Skip to main navigation menu Skip to main content Skip to site footer
Plant Science Today (PST)

Research Articles

Vol. 13 No. 2 (2026)

Foliar potassium nutrition and water stress: Molecular and physiological adaptation mechanisms via the proline biosynthesis pathway in maize

DOI
https://doi.org/10.14719/pst.11398
Submitted
21 August 2025
Published
14-04-2026 — Updated on 21-04-2026
Versions

Abstract

A field study was conducted at the Anbar University College of Agriculture research station during the autumn season of 2024 to evaluate the effects of irrigation intervals and foliar potassium application levels on the expression of the pyrroline-5-carboxylate synthase (P5CS) gene, the activity of the pyrroline-5-carboxylate synthase enzyme, proline accumulation and selected growth and yield traits of maize. The experiment followed a split-plot arrangement within a randomized complete block design (RCBD). The results revealed that extending the irrigation interval significantly enhanced the expression of the P5CS gene, with the 15-day irrigation interval (W2) recording the highest gene expression levels. This increase in expression positively influenced the activity of the pyrroline-5-carboxylate synthase enzyme, which reached 3.383 absorbance units min-1 g-1 fresh weight. Consequently, proline accumulation increased, with an average content of 52.36 µmol g-1 fresh weight. However, prolonged irrigation intervals adversely affected most growth and yield traits. The control treatment (W0) recorded the highest averages for plant height (196.00 cm), leaf area (4780.66 cm2 plant-1), chlorophyll content (55.14 SPAD units), number of kernels per ear (361.55 kernels ear-1) and individual plant yield (126.55 g plant-1). Conversely, foliar potassium application mitigated the adverse impacts of water stress by reducing the plant’s reliance on increased proline accumulation. Foliar potassium supply suppressed the expression of the P5CS gene, leading to reduced enzymatic activity and lower proline content under high potassium level (K2), with average values of 1.353 absorbance units min-1 g-1 fresh weight and 27.67 µmol g-1 fresh weight, respectively. Moreover, the high potassium level (K2) improved several growth and yield traits, recording the highest averages for leaf area (4242.22 cm2 plant-1), chlorophyll content (49.21 SPAD units), grain number per ear (276.77 grains plant-1) and plant yield (101.88 g plant-1).

