1 Introduction

Bell pepper (Capsicum annuum L.), belonging to the Solanaceae family, is a widely cultivated and economically significant vegetable crop in Nepal (Vivek et al., 2017; Rekha et al., 2018). Commonly known as sweet pepper or Shimla mirch, it is valued for its rich nutritional profile, vibrant color, and versatility in culinary uses. Although it is a perennial plant, it is usually grown as an annual crop due to climatic suitability. The crop thrives in tropical to sub-temperate conditions, and is adaptable to elevations up to 2 000 meters, making it suitable for diverse agro-climatic zones of Nepal. Bhojpur district, a notable vegetable production area, has emerged as a key site for capsicum cultivation, covering approximately 482 hectares with an average yield of 1,817 metric tons per hectare (MoALD, 2023). The crop prefers fertile, humus-rich, well-drained soil with a pH between 5.5 and 5.6, and optimal growth occurs between 21  °C and 25  °C. Temperatures above or below this range can negatively affect germination and fruit development (Demir et al., 2010).

Despite its importance, bell pepper cultivation in Nepal faces several constraints such as low germination rates, poor seedling vigor, pest and disease incidence, and inadequate nursery management (Agarwal et al., 2007). Among these, low seed germination and weak seedling vigor remain primary bottlenecks affecting overall productivity. Seedling performance is influenced by seed quality, environmental conditions, and especially by the growing media used (Sabatino, 2020). The selection of appropriate growing media is critical for improving seed germination, seedling uniformity, and transplant quality. An ideal medium should offer a balanced structure for anchorage, aeration, moisture retention, and nutrient availability (Khanal et al., 2024). Several studies have evaluated various growing media combinations to enhance the early-stage growth of vegetable crops.

For instance, Abad et al. (2002) and Sabatino (2020) emphasized the physical and chemical characteristics of substrates—such as coco peat, vermicompost, peat moss, perlite, and FYM-in determining seedling performance. However, much of the global research has focused on standardized conditions in controlled environments, and findings may not always translate effectively to Nepal’s unique agro-ecological settings. While Bhusal et al. (2023) and Khanal et al. (2024) have recently studied substrate effects in the Nepalese context, their findings are geographically limited and do not specifically address bell pepper under portray-based systems in high-altitude regions like Bhojpur. Moreover, comparative evaluations of commonly accessible local substrates in terms of their influence on germination rate, shoot length, root vigor, and seedling quality remain insufficiently explored.

However, traditional transplanting methods still dominate in many parts of Nepal, primarily due to high initial investment costs and limited awareness among farmers (Bosland et al., 2012). These methods are often linked to lower productivity, inferior seedling quality, and increased production costs (Bhusal et al., 2023). In addition, unpredictable environmental conditions frequently disrupt timely seedling production, resulting in inconsistent cropping cycles (Khanal et al., 2024). To address these challenges, portray-based seedling production systems have emerged as a viable alternative. This technique enables the timely and uniform production of healthy seedlings, reduces input costs, and improves seedling vigor (Behera, 2016). It is particularly effective in regions where traditional nursery beds are vulnerable to climate-induced stresses. A critical determinant of success in portray-based nurseries is the choice of growing media (Agarwal et al., 2007).

Various soil-based and soilless substrates—such as soil, sand, coco peat, peat moss, farmyard manure (FYM), vermicompost, rice husk, perlite, and vermiculite—have been studied for their effectiveness in improving germination and early growth (Bhusal et al., 2023; Khanal et al., 2024). Each medium possesses distinct physical and chemical properties that influence water retention, nutrient availability, aeration, and microbial activity (Abad et al., 2002). The integration of modern nursery practices with optimal growing media has demonstrated improvements in germination rates, reduction in seedling mortality, and enhanced early vigor (Bhusal et al., 2023). In areas like Bhojpur, where vegetable cultivation underpins local livelihoods, adopting improved nursery techniques such as portray-based seedling production with context-specific growing media can play a transformative role in sustainable agricultural development (Agarwal et al., 2007; Khanal et al., 2024).

