Current IssueSpecial IssueEditorial BoardOnline First ArticlesArchive
Current IssueSpecial IssueEditorial BoardOnline First ArticlesArchive

ABSTRACT

Background: The study was designed to enhance the growth and biochemical composition of the saplings, therefore accelerating their attainment of optimal growth for transplantation to their permanent sites.

Methods: A factorial experiment was performed using an RCBD with 12 treatments and three replications. A total of 108 apple saplings cv. Sharabi were used. The effects of poultry manure and CPPU were assessed on vegetative and root growth, leaf area, total chlorophyll and leaf P, K, Ca and Mg contents.

Result: The results revealed that the addition of processed poultry waste significantly affected all characteristics with the high level (150 g pot-1) exhibited superior values for all traits. Conversely, applying the growth regulator CPPU through spraying had a significant impact on all characteristics, with treatment (9 mg L-1) achieving the best significant effect for all traits. The interaction between the two investigated factors exerted a significant effect on all evaluated parameters, with the exception of leaf phosphorus content. Notably, the (150 g pot-1 + 9 mg L-1) treatment combination yielded the optimal values across all assessed traits, whereas the minimum values were consistently recorded under the control treatment.

INTRODUCTION

Organic agriculture has attracted increasing interest as an approach to improving agricultural sustainability through organic nutrient sources and practices that support soil fertility, biological activity and nutrient cycling (Meshram et al., 2026). The effectiveness of organic amendments depends on their quality, application rate and compatibility with crop requirements (Shobo et al., 2025). Poultry manure supplies organic matter and mineral nutrients, supporting plant nutrition and improving growing-medium conditions (Azuka and Idu, 2022). Its agricultural performance depends on storage conditions, application rate and frequency (Akintoye et al., 2026). Application strategies should therefore be adapted to the crop and production system. Studies on fruit seedlings demonstrate both the potential of poultry manure and the variability of plant responses. In mango, poultry manure combined with oil palm bunch ash produced the strongest overall response, improving plant height, stem girth, leaf number, root length and mineral nutrition compared with mineral fertilization. However, these benefits reflect the combined amendments rather than poultry manure alone (Moyin-Jesu and Adeofun, 2008). In papaya, poultry manure mixed with decomposed buriti stem increased seedling height, leaf area, leaf number and shoot dry matter compared with soil alone. Root responses varied with mixture proportions and increasing the organic formulation did not consistently improve growth, emphasizing the importance of substrate composition (Sousa et al., 2019). In apple seedlings grown in saline-alkali soil, chicken manure combined with microbial fertilizer produced the highest root activity at 75 g manure kg-1 soil and the highest leaf SPAD value at 100 g kg-1 after 120 days. It also reduced soil salt content, pH and bulk density, while leaf area remained statistically unchanged (Miao et al., 2022). These findings support poultry manure use in fruit nurseries but show that responses depend on application rate, substrate composition, plant material and growing conditions. Therefore, evaluating processed poultry manure rates for apple saplings under local nursery conditions is necessary to guide appropriate fertilization practices.
       
Plant growth regulators are used in agricultural production to promote vegetative growth and improve specific yield-related and postharvest attributes, including increased fruit size, reduced fruit drop and extended shelf life, depending on the regulator and its application conditions (Yirmibeş et al., 2025). One of these regulators is forchlorfenuron [N-(2-chloro-4-pyridyl)-N¢-phenylurea; CPPU], it is known for its ability to resist fast metabolism, resulting in a prolonged period of effectiveness. Its physiological activity is represented by stimulating cell division and increasing cell expansion (Chawla et al., 2025). It also disrupts apical dominance and encourages the development of lateral shoots (Oshchepkov et al., 2020), besides enhancing the quality and quantity of numerous horticultural crops (Hussein et al., 2022). Previous studies have investigated chicken manure application in Fig (Shamsuddin et al., 2020) and foliar bioregulators, including CPPU, in gladiolus (Padmalatha et al., 2013). Although poultry manure and CPPU have been investigated individually in horticultural crops, their combined effects on nursery-grown apple saplings remain insufficiently understood. Specifically, it is unclear whether the response of ‘Sharabi’ apple saplings to CPPU varies with the application rate of processed poultry manure. Clarifying this interaction is necessary to identify combinations that support sapling growth and mineral nutrition under local nursery conditions. Therefore, this study evaluated three rates of processed poultry manure and four CPPU concentrations in a factorial experiment to determine their individual and interaction effects on leaf area, total chlorophyll content and leaf phosphorus, potassium, calcium and magnesium contents.

MATERIALS AND METHODS

Experimental site and plant material
 
The experiment was conducted during the 2026 growing season in the lath house of the Department of Horticulture and Landscape Gardening, College of Agriculture, University of Anbar, Iraq, using apple saplings cv. Sharabi grafted onto quince rootstock. The effects of processed poultry manure and foliar forchlorfenuron (CPPU) application were evaluated by measuring leaf area, total chlorophyll content and leaf mineral composition. All saplings received the same management practices, including drip irrigation and pest control. Before treatment application, samples of the growing medium were collected to determine its physical and chemical properties (Table 1).

Table 1: Some chemical and physical traits of the soil.


 
Experimental treatments
 
Two factors were evaluated. The first factor was processed poultry manure applied at three rates: 0 (P0), 75 (P1) and 150 g pot-1 (P2). The manure was incorporated into the growing medium once, on 10 March 2026. The control treatment received no poultry manure. According to the manufacturer (Reefco), the product contained 15-20% moisture, 70-75% organic matter, 2-3% total nitrogen, 1.5-2% total phosphorus, 2.5-3% total potassium, 3-4% calcium and 3% magnesium, with a pH of 7-8. These values represent the manufacturer’s specifications. The second factor was foliar CPPU application at four concentrations: 0 (C0), 3 (C1), 6 (C2) and 9 mg L-1 (C3). Applications were conducted on 10 April, 10 May and 10 June 2026.
 
Experimental design and statistical analysis
 
The experiment was arranged as a 3 x 4 factorial in a randomized complete block design (RCBD) with three blocks. Each block contained all 12 treatment combinations, randomly assigned to experimental units. Each experimental unit comprised three saplings, giving 36 experimental units and 108 saplings in total. Data were analyzed using analysis of variance appropriate for a factorial RCBD in Genstat. The analysis evaluated the effects of poultry manure, CPPU and their interaction while accounting for block effects. Means were compared using the least significant difference (LSD) test at the 5% significance level (Al-Mohammadi and Al-Mohammadi, 2012). In the figures, P denotes the processed poultry manure factor and C denotes the CPPU foliar application factor. LSD0.05 represents the least significant difference at the 5% significance level; values reported for P and C apply to comparisons among the respective main-effect means.
 
Studied traits
 
On 10 July 2026, fully expanded leaf samples were randomly collected from the middle parts of the branches. The following measurements were conducted (Leaf area, total chlorophyll, percentage of phosphorus, potassium, calcium and magnesium content of the leaves). All chemical analyses were performed at the Central Laboratory of the College of Agriculture, University of Anbar.

