Effect of foliar application of biostimulants on the morphology and flowering of Lisianthus hybrid Rosita 3 Clear Pink under protected cultivation

Introduction

Lisianthus, scientifically Eustoma grandiflorum (Raf.) Shinn., syn. Lisianthus russelianus Hook. (2n = 36) belongs to the family Gentianaceae, which is commonly known as 'Texas Blue Bell' and 'Prairie Gentian' (Halevy and Kofranek, 1984) [7] . Eustoma is named after two Greek words, Eu (beautiful, good, well) and stoma (mouth). Lisianthus is derived from Greek words, lysis (dissolution) and anthos (flower). It is an important ornamental plant, ranked among top 10 cut flowers worldwide for its elegant, rose-like blooms in bright and pastel colours and excellent post-harvest life (Musembi et al., 2015) [14] . It is herbaceous annual to short-lived perennial with funnel-shaped flowers on long, straight stems with simple, slightly succulent bluish-green leaves. The growth and quality are variety-specific, thriving best within a pH range of 6.3 to 6.7 (Harbaugh and Woltz, 1991) [8] . The ideal range of temperature is between 15 °C and 25 °C. Excessively high temperatures during seedling growth may lead to rosetting with up to 3 pairs of leaves (Harbaugh, 2007) [9] . The optimum light intensity for Lisianthus is 4,000-6,000 foot-candles. These plants are mainly propagated by seeds, vegetatively by rooted cuttings and through micropropagation. Lisianthus is slowgrowing ornamental crop that takes about 5-6 months from seed sowing to flowering under optimum growing conditions (Halevy and Kofranek, 1984) [7] . Transplantation is generally done after 8-12 weeks, at 4-6 pair of true leaves stage. A spacing of 10 cm × 10 cm (100 plants/m 2 ) was optimum for improving growth, flower quality, yield and profitability of Lisianthus under naturally ventilated polyhouse conditions (Ganiger et al., 2025) [5] . Lisianthus flowers are available in various colours, such as blue, purple, white, pink, and bicolour, that are widely used as cut flowers, for bridal bouquets, as flowering pot plants, floral displays and in many other special flower arrangements. In recent decades, floriculture has increasingly shifted towards sustainable and eco-friendly production practices to overcome limitations of intensive cultivation.

Among these, biostimulants have gained importance for enhancing plant growth, flower quality and productivity while promoting environmentally responsible cultivation (Wezel 2014) [24] . Biostimulants are substances or microorganisms, other than fertilizers, that stimulate natural plant processes, improve nutrient use efficiency, enhance tolerance to abiotic stress and ultimately improve crop growth and quality (Zhang and Schmidt, 2000; Traon et al., 2014) [25,22] . Therefore, the present investigation entitled "Effect of foliar application of biostimulants on the morphology and flowering of Lisianthus hybrid Rosita 3 Clear Pink under protected cultivation" was undertaken with the following objectives: 1. To study the effect of foliar application of biostimulants on the morphology of Lisianthus 2. To study the effect of foliar application of biostimulants on flowering of Lisianthus

Materials and Methods

Experimental site

The experiment was conducted during 2025-26 in naturally ventilated polyhouse at the Department of Horticulture, College of Agriculture, Shivamogga, located in Southern Transition Zone (Zone 7) of Karnataka and lies at 13°55′ N latitude, 75°34′ E longitude and 650 m above MSL. The study was conducted using Randomized Complete Block Design (RCBD), comprising fifteen treatments, each replicated three times. Lisianthus seedlings were transplanted on raised beds at spacing of 10 × 10 cm, accommodating 100 plants per 1.0 × 1.0 m 2 plot.

Planting material

The Lisianthus seedlings used for the experiment were procured from Sakata Seed India Pvt. Ltd., Bengaluru.

