The global cut-flower industry is expanding rapidly, with the market valued at USD 31.1 billion in 2024 and projected to more than double by 2034 as consumers seek novel, high-impact blooms for décor, gifting and events. Within this space, tropical ornamentals occupy a lucrative niche because their vivid colours, bold architectures and long vase life command premium prices in temperate markets. Heliconia-a monotypic genus in the family Heliconiaceae-has emerged as a flagship of this segment. As stated by Müller-Wille (2017), it's named after Mount Heliconia, home of the muses; the genus comprises of 100 naturally occurring species and numerous cultivars distinguished by strikingly pigmented bracts that protect inconspicuous true flowers. Plants are herbaceous, rhizomatous and range from 0.5 m to nearly 4.5 m in height, traits that lend themselves equally to landscape use and cut-flower production. Although Heliconia is native to the Neotropics, its adaptability to warm, humid conditions and tolerance of partial shade have facilitated successful cultivation across the tropics and subtropics. In India, the hot-humid littoral belt of Odisha offers congenial agro-climatic conditions; growers already intercrop Heliconia in orchard systems where dappled light and organic matter are abundant (Basantia and Beura, 2022). Among commercial cultivars, H. psittacorum L.f.  × H. spathocircinata cv. ‘Golden Torch’ is favoured for its compact habit, persistent yellow bracts and steady year-round demand. Growing media composition affects nutrient availability, aeration and water-holding capacity, thereby influencing plant performance. Several authors (Ekwu and Mbah, 2007; Baiyeri and Mbah, 2006) had advocated for the replacement of natural top soil as growth medium of floricultural crops with other available options due to some of its shortcomings such as non-sustainability and as a non-renewable resources. Continuous digging of agricultural soils meant for cropping, arable land could make the land susceptible to erosion and other forms of soil degradation (Bhat et al., 2019). Growing media are materials, other than soils in situ, in which plants are grown. A perfect growth media serves various function especially enact as a nutrition reservoir in favor of plant’s growth and development but as they’re quite specific regarding their action. Since organic substrates are most approachable, eco-friendly and biodegradable, thus, the use of several ecological components could serve as next available alternative. Although plants are able to use a few nutrients from the air, most of the nutrients that a plant needs must be present in the growing medium (soil). Minerals such as nitrogen, potassium, phosphorous, calcium and magnesium are taken up through the plant’s roots. In India, the hot-humid littoral belt of Odisha offers congenial agro-climatic conditions; growers already intercrop Heliconia in orchard systems where dappled light and organic matter are abundant (Basantia and Beura, 2022). Light environment is a primary driver of growth and floral quality in Heliconia. Each part of a natural or artificial environment affects the survival and quality of a plants life. Photosynthesis is the process by which green plants make their own food. In the presence of light energy, plants manufacture food (mainly sugars), by combining carbon dioxide and water in the presence of chlorophyll to release oxygen and water. It takes time and patience to grow plants, some more so than others. Most plants require a particular number of days, months, or even years to produce flowers. Early work in Florida demonstrated that H. psittacorum produced more stems under full sunlight than under 63% shade (Broschat and Donselman, 1983), whereas subsequent photoperiod studies in Hawaii showed that short-day induction synchronised bud initiation in H. stricta ‘Dwarf Jamaican’, provided plants had accumulated at least four expanded leaves beforehand (Criley and Kawabata, 1986). Recent physiological analyses confirm that excessive irradiance can induce photoinhibition and anatomical adjustments-thicker cuticles, higher stomatal density-across genotypes, underscoring the need to fine-tune shade levels for each production system. Conversely, 50% shade has been shown to enhance leaf area, chlorophyll content and inflorescence length in several genotypes without significantly depressing yield. Keeping the above information as background the present investigation was devised with the objective of examining the requirement of light intensity and different composition of media best suited for better growth and yield of cut blooms of Heliconia var. Golden torch.

Experimental site and climate
 
The work was conducted as a two-year pot experiment (2022-23 and 2023-24) on the south-facing terrace garden of the Department of Floriculture and Landscaping, Institute of Agricultural Sciences (IAS), Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, India (20°15′  N, 85°50′ E; 25.5 m a.s.l.). The site lies ~63 km inland from the Bay of Bengal and enjoys a warm sub-tropical climate with a mean annual rainfall of 1,522 mm, 85 % of which is received between July to September. Average daily maxima reach 35-40°C in May-June, while minima drop to 13-15°C in December-January; relative humidity varies between 40% (pre-monsoon) and 90% (monsoon).
 