RESULTS AND DISCUSSION

Leaf area (cm²)
 
Processed poultry manure application significantly affected leaf area (Fig 1). Compared with P0 (20.01 cm2), P1 increased leaf area to 21.55 cm2, but this difference was not significant). In contrast, P2 significantly increased leaf area to 23.94 cm2. For CPPU, C1 produced a leaf area of 19.94 cm2, which did not differ significantly from C0 (19.59 cm2). However, C2 and C3 significantly increased leaf area to 23.07 and 24.72 cm2, respectively, compared with C0. The poultry manure x CPPU interaction was also significant (Table 2), with the highest leaf area recorded under P2C3 and the lowest under P0C0.

Fig 1: Effect of processed poultry waste application and CPPU foliar spray on leaf area of “Sharabi” apple saplings.



Table 2: Interactive effects of processed poultry waste application and CPPU foliar spray on some studied characteristics of “Sharabi” apple saplings.


       
P0, P1 and P2 represent processed poultry manure application rates of 0, 75 and 150 g pot-1, respectively. C0, C1, C2 and C3 represent foliar forchlorfenuron (CPPU) concentrations of 0, 3, 6 and 9 mg L-1, respectively.
       
The increase in leaf area under P2 may reflect improved nutrient supply and growing-medium conditions following processed poultry manure application. Organic amendments can improve soil physical properties, potentially providing more favorable conditions for root development and nutrient acquisition (Sruthi et al., 2025; Donbiaksiam et al., 2026). Nitrogen supplied by the manure supports amino acid and protein synthesis, as well as the cellular processes involved in leaf development and expansion (Wang et al., 2024; Zayed et al., 2023). Potassium may also contribute through its role in osmotic adjustment and the maintenance of cell turgor required for expansion (Hasanuzzaman et al., 2018). The significant increases under C2 and C3, compared with C0, are consistent with the cytokinin activity of CPPU, which can promote cell division and leaf development (Werner et al., 2001). The highest value under P2C3 suggests that adequate nutrient supply may support the leaf expansion response to CPPU, although the underlying mechanisms were not measured directly.
 
Total chlorophyll content of the leaves (mg g-1 FW)
 
Processed poultry manure significantly affected total chlorophyll content (Fig 2). Both P1 (1.28 mg g-1 FW) and P2 (1.32 mg g-1 FW) significantly increased total chlorophyll compared with P0 (1.22 mg g-1 FW). For CPPU, C1 (1.25 mg g-1 FW) did not differ significantly from C0 (1.23 mg g-1 FW), whereas C3 significantly increased total chlorophyll to 1.34 mg g-1 FW. C2 recorded 1.28 mg g-1 FW. The poultry manure x CPPU interaction was significant (Table 2), with the highest total chlorophyll content recorded under P2C3 and the lowest under P0C0.

Fig 2: Effect of processed poultry waste application and CPPU foliar spray on the total chlorophyll content of “Sharabi” apple saplings leaves.


       
The higher total chlorophyll content under P1 and P2 may be associated with the nutritional contribution of processed poultry manure, particularly its nitrogen and magnesium contents. Nitrogen supports chlorophyll synthesis and the formation of proteins involved in the photosynthetic apparatus (Fathi, 2022), while magnesium contributes to chlorophyll structure and the activation of enzymes involved in photosynthetic metabolism (Senbayram et al., 2015). The significant increase under C3 may reflect the influence of CPPU on chloroplast development and the maintenance of leaf chlorophyll, consistent with the physiological functions of cytokinins (Sakakibara et al., 2006). Cytokinin-related regulation of nucleic acid and protein synthesis may also support these processes (Smith et al., 2017). The highest chlorophyll content under P2C3 may therefore reflect complementary nutritional and growth-regulatory effects. However, increased chlorophyll content alone does not establish an increase in net photosynthetic rate.
 
Phosphorus percentage in the leaves
 
Processed poultry manure significantly affected leaf phosphorus concentration (Fig 3). Both P1 (0.42%) and P2 (0.43%) significantly increased leaf phosphorus compared with P0 (0.37%). Similarly, CPPU application significantly increased leaf phosphorus at C1 (0.41%), C2 (0.42%) and C3 (0.44%) compared with C0 (0.34%). The highest concentrations were recorded under P2 and C3 for the respective factors. However, the poultry manure x CPPU interaction was not significant (Table 2).

Fig 3: Effect of processed poultry waste application and CPPU foliar spray on the phosphorus content of “Sharabi” apple saplings leaves.


       
The significant increases in leaf phosphorus under P1 and P2 may partly result from phosphorus supplied by processed poultry manure. Organic matter decomposition may additionally modify phosphorus availability through changes in soil chemical conditions and interactions involving humic substances (Kobierski et al., 2017). Changes in rhizosphere pH could also influence nutrient availability, although their direction and magnitude depend on the amendment and soil conditions (Raghavendar, 2026). Phosphorus is involved in energy transfer and the formation of compounds essential for plant metabolism and growth (Khan et al., 2023; Al-Dulaimy and Mohammed, 2024). The higher leaf phosphorus concentrations under all CPPU treatments may be associated with cytokinin-mediated changes in nutrient allocation toward developing tissues (Davies, 2004). Nevertheless, leaf concentration measurements alone cannot distinguish increased uptake from altered internal distribution. The nonsignificant interaction indicates that a combined effect beyond the individual factor effects was not demonstrated for this trait.
 
Potassium percentage in the leaves
 
Processed poultry manure significantly affected leaf potassium concentration (Fig 4). P2 significantly increased leaf potassium to 2.04% compared with 1.89% under P0, while P1 recorded 1.97%. For CPPU, C1 (1.91%) did not differ significantly from C0 (1.84%). However, C2 (1.98%) and C3 (2.15%) significantly increased leaf potassium compared with C0. The poultry manure x CPPU interaction was significant (Table 2), with the highest leaf potassium concentration recorded under P2C3 and the lowest under P0C0.

Fig 4: Effect of processed poultry waste application and CPPU foliar spray on the potassium content of “Sharabi” apple saplings leaves.


       
The significantly higher leaf potassium concentration under P2 may be attributed partly to potassium supplied by processed poultry manure and its potential effects on nutrient availability in the growing medium (Al-Jaf  et al., 2023). Potassium supports enzyme activation, photosynthesis and carbohydrate metabolism (Rawat et al., 2022). The significant increases under C2 and C3 may reflect changes in nutrient demand and allocation associated with CPPU-induced leaf development. Greater leaf area and chlorophyll content could potentially support carbon assimilation and the metabolic processes associated with nutrient acquisition, although these processes were not directly assessed (Taiz and Zeiger, 2010). The highest potassium concentration under P2C3 suggests that the response to CPPU depended partly on manure supply. This interpretation is broadly consistent with the nutritional responses to CPPU-containing treatments reported by Mohammed and Al-Dulaimy (2023) and Al-Hameedi and Al-Tamimi (2025).
 
Calcium percentage in the leaves
 
Processed poultry manure significantly affected leaf calcium concentration (Fig 5). P1 (1.29%) did not differ significantly from P0 (1.27%), whereas P2 significantly increased leaf calcium to 1.36%. For CPPU, C1 (1.27%) did not differ significantly from C0 (1.26%), while C3 significantly increased leaf calcium to 1.38%. C2 recorded a calcium concentration of 1.32%. The poultry manure x CPPU interaction was significant (Table 2), with the highest leaf calcium concentration recorded under P2C3 and the lowest under P0C0.

Fig 5: Effect of processed poultry waste application and CPPU foliar spray on the calcium content of “Sharabi” apple saplings leaves.


