Saad Ali Hussein Al-Akabi (1), Tahseen Ali Ibrahim AL-Abtan (2), Amjad Shaker Hamoud Al-Bawi (3), Enas Saad Sobeih (4)
General Background: Maize (Zea mays L.) is one of the world’s most important cereal crops, serving as a key food, feed, and industrial raw material. In Iraq, maize productivity remains below the global average due to nutrient imbalances and suboptimal fertilization practices. Specific Background: Potassium plays a crucial physiological role in plant growth, yet its availability is limited in many Iraqi soils. Additionally, humic acid, when applied as a foliar spray, enhances nutrient absorption and photosynthetic efficiency. Knowledge Gap: Limited studies have explored the interactive effects of potassium fertilization and foliar-applied humic acid on maize vegetative growth under Iraqi soil conditions. Aims: This study aimed to evaluate the response of maize (cv. 5018) vegetative traits to different levels of potassium (120 and 140 kg ha⁻¹) and humic acid (3 and 4 ml L⁻¹) applied through foliar feeding. Results: The results showed that 120 kg ha⁻¹ potassium significantly enhanced plant height (249.50 cm), stem diameter (2.38 cm), number of leaves (15.64 plant⁻¹), and dry weight (182.94 g). Foliar application of humic acid at 4 ml L⁻¹ further improved stem diameter and leaf number. Novelty: This research highlights the synergistic potential of potassium and humic acid in optimizing maize vegetative performance in potassium-limited soils. Implications: The findings provide a practical basis for refining fertilization strategies to enhance maize productivity in similar agroecological regions.Highlight :
Potassium levels of 120 and 140 kg ha⁻¹ increased plant height and stem diameter.
Humic acid at 3 and 4 ml L⁻¹ improved stem diameter and number of leaves.
Combined potassium and humic treatments enhanced overall vegetative growth.
Keywords : Maize, Potassium, Foliar Feeding, Humic Acid, Growth Traits
Food and Agriculture Organization (FAO), Food and Agriculture Organization Outlook. Rome, Italy: FAO, 2013, p. 106. [Online]. Available: [https://www.fao.org](https://www.fao.org)
M. A. A. Bukhsh, H. A. R. Ahmad, A. U. Malik, S. Hussain, and M. Ishaque, “Agro-Physiological Traits of Three Maize Hybrids as Influenced by Varying Potassium Application,” Life Science International Journal, vol. 4, pp. 1487–1496, 2010.
M. M. Al-Sahoki, Guidelines for Growing Yellow Corn. Baghdad, Iraq: Ministry of Agriculture, General Authority for Agricultural Guidance and Cooperation, 2011.
S. Kim and B. E. Dale, “Global Potential Bioethanol Production from Wasted Crops and Crop Residues,” Biomass and Bioenergy, vol. 26, no. 4, pp. 361–375, 2004, doi: 10.1016/S0961-9534(03)00123-6.
A. A. Mudhahi, B. H. Hamid, and A. M. Fares, “Self-Sufficiency and Food Deficit of Major Cereal Crops in Some Arab Countries for the Period 2005–2015,” Iraqi Journal of Agricultural Sciences, vol. 43, pp. 130–146, 2012.
F. M. M. Al-Tahir, “The Effect of Foliar Feeding with Iron, Zinc and Potassium on the Growth and Yield of Wheat,” Ph.D. dissertation, College of Agriculture, University of Baghdad, Baghdad, Iraq, 2005.
O. A. A. Al-Samarrai, “Potassium Status and Behavior in Protected Agricultural Soils,” Ph.D. dissertation, Dept. of Soil Sciences, College of Agriculture, University of Baghdad, Baghdad, Iraq, 2005.
F. H. Al-Sahaf, Applied Plant Nutrition. Baghdad, Iraq: Dar Al-Hikma Press, Ministry of Higher Education and Scientific Research, University of Baghdad, 1989.
A. D. Peuke, W. D. Jeschke, and W. Hartung, “Foliar Application of Nitrate or Ammonium as Sole Nitrogen Supply in Ricinus communis. II. The Flow of Cations, Chloride and Abscisic Acid,” New Phytologist, vol. 140, no. 4, pp. 625–636, 1998, doi: 10.1046/j.1469-8137.1998.00312.x.
S. A. N. A. Al-Naimi, Fertilizers and Soil Fertility. Mosul, Iraq: Dar Al-Kutub for Printing and Publishing, Ministry of Higher Education and Scientific Research, University of Mosul, 1999.