References

  1. 1. Dunn S. Zea mays L.: cultivation and uses. New York: Nova Science Publishers Inc.; 2021.
  2. 2. Ceccarelli SG, Baum SM, Udupa SM. Breeding for drought resistance in changing climate. In: Rao SC, Ryan J, editors. Dryland agriculture. Madison (WI): Crop Sci Soc Am; 2004. p. 677–90. https://doi.org/10.2135/cssaspecpub32.c11
  3. 3. Cui Y, Zhao N. Oxidative stress and change in plant metabolism of maize (Zea mays L.) growing in contaminat-ed soil with elemental sulfur and toxic effect of zinc. J Plant Physiol. 2004;8(4):112–23.
  4. 4. Al-Fahdawy HSM, Salih MS, Al-Fahdawy MIK, Al-Hadethi AAH, Al-Fahdawi OI, Abdulmajeed AH, et al. Utilisa-tion of four natural absorbents in removing heavy metals from sewage water and reducing their accumulation in maize leaves. Agric (Poľnohospodárstvo). 2024;70(2):87–96. https://doi.org/10.2478/agri-2024-0007
  5. 5. Cakmak I. The role of potassium in alleviating detrimental effects of biotic stresses in plants. J Plant Nutr Soil Sci. 2005;168:521–30. https://doi.org/10.1002/jpln.200420485
  6. 6. Elsahooki MM. Maize: its production and improvement. Baghdad: Ministry of Higher Education and Scientific Research, University of Baghdad; 1990.
  7. 7. Arab Organization for Agricultural Development. The state of Arab food security. Cairo: League of Arab States; 2023.
  8. 8. Amtmann A, Troufflard S, Armengaud P. The effect of potassium nutrition on pest and disease resistance in plants. Physiol Plant. 2008;133:682–91. https://doi.org/10.1111/j.1399-3054.2008.01075.x
  9. 9. Römheld V, Kirkby EA. Research on potassium in agriculture: needs and prospects. Plant Soil. 2010;335:155–80. https://doi.org/10.1007/s11104-010-0520-1
  10. 10. Al-Zubaidi AH, Salman KI, Al-Tamimi RAK. Origin and nature of palygorskite mineral in Iraqi soils. Iraqi J Agric Sci. 2002;33(1):31–40.
  11. 11. Cazares BX, Ortiga FA, Elens LF, Medrano RR. Drought tolerance in crop plants. Am J Plant Physiol. 2010;5(5):242–56.
  12. 12. Mishra N, Jiang C, Chen L, Paul A, Chatterjee A, Shen G. Achieving abiotic stress tolerance in plants through antioxidative defense mechanisms. Front Plant Sci. 2023;14:1110622. https://doi.org/10.3389/fpls.2023.1110622
  13. 13. Al-Fahdawy MIK, AlFahdawy HSM, Menajid MH, Al-Fahdawi OI, Abdulmajeed AH, Abdulmageed LH, et al. Ef-fect of ground application and foliar nutrition with yeast on vegetative growth characteristics of hot pepper plants Capsicum annuum L. IOP Conf Ser Earth Environ Sci. 2024;1371:052085. https://doi.org/10.1088/1755-1315/1371/5/052085
  14. 14. Livak KJ, Schmittgen TD. Analysis of relative gene expression data using real-time quantitative PCR and the 2-ΔΔCT method. Methods. 2001;25(4):402–8. https://doi.org/10.1006/meth.2001.1262
  15. 15. Parre E, De Virville JD, Cochet F, Leprince AS, Richard L, Delessert C, et al. A new method for accurately meas-uring Δ-1-pyrroline-5-carboxylate synthetase activity. Methods Mol Biol. 2010;639:189–200. https://doi.org/10.1007/978-1-60761-702-0_21
  16. 16. Bates LS, Waldren RP, Teare ID. Rapid determination of free proline for water stress studies. Plant Soil. 1973;39:205–7. https://doi.org/10.1007/BF00018060
  17. 17. McKee GW. A coefficient for computing leaf area in hybrid corn. Agron J. 1964;56:240–1. https://doi.org/10.2134/agronj1964.00021962005600020038x
  18. 18. Al-Rawi KM, AbdAl-Aziz MK. Design and analysis of agricultural experiments. Mosul: Ministry of Higher Educa-tion and Scientific Research, University of Mosul; 2000.
  19. 19. Yooyongwech S, Cha-um S, Supaibulwatana K. Proline-related gene expression and physiological changes in indica rice in response to water deficit stress. Plant Omics. 2012;5(6):597–603.
  20. 20. Soleiman V, Ahmed J, Golkar S, Sadegzadeh B. Expression profiling of PAP3, BZIP, and P5CS genes in soybean under drought stress conditions. Turk J Bot. 2015;39:952–61. https://doi.org/10.3906/bot-1505-12
  21. 21. Maghsoudi K, Emam Y, Niazi A, Pessarakli M, Arvind MJ. P5CS expression level and proline accumulation in sensitive and tolerant wheat cultivars under drought stress conditions in the presence or absence of silicon and salicylic acid. J Plant Interact. 2018;13(1):461–71. https://doi.org/10.1080/17429145.2018.1506516
  22. 22. Szepesi A, Szőllősi R. Mechanism of proline biosynthesis and role of proline metabolism enzymes under envi-ronmental stress in plants. In: Hasanuzzaman M, editor. Plant metabolites and regulation under environmen-tal stress. Amsterdam: Elsevier; 2018. p. 337–53. https://doi.org/10.1016/B978-0-12-812689-9.00017-0
  23. 23. Hua XJ, Van De Cotte B, Van Montagu M, Verbruggen N. Developmental regulation of pyrroline-5-carboxylate reductase gene expression in Arabidopsis. Plant Physiol. 1994;114(4):1215–24. https://doi.org/10.1104/pp.114.4.1215