Given the importance of growing media in determining the success of bell pepper cultivation, this study aims to evaluate the effects of different growing media on seed germination and seedling traits. The findings of this research will provide valuable insights into the selection of optimal growing media for capsicum seedling production in Bhojpur, Nepal. By identifying the most effective growing media, this study seeks to enhance seedling quality, improve transplanting success rates, and ultimately boost capsicum productivity in the region.

2 Materials and Methods

2.1 Experimental site and geographical location

The experiment was conducted from January to June 2023 at the research facility of the Agricultural Knowledge Center (AKC), Dandagaun, Bhojpur Municipality-7, Bhojpur. The study site is geographically positioned at 27°10'0" North latitude and 87°03'0" East longitude, with an elevation of 1,560 meters above sea level. Bhojpur district, located in Koshi Zone within Province No. 1 of Nepal, lies in the mid-hills of Eastern Nepal and provides a diverse agro-climatic environment suitable for vegetable cultivation. During the experimental period, the study area experienced significant climatic variations.

The mean temperature ranged from a minimum of 12 °C to a maximum of 28 °C, with considerable daily and weekly fluctuations. The relative humidity varied between 65% and 95%, indicating a generally humid environment conducive to seed germination and seedling growth. Precipitation levels ranged from 10 mm to 120 mm per week, affecting soil moisture availability and seedling development. To further analyze the environmental conditions of the experimental site, a geographical representation of the study area was prepared using GIS tools (Figure 1).

2.2 Experimental setup and treatments details

The experiment was conducted inside a plastic tunnel at Bhojpur, Nepal, to evaluate the influence of different growing media on the seedling performance of two bell pepper varieties. The soil used in the experiment was loamy in texture, classified as loam, with a moderately acidic pH of 5.9. A 2 × 5 factorial Completely Randomized Design (CRD) was adopted, involving two factors: Factor A (variety) with two levels—Sagar Hybrid F1 and California Wonder F1—and Factor B (growing media) with five levels—control (soil only), soil + coco peat, soil + farmyard manure (FYM), soil + vermicompost, and soil + coco peat+FYM + vermicompost (Figure 2).

Each treatment was replicated three times, resulting in a total of 30 experimental units. To enhance germination, the seeds were soaked in clean water for 12 hours prior to sowing. Sowing was performed using plastic portray trays, commonly used by local farmers, with each tray consisting of 50 cells (10 × 5 configuration). Two treatments were assigned per tray, with each treatment occupying 25 cells, and a single seed was sown per cell. The cells were filled halfway with the respective growing media, followed by seed placement, and then covered with the remaining media. Each treatment unit received 20 seeds, and five seedlings were randomly selected from each for observation. The trays were arranged randomly inside the plastic tunnel as per the CRD layout. Light irrigation was applied based on the moisture condition of the growing media to ensure proper germination and uniform seedling development throughout the experimental period.

2.3 Observation and data collection

Throughout the experiment, various germination and growth parameters were systematically recorded. Germination was monitored daily for seven days following showing to assess germination characteristics and trends. The number of germinated seeds was counted continuously during this period to evaluate germination performance. For growth analysis, five seedlings were randomly selected from each replication at 12, 18, 24, and 30 days after sowing (DAS). These selected seedlings were carefully uprooted and examined to measure key growth parameters. This approach enabled a detailed assessment of seedling development over time, providing valuable insights into their growth dynamics under different growing media conditions.

2.4 Germination parameters

This study aimed to evaluate essential germination parameters, including germination percentage, germination energy, germination speed, vigor index, and the germination rate index. Germination percentage represents the proportion of seeds that successfully sprout under optimal conditions, serving as an indicator of seed viability. Germination energy measures the percentage of seeds that germinate within a specific period, providing insight into seedling uniformity and early vigor. Germination speed reflects the rate at which seeds emerge over time, emphasizing differences in efficiency. The vigor index integrates various seed traits that influence seedling development, making it a critical measure of seedling strength. Meanwhile, the germination rate index offers a cumulative assessment of germination speed by considering the number of seeds germinated at different time points. These parameters were determined using the formulas established by Mehata et al. (2023), ensuring a methodical and comprehensive analysis of seed germination behavior. This systematic approach enabled a thorough examination of seed performance across treatments, enhancing the understanding of seedling establishment and initial growth.

