[37]	Li F L, Luo C K, Lu X P, Tian L, Li P F. 2021. Current status and prospect of research on physiology and genetic mechanism of alkali tolerance in rice. J Plant Genet Resour, 22(2): 283-292. (in Chinese with English abstract)
[38]	Liang X L, Fang S M, Ji W B, Zheng D F. 2015. The positive effects of silicon on rice seedlings under saline-alkali mixed stress. Commun Soil Sci Plant Anal, 46(17): 2127-2138.
[39]	Liang Y C, Nikolic M, Bélanger R, Gong H J, Song A L. 2015. History and introduction of silicon research. In: Silicon in Agriculture. Dordrecht, the Netherlands: Springer: 1-18.
[40]	Liang Z W, Wang Z C, Ma H Y, Yang F, Huang L H, Kong X J, Yan C, Liu M, Wang M M, Qi C Y. 2008. The progress in improvement of high pH saline-alkali soil in the Songnen Plain by stress tolerant plants. J Jilin Agric Univ, 30: 517-528. (in Chinese with English abstract)
[41]	Liu H P, Able A J, Able J A. 2022. Priming crops for the future: Rewiring stress memory. Trends Plant Sci, 27(7): 699-716.
[42]	Liu L L, Wang B S. 2021. Protection of halophytes and their uses for cultivation of saline-alkali soil in China. Biology, 10(5): 353.
[43]	Liu X L, Zhang H, Jin Y Y, Wang M M, Yang H Y, Ma H Y, Jiang C J, Liang Z W. 2019. Abscisic acid primes rice seedlings for enhanced tolerance to alkaline stress by upregulating antioxidant defense and stress tolerance-related genes. Plant Soil, 438(1): 39-55.
[44]	Liu X L, Xie X Z, Zheng C K, Wei L X,Li X W Jin Y Y, Zhang G H, Jiang C J, Liang Z W. 2022. RNAi-mediated suppression of the abscisic acid catabolism gene OsABA8ox1 increases abscisic acid content and tolerance to saline-alkaline stress in rice (Oryza sativa L.). Crop J, 10(2): 354-367.
[45]	Llorens E, González-Hernández A I, Scalschi L, Fernández-Crespo E, Camañes G, Vicedo B, García-Agustín P. 2020. Priming mediated stress and cross-stress tolerance in plants: Concepts and opportunities. In: Hossain M A, Liu F L, Burritt D J, Fujita M, Huang B R. Priming-mediated Stress and Cross-stress Tolerance in Crop Plants. UT, USA: Academic Press: 1-20.
[46]	Lu X P, Min W F, Shi Y F, Tian L, Li P F, Ma T L, Zhang Y X, Luo C K. 2022. Exogenous melatonin alleviates alkaline stress by removing reactive oxygen species and promoting antioxidant defence in rice seedlings. Front Plant Sci, 13: 849553.
[47]	Luo C K, Tian L, Bi J T, Xiao G J. 2019. Effects of rice planting years on saline-alkali soil trace elements, rice yield and quality. Ecol Environ Sci, 28(8): 1577-1584.
[48]	Lv B S, Li X W, Ma H Y, Sun Y, Wei L X, Jiang C J, Liang Z W. 2013. Differences in growth and physiology of rice in response to different saline-alkaline stress factors. Agron J, 105(4): 1119-1128.
[49]	Lv B S, Ma H Y, Li X W, Wei L X, Lv H Y, Yang H Y, Jiang C J, Liang Z W. 2015. Proline accumulation is not correlated with saline-alkaline stress tolerance in rice seedlings. Agron J, 107(1): 51-60.
[50]	Ma H Y, Liang Z W. 2007. Effects of different soil pH and soil extracts on the germination and seedling growth of Leymus chinensis. Chin Bull Bot, 24(2): 181-188. (in Chinese with English abstract)
[51]	Maas E V, Grattan S R. 1999. Crop yields as affected by salinity, In: Skaggs R W, van Schilfgaarde J Agrcicultural Drainage. WI, USA: American Society of Agronomy: 38: 55-110.
[52]	Mauch-Mani B, Baccelli I, Luna E, Flors V. 2017. Defense priming: An adaptive part of induced resistance. Annu Rev Plant Biol, 68: 485-512. PMID
[53]	Minhas P S, Yadav R K, Sharma P C. 2021. Managing salt-affected soils for sustainable agriculture. New Delhi, India: ICAR.
[54]	Mittler R, Blumwald E. 2015. The roles of ROS and ABA in systemic acquired acclimation. Plant Cell, 27(1): 64-70.
[55]	Mittler R. 2017. ROS are good. Trends Plant Sci, 22(1): 11-19. PMID
[56]	Müller K, Linkies A, Vreeburg R A M, Fry S C, Krieger-Liszkay A, Leubner-Metzger G. 2009. In vivo cell wall loosening by hydroxyl radicals during cress seed germination and elongation growth. Plant Physiol, 150(4): 1855-1865.
