Effect of Irrigation Levels and Silicon on Growth and Productivity of Barley (Hordeum vulgare L.)

Globally, barley (Hordeum vulgare L.) is cultivated in both temperate and tropical climates due to its wide adaptability (Al-Hajaj et al., 2022). After rice, maize and wheat, barley ranks fourth in global cereal production. The top barley-producing countries include Canada, Russia, Australia, Ukraine and Germany (Bvenura and Kambizi, 2022). In India, it serves as a staple grain during winter, especially in the western plains and is widely used as feed for livestock and poultry, as well as for human consumption (Verma et al., 2022). Much of the barley grown in India also supports industrial applications, particularly in whiskey and beer production and as animal feed (Kumar et al., 2018). Due to its strong resilience to harsh environmental conditions and minimal input requirements, barley is often referred to as the “poor man’s crop” (Chhokar et al., 2022).
       
Drought stress is projected to reduce global agricultural productivity by up to 30% by 2025, posing a significant challenge to sustainable agriculture, especially in dry and semi-arid regions with limited water resources (Rajanna et al., 2023). Global warming and climate instability are aggravating water scarcity for crops in many countries (Khondoker et al., 2023). Among the various limiting factors in crop production, water availability is one of the most critical. In semi-arid regions, soil water deficit resulting from low precipitation and increased evapotranspiration is a major stressor for plants (Bello et al., 2024). Meteorological drought-characterized by a prolonged decline in rainfall-combined with elevated evapotranspiration leads to agricultural drought (Sun et al., 2023).
       
Water shortages induce plant stress that alters key physiological processes, such as stomatal closure and reduced growth, thereby lowering water consumption and ultimately reducing crop output (Wu et al., 2022). Effective water management in crops like barley involves understanding how water stress impacts growth and productivity, along with continuous monitoring of plant and soil water status (Trușcă et al., 2023). Crop water stress, mainly caused by insufficient soil moisture, directly affects irrigation strategies, especially when roots fail to access adequate water or when transpiration rates become excessively high (Kang et al., 2021). Classifying water stress as light, moderate, or severe is essential for planning irrigation efficiently and ensuring stable long-term yield (Seleiman et al., 2021).
       
Silicon (Si), the second most abundant element in earth crust (28.8%) after the oxygen (47%) (Jain, 2025), plays an important role in various plant physiological processes (Souri et al., 2021), particularly in alleviating stress caused by both abiotic and biotic factors like drought (Wade et al., 2022). Since its absorption and transport rely on the transpiration stream, shifts in water availability due to climate change may hinder silicon’s effectiveness in improving crop performance (Kuhla et al., 2021). Therefore, it is vital to understand how future changes in rainfall patterns may affect Si absorption to fully harness its potential benefits (Thakral et al., 2021). Silicon application enhances plants’ drought tolerance through several mechanisms: boosting antioxidant defense systems, increasing CO₂ uptake during water stress (Bhardwaj and Kapoor, 2021), reducing transpiration by forming a cuticle-Si layer and reinforcing plant structure to prevent lodging (Wade et al., 2022; Malik et al., 2021). As climate change continues to threaten water availability, the use of Si to alleviate drought-induced yield losses in crops like barley is receiving increased attention (Irfan et al., 2023).

Experimental site and soil
 
The present study was conducted in Rabi season of 2023-2024 at Lovely Professional University, Phagwara (Punjab) at the experimental site of the Agricultural Research Field, Department of Agronomy, School of Agriculture. Lovely Professional University is situated 8 km from Phagwara, at an elevation of 245 meters above mean sea level (AMSL). The region has a subtropical climate and is located at 31.2560^oN latitude and 75.7051^oE longitude. Soil samples were randomly collected from various locations in the experimental field using a soil auger, down to a depth of 15 cm, to evaluate the fertility status and physiological and chemical characteristics of the soil. According to the triangle technique of soil classification established by the International Society of Soil Science (ISSS), the soil in the experimental field may texturally be categorized as sandy loam.
 
Experimental design and treatment details
 
The experiment was laid out in a split plot design with three replications. Within each of the 45 plots that made up each replication, the treatments were placed at random. As a result, 15 treatment combinations with irrigation levels in main plots and foliar silicon levels in sub-plots were compared. The variables under investigation comprised of three levels of irrigation : I₁: Control (no irrigation), I₂: Two irrigations (tillering + grain development stage) and I₃: Four irrigations (tillering + jointing + boot + grain development stage). Additionally, five levels of foliar silicon application were examined : S₁: 0% (control), S₂: 0.50% (tillering stage), S₃: 0.50% (tillering + booting stage), S₄: 1% (tillering stage) and S₅: 1% (tillering + booting stage). For foliar spray, powdered water-soluble kaolinite-based greensil silicon (95% silica compound) was utilized. The barley variety used was PL 891, known for its adaptability and suitability under Punjab agro-climatic conditions. The crop was sown with a row spacing of 22.5 cm. A recommended basal dose of fertilizers was applied at sowing time, consisting of 55 kg ha^-1 of urea, 27 kg ha^-1 of DAP and 75 kg ha^-1 of murate of potash.
 
