Influence of biostimulants on flowering behaviour of different varieties of Calendula

Introduction

Calendula (Calendula officinalis L.) belongs to the order Asterales and family Asteraceae. The genus name Calendula is derived from the Latin word Calendae, which means 'first day of each month'. The genus has 29 species including Calendula officinalis L., Calendula (pot marigold) is widely used as an ornamental plant due to its bright yellow-orange flowers, long blooming period, and ease of cultivation. It is commonly grown in garden beds, borders, and pots, enhancing the aesthetic appeal of both private and public landscapes. Studies have highlighted that Calendula is extensively cultivated for ornamental and medicinal purposes (Arora et al., 2013) [1] . The term Panchagavya represents 'Pancha' means five and 'Gavya' means produce from cows (Bunkar, 2020) [2] . Panchagavya is composed of five cow products: cow dung, ghee, milk, curd, and cow urine. Foliar application of neem leaf extract has been reported to improve plant growth and physiological performance in different horticultural crops. The extract decreases oxidative stress caused by environmental variables while increasing chlorophyll synthesis, nutrient intake, photosynthetic efficiency, and antioxidant enzyme activity. Increased plant height, branch count, leaf area, and biomass accumulation are all signs of rapid vegetative growth, which is encouraged by these physiological developments. In ornamental crops, higher flower yield and better flowering performance are naturally supported by better vegetative growth. (Verma et al., 2021) [3] . Moringa leaf extract is also gaining popularity as a bio-stimulant. Foliar application of moringa leaf extract at a concentration of 3% significantly improved the number of branches (66%), leaves (52%), leaflets (42%), leaf chlorophyll a (41%) and b (71%), and total chlorophyll (49%) contents. (Batool et al., 2020) [4]

Materials and method

The current study, " Influence of Biostimulants on Flowering Behaviour of Different Varieties of Calendula " in the Chhattisgarh plain zone, was conducted at the Floriculture Farm College of Horticulture and Research Station in Sankara, Patan, Durg (C.G.) 2025-2026. A factorial randomized block design (FRBD) was used to assess the effect of various biostimulants on the growth, flowering, and yield of different Calendula varieties. Twelve treatments with two factors (factor 1 -variety and factor 2 -biostimulants) were randomly assigned to ensure uniformity. The entire lot of seedlings was randomized and divided into 36 plots.

Treatment combination

The experiment will be conducted in a Factorial Randomized Block Design (RBD) with three replications. The details of the treatments are presented in Table 1.

Table 1. Treatments Details

Treatment Notation

Treatment Combinations

Biostimulant treatments

The biostimulant treatments consisted of irrigation (control), Panchagavya (4%), neem leaf extract (5%), and Moringa leaf extract (5%). The first foliar spray was applied 6 days after transplanting (DAT), followed by the second spray 15 days after the first spray, and the third spray 15 days after the second spray.

Flowering parameter

The observations on flowering parameters were recorded from five randomly tagged plants in each plot. The days to first bud initiation and first flower opening were counted from the date of transplanting, while the days to 50% flowering were recorded when half of the plants in a plot had flowered. The number of flowers per plant was counted at maturity and averaged. Flower stalk length was measured in centimeters using a 1-m scale, flower diameter was measured across the maximum width of the flower head using a Vernier caliper, and flowering duration was recorded as the number of days from opening of the first flower to senescence of the last flower.

Result and discussion

Days to first flower bud initiation

Factor A (varieties) significantly influenced the duration until the first flower bud began to form. Lower values correspond to earlier initiation, with V 3 initiating the earliest at an average of 30.93 days, followed by V 2 at 31.16 days. V 1 took the longest, averaging 32.73 days, indicating a delay in initiation. Factor B (biostimulant treatments) also had a notable impact on the timing of the first flower bud's appearance. The earliest initiation occurred with B 2 (Neem Leaf Extract Spray 5%), averaging 31.19 days, followed by B 3 (Moringa Leaf Extract Spray 5%) at 31.22 days, and B 0 at 31.53 days. B 1 (Panchagavya Spray 4%) had the highest average at 32.47 days. The interaction between Factors A and B was statistically significant at the 5% level. Among all treatment combinations, V 2 B 2 resulted in the earliest flower bud initiation at 29.00 days, which was statistically significant and indicated the most favorable response. This was followed by V 3 B 3 and V 3 B 0 , both at 30.00 days, while V 1 B 1 took the longest at 34.57 days, showing delayed initiation. Singh et al. (2015) found earlier flower bud initiation in marigold with Panchagavyabased biodynamic management, and Trivedi et al. (2016) [5] noted earlier reproductive development in roses with bio-enhancer application.