Biostimulants

Organic manures like farmyard manure (FYM) 2kg/m 2 and vermicompost were applied as soil application as basal dressing. Trichoderma harzianum and Mycorrhiza were commonly applied for all treatments except for the control. The recommended fertilizer dose for Lisianthus was 15 g N, 18 g P 2 O 5 and 18 g K 2 O m -2 , supplied through urea, single superphosphate (SSP) and muriate of potash (MOP), respectively. The biostimulants Panchagavya and Jeevamrutha were prepared as recommended by TNAU Organic Farming Practices "Panchagavya" and "Jeevamrutha" (Anon., 2014). The PGPR consortium was procured from the Organic Farming Research Centre (OFRC), comprising Azospirillum brasilense, Pseudomonas fluorescens and Bacillus subtilis. These biostimulants were applied as foliar sprays at 15, 30 and 45 days after transplanting (DAT).

Treatment details

T 1 (Panchagavya @ 4%) T 2 (Panchagavya @ 6%) T 3 (Jeevamrutha @ 10%) T 4 (Jeevamrutha @ 15%) T 5 (PGPR @ 2%) T 6 (PGPR @ 4%) T 7 (Panchagavya @ 4% + Jeevamrutha @ 10%) T 8 (Panchagavya @ 6% + Jeevamrutha @ 15%) T 9 (Panchagavya @ 4% + PGPR @ 2%) T 10 (Panchagavya @ 6% + PGPR @ 4%) T 11 (Jeevamrutha @ 10% + PGPR @ 2%) T 12 (Jeevamrutha @ 15% + PGPR @ 4%) T 13 (Panchagavya @ 4% + Jeevamrutha @ 10% + PGPR @ 2%) T 14 (Panchagavya @ 6% + Jeevamrutha @ 15% + PGPR @ 4%) T 15 (Untreated Control)

Planting and after-care

Ninety-day-old seedlings were transplanted on 20 th December, 2025. Standard aftercare practices, including irrigation (overhead system), staking, netting, gap filling, weeding, foliar spray of micronutrients and plant protection measures, were adopted.

Observations

Five plants were randomly selected, tagged and observations were recorded in each treatment at appropriate stages and statistically analysed for different growth parameters like plant height (cm), plant spread (E-W and N-S) (cm), internodal length (cm), stem girth (mm), number of leaves, leaf area per plant (cm 2 ), leaf area index, number of branches at peak growth stage. Flowering parameters like days taken for flower bud initiation, flower opening (days), 50 percent flowering (days), flower stalk harvesting (days) and duration of flowering (days) were recorded.