2.5 Vegetative growth metrics

The evaluation of capsicum seedling growth parameters involved precise measurements of root and shoot lengths using a graduated scale. At 25, 30, 35, and 40 days after sowing (DAS), five randomly selected seedlings were carefully uprooted, and their root and shoot lengths were recorded. Additionally, an electronic weighing machine was employed to determine the fresh weight of these seedlings. To assess dry weight, a separate set of five seedlings was subjected to an air-drying process. This integrative methodology facilitated a comprehensive analysis of capsicum seedling development, capturing both morphological dimensions and biomass accumulation across distinct growth stages.

2.6 Statistical analysis

The collected raw data was systematically arranged in chronological sequence for both treatment and replication blocks using MS Excel 2021 (Microsoft Corporation, Washington, USA). Subsequent statistical analysis was performed in R Studio (Version 4.2.2, Boston, Massachusetts, USA) by conducting ANOVA. Mean comparisons among different treatments were carried out using Duncan’s Multiple Range Test (DMRT) at a 5% significance level. Furthermore, R Studio facilitated an in-depth examination of interactive effects between treatments and varieties, allowing for a more nuanced understanding of treatment-specific responses across different genetic backgrounds.

3 Results and Analysis

3.1 Effect of different treatments on germination parameters of capsicum varieties

Significant variation was observed among treatments and varieties for germination percentage at early stages, particularly at 12 days after sowing (DAS), where the varietal effect was statistically significant (p < 0.05) (Table 1). Variety V2 (California Wonder F1) exhibited slightly higher germination (33%) compared to V1 (Sagar Hybrid F1) at 28%. However, from 18 DAS onwards, no significant differences were found between varieties, indicating that both ultimately reached comparable final germination percentages (82%-83%) by 30 DAS.

In contrast, the effect of growing media on germination was highly significant across all time points (p < 0.001 at 12 and 18 DAS, p < 0.01 at 24 and 30 DAS). Among the five media, M4 (soil + vermicompost) consistently exhibited the highest germination, reaching 90.83% at 30 DAS, followed closely by M5 (soil + FYM + coco peat), which reached 85.83%. These findings underscore the influence of organic matter-enriched media on seed emergence. The control (M1), consisting of plain soil, lagged significantly, achieving only 70.5% germination at 30 DAS. Although the interaction between variety and media was not statistically significant for germination percentage, trends revealed that V2.M5 (California Wonder in soil + FYM + coco peat) attained the highest final germination (88.33%), while the lowest was recorded in V2.M1 (control) at just 64.66%.

In terms of germination rate index (GRI), no significant effect of variety was observed; however, the effect of growing media was highly significant (p < 0.001). M4 and M5 media yielded the highest GRI values at 67.70 and 64.60, respectively, indicating rapid and uniform germination under these treatments. Conversely, M1 recorded the lowest GRI (50.02), confirming the detrimental effect of nutrient-deficient media on germination speed. Although interaction effects were not statistically significant, numerically higher GRI values were observed in V1.M4 (68.70) and V2.M5 (66.80), suggesting that both media and variety together can enhance early seed performance.

Seedling vigor index (SVI) exhibited a statistically significant interaction effect between variety and media (p < 0.05), even though the main effects of variety and media were individually non-significant. The combination V2.M5 recorded the highest SVI (1133.83), followed by V1.M4 (933.63) and V1.M5 (766.26), all of which grew in organically enriched media. In contrast, V1.M1 and V2.M1, both under control treatment, showed the lowest SVI values at 398.38 and 477.18, respectively. These outcomes suggest that media enriched with vermicompost, FYM, and coco peat substantially contribute to better seedling vigor, especially when paired with genetically responsive cultivars.

