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Plant Science Today (PST)

Research Articles

Vol. 13 No. 2 (2026)

The role of amino acids glycine and phenylalanine in some physiological characteristics of guava seedlings newly introduced to Iraq

DOI
https://doi.org/10.14719/pst.11732
Submitted
10 September 2025
Published
14-04-2026 — Updated on 21-04-2026
Versions

Abstract

This work uses environmentally acceptable amino acids as biomolecules to support important physiological processes and increase tolerance to biotic and abiotic environmental challenges in recently imported Psidium guajava L. in Iraq. Some amino acids affect the later growth of guava seedlings in a new environment. A fully randomized block design factorial experiment on guava seedlings examined the effects of glycine and phenylalanine at three concentrations each (0, 250 and 500 mg L-1 for glycine and 0, 150 and 300 mg L-1 for phenylalanine). Combining glycine (500 mg L-1) with phenylalanine (300 mg L-1) resulted in significant increases in all guava seedling parameters, surpassing their individual effects. These gains included increased leaf chlorophyll, carbohydrate content and decreased nutrient leaching. The results show that foliar spraying with glycine and phenylalanine improved the physiological and phenological features of guava seedlings. The study found that foliar spraying with glycine and phenylalanine improved guava seedling development, productivity and quality in Iraq.

References

  1. 1. Omayio DG, Abong GO, Okoth MW, Gachuiri CK, Mwang'ombe AW. Current status of guava (Psidium guajava L.) production, utilization, processing and preservation in Kenya: A review. Curr Agric Res J. 2019;7(3). https://doi.org/10.12944/CARJ.7.3.07
  2. 2. Sun W, Shahrajabian MH, Kuang Y, Wang N. Amino acids biostimulants and protein hydrolysates in agricultural sciences. Plants. 2024;13(2):210. https://doi.org/10.3390/plants13020210
  3. 3. Henderson BC, Sanderson JM, Fowles AA. A review of the foliar application of individual amino acids as biostimulants in plants. Discov Agric. 2025;3(1):69. https://doi.org/10.1007/s44279-025-00222-7
  4. 4. Abdelkader M, Voronina L, Baratova L, Shelepova O, Zargar M, Puchkov M, et al. Biostimulants-based amino acids augment physio-biochemical responses and promote salinity tolerance of lettuce plants (Lactuca sativa L.). Horticulturae. 2023;9(7):807. https://doi.org/10.3390/horticulturae9070807
  5. 5. Shan T, Jin P, Zhang Y, Huang Y, Wang X, Zheng Y. Exogenous glycine betaine treatment enhances chilling tolerance of peach fruit during cold storage. Postharvest Biol Technol. 2016;114:104–10. https://doi.org/10.1016/j.postharvbio.2015.12.005
  6. 6. Jiang J, Fan X, Zhang Y, Tang X, Li X, Liu C, et al. Construction of a high-density genetic map and mapping of firmness in grapes (Vitis vinifera L.) based on whole-genome resequencing. Int J Mol Sci. 2020;21(3):797. https://doi.org/10.3390/ijms21030797
  7. 7. Ashraf MFMR, Foolad MR. Roles of glycine betaine and proline in improving plant abiotic stress resistance. Environ Exp Bot. 2007;59(2):206–16. https://doi.org/10.1016/j.envexpbot.2005.12.006
  8. 8. Teixeira WF, Fagan EB, Soares LH, Umburanas RC, Reichardt K, Neto DD. Foliar and seed application of amino acids affects the antioxidant metabolism of the soybean crop. Front Plant Sci. 2017;8:327. https://doi.org/10.3389/fpls.2017.00327
  9. 9. Samani MR, Abdollah GP, Fariborz M, Ahmad RG. L-Phenylalanine and bio-fertilizers interaction effects on growth, yield and chemical compositions and content of essential oil from the sage (Salvia officinalis L.) leaves. Ind Crops Prod. 2019;137:1–8. https://doi.org/10.1016/j.indcrop.2019.05.019
  10. 10. Ramzan T, Shahbaz M, Maqsood MF, Zulfiqar U, Saman RU, Lili N, et al. Phenylalanine supply alleviates drought stress in mustard (Brassica campestris) by modulating plant growth, photosynthesis, and antioxidant defense system. Plant Physiol Biochem. 2023;201:107828. https://doi.org/10.1016/j.plaphy.2023.107828