       
The significant increase in leaf calcium concentration under P2 may partly reflect the calcium supplied by processed poultry manure. Calcium contributes to cell-wall structure through its association with pectic substances and supports tissue integrity during development (Kour et al., 2023). It also plays important roles in membrane stability and cellular signaling (Thor, 2019), as well as the regulation of cellular processes associated with growth (Wdowiak et al., 2024). The higher calcium concentration under C3 may reflect indirect effects of CPPU on leaf development and calcium delivery to growing tissues. However, the present measurements do not establish whether this response resulted from altered uptake, transport or tissue growth. The highest concentration under P2C3 suggests that manure supply influenced the calcium response to CPPU, consistent with the significant interaction.
 
Magnesium percentage in the Leaves
 
Processed poultry manure significantly affected leaf magnesium concentration (Fig 6). P1 (0.44%) did not differ significantly from P0 (0.42%), whereas P2 significantly increased leaf magnesium to 0.51%. For CPPU, C1 (0.45%) did not differ significantly from C0 (0.42%), while C3 significantly increased leaf magnesium to 0.50%. C2 recorded a magnesium concentration of 0.47%. The poultry manure x CPPU interaction was significant (Table 2), with the highest leaf magnesium concentration recorded under P2C2 and the lowest under P0C0.

Fig 6: Effect of processed poultry waste application and CPPU foliar spray on the magnesium content of “Sharabi” apple saplings leaves.


       
The significantly higher leaf magnesium concentration under P2 may partly result from the magnesium supplied by processed poultry manure. Magnesium supports photosynthesis and numerous enzyme reactions involved in energy metabolism (Senbayram et al., 2015). It also contributes to carbohydrate transport from source leaves to sink organs (Ferreira et al., 2023) and participates in physiological responses to abiotic stress (Ahmed et al., 2023), although stress tolerance was not evaluated in this experiment (Walaa et al., 2026). The significant increase under C3 may be associated with CPPU-related changes in leaf development and nutrient allocation. The highest magnesium concentration under P2C2, despite the highest CPPU main-effect mean occurring under C3, illustrates the importance of considering treatment combinations when interpreting the significant interaction. The beneficial nutritional response to manure application is broadly consistent with the olive studies cited by Khalil and Abdulqader (2023) and Almashhadani and Al-Hadethi (2025).

CONCLUSION

It is concluded from this study that the addition of processed poultry manure and the foliar application of the growth regulator CPPU significantly impacted the evaluated parameters of the apple saplings cv. Sharabi. Therefore, based on the study results, we recommend adding poultry manure at a level of 150 g pot-1 and foliar application with CPPU at a rate of 9 mg L-1 to improve leaf area and the chlorophyll and nutrient contents of the sapling leaves.

CONFLICT OF INTEREST

Authors have declared that there are no conflicts of interest.

REFERENCES


  1. Ahmed, N., Zhang, B., Bozdar, B., Chachar, S., Rai, M. and Li, J. (2023). The power of magnesium: Unlocking the potential for increased yield, quality and stress tolerance of horticultural crops. Frontiers in Plant Science. 14: 1285512. doi: 10.3389/fpls.2023.1285512.

  2. Akintoye, O.H., Odedina, J.N., Makinde, E.A. and Adigbo, S.O. (2026). Storage, application rate and frequency of poultry manure determine variations in soil nutrients and leafy yield of fluted pumpkin. Turkish Journal of Agriculture- Food Science and Technology. 14(6): 1673-1682. doi: 10.24925/turjaf.v14i6.1673-1682.8710.

  3. Al-Dulaimy, A.F.Z. and Mohammed, O.A.J. (2024). Response of local sweet orange transplants to spraying with micronutrients and CPPU. Anbar Journal of Agricultural Sciences. 22(2): 806-823. doi: 10.32649/ajas.2024.184460.

  4. Al-Hameedi, R.S.H. and Al-Tamimi, H.M.A. (2025). Effect of humic acid fertilization and CPPU growth regulator spray on some chemical indicators of selected citrus rootstocks. IOP Conference Series: Earth and Environmental Science. 1549: 012099. doi: 10.1088/1755-1315/1549/ 1/012099.

  5. Al-Jaf, I.H.M., Al-Hayali, R.E.Y., Al-Dulaimy, A.F.Z. and Al Miahy, F.H.R. (2023). Response of cucumber plants to the addition of animal waste and dry yeast suspension. Bionatura. 8(1): 1-5.

  6. Almashhadani, B.M.K. and Al-Hadethi, M.E.A. (2025). Effect of irrigation intervals and poultry manure in growth of olive transplants (Olea europaea L.). IOP Conference Series: Earth and Environmental Science. 1487: 012033. doi: 10.1088/1755-1315/1487/1/012033.

  7. Al-Mohammadi, S.M. and Al-Mohammadi, F.M. (2012). Statistics and Experimental Design. Osama Publishing and Distribution House, Amman, Jordan.

  8. Azuka, C.V. and Idu, M.C. (2022). Effect of organic manures application on soil physicochemical properties of coarse- textured Ultisol and okra productivity in Nsukka, Southeastern Nigeria. Agricultural Science Digest. 42(2): 145-151. doi: 10.18805/ag.D-326.

  9. Chawla, R., Guleria, T. and Thakur, A. (2025). Role of plant growth regulators in fruit crop production: A comprehensive review. Applied Fruit Science. 67: 294. doi: 10.1007/ s10341-025-01535-z.

  10. Davies, P.J. (2004). Plant Hormones: Biosynthesis, Signal Transduction, Action. 3rd ed. Kluwer Academic Publishers, Dordrecht, Boston and London.

  11. Donbiaksiam, T., Jyotsna, N., Zeshmarani, S., Singh, L.B., Hijam, C. and Singh, S.P. (2026). Effect of poultry manure compost on soil fertility and productivity within a protected cultivation environment in polyhouse condition. Indian Journal of Agricultural Research. 4(2): 1-7. doi: 10.18805/IJARe.A-6458.

  12. Fathi, A. (2022). Role of nitrogen (N) in plant growth, photosynthesis pigments and N use efficiency: A review. Agrisost. 28: 1-8. doi: 10.5281/zenodo.7143588.

  13. Ferreira, L.S., Oliveira, V.S., Marchiori, J.J.P., Ferreira, T.C., Bernabé, A.C.B. and Boone, G.T.F. (2023). The nutrient magnesium in soil and plant: A review. International Journal of Plant and Soil Science. 35(8): 136-144. doi: 10.9734/ijpss/ 2023/v35i82890.

  14. Hasanuzzaman, M., Bhuyan, M.H.M.B., Nahar, K., Hossain, M.S., Mahmud, J.A. and Hossen, M.S. (2018). Potassium: A vital regulator of plant responses and tolerance to abiotic stresses. Agronomy. 8(3): 31-60.  doi: 10.3390/agronomy 8030031.

  15. Hussein, S.A., Kanber, H.S. and Lateef, M.A. (2022). Growth regulators’ role on the growth and yield of grapes (Vitis vinifera L.): A review. European Journal of Research Development and Sustainability. 3(2): 85-88.

  16. Khalil, H.S. and Abdulqader, S.M. (2023). Effect of organic manure, biofertilizer and foliar spray of ascorbic acid on vegetative growth and fruit quality of Basheqi cv. of olive (Olea europaea L.). Kufa Journal of Agricultural Sciences. 15(2): 96-113.  doi: 10.36077/kjas/2023/v15i2.10625.