Plant material and preparation
 
Rhizomes of Heliconia (H. psittacorum L.f. × H. spathocircinata) ‘Golden Torch’ were obtained from the Government Nursery, Unit-2, Bhubaneswar. Propagules were prepared by rhizome division following Criley’s protocol: segments (6-12 cm pseudostem attached), which were trimmed, dusted with a benzimidazole fungicide and cured for 48 h under shade until root initials emerged.
 
Experimental design and treatments
 
The factorial experiment consisted of two factors, viz., two light intensity levels and three media compositions which was laid out in a Completely Randomised Design with four replications. Each treatment per replication comprised of five 12 L UV-stabilised polyethylene bags. The treatment details are presented in Table 1.


 
Execution of the experiment and Substrate characterisation
 
Prior to commencement of the experiment a portion of the terrace garden of the department of floriculture and landscaping was earmarked and cleaned properly. To create two environmental conditions i.e. light intensity levels as per the requirement, a part of the demarcated area was kept open allowing 100% sun light and the other portion was utilized to create shade by fixing U.V stabilized Agro shade net allowing 50% light at a height of 3.90 meters from the ground /floor level.
       
The clay soil used in the substrate contained 16.2 % sand, 27.3 % silt and 50.5 % clay with pH 5.6, EC 0.31 dS m^-1 and available N 265 kg ha^-1, P 55 kg ha^-1 and K 122 kg ha^-1 (Jackson 1976 methods). Other components were well decomposed air dried Farmyard manure (FYM) and cocopeat which had EC ≤0.4 dS m^-1 after leaching. The substrate contained soil, FYM, cocopeat in different ratios on volume basis as presented in Table 2.  Polybags were perforated laterally and at the base to ensure drainage, filled with the designated medium to within 2 cm of the rim and planted on 22 March 2022 with one rhizome segment per bag at 7.5 cm depth. All bags were drenched with 0.15% carbendazim and lightly watered to initiate sprouting.


 
Crop management
 
Polybags were perforated laterally and at the base to ensure drainage, filled with the designated medium to within 2 cm of the rim and planted on 22 March 2022 with one rhizome segment per bag at 7.5 cm depth. All bags were drenched with 0.15% carbendazim and lightly watered to initiate sprouting. Bags were watered at every 2-3 days interval during establishment, then at 3-5 days interval for both the light intensity depending on moisture status (rainy-season drainage ensured). A 2% water-soluble fertiliser (19 : 19 : 19 NPK) was drenched at three-month intervals. Hand weeding was done as required. Cut-worm and spider-mite infestations in shade conditions were controlled with 0.05% chlorpyriphos applied at 10 to 15 days intervals.
 
Environmental monitoring
 
Photosynthetically active irradiance was estimated twice weekly at 11:00 and 15:00 h with a digital lux meter (Model 5200). Mean midday irradiance under the 50% net was 45-55 klx, roughly half that of open sun (90-105 klx). Air temperature and relative humidity were recorded concurrently with a max-min thermometer and digital hygrometer.
 
Data collection
 
All the five tagged plants under each treatment and replication were used for recording observations on various vegetative, reproductive, physiological and biochemical traits as well as flower yield which are as follows:
i. Vegetative traits - days to 80 % sprouting, number of sprouts bag^-1, plant height (monthly), days for leaf unfurling, leaves clump^-1, leaf area (length × breadth × empirical factor determined with Leaf Area Meter-SYSTRONICS-211), suckers bag^-1 and percentage of vegetative shoots converting to flowering shoots.
ii. Reproductive traits- days to first visible bud, days to full spike opening, spike length, stalk length (junction of pedicel to first bract), bracts spike^-1, flowering duration of spike and number of spikes clump^-1.
iii. Physiological and biochemical traits - net photosynthetic rate (portable IRGA), transpiration rate (Ganong potometer), chlorophyll content (SPAD-502; converted with Y = 0.178  × -3.531) and carotenoids in petals (acetone extract, UV-Vis spectrophotometer at 450, 470 and 480 nm; expressed as mg g^-1 fresh weight).
iv. Flower yield-Harvestable flowers were cut when the lowermost bract opened; data from all flushes were pooled to compute annual yield.
 