Statistical analysis
 
IBM SPSS version 26 was used to perform an ANOVA on barley growth data to assess the effects of treatment variables. The analysis tested various parameters at a 95% confidence level (p≤0.05) to determine significant variations in morphology, phenology, yield characteristics, biochemical attributes and plant-water relation.

Morpho-phenological parameters of barley
 
Leaf area was significantly influenced by irrigation and silicon application (p<0.05). Compared to I₁ (control), I₂ and I₃ showed increases of 10.6% and 22.8%, respectively, due to improved moisture availability. Si₃ recorded the highest leaf area, with a 20.7% rise over Si₁ (p<0.05). A significant interaction effect was observed among irrigation and silicon levels (Table 1).


       
The increased leaf expansion in watered plants was the result of rise in leaf area. The process of leaf expansion was facilitated by both turgor forces and increased turgor pressure in the cells as a result of increasing soil moisture (Wang et al., 2024). Previous experiments conducted with silicon have reported where in silicon treatment can maintain leaf area compared to the untreated plants grown under drought conditions (Ahsan et al., 2023). Crops have also shown to have greater value of leaf area index under silicon treatment when compared to the silicon free growing conditions (Eghlima et al., 2024).
       
Heading stage was significantly delayed with increasing irrigation (p<0.05). Compared to I₁, treatments I₂ and I₃ extended the time to heading by 5.8% and 9.9%, respectively. Silicon treatments showed no significant effect on days to heading (Table 1).
       
Days to flowering were also significantly influenced by irrigation (p<0.05). Irrigation at I₂ and I₃ increased the duration to flowering by 8.3% and 12.2%, respectively, compared to I1. No significant variation was observed among silicon treatments for this parameter (Table 1).
       
Physiological maturity showed significant differences across irrigation treatments (p<0.05). Compared to I₁, treatment I₂ extended the crop duration by 4.3%, while I₃ delayed it by 8.9%, pointing toward enhanced longevity under improved irrigation. Silicon levels, however, did not significantly influence this parameter (Table 1).
       
The most crucial factor in how different crops adjust to their growing conditions is phenological growth. It has been believed that the plant or a portion of the plant, has a developmental clock that is temperature-dependent and advances at a certain rate for each of the aforementioned phases (Nasir, 2022). The crop receiving constant access to moisture, which led to an increase in plant growth, might be the cause of the delay in the development of various phenological phases. Early development occurs when the plant is forced to finish its life cycle quickly due to water stress. Longer crop longevity and the longer reproductive phase of crop growth have also been recorded with increased irrigation levels (Kumar et al., 2018; Zabihullah, 2020). This may be also be explained by the fact that sufficient moisture availability improved both the vegetative and reproductive phases of the plant. Stress at any stage of crop growth reduced the plant’s life cycle by a few days since the plants sought to finish it as soon as possible in order to avoid or escape stressful situations (Kavita, 2021).
 
Yield attributing characteristics
 
Weight of grains per spike was significantly affected by irrigation and silicon application (p<0.05). I₂ and I₃ increased grain weight by 26.4% and 50.4%, respectively, over I₁ (1.25 g), with I₃ recording the highest (1.88 g). Silicon treatment Si₃  showed a 36.9% improvement over Si₁, with a grain weight of 1.89 g. Si₂ (1.75 g) and Si₄ (1.66 g) also showed significant gains. The I × Si interaction was significant, with I₃ × Si₃ showing the highest grain weight (Table 2).


       
By keeping grains at their ideal moisture levels, irrigation guarantees a sufficient supply of water for grain filling, thereby increasing grain weight. Better nutrient absorption and photosynthesis are facilitated by regular water supply, which promotes more robust grain growth. Plants are able to effectively acquire and retain more nutrients, which leads to the production of bigger and heavier grains (Tahir et al., 2024). By improving the structural integrity and stress resilience of plants, silicon makes grains heavier by providing them with greater support and nutrition distribution. Enhancing photosynthetic efficiency and nutrient absorption results in enhanced grain filling efficacy. Furthermore, silicon aids in reducing stress that could otherwise restrict grain growth and weight. When comparing the non-silicon supplemented plants to the silicon-treated plants, an increase in grain weight (g) was seen and the increase was statistically significant (Das et al., 2023).
       
Biological yield also responded significantly to treatments (p<0.05). I₃ produced the highest yield (89.95 q ha^-1), showing a 52.6% increase over I₁ (58.91 q ha^-1). Among silicon treatments, Si₃ recorded the highest biological yield (87.86 q ha^-1), which was 34.5% more than Si₁ (65.34 q ha^-1). The interaction effect between irrigation and silicon levels was statistically significant (Table 2).
       
