Role of early seedling establishment in estimating crop yields

Crop yield is the cumulative determinant of the sequence of biological events initiated during seed imbibition. Among these events, early seedling establishment—encompassing germination, radicle protrusion, coleoptile or hypocotyl elongation, and the transition to photoautotrophic growth—represents the most critical and irreversible determinant of final plant density and yield potential. A crop that fails to establish a uniform, vigorous plant stand within the optimal planting window directly impacts the yield characteristics, which cannot be fully recovered by subsequent agronomic interventions. Conversely, successful establishment ensures the development of vigorous, synchronized seedlings, enabling crops to efficiently utilize available resources such as light, water, and nutrients, thereby supporting plant growth and development throughout the growing season. 

Moreover, to feed the projected 10 billion population by 2050, crop production should increase by 25–70% despite declining arable land, depleting freshwater resources, and the increasing frequency of extreme weather events. Meeting this demand requires achieving yields closer to the genetic potential of modern cultivars, a goal often constrained by the reliability of early seedling establishment and combined early-season biotic and abiotic stresses. 

Addressing these constraints at the seed level through enhancement strategies such as seed treatment and seed priming provides a targeted pre-sowing solution by improving germination synchrony, seedling vigor, and stress tolerance, thereby reducing the yield gap between attainable and actual yields. These strategies also offer a cost-effective and scalable pathway to optimizing stand establishment across diverse production systems. This article highlights how successful early seedling establishment lays the foundation for yield formation, reviews the role of seed enhancement technologies in protecting seedlings from early-season stresses, and discusses their potential to improve productivity, resource-use efficiency, and economic returns for growers. 

Importance of early seedling growth

Crop yield is a complex trait governed by the dynamic interaction of genetic potential, environmental conditions, and agronomic management interventions across all crop stages (Shi et al., 2009). Among these, early seedling establishment, which comprises germination, radicle protrusion, coleoptile or hypocotyl elongation, and the transition to photoautotrophic growth, is irreversible and serves as the biological foundation on which all subsequent growth, resource acquisition, and yield component development are built. The quality of this seedling establishment phase is driven by three interconnected mechanisms: plant population and sink capacity, canopy architecture and light interception, and root system development and drought resilience, all of which have compounding effects on final yield from the first day of crop growth (Figure 1; Burgess et al. 2022).  

Mechanism 1: Plant population and sink capacity

Each successful seedling that emerges in the field represents a yield-bearing unit later in the growth stages, an economic site capable of supporting reproductive organ development, grain fill, and harvestable yield. Plant stand density, expressed as the number of plants per unit area, is the foundational yield component that determines the yield potential. Scattered or non-uniform emergence in the field creates an empty space that cannot be replaced and represents a permanent loss of sink capacity, as reflected in a reduction in the total number of pods, ears, or grains. To a certain extent, the neighboring plants may partially compensate for this reduction through increased branching, tillering, or additional pod formation and seed fill per surviving plant, but this compensation could be metabolically constrained. This phenomenon is known as the density compensation of plasticity in plant populations (Weiner, 2004).

Individual plants that attain their biological threshold under optimal resource availability have limited capacity to expand further, and the degree of compensation declines sharply as environmental abiotic stressors increase or the growing season shortens. On the other hand, a late-emerging plant contributes less yield than the plant that has emerged on time. This is because of its restricted canopy and root growth and reduced reproductive development, which reflects the compounding disadvantage of a delayed emergence, as well as various abiotic factors during the season that no subsequent management practices can address or compensate for the yield loss. Quantitatively, a 10% reduction in final plant density below the economic optimum results in approximately a 5–8% yield loss in maize and 3–6% in soybean, accumulating directly from the establishment window and persisting through harvest (Andrade & Abbate, 2005; Egli, 1988; Stivers & Swearingin, 1980).  

Mechanism 2: Canopy architecture and light interception

Synchronized seedling emergence plays a critical role in determining how efficiently a crop stand captures solar energy, the primary driver of biomass accumulation and yield production. Quick seedling emergence within a narrow time window results in a uniform plant stand, which promotes rapid leaf area development and early canopy closure. This helps intercept a greater portion of incoming photosynthetically active radiation (PAR), thereby enhancing photosynthetic efficiency. Moreover, early and effective radiation capture increases biomass production, improves resource-use efficiency, and ultimately contributes to greater yield potential (Zhang et al., 2021). 

In contrast, uneven emergence creates variability in plant canopy structure and plant morphology, leading to suboptimal light interception and reduced crop productivity. Plants emerging 24-48 hours behind their neighbors are placed in a chronologically suppressed light environment that permanently reduces their photosynthetic capacity, early biomass accumulation, and the number of reproductive organs they initiate (Roig-Villanova & Martinez-Garcia, 2016). 