Statistical analysis
 
Data from both the years were pooled after homogeneity of variance was confirmed. Percentages were arcsine-transformed wherever was necessary. A two-way ANOVA appropriate to the factorial CRD was performed and treatment means were separated with the critical difference (CD) at P≤0.05. All analyses were executed in R 4.3.1 (R Core Team, 2024).

Sprouting, early vegetative growth, leaf production and canopy development
 
Sprouting and vegetative growth of H. psittacorum L.f.  × H. spathocircinata cv. ‘Golden Torch’ were significantly affected by growing media (M), environment (E) and their interaction (P≤0.05) (Table 3). Plants under full sun (E₁) reached 80% sprouting earlier (17.15 days) than under 50% shade (E₂; 19.47 days; CD_0.05 = 0.44), consistent with enhanced irradiance promoting rhizome activity likely promoted faster rhizome respiration and meristematic activity, leading to earlier emergence, a response previously reported in heliconia and other tropical monocot ornamentals (Broschat and Donselman, 1983; Criley, 1986b). Among media, M₁ (17.44 days) and M₂ (17.61 days) were at par but significantly earlier than M₃ (19.89 days; CD_0.05 = 0.54). The delayed sprouting in M₃  may be attributed to its higher FYM proportion, which could have increased moisture retention and reduced aeration around the rhizome, thereby slowing bud activation, while the slowest sprouting occurred in M₃ × E₂ (CD_0.05 = 0.76), indicating that reduced light combined with relatively heavier organic media adversely affected early establishment. In contrast, plant height at 3 months was greater under shade (21.17 cm) than open conditions (19.68 cm; CD_0.05 = 0.12), with M₂  (21.36 cm) and M₃  (21.69 cm) exceeding M₁ (CD_0.05 = 0.15) and a significant M × E interaction, indicating that the magnitude of height increase under shade was more pronounced in organic-rich media, highlighting the synergistic influence of substrate composition and light regime. During flowering, shade further increased height (4.41 ft vs 2.62 ft; CD_0.05 = 0.24), with M₃ (3.84 ft) > M₂  (3.44 ft) > M₁ (3.26 ft). This response reflects typical shade-induced elongation, driven by altered light quality and reduced irradiance, which stimulates internodal extension to enhance light interception. Similar shade-mediated height increases have been reported in heliconia and other tropical ornamentals under protected cultivation (Naik et al., 2019). Leaf unfurling was faster under open conditions (6.07 days) than shade (9.75 days; CD_0.05 = 0.47), though M3 recorded the shortest duration (7.46 days vs M₁ : 8.26 days; CD_0.05 = 0.82), demonstrated that leaf developmental dynamics were jointly regulated by substrate composition and light environment. Leaf number was higher in open conditions (7.07 vs 6.21) and maximized in M₂ × E₁ emphasizing the synergistic effect of adequate light and balanced growing media. Increased light availability under open conditions enhances photosynthetic activity and assimilate supply, thereby promoting leaf initiation and expansion and media with balanced proportions of soil, FYM, cocopeat likely provided optimal aeration and nutrient availability, supporting sustained vegetative growth (Broschat and Donselman, 1983; Naik et al., 2019; Ribeiro et al., 2024). Conversely, leaf area increased under shade (1112.90 cm² vs 775.87 cm²), with maximum values in M₂  and under M₂ × E₂, reflecting adaptive expansion under low light (Criley and Kawabata, 1986; Linares-Gabriel et al., 2020). Overall, full sun favoured early sprouting and leaf production, while shade combined with organic-rich media enhanced plant height and leaf area, demonstrating strong interactive effects on heliconia growth and development.


 
Transition from vegetative to reproductive phase
 
The duration from vegetative to flowering shoot emergence was significantly affected by both growing environment and media composition as stated in Table 4. Plants grown under open conditions transitioned to the reproductive phase earlier than those under shade. Higher light intensity accelerates carbohydrate accumulation and promotes floral induction by enhancing source-sink relationships, resulting in earlier flowering initiation (Broschat and Donselman, 1983; Zhang et al., 2023). Among media, M₂ recorded the shortest vegetative to flowering duration, while M₃ exhibited the longest duration. Excess FYM in M₃ may have promoted prolonged vegetative growth, delaying floral initiation. Similar delays in reproductive transition under nutrient-rich conditions have been reported in clonal and tropical ornamental species (Lopp and Sammul, 2017). The significant M × E interaction indicated that early flowering shoot emergence was most pronounced under M₂ × E₁, highlighting the importance of synchronizing nutrient availability with optimal light conditions.