  17. Khan, F., Siddique, A.B., Shabala, S., Zhou, M. and Zhao, C. (2023). Phosphorus plays key roles in regulating plants’ physiological responses to abiotic stresses. Plants. 12(15): 2861.  doi: 10.3390/plants12152861.

  18. Kobierski, M., Bartkowiak, A., Lemanowicz, J. and Piekarczyk, M. (2017). Impact of poultry manure fertilization on chemical and biochemical properties of soils. Plant, Soil and Environment. 63: 558-563. doi: 10.17221/668/2017-PSE.

  19. Kour, J., Khanna, K., Singh, A.D., Dhiman, S., Bhardwaj, T. and Devi, K. (2023). Calcium’s multifaceted functions: From nutrient to secondary messenger during stress. South African Journal of Botany. 152: 247-263.  doi: 10.1016/ j.sajb.2022.11.048.

  20. Meshram, S., Mansor, H.B. and Adhikari, T.B. (2026). Recent advances in organic agriculture: Innovations, challenges and opportunities. Frontiers in Plant Science. 16: 1681928.  doi: 10.3389/fpls.2025.1681928.

  21. Miao, P., Li, F., Cui, G. and Wang, Z. (2022). Effects of mixed application of microbial fertilizer and chicken manure on apple seedling growth and saline-alkali soil improvement. Journal of Northern Agriculture. 50(5): 41-47. doi: 10.12190/j.issn.2096-1197.2022.05.06.

  22. Mohammed, O.A.J. and Al-Dulaimy, A.F.Z. (2023). Effect of spraying with micronutrients and CPPU on the chemical content of local orange saplings. International Journal of Agricultural and Statistical Sciences. 19(Suppl.1): 1187-1195.  doi: 10.59467/IJASS.2023.19.1187.

  23. Moyin-Jesu, E. I. and Adeofun, C. O. (2008). Comparative evaluation of different organic fertilizer on the soil fertility, leaf mineral composition and growth performance of mango seedlings (Magnifera indica L.). Emirates Journal of Food and Agriculture. 20(1): 18-30. doi: 10.9755/ejfa.v12i1.5178.

  24. Oshchepkov, M., Kalistratova, A., Savelieva, E., Romanov, G. and Bystrova, N. (2020). Natural and synthetic cytokinins and their applications in biotechnology, agrochemistry and medicine. Russian Chemical Reviews. 89: 787-810.  doi: 10.1070/RCR4921.

  25. Padmalatha, T., Satyanarayana Reddy, G., Chandrasekhar, R., Siva Shankar, A. and Chaturvedi, A. (2013). Effect of foliar sprays of bioregulators on growth and flowering in gladiolus. Indian Journal of Agricultural Research. 47(3): 192-199.

  26. Raghavendar, M. (2026). Transforming poultry manure into value: Commercial strategies for composting, bioenergy and animal nutrition. Indian Journal of Veterinary and Animal Sciences Research. 55(2): 23-33.

  27. Rawat, J., Pandey, N. and Saxena, J. (2022). Role of Potassium in Plant Photosynthesis, Transport, Growth and Yield. In Role of Potassium in Abiotic Stress. Springer, Singapore.  doi: 10.1007/978-981-16-4461-0_1.

  28. Sakakibara, H. (2006). Cytokinin activity, biosynthesis and translocation. Annual Review of Plant Biology. 57: 431-449. doi: 10.1146/annurev.arplant.57.032905.105231.

  29. Senbayram, M., Gransee, A., Wahle, V. and Thiel, H. (2015). Role of magnesium fertilisers in agriculture: Plant-soil continuum. Crop and Pasture Science. 66(12): 1219-1229. doi: 10.1071/CP15104.

  30. Shamsuddin, M.S., Rozilawati, S., Che Amri, C.N.A. and Shuhada, T.N. (2020). Yield performance of Ficus carica as affected by different rate of chicken manure. Indian Journal of Agricultural Research. 54(6): 807-810.  doi: 10.18805/IJARe.A-546.

  31. Shobo, B.A., Joseph-Adekunle, T.T., Ogunleye, M.T., Akintunde, A.O., Afodu, O.J. and Bodunde, G.J. (2025). Growth, fruit characteristics and seed yield of tomato (Lycopersicon esculentum Mill) in response to fertilizer application. Indian Journal of Agricultural Research. 59(5): 797- 801. doi: 10.18805/IJARe.AF-705.

  32. Smith, S., Li, C. and Li, J. (2017). Hormone Function in Plants. In Hormone Metabolism and Signaling in Plants. Elsevier Inc., pp. 1-38.

  33. Sousa, T.O., Fonseca, W.L., Oliveira, A.M., Zuffo, A.M., Nery, M.C., Magalhães, M.A., Sales, T.S., Fialho, C.M.T. and Alves, K.A. (2019). Development of papaya tree in organic substrates. Australian Journal of Crop Science. 13(10): 1600-1606. doi: 10.21475/ajcs.19.13.10.p1812.

  34. Sruthi, B., Singh, A.K., Ao, M. and Gadi, Y. (2025). Effect of organic manures on soybean [Glycine max (L.) Merrill] performance and soil properties in Northeast of India, Nagaland. Indian Journal of Agricultural Research. 59(9): 1476-1480. doi: 10.18805/IJARe.A-6229.

  35. Taiz, L. and Zeiger, E. (2010). Plant Physiology. 4th ed. Sinauer Associates, Sunderland, MA, USA.

  36. Thor, K. (2019). Calcium-Nutrient and messenger. Frontiers in Plant Science. 10: 440.  doi: 10.3389/fpls.2019.00440.

  37. Walaa, S.K., Ragheed, M.H.A., Basim, M.A., Idrees, H.M.S.A. and Ahmed, F.Z.A. (2026). Effect of poultry manure and spraying with urea on growth and yield parameters of local lettuce. Plant Science Today. 13(2): 1-6. doi: 10.14719/pst.14186.

  38. Wang, Q., Li, S., Li, J. and Huang, D. (2024). The utilization and roles of nitrogen in plants. Forests. 15(7): 1191. doi: 10.3390/f15071191.

  39. Wdowiak, A., Podgórska, A. and Szal, B. (2024). Calcium in plants: An important element of cell physiology and structure, signaling and stress responses. Acta Physiologiae Plantarum. 46: 108.  doi: 10.1007/s11738-024-03733-w.

  40. Werner, T., Motyka, V., Strnad, M. and Schmülling, T. (2001). Regulation of plant growth by cytokinin. Proceedings of the National Academy of Sciences of the United States of America. 98: 10487-10492.  doi: 10.1073/pnas.171304098.

  41. Yirmibeº, B., Lachin, A., Ülger, N. and Karaçam, E. (2025).  The utilization of plant growth regulators (PGRs) in agricultural application and the effecting mechanisms. Research in Agricultural Sciences. 56(2): 180-185. doi: 10.17097/ agricultureatauni.1540336.

  42. Zayed, O., Hewedy, O.A., Abdelmoteleb, A., Ali, M., Youssef, M.S. and Roumia, A.F. (2023). Nitrogen journey in plants: From uptake to metabolism, stress response and microbe interaction. Biomolecules. 13(10): 1443. doi: 10.3390/ biom13101443.
Published In
Agricultural Science Digest
Article Metrics
Metrics Icon
35
Views
0
Citations
Reviewed By
Share Article
Download Article
In this Article
    Contact us
    Follow us

    ABSTRACT

    Background: The study was designed to enhance the growth and biochemical composition of the saplings, therefore accelerating their attainment of optimal growth for transplantation to their permanent sites.