The interaction between cultivars and growing media for germination percentage, germination rate index and vigor index are presented in Figure 3, Figure 4, and Figure 5, respectively. This shows that both Sagar Hybrid F1 and California Wonder responded positively to enriched growing media, with Sagar Hybrid F1 consistently outperforming in germination percentage and rate, especially under Soil + Vermicompost. California Wonder showed the highest vigor index under Soil + Cocopeat + FYM + Vermicompost, indicating that organic media combinations significantly enhance early seedling performance.

3.2 Effect of different treatments on seedling length

The analysis of variance revealed a highly significant difference (p < 0.001) in seedling length between the two Capsicum varieties (Table 2). Across all observation periods—25, 30, 35, and 40 days after sowing (DAS)—California Wonder (V2) consistently exhibited longer seedlings than Sagar Hybrid F1 (V1). At 40 DAS, V2 achieved a maximum seedling length of 4.66 cm, while V1 reached 3.90 cm, with mean values of 3.14 cm and 2.65 cm, respectively. Growth media composition had a significant effect (p < 0.001) on seedling elongation at all developmental stages. The highest seedling length was observed in M5 (Soil + Cocopeat + FYM + Vermicompost in 1:1:1:1), recording 6.91 cm at 40 DAS. This was followed by M4 (Soil + Vermicompost) with 5.25 cm, and M3 (Soil + FYM) with 4.46 cm.

In contrast, the control treatment M1 (Soil only) produced the shortest seedlings, with just 1.20 cm at 25 DAS and a mean of 1.71 cm across the growth period. Although the interaction between varieties and growth media was statistically non-significant, Figure 6 illustrates a clear trend in the interaction dynamics. Notably, California Wonder (V2) displayed enhanced responsiveness to organic-enriched media, particularly M5, where it attained the highest seedling length (7.36 cm) at 40 DAS. Sagar (V1) also responded well to M5, reaching 6.46 cm, yet remained consistently lower than V2 across all treatments. These visual trends highlight the synergistic effect of varietal potential and substrate quality in promoting seedling vigor.

3.3 Effect of growing media on stem diameter

Table 3 presents the influence of different growth media mixtures and Capsicum varieties on stem diameter. The analysis of variance showed highly significant differences (p < 0.001) between the varieties at 25, 30, and 35 days after sowing (DAS), and a significant difference (p < 0.05) at 40 DAS. Among the varieties, California Wonder (V2) consistently outperformed Sagar (V1) in stem thickness, attaining the highest diameter of 0.24 cm at 40 DAS, compared to 0.23 cm in V1. On average, V2 had a stem diameter of 0.20 cm, while V1 had 0.19 cm. Growth media composition had a profound and highly significant effect (p < 0.001) on stem diameter throughout the seedling stage. The maximum stem thickness (0.28 cm) was observed in M5 (Soil + Cocopeat + FYM + Vermicompost in 1:1:1:1 ratio) at 40 DAS, followed by M4 (Soil + Vermicompost) with 0.26 cm, and M3 (Soil + FYM) with 0.25 cm. The smallest stem diameter (0.11 cm) was recorded in the control treatment (M1: Soil alone) at 25 DAS. These results underscore the superior role of organic-enriched substrates in promoting stem robustness during early growth stages.

While the variety × media interaction effect was not statistically significant at most stages, Figure 7 depicts discernible trends. California Wonder (V2) again showed greater responsiveness to organic amendments, particularly in M5, where it achieved a stem diameter of 0.28 cm, closely followed by M4 and M3. In contrast, Sagar (V1) showed consistently thinner stems under all media, though it also responded positively to M5, reaching 0.29 cm, its highest recorded value. These trends in Figure 7 illustrate the cumulative benefit of genetic potential and media quality in enhancing stem thickness.