  11. 11. Kanbargi KD, Sonawane SK, Arya SS. Encapsulation characteristics of protein hydrolysate extracted from Ziziphus jujube seed. Int J Food Prop. 2017;20:3215–22. https://doi.org/10.1080/10942912.2017.1282516
  12. 12. Ehret DL, Redmann RE, Harvey BL, Cipywnyk A. Salinity-induced calcium deficiencies in wheat and barley. Plant Soil. 1990;128:143–51. https://doi.org/10.1007/BF00011103
  13. 13. Zaehringer MV, Davis KR, Dean LL. Persistent-green color snap beans (Phaseolus vulgaris L.): Color-related constituents and quality of cooked fresh beans. J Am Soc Hortic Sci. 1974;99(1):89–92. https://doi.org/10.21273/JASHS.99.1.89
  14. 14. Siddique MRB, Hamid A, Islam MS. Drought stress effects on water relations of wheat. Bot Bull Acad Sin. 2000;41(1):35–39.
  15. 15. Noroozlo YA, Souri MK, Delshad M. Stimulation effects of foliar applied glycine and glutamine amino acids on lettuce growth. Open Agric. 2019;4:164–72. https://doi.org/10.1515/opag-2019-0016
  16. 16. Mohammadipour N, Souri MK. Beneficial effects of glycine on growth and leaf nutrient concentrations of coriander (Coriandrum sativum) plants. J Plant Nutr. 2019;42:1637–44. https://doi.org/10.1080/01904167.2019.1628985
  17. 17. D’Mello J. Delivering innovative solutions and paradigms for a changing environment. In: Amino Acids in Higher Plants. Wallingford (UK): CAB Int.; 2015. p. 538–83. https://doi.org/10.1079/9781780642635.0538
  18. 18. Xiaochuang C, Chu Z, Lianfeng Z, Junhua Z, Hussain S, Lianghuan W, et al. Glycine increases cold tolerance in rice via regulation of N uptake, physiological characteristics and photosynthesis. Plant Physiol Biochem. 2017;112:251–60. https://doi.org/10.1016/j.plaphy.2017.01.008
  19. 19. Ma Q, Cao X, Wu L, Mi W, Feng Y. Light intensity affects the uptake and metabolism of glycine by pakchoi (Brassica chinensis L.). Sci Rep. 2016;6:21200. https://doi.org/10.1038/srep21200
  20. 20. El-Sayed AFM. Is dietary taurine supplementation beneficial for farmed fish and shrimp? A comprehensive review. Rev Aquac. 2014;6:241–55. https://doi.org/10.1111/raq.12042
  21. 21. Mosa WF, Ali HM, Abdelsalam NR. The utilization of tryptophan and glycine amino acids as safe alternatives to chemical fertilizers in apple orchards. Environ Sci Pollut Res. 2021;28:1983–91. https://doi.org/10.1007/s11356-020-10658-7
  22. 22. Souri MK, Hatamian M. Aminochelates in plant nutrition: A review. J Plant Nutr. 2015;42:67–78. https://doi.org/10.1080/01904167.2018.1549671
  23. 23. Souri MK, Naiji M, Kianmehr MH. Nitrogen release dynamics of a slow-release urea pellet and its effect on growth, yield, and nutrient uptake of sweet basil (Ocimum basilicum L.). J Plant Nutr. 2019;42:604–14. https://doi.org/10.1080/01904167.2019.1568460
  24. 24. Adams ZP, Ehlting J, Edwards R. The regulatory role of shikimate in plant phenylalanine metabolism. J Theor Biol. 2019;462:158–70. https://doi.org/10.1016/j.jtbi.2018.11.005
  25. 25. Teixeira WF, Soares LH, Fagan EB, Mello SC, Reichardt K, Dourado-Neto D. Amino acids as stress reducers in soybean plant growth under different water-deficit conditions. J Plant Growth Regul. 2019;38:1–15. https://doi.org/10.1007/s00344-019-10032-z
  26. 26. Almas HI, Zaib-un-Nisa, Sumera A, Abida K, Fozia F, Muneeb M, et al. Exogenous application of methionine and phenylalanine confers salinity tolerance in tomato by concerted regulation of metabolites and antioxidants. J Soil Sci Plant Nutr. 2021;21:3051–64. https://doi.org/10.1007/s42729-021-00588-9
  27. 27. Marium A, Abida K, Muhammad YA, Hina K, Zill-i-Huma N. Enhancement in biomass and nutrients uptake in cucumber through methionine and phenylalanine under saline soils. Pak J Agric Sci. 2021;58(1):125–34.
  28. 28. Gonzalez-Morales S, Solis-Gaona S, Valdes-Caballero MV, Juarez-Maldonado A, Loredo-Trevino A, Benavides-Mendoza A. Transcriptomics of biostimulation of plants under abiotic stress. Front Genet. 2021;12:36. https://doi.org/10.3389/fgene.2021.583888

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