    Methods: A factorial experiment was performed using an RCBD with 12 treatments and three replications. A total of 108 apple saplings cv. Sharabi were used. The effects of poultry manure and CPPU were assessed on vegetative and root growth, leaf area, total chlorophyll and leaf P, K, Ca and Mg contents.

    Result: The results revealed that the addition of processed poultry waste significantly affected all characteristics with the high level (150 g pot-1) exhibited superior values for all traits. Conversely, applying the growth regulator CPPU through spraying had a significant impact on all characteristics, with treatment (9 mg L-1) achieving the best significant effect for all traits. The interaction between the two investigated factors exerted a significant effect on all evaluated parameters, with the exception of leaf phosphorus content. Notably, the (150 g pot-1 + 9 mg L-1) treatment combination yielded the optimal values across all assessed traits, whereas the minimum values were consistently recorded under the control treatment.

    INTRODUCTION

    Organic agriculture has attracted increasing interest as an approach to improving agricultural sustainability through organic nutrient sources and practices that support soil fertility, biological activity and nutrient cycling (Meshram et al., 2026). The effectiveness of organic amendments depends on their quality, application rate and compatibility with crop requirements (Shobo et al., 2025). Poultry manure supplies organic matter and mineral nutrients, supporting plant nutrition and improving growing-medium conditions (Azuka and Idu, 2022). Its agricultural performance depends on storage conditions, application rate and frequency (Akintoye et al., 2026). Application strategies should therefore be adapted to the crop and production system. Studies on fruit seedlings demonstrate both the potential of poultry manure and the variability of plant responses. In mango, poultry manure combined with oil palm bunch ash produced the strongest overall response, improving plant height, stem girth, leaf number, root length and mineral nutrition compared with mineral fertilization. However, these benefits reflect the combined amendments rather than poultry manure alone (Moyin-Jesu and Adeofun, 2008). In papaya, poultry manure mixed with decomposed buriti stem increased seedling height, leaf area, leaf number and shoot dry matter compared with soil alone. Root responses varied with mixture proportions and increasing the organic formulation did not consistently improve growth, emphasizing the importance of substrate composition (Sousa et al., 2019). In apple seedlings grown in saline-alkali soil, chicken manure combined with microbial fertilizer produced the highest root activity at 75 g manure kg-1 soil and the highest leaf SPAD value at 100 g kg-1 after 120 days. It also reduced soil salt content, pH and bulk density, while leaf area remained statistically unchanged (Miao et al., 2022). These findings support poultry manure use in fruit nurseries but show that responses depend on application rate, substrate composition, plant material and growing conditions. Therefore, evaluating processed poultry manure rates for apple saplings under local nursery conditions is necessary to guide appropriate fertilization practices.
           
    Plant growth regulators are used in agricultural production to promote vegetative growth and improve specific yield-related and postharvest attributes, including increased fruit size, reduced fruit drop and extended shelf life, depending on the regulator and its application conditions (Yirmibeş et al., 2025). One of these regulators is forchlorfenuron [N-(2-chloro-4-pyridyl)-N¢-phenylurea; CPPU], it is known for its ability to resist fast metabolism, resulting in a prolonged period of effectiveness. Its physiological activity is represented by stimulating cell division and increasing cell expansion (Chawla et al., 2025). It also disrupts apical dominance and encourages the development of lateral shoots (Oshchepkov et al., 2020), besides enhancing the quality and quantity of numerous horticultural crops (Hussein et al., 2022). Previous studies have investigated chicken manure application in Fig (Shamsuddin et al., 2020) and foliar bioregulators, including CPPU, in gladiolus (Padmalatha et al., 2013). Although poultry manure and CPPU have been investigated individually in horticultural crops, their combined effects on nursery-grown apple saplings remain insufficiently understood. Specifically, it is unclear whether the response of ‘Sharabi’ apple saplings to CPPU varies with the application rate of processed poultry manure. Clarifying this interaction is necessary to identify combinations that support sapling growth and mineral nutrition under local nursery conditions. Therefore, this study evaluated three rates of processed poultry manure and four CPPU concentrations in a factorial experiment to determine their individual and interaction effects on leaf area, total chlorophyll content and leaf phosphorus, potassium, calcium and magnesium contents.

    MATERIALS AND METHODS

    Experimental site and plant material
     
    The experiment was conducted during the 2026 growing season in the lath house of the Department of Horticulture and Landscape Gardening, College of Agriculture, University of Anbar, Iraq, using apple saplings cv. Sharabi grafted onto quince rootstock. The effects of processed poultry manure and foliar forchlorfenuron (CPPU) application were evaluated by measuring leaf area, total chlorophyll content and leaf mineral composition. All saplings received the same management practices, including drip irrigation and pest control. Before treatment application, samples of the growing medium were collected to determine its physical and chemical properties (Table 1).

    Table 1: Some chemical and physical traits of the soil.


     
    Experimental treatments
     
    Two factors were evaluated. The first factor was processed poultry manure applied at three rates: 0 (P0), 75 (P1) and 150 g pot-1 (P2). The manure was incorporated into the growing medium once, on 10 March 2026. The control treatment received no poultry manure. According to the manufacturer (Reefco), the product contained 15-20% moisture, 70-75% organic matter, 2-3% total nitrogen, 1.5-2% total phosphorus, 2.5-3% total potassium, 3-4% calcium and 3% magnesium, with a pH of 7-8. These values represent the manufacturer’s specifications. The second factor was foliar CPPU application at four concentrations: 0 (C0), 3 (C1), 6 (C2) and 9 mg L-1 (C3). Applications were conducted on 10 April, 10 May and 10 June 2026.
     
    Experimental design and statistical analysis
     
    The experiment was arranged as a 3 x 4 factorial in a randomized complete block design (RCBD) with three blocks. Each block contained all 12 treatment combinations, randomly assigned to experimental units. Each experimental unit comprised three saplings, giving 36 experimental units and 108 saplings in total. Data were analyzed using analysis of variance appropriate for a factorial RCBD in Genstat. The analysis evaluated the effects of poultry manure, CPPU and their interaction while accounting for block effects. Means were compared using the least significant difference (LSD) test at the 5% significance level (Al-Mohammadi and Al-Mohammadi, 2012). In the figures, P denotes the processed poultry manure factor and C denotes the CPPU foliar application factor. LSD0.05 represents the least significant difference at the 5% significance level; values reported for P and C apply to comparisons among the respective main-effect means.
     
    Studied traits
     
    On 10 July 2026, fully expanded leaf samples were randomly collected from the middle parts of the branches. The following measurements were conducted (Leaf area, total chlorophyll, percentage of phosphorus, potassium, calcium and magnesium content of the leaves). All chemical analyses were performed at the Central Laboratory of the College of Agriculture, University of Anbar.

    RESULTS AND DISCUSSION

    Leaf area (cm²)
     
    Processed poultry manure application significantly affected leaf area (Fig 1). Compared with P0 (20.01 cm2), P1 increased leaf area to 21.55 cm2, but this difference was not significant). In contrast, P2 significantly increased leaf area to 23.94 cm2. For CPPU, C1 produced a leaf area of 19.94 cm2, which did not differ significantly from C0 (19.59 cm2). However, C2 and C3 significantly increased leaf area to 23.07 and 24.72 cm2, respectively, compared with C0. The poultry manure x CPPU interaction was also significant (Table 2), with the highest leaf area recorded under P2C3 and the lowest under P0C0.