3.4 Effect of different growing media on the number of leaves

Table 4 presents the effect of growth media mixtures with capsicum varieties on the number of leaves, while Figure 8 illustrates the interaction effects between varieties and media types across four developmental stages (25, 30, 35, and 40 days after sowing DAS). The analysis showed no significant difference between the two varieties (V1: Sagar Hybrid F1, V2: California Wonder) in the number of leaves at any growth stage, with mean values ranging from 0.53 to 3.12 leaves per plant. This indicates that genetic variation alone did not significantly influence leaf emergence during early growth stages under the experimental conditions. In contrast, a highly significant effect (p < 0.001) was observed among the different growing media treatments at all growth stages. At 40 DAS, the highest number of leaves (5.13) was recorded in the treatment M5 (Soil + Cocopeat + FYM + Vermicompost at 1:1:1:1), followed by M4 (Soil + Vermicompost, 4.10) and M3 (Soil + FYM, 3.70). These enriched organic mixtures clearly promoted superior leaf development compared to the control (M1: soil alone), where seedlings failed to develop leaves at 25 and 30 DAS and only produced 0.73 leaves on average by 40 DAS.

Table 4 Effect of growth media mixtures with capsicum varieties on number of leaves Note: ***Significant at 0.1% level of significance, NS: Non-significant, LSD: Least significant difference, SEM: Standard error of the mean, CV: Coefficient of difference, Where M represents growing media and V represents varieties, different lowercase letters represent mean comparison

Figure 8 reveals the interaction trends between varieties and media types. Although the interaction effect was not statistically significant, graphical analysis shows that both varieties exhibited the highest leaf counts when grown in M5, with V1 and V2 producing 5.26 and 5.00 leaves, respectively, at 40 DAS. Interestingly, V1 (Sagar Hybrid F1) responded more favorably to M5, surpassing V2 at certain stages such as 35 DAS (4.60 vs. 4.06 leaves). Meanwhile, V2 showed slightly better performance than V1 in M4 and M3 treatments. The control and cocopeat-only treatments (M1 and M2) consistently resulted in minimal leaf development for both varieties.

Figure 8 Interactions between varieties and growing media on leaf number

3.5 Effect of growing media on root length and leaf area

The findings from Table 5, supported by the interaction plots in Figure 9 and Figure 10, reveal that both capsicum variety and growing media significantly affected root length and leaf area 40 days after sowing, although the interaction effect was statistically non-significant for both traits (p > 0.05). Among the varieties, California Wonder (V2) recorded significantly greater root length (4.36 cm) compared to Sagar Hybrid F1 (V1) (3.72 cm), while for leaf area, although no significant difference was detected, California Wonder showed a numerically higher mean value (4.28 cm²) than Sagar Hybrid F1 (3.33 cm²). The media treatment Soil + Cocopeat + FYM + Vermicompost (M5) significantly outperformed all others, resulting in the longest roots (5.70 cm) and largest leaf area (9.75 cm²), followed by Soil + FYM (M4) and Soil + Cocopeat + FYM (M3).

Table 5 Effect of growth media mixtures with capsicum varieties on root length and leaf area Note: ***Significant at 0.1% level of significance, NS: Non-significant, LSD: Least significant difference, SEM: Standard error of the mean, CV: Coefficient of difference, Where M represents growing media and V represents varieties, different lowercase letters represent mean comparison

The poorest growth was seen in the Control (M1) and Soil + Cocopeat (M2), both of which had notably lower values for root length and leaf area. As shown in Figure 9, California Wonder showed a sharp increase in root length under enriched media (especially M5), peaking above 6 cm, while Sagar Hybrid F1 also improved with enrichment but to a lesser extent. Similarly, in Figure 10, both varieties had the lowest leaf areas under M1 and M2, while the highest was recorded for California Wonder under M5, exceeding 10 cm², compared to Sagar Hybrid F1’s 8.78 cm² under the same treatment. These trends suggest that while varietal differences exist, growing media composition has a much stronger influence, particularly when supplemented with organic amendments like FYM and vermicompost. Although the varietal × media interaction was not statistically significant, the graphical patterns confirm that California Wonder responds more positively to enriched conditions, especially in terms of root elongation and canopy development, emphasizing the importance of integrated organic media for robust seedling establishment.

