Impact of taurine and citric acid foliar spraying and their combination on a few wheat crop growth and yield aspects Iba 99, a variety of Triticum aestivum L

Introduction

Due to its high carbohydrate, protein, and nutritional content, wheat is a crucial field crop and a global staple. Additionally, its resilience to different temperatures makes it a significant crop in Iraqi agriculture, particularly in semiarid locations (Alagely et al., 2023) [2] . Iraq has focused on developing local wheat varieties that may survive in various climates. Iba is a popular Iraqi crop. The tremendous genetic diversity of this species helps it to boost its productivity and adapt to different agricultural approaches, making it unique. Al-Kaab et al. (2016) [6] . Many studies have shown that Iba 99 responds to fertilizer and planting density. Its increased growth and output demonstrate its adaptation and resistance to new settings. This was Al-Hamdani and colleagues (2016) [4] . Citric acid is an important organic acid in plants because it enhances micronutrient availability including zinc, iron, and manganese. Mengel (2002) [31] , Güneş et al. (2007) [18] . When applied topically to plants, it stimulates nutrient uptake by activating growth and photosynthetic enzymes. Citric acid also boosts photosynthesis and chlorophyll, improving plant physiological efficiency. It helps cells maintain ionic equilibrium and reduces the effects of dehydration and hunger. (Ali, 2024) [5] . Citric acid has also been shown to improve feeding efficiency and lessen the impact of environmental stress on nutrient uptake, both of which have a positive impact on the development of vegetative traits and yield components. (Touhami et al., 2017) [43] . Taurine is considered one of the organosulfur compounds and is a non-protein amino acid widely distributed in nature. It plays multiple vital roles related to regulating physiological processes and resisting stress.

Although its presence in plants is in limited quantities compared to animals, recent studies have indicated the possibility of utilizing it as a growth-stimulating compound when applied externally, especially under conditions of environmental stress. Scientific research indicates that taurine has an important role as an antioxidant, as it works to reduce the accumulation of free radicals and protect cell membranes from oxidative damage, which positively affects the stability of vital processes within the plant (Schaffer et al., 2010) [39] . The results of some studies have shown that foliar spraying with taurine leads to improved vegetative growth characteristics and increased photosynthetic efficiency by maintaining the integrity of chloroplasts and enhancing the activity of enzymes associated with photosynthesis. It also contributes to improving the absorption and translocation of nutrients within the plant, which leads to increased crop productivity, especially in environments with limited resources (Redmond et al., 2016) [36] . This research investigates foliar spraying citric acid and taurine and their interactions, affects several wheat development and yield characteristics (Iba99).

Materials and Methods

In the Al-Shafi'iyah area, which is 14 kilometers west of the Al-Diwaniyah Governorate's center, To test citric acid foliarly, researchers sprayed multiple amounts in 2024-2025 winter growth. (C6H8O7) produced by TTCA Co., Ltd., of Chinese origin, and taurine (Aminoethanesulfonic acid-2 C2H7NO3S) manufactured by Foodchem International, of Chinese origin, and their interplay on a few wheat variety www.extensionjournal.com growth and yield parameters (Iba 99). The experiment was carried out using factorial trials with two factors: citric acid spraying was the first factor. (C0: no spraying, C1: 1.5 g/L, C2: 3 g/L), The second step was taurine spraying (T 0: no spraying, T 1: 0.5 g/L, C2: 1 g/L). The interaction was observed with three replicates per treatment. Tilling, smoothing, and leveling were the methods used to prepare the soil. Then, using the techniques outlined by Page et al. (1982) [35] and Black (1965) [9] , The physical and chemical parameters were assessed using random samples (Table 1). Each 2-by-3-meter patch was 50 cm apart. After that, each plot had 15 2-meter-long, 20-cm-apart rows. Seeding depth was 6 cm and pace was 100 kg ha⁻¹. The planting fertilizer used was 80 kg ha⁻³ triple superphosphate (46% P₂O₄). Application of 120 kg ha⁻¹ nitrogen fertilizer occurred twice: 15 days post-planting during germination and 45 days thereafter. Urea, 46% nitrogen, was the nitrogen fertilizer. Hoeing and weeding were done as required. Until the season finished, this was vital. The Studied Traits Plant Height After 10 plants in each experimental unit bloomed, we randomly measured their height from soil surface to spike top using a metric ruler.