    Fig 1: Effect of processed poultry waste application and CPPU foliar spray on leaf area of “Sharabi” apple saplings.



    Table 2: Interactive effects of processed poultry waste application and CPPU foliar spray on some studied characteristics of “Sharabi” apple saplings.


           
    P0, P1 and P2 represent processed poultry manure application rates of 0, 75 and 150 g pot-1, respectively. C0, C1, C2 and C3 represent foliar forchlorfenuron (CPPU) concentrations of 0, 3, 6 and 9 mg L-1, respectively.
           
    The increase in leaf area under P2 may reflect improved nutrient supply and growing-medium conditions following processed poultry manure application. Organic amendments can improve soil physical properties, potentially providing more favorable conditions for root development and nutrient acquisition (Sruthi et al., 2025; Donbiaksiam et al., 2026). Nitrogen supplied by the manure supports amino acid and protein synthesis, as well as the cellular processes involved in leaf development and expansion (Wang et al., 2024; Zayed et al., 2023). Potassium may also contribute through its role in osmotic adjustment and the maintenance of cell turgor required for expansion (Hasanuzzaman et al., 2018). The significant increases under C2 and C3, compared with C0, are consistent with the cytokinin activity of CPPU, which can promote cell division and leaf development (Werner et al., 2001). The highest value under P2C3 suggests that adequate nutrient supply may support the leaf expansion response to CPPU, although the underlying mechanisms were not measured directly.
     
    Total chlorophyll content of the leaves (mg g-1 FW)
     
    Processed poultry manure significantly affected total chlorophyll content (Fig 2). Both P1 (1.28 mg g-1 FW) and P2 (1.32 mg g-1 FW) significantly increased total chlorophyll compared with P0 (1.22 mg g-1 FW). For CPPU, C1 (1.25 mg g-1 FW) did not differ significantly from C0 (1.23 mg g-1 FW), whereas C3 significantly increased total chlorophyll to 1.34 mg g-1 FW. C2 recorded 1.28 mg g-1 FW. The poultry manure x CPPU interaction was significant (Table 2), with the highest total chlorophyll content recorded under P2C3 and the lowest under P0C0.

    Fig 2: Effect of processed poultry waste application and CPPU foliar spray on the total chlorophyll content of “Sharabi” apple saplings leaves.


           
    The higher total chlorophyll content under P1 and P2 may be associated with the nutritional contribution of processed poultry manure, particularly its nitrogen and magnesium contents. Nitrogen supports chlorophyll synthesis and the formation of proteins involved in the photosynthetic apparatus (Fathi, 2022), while magnesium contributes to chlorophyll structure and the activation of enzymes involved in photosynthetic metabolism (Senbayram et al., 2015). The significant increase under C3 may reflect the influence of CPPU on chloroplast development and the maintenance of leaf chlorophyll, consistent with the physiological functions of cytokinins (Sakakibara et al., 2006). Cytokinin-related regulation of nucleic acid and protein synthesis may also support these processes (Smith et al., 2017). The highest chlorophyll content under P2C3 may therefore reflect complementary nutritional and growth-regulatory effects. However, increased chlorophyll content alone does not establish an increase in net photosynthetic rate.
     
    Phosphorus percentage in the leaves
     
    Processed poultry manure significantly affected leaf phosphorus concentration (Fig 3). Both P1 (0.42%) and P2 (0.43%) significantly increased leaf phosphorus compared with P0 (0.37%). Similarly, CPPU application significantly increased leaf phosphorus at C1 (0.41%), C2 (0.42%) and C3 (0.44%) compared with C0 (0.34%). The highest concentrations were recorded under P2 and C3 for the respective factors. However, the poultry manure x CPPU interaction was not significant (Table 2).

    Fig 3: Effect of processed poultry waste application and CPPU foliar spray on the phosphorus content of “Sharabi” apple saplings leaves.


           
    The significant increases in leaf phosphorus under P1 and P2 may partly result from phosphorus supplied by processed poultry manure. Organic matter decomposition may additionally modify phosphorus availability through changes in soil chemical conditions and interactions involving humic substances (Kobierski et al., 2017). Changes in rhizosphere pH could also influence nutrient availability, although their direction and magnitude depend on the amendment and soil conditions (Raghavendar, 2026). Phosphorus is involved in energy transfer and the formation of compounds essential for plant metabolism and growth (Khan et al., 2023; Al-Dulaimy and Mohammed, 2024). The higher leaf phosphorus concentrations under all CPPU treatments may be associated with cytokinin-mediated changes in nutrient allocation toward developing tissues (Davies, 2004). Nevertheless, leaf concentration measurements alone cannot distinguish increased uptake from altered internal distribution. The nonsignificant interaction indicates that a combined effect beyond the individual factor effects was not demonstrated for this trait.
     
    Potassium percentage in the leaves
     
    Processed poultry manure significantly affected leaf potassium concentration (Fig 4). P2 significantly increased leaf potassium to 2.04% compared with 1.89% under P0, while P1 recorded 1.97%. For CPPU, C1 (1.91%) did not differ significantly from C0 (1.84%). However, C2 (1.98%) and C3 (2.15%) significantly increased leaf potassium compared with C0. The poultry manure x CPPU interaction was significant (Table 2), with the highest leaf potassium concentration recorded under P2C3 and the lowest under P0C0.

    Fig 4: Effect of processed poultry waste application and CPPU foliar spray on the potassium content of “Sharabi” apple saplings leaves.


           
    The significantly higher leaf potassium concentration under P2 may be attributed partly to potassium supplied by processed poultry manure and its potential effects on nutrient availability in the growing medium (Al-Jaf  et al., 2023). Potassium supports enzyme activation, photosynthesis and carbohydrate metabolism (Rawat et al., 2022). The significant increases under C2 and C3 may reflect changes in nutrient demand and allocation associated with CPPU-induced leaf development. Greater leaf area and chlorophyll content could potentially support carbon assimilation and the metabolic processes associated with nutrient acquisition, although these processes were not directly assessed (Taiz and Zeiger, 2010). The highest potassium concentration under P2C3 suggests that the response to CPPU depended partly on manure supply. This interpretation is broadly consistent with the nutritional responses to CPPU-containing treatments reported by Mohammed and Al-Dulaimy (2023) and Al-Hameedi and Al-Tamimi (2025).
     
    Calcium percentage in the leaves
     
    Processed poultry manure significantly affected leaf calcium concentration (Fig 5). P1 (1.29%) did not differ significantly from P0 (1.27%), whereas P2 significantly increased leaf calcium to 1.36%. For CPPU, C1 (1.27%) did not differ significantly from C0 (1.26%), while C3 significantly increased leaf calcium to 1.38%. C2 recorded a calcium concentration of 1.32%. The poultry manure x CPPU interaction was significant (Table 2), with the highest leaf calcium concentration recorded under P2C3 and the lowest under P0C0.

    Fig 5: Effect of processed poultry waste application and CPPU foliar spray on the calcium content of “Sharabi” apple saplings leaves.