[57]	Munns R, Tester M. 2008. Mechanisms of salinity tolerance. Annu Rev Plant Biol, 59: 651-681. PMID
[58]	Nandal M, Hooda R. 2013. Salt tolerance and physiological response of plants to salinity: A Review. Int J Sci Eng Res, 4(10): 45-67.
[59]	Paz R C, Rocco R A, Reinoso H, Menéndez A B, Pieckenstain F L, Ruiz O A. 2012. Comparative study of alkaline, saline, and mixed saline-alkaline stresses with regard to their effects on growth, nutrient accumulation, and root morphology of Lotus tenuis. J Plant Growth Regul, 31(3): 448-459.
[60]	PRB Population Reference Bureau. 2020. The 2020 World population data sheet. [2023-01-01]. https://interactives.prb.org/2021-wpds/.
[61]	Qadir M, Schubert S, Ghafoor A, Murtaza G. 2001. Amelioration strategies for sodic soils: A review. Land Degrad Dev, 12(4): 357-386.
[62]	Radi A A, Abdel-Wahab D A, Hamada A M. 2012. Evaluation of some bean lines tolerance to alkaline soil. J Biol Earth Sci, 2(1): B18-B27.
[63]	Rao P S, Mishra B, Gupta S R, Rathore A. 2008. Reproductive stage tolerance to salinity and alkalinity stresses in rice genotypes. Plant Breed, 127(3): 256-261.
[64]	Rao Y, Peng T, Xue S W. 2023. Mechanisms of plant saline- alkaline tolerance. J Plant Physiol, 281: 153916.
[65]	Rehman H U, Aziz T, Farooq M, Wakeel A, Rengel Z. 2012. Zinc nutrition in rice production systems: A review. Plant Soil, 361(1): 203-226.
[66]	Rhaman M S, Imran S, Rauf F, Khatun M, Baskin C C, Murata Y, Hasanuzzaman M. 2020. Seed priming with phytohormones: An effective approach for the mitigation of abiotic stress. Plants, 10(1): 37.
[67]	Sah S K, Reddy K R, Li J X. 2016. Abscisic acid and abiotic stress tolerance in crop plants. Front Plant Sci, 7: 571. PMID
[68]	Sako K, Nguyen H M, Seki M. 2021. Advances in chemical priming to enhance abiotic stress tolerance in plants. Plant Cell Physiol, 61(12): 1995-2003. PMID
[69]	Savvides A, Ali S, Tester M, Fotopoulos V. 2016. Chemical priming of plants against multiple abiotic stresses: Mission possible. Trends Plant Sci, 21(4): 329-340. PMID
[70]	Shahid S A, Zaman M, Heng L E. 2018. Soil salinity: Historical perspectives and a world overview of the problem. In: Zaman M, Shahid S A, Heng L E. Guideline for Salinity Assessment, Mitigation and Adaptation Using Nuclear and Related Techniques. Cham, Switzerland: Springer International Publishing: 43-53.
[71]	Sharma M, Gupta S K, Deeba F, Pandey V. 2017. Effects of reactive oxygen species on crop productivity: An overview. In: Singh V P, Singh S, Tripathi D K, Prasad S M, Chauhan D K. Reactive Oxygen Species in Plants: Boon or Bane-Revisiting the Role of ROS. Chichester, UK: John Wiley & Sons Ltd: 117-136.
[72]	Sharma M, Mahajan P, Singh H P, Batish D R, Kohli R K. 2019. 24-Epibrassinolide pre-treatment reduces alkaline-induced oxidative stress in red rice seedlings. Environ Sci Pollut Res, 26(22): 23192-23197.
[73]	Sharma M, Kumar P, Verma V, Sharma R, Bhargava B, Irfan M. 2022. Understanding plant stress memory response for abiotic stress resilience: Molecular insights and prospects. Plant Physiol Biochem, 179: 10-24.
[74]	Shasmita B B S, Mohapatra P K, Naik S K, Mukherjee A K. 2022. Biopriming for induction of disease resistance against pathogens in rice. Planta, 255(6): 113. PMID
[75]	Shukla A K, Yadav A K. 2017. Response of PGRS on growth, biochemical changes and yield of rice (Oryza sativa L.) under sodic soil. Trends Biosci, 10(34): 7297-7300.