Mechanism 3: Root architecture and drought resilience 

The development of root system architecture during the first two to three weeks after emergence plays a pivotal role in crop performance and yield stability. This early growth phase represents a critical, and largely non-renewable developmental window, during which favorable soil moisture and temperature conditions support rapid root elongation, lateral root formation, and overall root system expansion (Wang et al., 2026). 

Seedlings that emerge rapidly and uniformly will have this developmental opportunity, producing deeper, more extensively branched root systems that can access water and nutrient resources beyond the surface layers. This helps improve resilience to intermittent drought and sustain physiological processes during critical reproductive stages (Wolny et al., 2018). Consequently, early root establishment is a key structural mechanism linking successful seedling establishment to improved drought tolerance, reproductive success, and yield formation (Osku et al., 2025).

In contrast, delayed or uneven emergence often results in restricted root development, characterized by shallow rooting depth and limited lateral branching, which remain confined to upper soil horizons that are more susceptible to drying and nutrient fluctuations. 

Collectively, these three mechanisms demonstrate the importance of early seedling establishment as a compounding process rather than a single event that determines the crop’s capacity to achieve its yield potential at harvest. Irregular plant density, canopy asymmetry, and shallow root systems during the establishment window accumulate into yield deficits that no subsequent agronomic input fully corrects. The most direct strategy for improving establishment reliability is to act before planting, at the seed level, through enhancement technologies that improve germination synchrony, seedling vigor, and early stress tolerance. These strategies fall into two broad categories: seed treatment and seed priming, which both target distinct dimensions of establishment vulnerability through different yet complementary mechanisms. 

What are seed enhancement strategies?

Pre-sowing technologies applied to seeds before planting are known as seed enhancement strategies, which help in improving germination speed, emergence uniformity, seedling vigor, and tolerance to abiotic stressors (Figure 2). These are the most targeted and cost-effective points of intervention in the crop production system that act directly at the seed level before any field investment is made. 

These strategies are broadly categorized into two primary approaches: seed treatment and seed priming, which differ fundamentally in their mode of action, biological targets, and physiological outcomes (Gohari et al., 2025). 

Seed treatment

Seed treatment serves as a frontline defense mechanism during the sensitive stages, such as planting and seedling establishment. Treatments are applied to the seed surface, creating a protective zone around the germinating seed and emerging radicle, safeguarding the young plant from biotic and abiotic stresses that affect crop stand establishment. Unlike genetic or physiological modifications that alter the seed’s intrinsic germination processes, seed treatments act externally, protecting the seed from the surrounding environment and increasing the likelihood of successful emergence in crops (Lamichhane et al., 2022). 

Modern seed treatment formulations typically combine multiple categories of active ingredients to address risks during the early establishment stages. Fungicidal active ingredients protect against soil-borne pathogens such as Pythium, Rhizoctonia, and Fusarium, which can cause seed decay, damping off, and poor crop stand establishment. Insecticidal treatments reduce risks from early-season soil pests and seed-feeding pests that attack germinating seeds and developing root systems. Biological seed treatments, including beneficial microorganisms such as Trichoderma spp. and plant growth-promoting rhizobacteria, help suppress pathogen activity through competitive interactions and enhance root growth and nutrient uptake. In addition, micronutrient coatings containing elements such as zinc, molybdenum, and iron can alleviate localized nutrient deficiencies in the germination zone, which supports key metabolic processes involved in germination and early seedling development.  

The primary advantages of seed treatment are protective in nature rather than transformative. By reducing disease and pest pressure, these methods improve microbial interactions and enhance nutrient availability around the seed, thereby increasing the likelihood of rapid, uniform emergence. Seed treatments contribute to stronger stand establishment, greater emergence uniformity, and improved early-season vigor, creating a foundation for enhanced crop performance throughout the growing season (Sivarathri et al., 2024).

Seed priming 

In contrast to seed treatments, which act externally to protect seeds during germination, seed priming modifies physiological processes within the seed during germination and improves seedling vigor. It is a controlled hydration technique that allows the seed to initiate the early phases of germination without radicle protrusion (Sivarathri et al., 2023). Metabolic activities associated with germination will be activated, including reserve mobilization, membrane repair, DNA and protein repair mechanisms, activation of antioxidant enzymes, and synthesis of stress-responsive proteins. The seed is subsequently re-dried to a storage-stable state, preserving these physiological advancements while maintaining the practical advantages of conventional seed handling, storage, and planting (Jarrar et al., 2024).  