           
    The significant increase in leaf calcium concentration under P2 may partly reflect the calcium supplied by processed poultry manure. Calcium contributes to cell-wall structure through its association with pectic substances and supports tissue integrity during development (Kour et al., 2023). It also plays important roles in membrane stability and cellular signaling (Thor, 2019), as well as the regulation of cellular processes associated with growth (Wdowiak et al., 2024). The higher calcium concentration under C3 may reflect indirect effects of CPPU on leaf development and calcium delivery to growing tissues. However, the present measurements do not establish whether this response resulted from altered uptake, transport or tissue growth. The highest concentration under P2C3 suggests that manure supply influenced the calcium response to CPPU, consistent with the significant interaction.
     
    Magnesium percentage in the Leaves
     
    Processed poultry manure significantly affected leaf magnesium concentration (Fig 6). P1 (0.44%) did not differ significantly from P0 (0.42%), whereas P2 significantly increased leaf magnesium to 0.51%. For CPPU, C1 (0.45%) did not differ significantly from C0 (0.42%), while C3 significantly increased leaf magnesium to 0.50%. C2 recorded a magnesium concentration of 0.47%. The poultry manure x CPPU interaction was significant (Table 2), with the highest leaf magnesium concentration recorded under P2C2 and the lowest under P0C0.

    Fig 6: Effect of processed poultry waste application and CPPU foliar spray on the magnesium content of “Sharabi” apple saplings leaves.


           
    The significantly higher leaf magnesium concentration under P2 may partly result from the magnesium supplied by processed poultry manure. Magnesium supports photosynthesis and numerous enzyme reactions involved in energy metabolism (Senbayram et al., 2015). It also contributes to carbohydrate transport from source leaves to sink organs (Ferreira et al., 2023) and participates in physiological responses to abiotic stress (Ahmed et al., 2023), although stress tolerance was not evaluated in this experiment (Walaa et al., 2026). The significant increase under C3 may be associated with CPPU-related changes in leaf development and nutrient allocation. The highest magnesium concentration under P2C2, despite the highest CPPU main-effect mean occurring under C3, illustrates the importance of considering treatment combinations when interpreting the significant interaction. The beneficial nutritional response to manure application is broadly consistent with the olive studies cited by Khalil and Abdulqader (2023) and Almashhadani and Al-Hadethi (2025).

    CONCLUSION

    It is concluded from this study that the addition of processed poultry manure and the foliar application of the growth regulator CPPU significantly impacted the evaluated parameters of the apple saplings cv. Sharabi. Therefore, based on the study results, we recommend adding poultry manure at a level of 150 g pot-1 and foliar application with CPPU at a rate of 9 mg L-1 to improve leaf area and the chlorophyll and nutrient contents of the sapling leaves.

    CONFLICT OF INTEREST

    Authors have declared that there are no conflicts of interest.

    REFERENCES


    1. Ahmed, N., Zhang, B., Bozdar, B., Chachar, S., Rai, M. and Li, J. (2023). The power of magnesium: Unlocking the potential for increased yield, quality and stress tolerance of horticultural crops. Frontiers in Plant Science. 14: 1285512. doi: 10.3389/fpls.2023.1285512.

    2. Akintoye, O.H., Odedina, J.N., Makinde, E.A. and Adigbo, S.O. (2026). Storage, application rate and frequency of poultry manure determine variations in soil nutrients and leafy yield of fluted pumpkin. Turkish Journal of Agriculture- Food Science and Technology. 14(6): 1673-1682. doi: 10.24925/turjaf.v14i6.1673-1682.8710.

    3. Al-Dulaimy, A.F.Z. and Mohammed, O.A.J. (2024). Response of local sweet orange transplants to spraying with micronutrients and CPPU. Anbar Journal of Agricultural Sciences. 22(2): 806-823. doi: 10.32649/ajas.2024.184460.

    4. Al-Hameedi, R.S.H. and Al-Tamimi, H.M.A. (2025). Effect of humic acid fertilization and CPPU growth regulator spray on some chemical indicators of selected citrus rootstocks. IOP Conference Series: Earth and Environmental Science. 1549: 012099. doi: 10.1088/1755-1315/1549/ 1/012099.

    5. Al-Jaf, I.H.M., Al-Hayali, R.E.Y., Al-Dulaimy, A.F.Z. and Al Miahy, F.H.R. (2023). Response of cucumber plants to the addition of animal waste and dry yeast suspension. Bionatura. 8(1): 1-5.

    6. Almashhadani, B.M.K. and Al-Hadethi, M.E.A. (2025). Effect of irrigation intervals and poultry manure in growth of olive transplants (Olea europaea L.). IOP Conference Series: Earth and Environmental Science. 1487: 012033. doi: 10.1088/1755-1315/1487/1/012033.

    7. Al-Mohammadi, S.M. and Al-Mohammadi, F.M. (2012). Statistics and Experimental Design. Osama Publishing and Distribution House, Amman, Jordan.

    8. Azuka, C.V. and Idu, M.C. (2022). Effect of organic manures application on soil physicochemical properties of coarse- textured Ultisol and okra productivity in Nsukka, Southeastern Nigeria. Agricultural Science Digest. 42(2): 145-151. doi: 10.18805/ag.D-326.

    9. Chawla, R., Guleria, T. and Thakur, A. (2025). Role of plant growth regulators in fruit crop production: A comprehensive review. Applied Fruit Science. 67: 294. doi: 10.1007/ s10341-025-01535-z.

    10. Davies, P.J. (2004). Plant Hormones: Biosynthesis, Signal Transduction, Action. 3rd ed. Kluwer Academic Publishers, Dordrecht, Boston and London.

    11. Donbiaksiam, T., Jyotsna, N., Zeshmarani, S., Singh, L.B., Hijam, C. and Singh, S.P. (2026). Effect of poultry manure compost on soil fertility and productivity within a protected cultivation environment in polyhouse condition. Indian Journal of Agricultural Research. 4(2): 1-7. doi: 10.18805/IJARe.A-6458.

    12. Fathi, A. (2022). Role of nitrogen (N) in plant growth, photosynthesis pigments and N use efficiency: A review. Agrisost. 28: 1-8. doi: 10.5281/zenodo.7143588.

    13. Ferreira, L.S., Oliveira, V.S., Marchiori, J.J.P., Ferreira, T.C., Bernabé, A.C.B. and Boone, G.T.F. (2023). The nutrient magnesium in soil and plant: A review. International Journal of Plant and Soil Science. 35(8): 136-144. doi: 10.9734/ijpss/ 2023/v35i82890.

    14. Hasanuzzaman, M., Bhuyan, M.H.M.B., Nahar, K., Hossain, M.S., Mahmud, J.A. and Hossen, M.S. (2018). Potassium: A vital regulator of plant responses and tolerance to abiotic stresses. Agronomy. 8(3): 31-60.  doi: 10.3390/agronomy 8030031.

    15. Hussein, S.A., Kanber, H.S. and Lateef, M.A. (2022). Growth regulators’ role on the growth and yield of grapes (Vitis vinifera L.): A review. European Journal of Research Development and Sustainability. 3(2): 85-88.

    16. Khalil, H.S. and Abdulqader, S.M. (2023). Effect of organic manure, biofertilizer and foliar spray of ascorbic acid on vegetative growth and fruit quality of Basheqi cv. of olive (Olea europaea L.). Kufa Journal of Agricultural Sciences. 15(2): 96-113.  doi: 10.36077/kjas/2023/v15i2.10625.