3.6 Effect of different growing media on mass of seedlings

The results presented in Table 6 and illustrated in Figure 11 and Figure 12 demonstrate that both the variety and growing media treatments significantly influenced the fresh weight and dry weight of capsicum seedlings, although their interaction effect was statistically non-significant. Among the varieties, California Wonder (V2) recorded a higher mean fresh weight (0.56 g) and dry weight (0.06 g) compared to Sagar Hybrid F1 (V1), which had 0.47 g fresh weight and 0.04 g dry weight, with significant varietal differences observed at the 5% level for both parameters. Regarding media treatments, the Soil + Cocopeat + FYM + Vermicompost (M5) treatment resulted in the highest values for both fresh weight (1.13 g) and dry weight (0.12 g), followed by Soil + FYM (M4) and Soil + Cocopeat + FYM (M3), which produced moderate values. In contrast, control (M1) and Soil + Cocopeat (M2) had the lowest values for both traits.

Table 6 Effect of growth media mixtures with capsicum varieties on fresh weight and dry weight Note: ***Significant at 0.1% level of significance, NS: Non-significant, LSD: Least significant difference, SEM: Standard error of the mean, CV: Coefficient of difference, Where M represents growing media and V represents varieties, different lowercase letters represent mean comparison

Figure 11 Interaction plot between growing media and cultivars of capsicum on fresh weight

Figure 12 Interaction plot between varieties and growing media on dry weight

These results are consistent with the interaction trends shown in Figure 11, where fresh weight peaked dramatically under M5 for both varieties, with California Wonder slightly outperforming Sagar Hybrid F1. A similar pattern was observed for dry weight in Figure 12, where California Wonder again showed higher dry matter accumulation under M5, followed by M4 and M3, and the lowest under M1 and M2. Though the interaction effect (V × M) was statistically non-significant (p > 0.05), the trend indicates that enriched media combinations, particularly those including vermicompost, significantly enhance seedling biomass. The variability (CV%) for fresh and dry weights was moderately high, at 27.33% and 24.82%, respectively, indicating environmental influence or individual seedling response variability. Overall, the results suggest that California Wonder had a superior biomass response, and Soil + Cocopeat + FYM + Vermicompost proved to be the most effective media combination for promoting early seedling growth in both varieties.

4 Discussion

The study revealed that growing media had a stronger influence on seed germination, germination rate index (GRI), and seedling vigor index (SVI) than variety. While varietal differences in germination were only significant at 12 DAS, both varieties reached similar final germination (~82%-83%) by 30 DAS. In contrast, media enriched with organic matter—especially M4 (soil + vermicompost) and M5 (soil + FYM + coco peat)—consistently enhanced germination (up to 90.83%), GRI (67.70), and SVI (1133.83). These findings align with Arancon et al. (2012a), who reported improved germination and seedling vigor in media amended with vermicompost due to increased microbial activity and nutrient availability. Similarly, Araujo et al. (2012) attributed better germination performance to the presence of beneficial microbes in organic substrates, which may explain the faster and more uniform emergence seen here. Awang et al. (2009) found that coco peat improved water retention and aeration, supporting our results where M5 showed strong GRI and SVI values. Bhardwaj (2013) also emphasized the role of FYM in enhancing seedling health through slow nutrient release. Compared to Agrawal et al. (2007), who linked improved germination to better physiological conditions, our findings confirm that enriched media modify both environmental and physiological factors to boost early seed performance.