Seed priming encompasses a diverse range of approaches that differ in the nature of the priming agent and the physiological responses they enhance (Hasanovic et al., 2025; Marthandan et al., 2020). Hydropriming, the simplest method, utilizes water alone to initiate metabolic activation and is widely valued for its low cost and ease of implementation. Osmopriming employs osmotic solutions such as polyethylene glycol, potassium nitrate, or inorganic salts to regulate water uptake, enabling precise control of seed hydration and metabolic activity. Nutripriming combines hydration with nutrient delivery, incorporating essential elements such as zinc, iron, manganese, or potassium into seed tissues to enhance both germination performance and early seedling nutrition.  Biostimulant priming utilizes materials such as humic acids, seaweed extracts, beneficial microorganisms, and plant growth-promoting rhizobacteria to enhance metabolic activity, promote root development, and improve stress resilience (Sivarathri et al., 2025). Chemical priming employs signaling molecules and bioactive compounds, including salicylic acid, hydrogen peroxide, polyamines, and other elicitors, that activate antioxidant defense systems and induce protective stress-response mechanisms (Zaid e al., 2022). Nano-priming represents an emerging frontier in seed enhancement technology, using engineered nanomaterials such as nano-zinc oxide, nano-titanium dioxide, and carbon-based nanostructures to enhance water uptake, regulate enzyme activity, and modulate stress-responsive gene expression (Nile et al., 2022).  

The fundamental advantages of seed priming are that it physiologically prepares seeds for rapid, uniform germination after planting. By advancing key metabolic processes prior to sowing, primed seeds accelerate germination and emergence, improve seedling establishment, increase tolerance to environmental stresses, and enhance early-seedling growth and development. Consequently, seed priming is a proactive strategy that strengthens a seed’s intrinsic capacity to withstand challenging conditions and capitalize on favorable growth opportunities during the critical establishment phase.  

Stressors during the growing season

The crop life cycle is divided into three phases: the seedling stage, the vegetative stage, and the reproductive stage, each characterized by unique physiological processes and yield-determining mechanisms. Exposure to biotic or abiotic stress can impose distinct limitations on crop performance by affecting specific yield components and determining the difference between genetic potential and final harvestable yield. Understanding the nature, timing, and yield consequences of these stage-specific stresses is important for identifying the role of early seedling establishment and seed enhancement strategies to overcome them.

Seedling stage stresses

The seedling stage, which spans from radicle emergence to the establishment of the first true leaves and photoautotrophic independence, is the most physiologically vulnerable phase in the entire crop life cycle (Figure 3). This phase is susceptible to a range of biotic and abiotic stressors that can affect stand density before the crop ever reaches canopy closure. Moreover, seedlings lack structural rigidity, cuticle thickness, root volume for soil exploration, and biochemical defense systems compared with mature plants, making the seedling stage disproportionately vulnerable (Beikircher et al., 2025). 

Among the abiotic factors, soil crusting and mechanical impedance represent the most prevalent physical stresses limiting seedling emergence in fine-textured soils following rainfall or overhead irrigation, creating a hardened surface layer that restricts the emerging coleoptile or hypocotyl from developing sufficient turgor pressure to penetrate. Suboptimal soil temperatures at planting suppress germination enzyme activity, reduce membrane fluidity, and slow radicle elongation rates, further making the seed vulnerable to pathogen attack and physical stress (Sivarathri et al., 2024). 

Soil-borne pathogens such as Pythium ultimum, Rhizoctonia solani, and Fusarium species exploit the metabolically active, germinating seed as a primary infection target, causing seed decay, pre-emergence damping-off, and post-emergence hypocotyl lesions that abort seedlings before or shortly after soil-surface emergence (Scheuerell et al., 2005). Waterlogging following post-planting rainfall induces hypoxic stress in the germination zone, inhibiting mitochondrial respiration, suppressing radicle elongation, and predisposing seedlings to secondary Pythium infection that compounds the physical stress of oxygen deficiency (Zhou et al., 2020). 

Collectively, stresses during the seeding stage act primarily on the first yield components, such as plants per unit area, causing permanent, irreversible stand reductions that are disproportionately consequential for final yield relative to stress losses sustained at later growth stages. 

Vegetative stage stresses

During the vegetative stage, leaf area establishment through canopy closure to the transition to reproductive development, stress impacts are expressed primarily through reduction in leaf area index, biomass accumulation rate, root system expansion, and the number of reproductive organs initiated at the transition to flowering. Limited rainfall during this stage reduces stomatal conductance, suppresses photosynthetic carbon assimilation, and limits leaf area expansion, which reduces the photosynthate pool available for reproductive organ initiation at the critical transition from vegetative to reproductive development (Qiao et al., 2024; Poudel et al., 2025).