    17. Khan, F., Siddique, A.B., Shabala, S., Zhou, M. and Zhao, C. (2023). Phosphorus plays key roles in regulating plants’ physiological responses to abiotic stresses. Plants. 12(15): 2861.  doi: 10.3390/plants12152861.

    18. Kobierski, M., Bartkowiak, A., Lemanowicz, J. and Piekarczyk, M. (2017). Impact of poultry manure fertilization on chemical and biochemical properties of soils. Plant, Soil and Environment. 63: 558-563. doi: 10.17221/668/2017-PSE.

    19. Kour, J., Khanna, K., Singh, A.D., Dhiman, S., Bhardwaj, T. and Devi, K. (2023). Calcium’s multifaceted functions: From nutrient to secondary messenger during stress. South African Journal of Botany. 152: 247-263.  doi: 10.1016/ j.sajb.2022.11.048.

    20. Meshram, S., Mansor, H.B. and Adhikari, T.B. (2026). Recent advances in organic agriculture: Innovations, challenges and opportunities. Frontiers in Plant Science. 16: 1681928.  doi: 10.3389/fpls.2025.1681928.

    21. Miao, P., Li, F., Cui, G. and Wang, Z. (2022). Effects of mixed application of microbial fertilizer and chicken manure on apple seedling growth and saline-alkali soil improvement. Journal of Northern Agriculture. 50(5): 41-47. doi: 10.12190/j.issn.2096-1197.2022.05.06.

    22. Mohammed, O.A.J. and Al-Dulaimy, A.F.Z. (2023). Effect of spraying with micronutrients and CPPU on the chemical content of local orange saplings. International Journal of Agricultural and Statistical Sciences. 19(Suppl.1): 1187-1195.  doi: 10.59467/IJASS.2023.19.1187.

    23. Moyin-Jesu, E. I. and Adeofun, C. O. (2008). Comparative evaluation of different organic fertilizer on the soil fertility, leaf mineral composition and growth performance of mango seedlings (Magnifera indica L.). Emirates Journal of Food and Agriculture. 20(1): 18-30. doi: 10.9755/ejfa.v12i1.5178.

    24. Oshchepkov, M., Kalistratova, A., Savelieva, E., Romanov, G. and Bystrova, N. (2020). Natural and synthetic cytokinins and their applications in biotechnology, agrochemistry and medicine. Russian Chemical Reviews. 89: 787-810.  doi: 10.1070/RCR4921.

    25. Padmalatha, T., Satyanarayana Reddy, G., Chandrasekhar, R., Siva Shankar, A. and Chaturvedi, A. (2013). Effect of foliar sprays of bioregulators on growth and flowering in gladiolus. Indian Journal of Agricultural Research. 47(3): 192-199.

    26. Raghavendar, M. (2026). Transforming poultry manure into value: Commercial strategies for composting, bioenergy and animal nutrition. Indian Journal of Veterinary and Animal Sciences Research. 55(2): 23-33.

    27. Rawat, J., Pandey, N. and Saxena, J. (2022). Role of Potassium in Plant Photosynthesis, Transport, Growth and Yield. In Role of Potassium in Abiotic Stress. Springer, Singapore.  doi: 10.1007/978-981-16-4461-0_1.

    28. Sakakibara, H. (2006). Cytokinin activity, biosynthesis and translocation. Annual Review of Plant Biology. 57: 431-449. doi: 10.1146/annurev.arplant.57.032905.105231.

    29. Senbayram, M., Gransee, A., Wahle, V. and Thiel, H. (2015). Role of magnesium fertilisers in agriculture: Plant-soil continuum. Crop and Pasture Science. 66(12): 1219-1229. doi: 10.1071/CP15104.

    30. Shamsuddin, M.S., Rozilawati, S., Che Amri, C.N.A. and Shuhada, T.N. (2020). Yield performance of Ficus carica as affected by different rate of chicken manure. Indian Journal of Agricultural Research. 54(6): 807-810.  doi: 10.18805/IJARe.A-546.

    31. Shobo, B.A., Joseph-Adekunle, T.T., Ogunleye, M.T., Akintunde, A.O., Afodu, O.J. and Bodunde, G.J. (2025). Growth, fruit characteristics and seed yield of tomato (Lycopersicon esculentum Mill) in response to fertilizer application. Indian Journal of Agricultural Research. 59(5): 797- 801. doi: 10.18805/IJARe.AF-705.

    32. Smith, S., Li, C. and Li, J. (2017). Hormone Function in Plants. In Hormone Metabolism and Signaling in Plants. Elsevier Inc., pp. 1-38.

    33. Sousa, T.O., Fonseca, W.L., Oliveira, A.M., Zuffo, A.M., Nery, M.C., Magalhães, M.A., Sales, T.S., Fialho, C.M.T. and Alves, K.A. (2019). Development of papaya tree in organic substrates. Australian Journal of Crop Science. 13(10): 1600-1606. doi: 10.21475/ajcs.19.13.10.p1812.

    34. Sruthi, B., Singh, A.K., Ao, M. and Gadi, Y. (2025). Effect of organic manures on soybean [Glycine max (L.) Merrill] performance and soil properties in Northeast of India, Nagaland. Indian Journal of Agricultural Research. 59(9): 1476-1480. doi: 10.18805/IJARe.A-6229.

    35. Taiz, L. and Zeiger, E. (2010). Plant Physiology. 4th ed. Sinauer Associates, Sunderland, MA, USA.

    36. Thor, K. (2019). Calcium-Nutrient and messenger. Frontiers in Plant Science. 10: 440.  doi: 10.3389/fpls.2019.00440.

    37. Walaa, S.K., Ragheed, M.H.A., Basim, M.A., Idrees, H.M.S.A. and Ahmed, F.Z.A. (2026). Effect of poultry manure and spraying with urea on growth and yield parameters of local lettuce. Plant Science Today. 13(2): 1-6. doi: 10.14719/pst.14186.

    38. Wang, Q., Li, S., Li, J. and Huang, D. (2024). The utilization and roles of nitrogen in plants. Forests. 15(7): 1191. doi: 10.3390/f15071191.

    39. Wdowiak, A., Podgórska, A. and Szal, B. (2024). Calcium in plants: An important element of cell physiology and structure, signaling and stress responses. Acta Physiologiae Plantarum. 46: 108.  doi: 10.1007/s11738-024-03733-w.

    40. Werner, T., Motyka, V., Strnad, M. and Schmülling, T. (2001). Regulation of plant growth by cytokinin. Proceedings of the National Academy of Sciences of the United States of America. 98: 10487-10492.  doi: 10.1073/pnas.171304098.

    41. Yirmibeº, B., Lachin, A., Ülger, N. and Karaçam, E. (2025).  The utilization of plant growth regulators (PGRs) in agricultural application and the effecting mechanisms. Research in Agricultural Sciences. 56(2): 180-185. doi: 10.17097/ agricultureatauni.1540336.

    42. Zayed, O., Hewedy, O.A., Abdelmoteleb, A., Ali, M., Youssef, M.S. and Roumia, A.F. (2023). Nitrogen journey in plants: From uptake to metabolism, stress response and microbe interaction. Biomolecules. 13(10): 1443. doi: 10.3390/ biom13101443.
    In this Article
      Contact us
      Follow us
      Published In
      Agricultural Science Digest

      Editorial Board

      View all (0)