The study found that both variety and growing media significantly influenced seedling length in Capsicum. California Wonder (V2) consistently produced longer seedlings than Sagar Hybrid (V1) across all time points, with a maximum length of 4.66 cm at 40 DAS. This varietal difference may be attributed to inherent genetic vigor and growth potential, as suggested by Khanal et al. (2024), who observed superior elongation in pepper genotypes with higher metabolic efficiency and better resource utilization. Growing media had an even greater effect, with M5 (soil + cocopeat + FYM + vermicompost) supporting the longest seedlings (6.91 cm), likely due to enhanced aeration, moisture retention, and sustained nutrient release. This is consistent with Mathowa et al. (2017), who reported improved seedling growth in nutrient-rich and well-aerated media. M4 and M3 also performed well, highlighting the contribution of organic amendments like vermicompost and FYM. These media may have facilitated better root development and nutrient uptake, as also noted by Olatunji et al. (2019), who emphasized the role of organic matter in promoting seedling elongation. Although the interaction between variety and media was not statistically significant, the stronger response of V2 in enriched media (especially M5) supports Matsubara et al. (2011), who found genotype-specific responses to substrate conditions in early seedling growth.

The study revealed that both varietal differences and growing media composition significantly influenced stem diameter in Capsicum seedlings. California Wonder (V2) consistently exhibited greater stem thickness than Sagar Hybrid (V1), with the highest diameter of 0.24 cm at 40 DAS. This aligns with Khanal et al. (2024), who reported that certain genotypes possess superior structural vigor due to enhanced physiological efficiency and better nutrient allocation. Growth media had a more pronounced effect, with M5 (soil + cocopeat + FYM + vermicompost) supporting the highest stem diameter (0.28 cm), followed by M4 and M3. These findings are consistent with Mathowa et al. (2017) and Olatunji et al. (2019), who found that organic-enriched substrates improve stem robustness through improved soil structure, water-holding capacity, and nutrient content. The high organic matter in M5 likely facilitated sustained nutrient release and optimal moisture balance, contributing to stronger stem development. Although the interaction effect between variety and media was not statistically significant, visual trends showed V2 responding more favorably to enriched substrates, especially M5. This supports Matsubara et al. (2011), who noted genotype-specific growth responses to substrate quality, and mirrors trends in seedling elongation. These outcomes confirm that the synergy between cultivar potential and media quality enhances early seedling vigor, particularly in structural parameters like stem diameter.

The number of leaves in Capsicum seedlings was significantly influenced by the growing media but not by variety. Across all stages, no significant varietal effect was observed, with V1 and V2 producing a similar number of leaves, suggesting that genetic differences alone did not drive leaf emergence under these conditions. This aligns with Singh et al. (2019a), who found that early leaf development in Capsicum is more responsive to substrate quality than to cultivar. In contrast, growing media had a highly significant effect (p < 0.001) at all stages. M5 (soil + cocopeat + FYM + vermicompost) supported the highest leaf production (5.13 leaves at 40 DAS), followed by M4 and M3.

The superior performance of these organic-enriched substrates can be attributed to their improved physical and chemical properties, which enhance nutrient uptake and moisture retention. This supports Rekha et al. (2018) and Ravindran et al. (2019), who highlighted the role of organic amendments in promoting leaf initiation through better root-zone conditions. Although the variety × media interaction was not statistically significant, trends revealed V1 responded slightly better in M5, while V2 performed marginally better in M3 and M4. These findings are consistent with Singh et al. (2019b), who reported that genotype-media interactions can influence growth patterns, even when not statistically significant.

Both variety and growing media significantly influenced root length and leaf area in Capsicum at 40 DAS, though their interaction was not statistically significant. California Wonder (V2) exhibited significantly longer roots (4.36 cm) than Sagar Hybrid (V1) (3.72 cm), while it also showed a higher, though non-significant, leaf area (4.28 cm² vs. 3.33 cm²). These varietal differences reflect inherent physiological capacities, as suggested by Ravindran et al. (2019), who noted that genotypes with greater root expansion are better at nutrient and water uptake. Growing media had a much more pronounced effect. M5 (Soil + Cocopeat + FYM + Vermicompost) produced the longest roots (5.70 cm) and largest leaf area (9.75 cm²), indicating superior physical and nutritional conditions. These findings align with Singh et al. (2019a) and Rekha et al. (2018), who observed enhanced root and canopy development in substrates rich in organic matter. The poor performance of M1 (control) and M2 (soil + cocopeat) further supports the role of balanced nutrient inputs in promoting early seedling growth. Although the interaction effect was not significant, graphical trends showed V2 responding more strongly to enriched media, particularly M5, where it exceeded 6 cm in root length and 10 cm² in leaf area. This supports Singh et al. (2019b), who emphasized the genotype-specific advantages under optimal media conditions.