Results and Discussion

Morphological parameters

The effect of foliar application of biostimulants on the morphological parameters of Lisianthus hybrid Rosita 3 Clear Pink, recorded at 75 Days After Transplanting (DAT) was assessed and the results of the experiment are presented in Table 1. Among the various treatments, Panchagavya @ 6% + Jeevamrutha @ 15% + PGPR @ 4% (T 14 ) recorded maximum plant height (92.75 cm), plant spread (10.85 cm E-W and 11.50 cm N-S), stem girth (8.90 mm), internodal length (7.80 cm), number of leaves per plant (52.50), leaf area (2420 cm 2 plant -1 ) and number of branches per plant (3.80) as depicted in figure 1. The significantly superior vegetative growth recorded in T 14 (Panchagavya @ 6% + Jeevamrutha @ 15% + PGPR @ 4%) could be attributed to the combined action of three biostimulants in enhancing plant growth and development. Panchagavya is a rich source of essential macro and micronutrients, beneficial microorganisms, amino acids, vitamins and naturally occurring plant growth regulators such as auxins and gibberellins, which stimulate cell division, cell elongation and overall vegetative growth (Natarajan, 2002) [15] . The presence of these bioactive compounds promotes vigorous shoot growth, resulting in increased plant height, stem girth and canopy spread. Similar results have been documented by Praveen et al. (2021) [18] in floribunda Rose cv. Mirabel, Rajiv et al. (2025) [19] in Jasmine, Ghosh (2024) [6] in Tuberose and Sendhilnathan et al. (2021) [20] in Celosia. Jeevamrutha acts as an effective microbial inoculant that enhances microbial activity in rhizosphere, accelerates nutrient mineralization and improves nutrient availability, thereby promoting root growth and efficient nutrient uptake (Palekar, 2006) [17] . Enhanced nutrient absorption supports greater leaf production, increased leaf expansion and higher biomass accumulation, which ultimately contributes to larger leaf area and improved plant architecture. These findings are agreement with those of Praveen et al. (2021) [18] in floribunda Rose cv. Mirabel, Singh et al. (2015) [21] and Choudhary et al. (2021) [4] in Marigold and Paikra et al. (2022) [16] in African marigold cv. Pusa Narangi Gainda. Further, PGPR organisms such as Azospirillum brasilense, Pseudomonas fluorescens and Bacillus subtilis may have enhanced plant growth through improved nutrient uptake, mineralization and mobilization, atmospheric nitrogen fixation, phosphorus solubilization, phytohormone production and root development (Vessey, 2003; Backer et al., 2018) [23,2] . These effects may have stimulated cell division and elongation, leaf initiation and expansion, resulting in vigorous vegetative growth. Enhanced nutrient availability and root development could have improved photosynthetic capacity and assimilate production, thereby promoting canopy development. Increased assimilate availability, together with phytohormonal activity and improved vascular development, may have contributed to thicker stems, longer internodes and increased lateral branching through enhanced axillary bud activation. These findings are in agreement with those of Rajiv et al. (2025) [19] in Jasmine, Borah et al. (2022) [3] in Gerbera and Moghadam and Shoor (2013) [13] in Petunia. The combined application of Panchagavya, Jeevamrutha and PGPR therefore exerted a synergistic effect by improving nutrient availability, stimulating beneficial microbial activity and enhancing endogenous growth regulators, resulting in superior vegetative growth compared to individual applications and untreated control.

Flowering parameters

The results of the experiment are presented in Table 2. Among various treatments, Panchagavya @ 6% + Jeevamrutha @ 15% + PGPR @ 4% (T 14 ) recorded minimum days taken for flower bud initiation (66.85), flower opening (76.25 days), 50 percent flowering (80.35 days) and flower stalk harvesting (84.70 days), besides recording the longest duration of flowering (24.20 days). The significantly fewer days taken for flower bud initiation, flower opening, 50 percent flowering and flower stalk harvesting, along with the longest flowering duration observed in T 14 (Panchagavya @ 6% + Jeevamrutha @ 15% + PGPR @ 4%), may be attributed to the enhanced physiological efficiency and balanced hormonal activity induced by the combined application of the bio-stimulants. Panchagavya supplies natural growth regulators, vitamins and essential nutrients that promote early floral differentiation, while Jeevamrutha improves nutrient availability through enhanced microbial activity (Natarajan, 2002; Palekar, 2006) [15,17] . PGPR facilitates the synthesis of phytohormones and improves nutrient acquisition, leading to efficient assimilate production and translocation towards developing floral buds (Vessey, 2003) [23] . The continuous availability of nutrients and photoassimilates favoured early reproductive development and sustained flower production, thereby extending the flowering duration. These findings conform with the reports of Harshavardhan et al. (2016) [10] in Carnation, Kumari et al. (2016) [12] in Chrysanthemum, Indhumathi et al. (2023) [11] in Gaillardia and Ghosh et al.

(2024) [6] in Tuberose, who also reported earlier flowering and prolonged flowering duration following the application of organic biostimulants.

Conclusion

From the present investigation, it can be said that combined foliar application of Panchagavya @ 6%, Jeevamrutha @ 15% and PGPR @ 4% significantly gave the best results in terms of morphological parameters and promoted early and prolonged flowering in Lisianthus hybrid Rosita 3 Clear Pink under protected cultivation, indicating synergistic effect of biostimulants in improving plant vigour and overall growth. Therefore, biostimulant combination may be suggested for commercial production of Lisianthus.

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