Figure 1. Days to First Flower Bud Initiation

Days to first flowering

Factor A (varieties) exerted the most substantial influence on the duration until the first flowering. Lower values corresponded to earlier flowering; thus, V 3 exhibited the earliest first flowering with a mean of 36.83 days, followed by V 2 at 37.28 days, whereas V 1 required the longest period at 40.22 days, indicating delayed flowering. Factor B (biostimulant treatments) also significantly affected the number of days until the first flowering. The earliest flowering occurred with B 2 (Neem Leaf Extract Spray 5%), averaging 37.32 days, followed by B 3 (Moringa Leaf Extract Spray 5%) at 37.96 days, and B 1 (Panchagavya Spray 4%) at 37.99 days, while B 0 (Irrigation) exhib-ited the highest mean of 39.17 days, suggesting delayed flowering. The interaction between Factors A and B was statistically significant at the 5% level. Among all treatment combinations, V 2 B 2 demonstrated the earliest initial flowering at 34.27 days, which was statistically superior and the most favorable combination. This was followed by V 2 B 1 and V 3 B 1 , both at 36.33 days, with V 1 B 1 showing the highest number of days to first flowering at 41.97 days, indicating later flowering. Trivedi et al. (2016) [5] reported enhanced flowering behavior and earlier reproductive development in roses under a bio-enhancer treatment containing Panchagavya. Patra et al. (2026) [6] documented improvements in flowering characteristics following the application of natural leaf extracts.

Number of flowers per plant

Among the primary effects, Factor A (varieties) did not significantly influence the number of flowers per plant. Although the variety V 3 exhibited the highest mean number of flowers at 38.18 per plant, followed by V 2 with 36.34 and V 1 with 34.73, these differences were not statistically significant. In contrast, Factor B (biostimulant treatments) had a significant impact on the number of flowers per plant. The highest mean number of flowers was recorded under treatment B 2 (Neem Leaf Extract Spray 5%), with 44.36 flowers per plant, followed by [6] reported enhanced flower production using natural leaf extract.

Figure 3. Number of Flowers Per Plant

The flower diameter was influenced by the different varieties and biostimulant treatments. Among the varieties, V 2 recorded a flower diameter of 4.13 cm, followed by V 3 (4.09 cm), while the minimum flower diameter was recorded in V 1 (3.97 cm). The variation among varieties indicates differences in their inherent floral characteristics. Among the biostimulant treatments, B 2 recorded the maximum flower diameter (4.29 cm), followed by B 0 (4.16 cm) and B 3 (3.96 cm). The minimum flower diameter was observed under B 1 (3.85 cm). Thus, B 2 was comparatively more effective in improving flower diameter. The interaction between varieties and biostimulants revealed considerable variation in flower diameter. The maximum flower diameter (4.61 cm) was recorded in V 3 B 2 , followed by V 2 B 2 (4.34 cm) and V 2 B 0 (4.24 cm). In contrast, the minimum flower diameter (3.75 cm) was recorded in V 3 B 3 , followed by V 1 B 1 (3.82 cm). This indicates that the effectiveness of biostimulants differed according to the variety, with the V 3 B 2 combination showing the highest flower diameter. Larger flowers were observed in roses after combined bio-enhancer therapy (Trivedi et al. (2016) [5] .

The length of flower stalks was significantly influenced by Factor A (Varieties). Variety V 1 produced the shortest flower stems, measuring 13.83 cm, whereas V 3 exhibited the longest flower stalks at 16.06 cm, with V 2 following at 14.83 cm. The statistical significance of these differences at the 5% level underscores the superiority of V 3 in generating longer flower stalks. Factor B (Biostimulant treatments) also had a notable impact on flower stem length. The longest flower stalks were observed with B 2 (Neem Leaf Extract Spray 5%), achieving a mean length of 17.96 cm, followed by B 1 (Panchagavya Spray 4%) at 15.24 cm, and B 3 (Moringa Leaf Extract Spray 5%) at 13.94 cm. In contrast, B 0 (Irrigation) resulted in the shortest flower stalks. This suggests that the foliar application of neem leaf extract was most ef-fective in promoting flower stalk elongation. The interaction between varieties and biostimulant treatments was significant at the 5% level. The combination of V 3 and B 2 (Variety 3 + Neem Leaf Extract Spray 5%) yielded the longest flower stalks at 19.93 cm, demonstrating statistical superiority over other treatments. This was followed by V 2 B 2 at 18.21 cm and V 3 B 1 at 16.33 cm. The shortest flower stalks, measuring 12.21 cm, were recorded under V 1 B 0 (Variety 1 + Irrigation), indicating that the absence of biostimulant application led to reduced flower stalk length. Overall, the combination of V 3 and Neem Leaf Extract Spray (5%) proved to be the most effective treatment for enhancing flower stalk length in calendula. Previous studies by Patil et al. (2006) [7] reported improved flower stalk characteristics in tuberose with Panchagavya-based treatment, while Singh et al. (2007) [8] noted longer spikes with 4% Panchagavya.