Leaf area (cm²)

The leaf area was measured after blooming using Liang et al.'s (1973) [23] method. Leaf area is calculated by multiplying width by length by 0.75.

Spike Length

The average of 10 randomly selected plants was measured from the base of the spike to the tip of the terminal spike (excluding the terminal spike).

At full maturity, each experimental unit randomly collected one square meter from shielded rows depending on spikes.

Each experimental unit's sample was weighed after randomly counting 1,000 grains with a seed counter to determine yield per square meter.

Manual analysis was performed on every experimental unit's square meter. The grains were weighed after being separated from straw. The weight of 1,000 grains for each treatment was estimated from this. After adding 14% moisture, it was converted from gm.m⁻² to ton.ha⁻¹.

Grain yield was determined from harvested plants. Grams per square meter were converted to tons per hectare for the plant's biomass, which included grains and straw.

Grain weight was removed from biomass weight to calculate straw yield.

Results and Discussion

The statistical analysis's findings in Table (2) showed significant differences at the probability level (P≤0.05) in the height of wheat plants as a result of the effect of citric acid and taurine, as well as the interaction between them. [11,25] . According to Menhas et al. (2024) [32] and Mahamud et al. (2026) [26] , citric acid helps plant cells create energy and regulate their metabolism, which stimulates cell division and elongation.

A recent wheat research demonstrated that citric acid as a chelating agent improves nutrient absorption, increasing vegetative growth and plant height (Mishra et al., 2024) [33] . El-Tohamy and El-Greadly (2007) [16] also found that citric acid considerably increased vine growth. Table (3) shows that citric acid significantly affected wheat plant leaf area parameters (P≤0.05), whereas taurine had a minor effect. The LSD values for citric acid and taurine show a strong interaction. (4.66) and for the interaction (8.07), which indicates the existence of the differences recorded between the treatments. In the experimental results, treatment C2 recorded the highest average leaf area of 49.00 cm², significantly surpassing treatments C1 and C0, which recorded values of 43.22 cm² and 36.33 cm², respectively. The significant differences between these www.extensionjournal.com treatments exceeded the LSD (least significant difference) of 4.66, indicating the positive effect of citric acid on enhancing the leaf area of wheat plants. The chelating action of citric acid, which increases the availability of nutrients, particularly micronutrients, and improves their absorption and transport within the plant, may account for this impact.

(Cunha-Chiamolera et al., 2025) [11] . Additionally, as a part of the tricarboxylic acid cycle, citric acid is intimately related to the fundamental metabolic functions of the plant. This increases leaf growth by boosting the synthesis of ATP, which is required for essential functions including cell division and elongation. (Aydemir, 2025) [7] . Increased structural efficiency was a result of this. Improvements in chlorophyll synthesis led to photosynthesis, which is consistent with the results of Mishra et al. (2024) [33] in wheat.

In terms of taurine, treatment T 1 ² recorded the greatest leaf area value of 43.33 cm², while treatments T 0 and T 2 recorded values of 42.89 cm² and 42.33 cm², respectively, according to Table (3). Nevertheless, despite a positive effect, the differences between them were less than the LSD (least significant difference) value (LSD = 4.66), suggesting that the taurine effect did not approach statistical significance. This can be explained by the fact that taurine acts as an antioxidant and osmotic regulator, contributing to cell membrane stability and reducing oxidative stress, thus improving the efficiency of physiological processes without a significant increase in leaf area (Nawaz et al., 2024) [34] . Furthermore, the relative decrease at the high concentration in treatment T 2 may be attributed to dose-related effects leading to equilibrium. Metabolic. As for the interaction, the treatment C2T 1 recorded the highest leaf area value at (50.00) cm². However, the differences between it and treatments C2T 0 and C2T 2 were less than the LSD (Least Significant Difference) value (LSD = 8.07), indicating no significant differences between them.