Both variety and growing media had significant effects on the fresh and dry weights of Capsicum seedlings, with growing media exerting a stronger influence. California Wonder (V2) consistently showed higher biomass accumulation, with fresh and dry weights of 0.56 g and 0.06 g, respectively, compared to Sagar Hybrid (V1), which recorded 0.47 g and 0.04 g. These findings align with Khanal et al. (2024) and Ravindran et al. (2019), who reported that varietal differences in biomass accumulation are linked to genotypic efficiency in resource uptake and translocation. Among media treatments, M5 (Soil + Cocopeat + FYM + Vermicompost) resulted in the highest biomass (1.13 g fresh and 0.12 g dry), demonstrating the superior nutritional and moisture-retaining capacity of this enriched mix. This agrees with Rekha et al. (2018) and Olatunji et al. (2019), who showed that organic amendments enhance seedling biomass by improving nutrient availability and root development. Poor performance in M1 (control) and M2 (soil + cocopeat) further emphasizes the importance of balanced organic inputs. Although the variety × media interaction was not statistically significant, trends showed that California Wonder responded more positively to organic-enriched substrates. These results are supported by Singh et al. (2019b), who highlighted that such media improve seedling growth across diverse genotypes, particularly in early stages.

5 Conclusion

The study demonstrated that the growth media composition significantly influenced the vegetative parameters of Capsicum varieties, with soil + cocopeat + FYM + vermicompost (1:1:1:1) emerging as the most effective medium. This treatment consistently showed superior results in seedling length (6.91 cm), stem diameter (0.28 cm), number of leaves (5.13), root length (5.70 cm), leaf area (9.75 cm²), fresh weight (1.13 g), and dry weight (0.12 g) at 40 DAS. The second-best performing medium was soil + vermicompost, which also provided substantial improvements in plant growth compared to control soil. The high performance of these media can be attributed to enhanced water retention, better aeration, and increased nutrient availability, as supported by various studies. Among the Capsicum varieties, California Wonder consistently exhibited higher vegetative growth than Sagar, particularly in seedling length, stem diameter, root length, and fresh weight. The lowest growth performance was observed in the control treatment (soil alone), indicating that organic amendments are essential for improving plant development. The findings emphasize the importance of integrating organic components like vermicompost, cocopeat, and FYM in seedling production to promote healthier and more vigorous growth, ultimately enhancing productivity in Capsicum cultivation. This study supports the use of organic amendments for sustainable vegetable farming.

Authors’ contributions

Prabin Sapkota, Rupesh Kumar Mehta, Chetana Roy, Abhishek Baniya: writing the article, creating the experimental setup, Literature research and statistical calculations of the data, performing the experiments, interpretation of the findings, literature research, and obtaining the necessary materials for the experiment. Jibisha Poudel, Sakshi Mandal, Arzu Chaudhary, Megha Upadhyay, Shafat Rukhsar, Lokesh Pokharel: interpretation of the findings, literature research, and obtaining the necessary materials for the experiment. All authors read and approved the final manuscript.

Acknowledgments

We express our sincere gratitude to G.P. Koirala College of Agriculture and Research Center for providing the necessary academic support and research facilities. We extend our heartfelt appreciation to the Prime Minister Agricultural Modernization Project for offering a platform to conduct this study. Their support was instrumental in the successful completion of this research. Our deepest thanks go to our advisors, faculty members, and fellow researchers for their invaluable guidance and constructive feedback throughout the study.

Conflict of Interest Disclosure

The authors affirm that this research was conducted without any commercial or financial relationships that could be construed as a potential conflict of interest.

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