Days to 50% flowering

Factor A (varieties) had a significant effect on the number of days taken to achieve 50% flowering. Lower values indicate earlier flowering. Among the varieties, V 3 had the earliest 50% flowering (44.98 days), followed by V 2 (46.97 days), and V 1 had the longest time to achieve 50% flowering (48.36 days), showing delayed flowering. Factor B (biostimulant treatments) had a significant effect on the number of days before 50% flowering. The earliest 50% flowering was observed under B 2 (Neem Leaf Extract Spray 5%) with a mean value of 45.03 days, followed by B 1 (Panchagavya Spray 4%) (45.89 days) and B 3 (Moringa Leaf Extract Spray 5%) (46.30 days), while B 0 (Irrigation) had the highest mean value (49.86 days), indicating de-layed flowering. The interaction effect between varieties and biostimulant treatments was not significant at the 5% level. Among all treatment combinations, V 3 B 2 (Variety 3 + 5% Neem Leaf Extract Spray) produced the earliest 50% flowering (42.10 days) and was statistically superior to the others. This was followed by V 2 B 2 (43.60 days) and V 3 B 1 (44.93 days). The largest number of days to 50% flowering (56.03 days) was observed with V 1 B 0 (Fiesta Gitana Orange + Irrigation), showing delayed flowering in the absence of biostimulant application. Overall, the combination of V 3 and Neem Leaf Extract Spray (5%) was found to be the most effective treatment for inducing earlier 50% flowering in calendula. Bellubbi et al. (2015) [9] reported a reduction in the time required to attain 50% flowering in gerbera following Panchagavya-based treatment.

Factor A (varieties) had a significant effect on flowering duration. Higher values led to a longer flowering period. Among the varieties, V 3 had the longest flowering time (44.83 days on average), followed by V 2 (41.69 days), while V 1 had the shortest flowering duration. This indicates that V 3 flowering occurred longer than the other varieties. Factor B (biostimulant treatments) had a significant effect on flowering time. B 1 (Panchagavya Spray 4%) had the longest flowering length (mean = 43.56 days), followed by B 2 (Neem Leaf Extract Spray 5%) (42.92 days) and B 3 (Moringa Leaf Extract Spray 5%) (42.77 days). The shortest flowering duration (40.41 days) was observed under B 0 (Irrigation), showing that the use of biostimulants de-layed the flowering period compared to the control. The interaction effect between varieties and biostimulant treatments was significant at the 5% level. V 3 B 2 (Variety 3 + Neem Leaf Extract Spray 5%) had the longest flowering time (48.03 days) and was statistically superior to the other treatments. Flowering period (38.63 days) was observed under V 1 B 0 (Variety 1 + Irrigation), indicating that this was the control treatment. Overall, the combination of V 3 and Neem Leaf Extract Spray (5%) showed to be the most efficient treatment for increasing calendula flowering time. Trivedi et al. (2016) [5] reported prolong flowering in rose under bio-enhancer application containing Panchagavya. Bhalla et al. (2006) [10] also observed improvement in post-harvest flower behavior following Panchagavya-based treatment in carnation.

Conclusion

The current study found that biostimulants and calendula varieties had significant effects on yield parameters, flower quality, and flowering behavior. Fiesta Gitana Orange (V 3 ) was superior to the other varieties in terms of earlier flowering, longer flowering times, more flowers per plant, and longer flower stems. Neem leaf extract spray (5%) (B 2 ) was the most effective biostimulant, encouraging early flower bud initiation, early blooming, maximum flower output, longer flower stalks, and superior overall flowering performance. The interaction treatment V 3 B 2 (Fiesta Gitana Orange + Neem Leaf Extract Spray 5%) was found to be the best combination to enhance flowering and yield performance in calendula under Chhattisgarh's agro-climatic conditions. As a result, the use of 5% neem leaf extract spray with the Fiesta Gitana Orange variety is advised for commercial calendula production to increase flower yield and enhance flower quality.

Acknowledgement

AcknowledgementWe express our gratitude to provided supervision by Dr. Bharti Sao, Assistant Professor, CHRS, Sankra, Durg (C.G.), Dr. Jitendra Kumar Sahu, Guest Teacher, CHRS, Sankra, Durg (C.G.), and other faculties of CHRS, Sankra, Durg (C.G.) during the research work.

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12. How to cite this article: Sahu D, Sao B, Netam N, Badkul AJ, Sao R, Verma A, et al. Influence of biostimulants on flowering behaviour of different varieties of Calendula. International Journal of Agriculture and Food Science. 2026;8(10):82-89. doi: https://www.doi.org/10.33545/2664844X.2026.v8.i10b.2003