On the other hand, the differences between treatments C2T 1 , which recorded the highest value, and C0T 1 , which recorded the lowest value, were much greater than the L.S.D value, indicating a significant interaction effect. This interaction can be explained by a synergistic effect, as citric acid improves nutrient absorption, while taurine enhances their utilization efficiency within the plant by reducing oxidative stress. This is reflected in improved physiological performance and increased leaf growth in wheat (Zaghloul et al., 2024) [45] . This indicates that improved mineral nutrition is the decisive factor in increasing leaf area, while taurine acts as a cofactor that enhances the physiological response within certain limits. This also confirms the importance of The synergy between nutritional factors and biostimulants in improving vegetative growth characteristics is in line with modern trends in the use of biostimulants to improve crop productivity (Sun et al., 2024) [40] . The statistical analysis's findings in Table (4) show that wheat spike length was significantly affected by citric acid levels, while taurine did not show an independent significant effect. The interaction between the two factors also did not have a significant effect according to the Least Significant Difference (L.S.D) test. The difference between the mean citric acid levels exceeded the L.S.D value of 0.53, particularly between C2 and the other treatments, indicating a real effect of improved mineral nutrition. On the other hand, the results indicate no significant effect of taurine or the interaction, as the differences between their means remained below the significance level (P≤0.05) defined by the L.S.D values. Furthermore, neither the taurine nor the interaction treatments showed statistically significant differences, as the calculated differences were lower than the calculated L.S.D values (L.S.D = 0.53 for taurine and L.S.D = 0.93 for the interaction). This suggests. The absence of a significant effect of these factors can be explained by the significant superiority of citric acid in light of its physiological role as an intermediate organic acid in the Krebs cycle, Plants absorb minerals better due to its chelating agent. Citric acid increases the solubility of elements such as iron, zinc, and manganese and improves their translocation through plant tissues, which positively impacts photosynthetic efficiency by increasing chlorophyll content and activating photosynthetic enzymes, most notably ribulose-1,5-bisphosphate carboxylase/oxygenase (Rellán-Álvarez et al., 2010; Aydemir, 2025) [37,7] . This study confirmed previous findings that organic acids, particularly citric acid, improved wheat's vegetative development and morphology. Kaya et al. (2020) showed that the addition of citric acid promoted growth and productivity by increasing photosynthetic efficiency and micronutrient uptake. In wheat, citric acid improved growthrelated aspects connected to decreased oxidative stress and greater nutrient availability (Aydemir, 2025) [7] . However, taurine increased little without being statistically different. Taurine readings rose somewhat, but not significantly. This can be explained within the framework of biostimulants, as taurine acts as a physiological regulator that contributes to modifying the plant's biological response without being a direct source of nutrients. Studies indicate that amino acidlike compounds enhance stress tolerance by regulating osmotic balance and stimulating antioxidant systems, in addition to their effect on hormonal signaling pathways such as auxins and cytokinins (Rouphael and Colla, 2020) [38] . However, the effectiveness of these compounds remains conditional on the plant's nutritional status, being more pronounced under conditions of stress or nutrient deficiency, which may explain the limited effect of taurine in this study. The results of the insignificant effect of taurine are consistent with a number of studies that have shown that the effect of amino acids or biostimulants is limited or insignificant when sufficient mineral nutrition is available.

The study by Sun et al. (2024) [40] The effect of amino acids in wheat is more pronounced under stress conditions, while their effect is less pronounced under ideal conditions. The researcher also pointed out that biostimulants operate within limited response ranges, and their effectiveness depends on the plant's nutritional balance, which explains why the effect of taurine did not reach a statistically significant level in this study. www.extensionjournal.com

As for non-significance in the interaction between citric acid and taurine, this can be explained by the concept of physiological response saturation. Improving mineral nutrition led to a high level of physiological efficiency, which reduced the possibility of demonstrating a significant additional effect from the biostimulant. In other words, citric acid acted as the primary growth promoter, while taurine's role was limited to physiological modification within statistically insignificant limits. This supports Colla et al. (2014)'s [10] finding that biostimulants' effects are synergistic and nutritionally dependent. The lengthier spikes may be caused by citric acid activating photosynthesis and other mechanisms that boost nutritional availability. Enzymatic activity divides and lengthens spike meristematic tissues, improving the antioxidant system and hormone balance. Since mineral nutrition is strongly related to biological processes that regulate development, this physiological mechanism may explain the obvious growth.