A. M. L. Al-Maamouri, “Effect of Spraying Liquid Fertilizer and Boron on the Growth of Yellow Corn,” Ph.D. dissertation, College of Agriculture, University of Baghdad, Baghdad, Iraq, 1997.
M. M. Al-Sahoki and K. M. Wahib, Applications in Designing and Analyzing Experiments. Baghdad, Iraq: Ministry of Higher Education and Scientific Research, University of Baghdad, 1990.
I. A. Hamid and L. Adra, “Effect of Plant Density and Nitrogen Fertilization on Some Growth Indicators of Yellow Corn (Hybrid Basil 2) and Productivity,” Damascus University Journal of Agricultural Sciences, vol. 27, pp. 65–81, 2011.
International Potash Institute (IPI), Potassium Increases Salinity Tolerance. Bern, Switzerland: IPI, 2000. [Online]. Available: [https://www.ipipotash.org](https://www.ipipotash.org)
F. Y. Baktash and K. M. Wahib, “Response of Yellow Corn to Levels of Nitrogen Fertilizer and Plant Densities,” Iraqi Journal of Agricultural Sciences, vol. 23, pp. 85–96, 2004.
H. Marschner, Mineral Nutrition of Higher Plants, 2nd ed. London, U.K.: Academic Press, 1995, pp. 436–460.
S. Haddad, H. Obaid, and L. Raad, Plant Physiology (Practical Part). Damascus, Syria: Faculty of Agricultural Engineering, Damascus University Publications, 2008.
N. Rafat, M. Yarnia, and D. H. Panah, “Effect of Drought Stress and Potassium Humate Application on Grain Yield Related Traits of Corn (CV.604),” Journal of Food, Agriculture and Environment, vol. 10, no. 2, pp. 580–584, 2012.
M. A. Hamza and S. H. Kazim, “Effect of Foliar Feeding with Youngerin Fertilizer on Some Growth Characteristics of Yellow Corn (Zea mays L.),” Technical Journal, vol. 23, pp. 178–184, 2010.
S. T. El-Emam and B. A. El-Ahmar, “Effect of NK Levels on Some Economic Characters of Sesame and Safflower,” Newsletter of Agricultural Research, vol. 18, pp. 101–107, 2003.
Y. Wang and J. Li, “Molecular Basis of Plant Architecture,” Annual Review of Plant Biology, vol. 59, pp. 253–279, 2008, doi: 10.1146/annurev.arplant.59.032607.092902.
J. R. Heckman and E. J. Kamprath, “Potassium Accumulation and Corn Yield Related to Potassium Fertilizer Rate and Placement,” Soil Science Society of America Journal, vol. 56, no. 1, pp. 141–148, 1995, doi: 10.2136/sssaj1992.03615995005600010022x.
J. M. Lashbini, Green Fodder Cultivation and Production Techniques. Cairo, Egypt: Egyptian Library for Publishing and Distribution, 2011.
E. Sarepoua, R. Tangwongchai, B. Suriharn, and K. Lertrat, “Relationships Between Phytochemicals and Antioxidant Activity in Corn Silk,” International Food Research Journal, vol. 20, no. 5, pp. 2073–2079, 2013.
I. Cakmak, “The Role of Potassium in Alleviating Detrimental Effect of Abiotic Stresses in Plants,” Journal of Plant Nutrition and Soil Science, vol. 168, no. 4, pp. 521–530, 2005, doi: 10.1002/jpln.200420485.
E. A. Lee and M. Tollenaar, “Physiological Basis of Successful Breeding Strategies for Maize Grain Yield,” Crop Science, vol. 47, no. S3, pp. S202–S215, 2007, doi: 10.2135/cropsci2007.04.0010IPBS.
T. A. Issa, Planting and Growth of Crops [Translator]. Baghdad, Iraq: Ministry of Higher Education and Scientific Research, University of Baghdad, 1984.
M. H. Hussein and K. M. Rabie, “Effect of Spraying Some Nutrients on the Growth and Yield of Peas (Pisum sativum L.),” Diyala Journal of Humanities Research, vol. 3, no. 16, pp. 39–47, 2009.
B. H. Hadi and K. M. Wahib, “Inheritance and Genetic Acquisition in Yellow Corn,” Anbar Journal of Agricultural Sciences, vol. 1, pp. 96–107, 2010.