Moreover, nitrogen deficiency limits chlorophyll synthesis, reduces Rubisco concentration, and suppresses the rate of leaf area development, thereby affecting radiation use efficiency (Sahoo et al., 2025). Weed competition for resources during this stage particularly affects stands with poor emergence uniformity, where canopy gaps created by missing or late-emerging plants provide microsites for competitive weed species, intensifying resource competition across the entire stand (Savic et al., 2025). Stressors during this stage affect the yield components, such as reproductive organs per plant, by affecting the photosynthate availability that drives flower and pod or ear initiation. 

Reproductive stage stresses

The reproductive stage, encompassing flowering, fertilization, embryo development, and grain fill, is the most yield-sensitive phase of the crop life cycle in terms of the severity of yield loss per unit of stress imposed (Shabbir et al., 2022). Among them, heat stress during anthesis is particularly destructive, as elevated temperatures significantly reduce pollen viability, leading to fertilization failure, embryo abortion, and pod or ear shedding, thereby reducing the number of seeds per pod or kernels per ear (Poudel et al., 2023). 

Moreover, drought stress during this stage reduces the rate of assimilate supply from source leaves to filling grains, increases the rate of leaf senescence, which affects the effective grain-filling phase, and activates abscisic acid signaling, thereby accelerating crop maturity and compromising grain-fill duration and reducing final seed weight (Poudel et al., 2024). The cumulative consequence of stress during the reproductive stage is a reduction in both the number and weight of individual seeds, which are most proximate to the final harvestable yield and therefore most directly determinative of the economic return from the entire season’s production.

How stress affects yield components

Crop yield is mathematically the product of four sequentially determined yield components, such as plants per unit area, reproductive organs per plant, seeds per organ, and individual seed weight, which are established during a specific developmental window, and each is differentially sensitive to the type, timing, and severity of stress encountered during that window (Figure 4; Taranto et al., 2023). The cascade of stress effects through this yield component hierarchy follows a consistent biological logic that stress at each stage reduces the components established during that stage, and because each component sets the numerical boundary within which subsequent components are expressed, losses compound multiplicatively rather than additively through the season. 

Plants per unit area are established entirely during the seedling stage and are the only component that is completely irreversible once established and cannot be substituted by any agronomic intervention. The second yield component, reproductive organs per plant, is expressed as pods per soybean plant, ears per maize plant, or tillers per wheat plant. It is established during the vegetative stage through the photosynthate-driven process of floral initiation and inflorescence development. Stressors during this stage reduce the number of reproductive organs produced per plant, a loss that partially offsets low stand density but compounds yield reductions when vegetative-stage stress follows seedling-stage stand losses. 

The third yield component, seeds per pod or kernels per ear, is the most sensitive reproductive stage. It is often restricted by heat stress and operates within a narrow developmental window that is highly yield determinative and highly sensitive to stressors. The fourth component is individual seed weight, which reflects the balance between assimilative supply from source tissues and the demand of competing filling sites during grain fill. It is affected by any stress that either reduces source strength by shortening grain fill duration or accelerates maturity signaling under terminal drought or heat conditions. 

The practical significance of this cascade for establishment-focused management is that protecting the first yield component, plant stand density through seed enhancement strategies, simultaneously buffers the crop’s capacity to maintain the second, third, and fourth components. This ensures that each plant enters subsequent stress events with the root architecture, canopy development, and physiological vigor needed to sustain assimilate supply and stress tolerance through flowering and grain filling. Seed priming, by improving the speed and uniformity of establishment, not only protects plants per unit area, but also supports crop development, structurally and physiologically, producing better plants that can maintain all four yield components under the stresses they will encounter throughout the growing season. 

Conclusions

Early seedling establishment is the most critical and irreversible determinant of crop yield, serving as the biological foundation on which the plant population, canopy architecture, root development, and most yield components are constructed. The compounding consequences of this could resonate through the seedling, vegetative, and reproductive stages in ways that no subsequent agronomic intervention can correct, underscoring the disproportionate yield leverage of pre-sowing investment relative to all other management practices.

Seed enhancement strategies, particularly the complementary combination of seed treatment and seed priming, directly address these establishment constraints at their biological origin by protecting the germinating seed from external threats while simultaneously reprogramming its internal physiology for faster, more uniform, and more stress-resilient emergence. By protecting the first and most irreversible yield component, plant stand density, these strategies simultaneously buffer the crop’s capacity to sustain reproductive organs per plant, seeds per organ, and individual seed weight under growing-season stresses. Seed priming represents a cost-effective, immediately adoptable, and agronomically compelling investment for reducing the yield gap between attainable and actual farm productivity.