Leaf abscission under drought conditions can lead to a decrease in the weight of plant shoots and a reduction in biological production. The improvement in moisture supply and its positive impact on biological yield plant^-1 were the main causes of the biological yield improvement (Nasir, 2022; Ghanem et al., 2024). The outcomes matched the findings of Prem et al. (2024). The higher biological yield may be the result of enhanced nutritional availability in the soil, higher chlorophyll content and enhanced photosynthetic activity, all of which have a positive impact on the metabolism of carbohydrates and activate the carbon-fixing enzyme for greater photosynthesis. A sufficient amount of silicon boosts photosynthetic activity, enabling the plant to gather sufficient photosynthates and increase dry matter synthesis (Das et al., 2023).
 
Biochemical parameters
 
SPAD chlorophyll index improved significantly with irrigation and silicon application (p<0.05). Compared to I₁, I₂ and I₃ increased SPAD values by 19.1% and 15.8%, respectively, indicating enhanced chlorophyll retention under better moisture availability. Among silicon treatments, Si‚  recorded a 19.3% increase in SPAD index over Si₁, while Si₃ (19.1%) and Si₅ (13.1%) also showed significant improvements, confirming the beneficial role of silicon in chlorophyll preservation (Table 2).
       
The value recorded from a SPAD meter is used as an indicator of how relative chlorophyll concentration reacts to various stimuli, such as moisture and extremely high or low temperatures. By the absence of irrigation, elevated concentrations of peroxidase and chlorophillase enzymes and reactive oxygen species (increase in O₂ and H₂O₂), which cause lipid peroxidation and a subsequent decrease in chlorophyll content (Choudhury et al., 2022). Drought stress causes chlorophyll degradation, leading to reduced chlorophyll concentrations and disrupting photosynthetic pigments, which impairs gas exchange and stunts plant growth and production (Khayatnezhad and Gholamin, 2021). Silicon application enhances plant structure and photo-synthesis by increasing chlorophyll levels, likely due to silicon accumulating in epidermal cells, which protects the photosynthetic apparatus from damage. (Bhardwaj and Kapoor, 2021). Similar findings of lower chlorophyll content when irrigation was stopped were also reported by Muhammad et al., (2022).
       
Proline content decreased with improved irrigation and silicon application (p<0.05). Compared to I₁, proline content declined by 7.2% under I₂ and by 3.9% under I₃, reflecting reduced stress conditions. Among silicon treatments, Si₂ lowered proline content by 6.5% compared to Si₁, followed by Si₃ (5.5%) and Si₄ (3.2%), suggesting silicon’s effectiveness in mitigating drought-induced stress responses (Table 2).
       
Proline, a heterocyclic amino acid that accumulates in the cytoplasm, aids in osmotic adjustment during stress and acts as an osmolyte, electron sink, radical scavenger and macromolecule stabilizer. Fewer studies have examined high proline levels as indicators of damage rather than stress tolerance (Hosseinifard et al., 2022). Proline accumulates in plants under water stress, helping to stabilize proteins, cellular structures and maintain turgor. With sufficient irrigation, proline levels are lower due to reduced water stress and better overall plant health. (Ghosh et al., 2022). The proline levels in stressed plants that decrease when silicon is added might be a sign that stress-related damage is decreasing. It turned out that silicon application in rice  (Bhardwaj et al., 2023) and sunflower (Ahmed and Tameemi, 2025) decreased the content of proline under stress.
 
Plant-water relations
 
Relative water content (RWC) responded significantly to irrigation and foliar silicon application (p<0.05). Compared to I₁, RWC increased by 19.2% under I₂ and 14.5% under I₃. Among silicon treatments, Si₂ showed the highest RWC, recording a 19.4% increase over Si₁. Si₃ (59.17%) and Si₄ (55.22%) were found to be statistically at par (p<0.05) (Table 2).
               
Relative water content has been demonstrated to be a valuable screening method for drought resistance in cereals and a trustworthy indicator of plant water status relative to their fully turgid condition. Water stress reduces the relative water content of crops by inducing water loss, increasing the buildup of harmful ions that damage cell membranes and hamper metabolic activities (Yadav et al., 2020). It is these effects that cause turgor loss in leaves. In contrast, irrigation maintains a strong turgor pressure and a relative leaf water content (Hemati et al., 2022). The ability of silicon to maintain the relative water contents under water stress is a significant property (Bukhari et al., 2021). The plant body’s relative water content and nutrient absorption were reduced by water stress; however, Si treatment performed an excellent role of maintaining the turgor presser, which encouraged greater plant growth and productivity (Qamar et al., 2020).

In conclusion, the growth, phenology, yield attributes and biochemical parameters of barley (Hordeum vulgare L.) are considerably influenced by the synergistic impact of irrigation levels and silicon application. The combination of silicon supplementation and optimal irrigation increases stress resistance, boosts nutrient absorption and maximizes water use efficiency. In addition to encouraging strong plant growth, this integrated strategy raises the potential production and enhances the quality of barley grains. The results highlight the importance of silicon application and strategic irrigation management for sustainable barley cultivation, especially in areas with limited water resources and unstable weather patterns. Future studies should aim to optimize agronomic practices for improved crop performance by researching further into the underlying processes of these interactions.

The authors wish to sincerely acknowledge Lovely Professional University, Punjab, India for providing facility of using research area and lab facilities for research purpose.