According to contemporary sustainable agriculture research, biostimulants complement dietary and environmental variables and increase nutrient efficiency to boost crop yields. The findings show that managing mineral nutrition is the first step to enhancing wheat growth features, with integrated biostimulant strategies possible. (Rouphael and Colla, 2020) [38] . A statistical study demonstrates that citric acid, taurine, and their combination greatly reduce wheat spikes (Table 5). (P≤0.05). The control treatment C0 generated 3.23 spikes per plant, whereas level C2 produced 4.50 spikes per plant, demonstrating that increasing citric acid concentrations enhanced spike quantity. Analysis of least significant differences showed big disparities (LSD = 0.46). The Krebs cycle's efficiency may be enhanced by citric acid's biostimulant properties. thus providing the energy necessary for cell division and the differentiation of meristematic tissues into spike primordia. The acid also lowers the soil pH in the area surrounding the roots, increasing the availability of micronutrients and phosphorus necessary for flowering. (El-Afifi et al.,2022) [13] .

As for taurine, the results in Table ( 4) indicate a significant response (P≤0.05), with level T 1 significantly outperforming other levels by recording a value of (3.97) spikes/plant⁻¹ compared to the other two levels, with a significant difference exceeding the value of the least significant difference (L.S.D=0.46). It is observed that increasing the taurine concentration to level T 2 resulted in a decrease in the average to (3.80) spikes/plant⁻¹, which indicates that the optimal response occurs at intermediate concentrations. The effect of taurine at level T 1 may be attributed to its nature as an osmotic regulator and antioxidant that protects cell membranes from environmental stresses, thus prolonging the functional efficiency of the leaves and consequently increasing the flow of metabolic products towards the developing spikes (Habib et al., 2025) [19] . This suggests that sulfur-containing amino acids may boost photosynthetic efficiency and output, as Zayed et al. (2020) [46] suggested.

As for the effect of the interaction, According to statistical analysis, Table 4 demonstrates substantial differences. (P≤0.05) in the interaction between the two study variables, with the least significant difference being 0.81. The interaction combination C2T 1 achieved the highest value for the number of spikes, reaching (4.63) spikes/plant⁻¹, thus significantly surpassing the treatment C0T 0 , which recorded the lowest value (3.23) spikes/plant⁻¹. Perhaps the reason for this significant superiority of the aforementioned interaction is attributed to a state of physiological synergy, where citric acid contributed to improving mineral absorption and providing carbon structures, while taurine worked to improve the physiological state of the plant and stress resistance, which together led to maximizing the number of spikes produced. This is consistent with the principle of integration between growth-regulating biostimulants (Kandil et al., 2021) [21] . The results in Table (6) show significant differences (P≤0.05) between citric acid and taurine, and their interaction, on the 1000-grain weight trait in wheat. These differences exceeded the LSD value, which is set at a probability level of (0.05). The results showed a significant advantage with the addition of citric acid, as treatment C2 recorded the highest average weight of (39.12) g, compared to the control treatment (C0), which recorded a value of (33.77) g. This result, which exceeded the LSD value of (1.43), may be attributed to the role of citric acid as one of the essential organic acids involved in the Krebs cycle. This helps plant cells produce energy in the form of ATP and support metabolic processes, which in turn influences the final grain size and filling process efficiency. Organic acids enhance wheat spike dry matter and nutrient absorption, supporting this notion (El-Afry et al., 2018) [14] .

Treatment T 1 reacted best to taurine, with (37.00) g. Taurine's biostimulant function boosts photosynthetic processes and cell membrane integrity, making it easier to move photosynthetic products from leaves to grains during important development stages. Similar to our results, Maleki et al. (2022) [27] observed that amino acids and their derivatives, such as taurine, increase grass plant production and nitrogen utilization efficiency.

As for the interaction between citric acid and taurine, the C2T 1 treatment recorded the highest grain weight of (39.67) g. This interaction indicates a state of physiological synergy, as citric acid improves the availability of elements in the soil and root zone, while taurine improves the internal www.extensionjournal.com biological processes of the plant, which led to maximizing the grain weight characteristic (Yakhin et al., 2017) [44] . These results are consistent with modern scientific trends that confirm that mixing biostimulants and organic acids gives results that surpass the use of each of them individually (Khan et al., 2019) [22] . [24] Organic acids contribute to regulating osmotic pressure and improving the plant's water balance, which is reflected in an increase in the number of spikes and grain weight (Tariq et al., 2023) [42] . This was also indicated by Hussain et al. (2022) [20] in their study on cereal crops, where they found that citric acid stimulates antioxidant enzymes, thus extending the lifespan of the scientific leaf.