[76]	Sun T, Du Z Y, Zhang R Z, Meng F X, Yang J, Ma J Y. 2004. Effect of salinity-alkalinity stress on tillering and yield of rice. J Jilin Agric Univ, 28(6): 597-605. (in Chinese with English abstract)
[77]	Wang C Y, Wu Z J, Shi Y I, Wang R Y. 2004. The resource of saline soil in the Northeast China. Chin J Soil Sci, 35: 643-647. (in Chinese with English abstract)
[78]	Wang L, Seki K, Miyazaki T, Ishihama Y. 2009. The causes of soil alkalinization in the Songnen Plain of Northeast China. Paddy Water Environ, 7(3): 259-270.
[79]	Wang Z C, Li Q S, Li X J, Song C C, Zhang G X. 2003a. Sustainable agriculture development in saline-alkali soil area of Songnen Plain, Northeast China. Chin Geogr Sci, 13(2): 171-174.
[80]	Wang Z C, Sun C Z, Li X J, Shao X W. 2003b. Integrated technique model of rice production on saline-alkali land. Syst Sci Comp Stud Agric, 1: 56-59.
[81]	Wei L X, Lv B S, Wang M M, Ma H Y, Yang H Y, Liu X L, Jiang C J, Liang Z W. 2015. Priming effect of abscisic acid on alkaline stress tolerance in rice (Oryza sativa L.) seedlings. Plant Physiol Biochem, 90: 50-57.
[82]	Wei L X, Lv B S, Li X W, Wang M M, Ma H Y, Yang H Y, Yang R F, Piao Z Z, Wang Z H, Lou J H, Jiang C J, Liang Z W. 2017. Priming of rice (Oryza sativa L.) seedlings with abscisic acid enhances seedling survival, plant growth, and grain yield in saline-alkaline paddy fields. Field Crops Res, 203: 86-93.
[83]	Wicke B, Smeets E, Dornburg V, Vashev B, Gaiser T, Turkenburg W, Faaij A. 2011. The global technical and economic potential of bioenergy from salt-affected soils. Energy Environ Sci, 4(8): 2669-2681.
[84]	Willems P, Mhamdi A, Stael S, Storme V, Kerchev P, Noctor G, Gevaert K,van Breusegem F. 2016. The ROS wheel: Refining ROS transcriptional footprints. Plant Physiol, 171(3): 1720-1733. PMID
[85]	Xia J B, Ren J Y, Zhang S Y, Wang Y H, Fang Y. 2019. Forest and grass composite patterns improve the soil quality in the coastal saline-alkali land of the Yellow River Delta, China. Geoderma, 349: 25-35.
[86]	Xiu L N. 2000. The alkili-saline land and agricultural sustainable development of the western Songnen Plain in China. Sci Geogr Sin, 1: 008.
[87]	Yang C W, Shi D C, Wang D L. 2008. Comparative effects of salt and alkali stresses on growth, osmotic adjustment and ionic balance of an alkali-resistant halophyte Suaeda glauca (Bge.). Plant Growth Regul, 56(2): 179-190.
[88]	Yin H N, Tang Z, Lu F. 2003. Analysis of eco-environment degradation mechanism in the west of Northeast Plain in China during the last 100 years. Res Soil Water Conserv, 10(4): 190-192.
[89]	Yu S X, Feng Q N, Xie H T, Li S, Zhang Y. 2017. Reactive oxygen species mediate tapetal programmed cell death in tobacco and tomato. BMC Plant Biol, 17(1): 76.
[90]	Zhang H, Liu X L, Zhang R X, Yuan H Y, Wang M M, Yang H Y, Ma H Y, Liu D, Jiang C J, Liang Z W. 2017. Root damage under alkaline stress is associated with reactive oxygen species accumulation in rice (Oryza sativa L.). Front Plant Sci, 8: 1580. PMID
[91]	Zhang X G, Huang B, Liang Z W, Zhao Y C, Sun W X, Hui W Y. 2013. Study on salinization characteristics of surface soil in western Songnen Plain. Soils, 45(2): 332-338. (in Chinese with English abstract)
[92]	Zhao G C, Qi C Y, Hou L G, Ma W, Sui P J, Liu L, Guo X M, Sun H J. 2012. Progress and prospect of rice production in Jilin Province at soda saline-alkaline land. J Shenyang Agric Univ, 43(6): 673-680. (in Chinese with English abstract)

Priming agent	Priming method	Stress type	Cellular and physiological response	Growth response	Reference
ABA (10 or 50 μmol/L)	Root drenching of seedlings, 1 d	Alkali (15 mmol/L NaCO₃, pH 10.87)	Increase SOD, CAT, APX and POD activities, RWC, and stress-related gene expression; reduce Na⁺/K⁺ ratio, O₂·̄ and H₂O₂ contents, and membrane injury	Increase seedling survival rate and growth	Wei et al, 2015; Liu et al, 2019