  24. 24. Hasanuzzaman M, Bhuyan MHMB, Nahar K, Hossain S, Al Mahmud J, Masud AAC, et al. Potassium: a vital regulator of plant responses and tolerance to abiotic stresses. Agronomy. 2018;8(3):31. https://doi.org/10.3390/agronomy8030031
  25. 25. Jaleel CA, Gopi R, Sankar B, Kishorekumar A, Panneerselvam R. Studies on germination, seedling vigour, lipid peroxidation and proline metabolism in Catharanthus roseus seedlings under salt stress. S Afr J Bot. 2007;73:190–5. https://doi.org/10.1016/j.sajb.2006.11.001
  26. 26. Zadebagheri M, Azarpanah A, Javanmardi S. Proline metabolite transport: an efficient approach in corn yield improvement in response to drought conditions. Int J Farming Allied Sci. 2014;3(5):453–61.
  27. 27. Wang Y, Wu W. Potassium transport and signaling in higher plants. Annu Rev Plant Biol. 2013;64:451–76. https://doi.org/10.1146/annurev-arplant-050312-120153
  28. 28. Bradford KJ, Hsiao TC. Physiological responses to moderate water stress. In: Lange OL, Nobel PS, Osmond CB, Ziegler H, editors. Physiological plant ecology II: water relations and carbon assimilation. Berlin: Springer; 1982. p. 263–324. https://doi.org/10.1007/978-3-642-68150-9_10
  29. 29. Issa TA. Crop plant physiology. Mosul: Ministry of Higher Education and Scientific Research, University of Mo-sul; 1990.
  30. 30. Bajehbaj AA. Effects of drought stress and different densities on oil yield and biomass yield of sunflower varie-ties. Afr J Biotechnol. 2011;10(29):5608–13.
  31. 31. Mojaddam M, Lack S, Shokuhfar A. Effect of irrigation ending date on physiological growth parameters and yields of sunflower hybrids. Environ Biol. 2012;6(1):33–41.
  32. 32. Oraki H, Khajani FP, Khana MA. Effect of water deficit stress on proline contents, soluble sugars, chlorophyll and grain yield of sunflower (Helianthus annuus L.) hybrids. Afr J Biotechnol. 2012;11(1):164–8. https://doi.org/10.5897/AJB11.619
  33. 33. Al-Asadi QTY. Tolerance of maize genotypes to water stress as influenced by proline [dissertation]. Karbala: University of Karbala; 2015.
  34. 34. Sadiq SA, Shahid M, Jan A, Nooruldin S. Effect of various levels of nitrogen, phosphorus and potassium (NPK) on growth, yield and yield components of sunflower. J Agric Soil. 2000;5(1):30–6. https://doi.org/10.3923/pjbs.2000.338.339
  35. 35. Yi L, Shenjiao Y, Shiqing L, Xinping C, Fang C. Growth and development of maize (Zea mays L.) in response to different field water management practices: resource capture and use efficiency. Agric For Meteorol. 2010;150:606–13. https://doi.org/10.3923/pjbs.2000.338.339
  36. 36. Ebrahimian E, Bybordi A. Effect of iron foliar fertilization on growth, seed and oil yield of sunflower grown un-der different irrigation regimes. Middle East J Sci Res. 2011;9(5):621–7.
  37. 37. Header HE. Effect of potassium nutrition on sink intensity and duration. Hanover: Agricultural Research Sta-tion; 1980.
  38. 38. Abu Dhahi YM, Al-Younis MA. Plant nutrition guide. Baghdad: Ministry of Higher Education and Scientific Re-search, University of Baghdad; 1988.
  39. 39. Levitt J. Responses of plants to environmental stress. 2nd ed. Vol. 2. New York: Academic Press; 1980.
  40. 40. Karron MG, Maranville JW. Response of wheat cultivars to different soil nitrogen and moisture regimes. I. Dry matter partitioning and root growth. J Plant Nutr. 1994;17:729–44. https://doi.org/10.1080/01904169409364763
  41. 41. Yue G, Zhuang Y, Li Z, Sun L, Zhang J. Differential gene expression analysis of maize leaf at heading stage in re-sponse to water-deficit stress. Biosci Rep. 2008;28:125–34. https://doi.org/10.1042/BSR20070023
  42. 42. Al-Amiri AA. Effect of some potassium sources, levels, and split application on the growth and yield of maize (Zea mays L.) [master’s thesis]. Baghdad: University of Baghdad; 2005.
  43. 43. Al-Zubaidi BMJ. Effect of organic and potassium fertilizers on potassium availability, growth, and yield of maize (Zea mays L.) [master’s thesis]. Baghdad: University of Baghdad; 2010.
  44. 44. Zinselmeier C, Westgate ME, Schussler JR, Jones RJ. Low water potential disrupts carbohydrate metabolism in maize (Zea mays L.) ovaries. Plant Physiol. 1995;107:385–91. https://doi.org/10.1104/pp.107.2.385
  45. 45. Hadi H, Khazaei F, Babaei N, Daneshian J, Hamidi A. Evaluation of water deficit on seed size and seedling growth of sunflower cultivars. Int J Agric Sci. 2012;2(3):280–90.
  46. 46. Al-Zubaie ARAH. Effect of potassium fertilization and copper foliar application on the uptake of some nutri-ents, growth, and yield of maize (Zea mays L.) [master’s thesis]. Baghdad: University of Baghdad; 2008.
  47. 47. Daneshian J, Kheybari M. Effect of water deficit stress on head characteristics of sunflower hybrids. Int J Agric Res Rev. 2013;3(4):917–22.
  48. 48. Malik MA, Saleem MF, Rehman A. Suitable level of N, P and K for harvesting the maximum returns of sun-flower (Helianthus annuus L.). Int J Agric Biol. 2004;6(2):240–2.

Downloads

Download data is not yet available.