The treatment with the highest yield, 3.91 tons ha⁻¹, was the one with taurine (T 1 ). This amino acid, which includes sulfur, enhances plant defenses and stabilizes metabolic processes, perhaps explaining this effect. This extends grain storage and leaf photosynthesis. This is from Zhang et al.

(2023) [47] . Maleki et al. (2022) [27] found that amino acid biostimulants boost photosynthetic efficiency and yield components in various plant conditions, and our findings agree. The interaction resulted in the maximum grain output (4.55 tons ha⁻) in treatment (C2T 1 ). This interaction shows a physiological synergy: taurine optimizes yield by improving internal plant processes and regulating element and metabolic product translocation to the ears, while citric acid increases soil and root zone nutrient availability. Khan et al.

(2019) [22] and Yakhin et al. (2017) [44] found that organic acids and biostimulants work better together than separately. [42] finding that organic acids improve wheat harvest biochemistry and physiology.

The treatment (T 1 ) improved taurine effect by 4.63 ton/ha -1 . Taurine, a biostimulant, regulates ionic homeostasis to stabilize metabolism and protect cells from environmental threats (Ahmed et al., 2024). Maleki et al. (2022) [27] found that taurine boosts plant resilience and vegetative growth, increasing dry matter production. Interaction-wise, C2T 1 hay production peaked at 5.28 tons ha -1 . This victory shows physiological equilibrium, as citric acid increased energy and soil nutrient availability while taurine helped internal absorption and tissue development.

Modern science shows that organic acids and amino biostimulants boost the plant's efficacy. (Zulfiqar et al., 2021) [48] . The statistical analysis in Table (9) demonstrates major implications. (P≤0.05) of both citric acid and taurine and their interaction on the biological yield of wheat. Data shows that citric acid levels steadily enhanced average yields. C2 outperformed C0, the control treatment, with 8.86 ton.ha -1 . As an organic acid, citric acid is crucial to the Krebs cycle, which enhances photosynthetic efficiency and creates energy for cell division and plant tissue growth. Citric acid increases total dry matter via chelating and helping plants absorb and transport micronutrients. Tahjib-Ul-Arif et al. (2019) [41] . Mallick et al. (2021) [30] found that organic acids modulate osmotic potential to improve wheat crop vegetative growth. The statistical analysis table above shows that taurine treatment, notably T 1 , generated 7.85 ton.ha -1 more. Taurine protects cell membranes from oxidative damage, extends leaf lifetime, and enhances light absorption and growth regulation. In 2022, El-Metwally and colleagues. Malekzadeh (2015) [28] found that amino acids improve nitrogen absorption, increasing wheat dry matter yield. At T 2 , there was a little reduction, suggesting physiological nitrogen saturation. www.extensionjournal.com

Additionally, binary interaction peaked at 9.13 ton.ha -1 during treatment C2T 1 . Citric acid supplies energy and carbon frameworks, while taurine protects the structural system; their synergy gives them dominance. The L.S.D. value of the interference (1.49) confirms that the differences between the interference treatments are significant and real differences resulting from the effectiveness of the materials used (Tahjib-Ul-Arif et al., 2019; Mallick et al.,2021) [41,30] . Foliar spraying with citric acid at the mentioned levels resulted in a significant and clear increase in most growth and yield characteristics, especially at the C2 level, confirming its effectiveness in enhancing photosynthetic efficiency and energy production within the plant. 2. Taurine demonstrated high efficacy as a biostimulant and antioxidant, particularly in treatment T 1 , as it contributed to protecting cell membranes and extending the functional lifespan of leaves, which positively impacted dry matter accumulation. 3. The dual interaction between citric acid and taurine, especially in treatment (C2T 1 ), achieved the best performance for the studied variety in most growth and yield characteristics, indicating a synergistic effect combining energy provision and physiological protection.

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