ABA (1 or 10 μmol/L)	Root drenching of seedlings, 1 d	SA fields (pH 9.74-10.13, EC_1:5 0.48-0.50)	Increase ABA-responsive gene expression	Increase seedling survival rate, plant growth and grain yield	Wei et al, 2017
Salicylic acid (50 or 100 mg/L), kinetin (100 or 150 mg/L)	Seed priming, 10 h	SA soil (pH 9.3)	Increase CAT and POD activities, proline, total chlorophyll and soluble carbohydrate contents; reduce Na⁺/K⁺ ratio	Improve plant growth and grain yield	Shukla and Yadav, 2017
24-epibrassinolide (0.01 μmol/L)	Root drenching of seedlings, 30 min	Alkali (25 mmol/L NaHCO₃)	Increase SOD, CAT and APX activities; reduce O₂·̄ and H₂O₂ contents, and membrane injury	Increase seedling dry weight, root and coleoptile lengths	Sharma et al, 2019
Melatonin (200 μmol/L)	Foliar spray on seedlings, 3 d	Alkali (20 mmol/L NaHCO₃/Na₂CO₃, pH 9.55)	Increase SOD, CAT, APX and POD activities, free proline, sucrose, fructose and chlorophyll contents, and RWC; reduce O₂·̄ and H₂O₂ contents, LOX activity, and membrane injury	Reduce leaf tip wilt index; increase root/shoot ratio	Lu et al, 2022
Na₂SiO₃·9H₂O (5 or 10 mmol/L)	Seed soaking	Alkali (25 mmol/L NaCl and 25 mmol/L Na₂CO₃)	Increase SOD, CAT and POD activities, and chlorophyll content; reduce membrane injury	Improve seed germination, shoot and root dry weights	Liang X L et al, 2015
NaCl (2.5-10.0 mmol/L), H₂O₂ (1.0-10.0 μmol/L)	Root drenching of seedlings, 7 d	SA stress (50 mmol/L Na⁺, pH 8.25)	Increase SOD, CAT, APX, POD and GR activities, Fe-acquisition and SPAD; reduce root K⁺ loss, H₂O₂ content, and membrane injury	Increase leaf and root dry weights	Kamanga et al, 2022

Priming agent	Priming method	Stress type	Cellular and physiological response	Growth response	Reference
ABA (10 or 50 μmol/L)	Root drenching of seedlings, 1 d	Alkali (15 mmol/L NaCO₃, pH 10.87)	Increase SOD, CAT, APX and POD activities, RWC, and stress-related gene expression; reduce Na⁺/K⁺ ratio, O₂·̄ and H₂O₂ contents, and membrane injury	Increase seedling survival rate and growth	Wei et al, 2015; Liu et al, 2019
ABA (1 or 10 μmol/L)	Root drenching of seedlings, 1 d	SA fields (pH 9.74-10.13, EC_1:5 0.48-0.50)	Increase ABA-responsive gene expression	Increase seedling survival rate, plant growth and grain yield	Wei et al, 2017
Salicylic acid (50 or 100 mg/L), kinetin (100 or 150 mg/L)	Seed priming, 10 h	SA soil (pH 9.3)	Increase CAT and POD activities, proline, total chlorophyll and soluble carbohydrate contents; reduce Na⁺/K⁺ ratio	Improve plant growth and grain yield	Shukla and Yadav, 2017
24-epibrassinolide (0.01 μmol/L)	Root drenching of seedlings, 30 min	Alkali (25 mmol/L NaHCO₃)	Increase SOD, CAT and APX activities; reduce O₂·̄ and H₂O₂ contents, and membrane injury	Increase seedling dry weight, root and coleoptile lengths	Sharma et al, 2019
Melatonin (200 μmol/L)	Foliar spray on seedlings, 3 d	Alkali (20 mmol/L NaHCO₃/Na₂CO₃, pH 9.55)	Increase SOD, CAT, APX and POD activities, free proline, sucrose, fructose and chlorophyll contents, and RWC; reduce O₂·̄ and H₂O₂ contents, LOX activity, and membrane injury	Reduce leaf tip wilt index; increase root/shoot ratio	Lu et al, 2022
Na₂SiO₃·9H₂O (5 or 10 mmol/L)	Seed soaking	Alkali (25 mmol/L NaCl and 25 mmol/L Na₂CO₃)	Increase SOD, CAT and POD activities, and chlorophyll content; reduce membrane injury	Improve seed germination, shoot and root dry weights	Liang X L et al, 2015
NaCl (2.5-10.0 mmol/L), H₂O₂ (1.0-10.0 μmol/L)	Root drenching of seedlings, 7 d	SA stress (50 mmol/L Na⁺, pH 8.25)	Increase SOD, CAT, APX, POD and GR activities, Fe-acquisition and SPAD; reduce root K⁺ loss, H₂O₂ content, and membrane injury	Increase leaf and root dry weights	Kamanga et al, 2022