 
Flower production, inflorescence quality and flower yield
 
Days to flowering in H. psittacorum L.f. x H. spathocircinata cv. ‘Golden Torch’ were significantly reduced under open conditions (165.41 days) compared to 50% shade (189.70 days), as reduced photosynthetic photon flux density and altered light quality, which negatively affect floral induction pathways in heliconia (Criley and Kawabata, 1986; Linares-Gabriel et al., 2020) in Table 4. Among media, M₂ induced earliest flowering, followed by M₁, while M₃  was significantly delayed; the earliest flowering occurred under M₂ × E₁ and the latest under M₃ × E₂, indicating that excessive organic matter combined with low light delays reproduction. Open conditions also enhanced leaf production, faster flowering transition, sprout number (4.62 vs 3.30) and flower yield per clump (3.68 vs 3.30), likely due to improved photosynthesis and assimilate accumulation (Broschat and Donselman, 1983; Criley, 1986a; Zhang et al., 2023). In contrast, shade increased leaf area and promoted elongation traits. Among media, M₃ produced the highest sprouts (4.47), flowers per clump (3.70), inflorescence length (24.26 inches), stalk length (17.83 inches) and bract number (4.72 vs M₂: 4.32; M₁ : 3.40; CD_0.05 = 0.37), attributed to improved nutrient availability, aeration and moisture retention (Ribeiro et al., 2024; Lopp and Sammul, 2017). Inflorescence (24.23 vs 19.03 inches) and stalk length (18.30 vs 14.94 inches) were significantly greater under shade, reflecting typical elongation under reduced irradiance and improved turgor (Naik et al., 2019; dos Santos et al., 2024; Singh et al., 2019). Significant interaction effects showed maximum sprouts, flower yield and bracts under M₃ × E₁, indicating that optimal light coupled with enriched growing media favoured bract differentiation and expansion, while the longest inflorescences occurred under M₃ × E₂, highlighting that high irradiance favours yield, whereas shade with organic-rich media enhances quality traits. Increased floral output under full sun has been reported in heliconia and other tropical ornamentals and is generally associated with improved source-sink relationships and faster assimilate translocation to developing inflorescences (Criley and Kawabata, 1986; Zhang et al., 2023). Organic-rich substrates have been shown to enhance spike elongation by maintaining favourable water relations and sustained nutrient supply during the reproductive phase (Ribeiro et al., 2024; Mondal and Hore, 2026). The significant M × E interaction, with maximum inflorescence length under M₃  × E₂, suggests that shaded environments amplify the positive effects of improved media composition on floral axis development. Shade-induced elongation is a well-documented adaptive response in tropical species, driven by increased internodal cell expansion under reduced irradiance and lower photoinhibitory stress (Naik et al., 2019; dos Santos et al., 2024). Overall, open conditions promoted early flowering and higher yield, while 50% shade improved floral quality and the consistent superiority of M₂  for earliness and M₃ for yield and quality confirms that optimizing both light and substrate is essential for efficient heliconia production (Linares-Gabriel et al., 2020).
 
Blooming period and duration of flowering
 
Blooming period per spike in H. psittacorum L.f. x H. spathocircinata cv. ‘Golden Torch’ was significantly longer under 50% shade (16.20 days) than open conditions (10.30 days; CD_0.05 = 0.50), likely due to reduced vapour pressure deficit and delayed senescence under moderated microclimate (Naik et al., 2019; dos Santos et al., 2024) (Table 4). Growing media also influenced blooming, with M₃ (13.71 days) and M₂ (13.57 days) outperforming M₁ (12.48 days) and the longest duration observed under M₃  × E₂, indicating a synergistic effect of shade and organic-rich substrate (Lopp and Sammul, 2017). Similarly, flowering duration per clump was higher under shade (62.08 days) than open conditions (51.18 days; CD_0.05 = 1.52), attributed to staggered spike emergence and delayed senescence (Criley and Kawabata, 1986; Linares-Gabriel et al., 2020). Among media, M₃ recorded the longest duration (60.70 days), followed by M₂ (57.62 days) and M₁ (51.56 days), with the maximum under M₃ × E₂ (64.82 days). Overall, while open conditions enhanced reproductive intensity (bract number), 50% shade significantly improved floral longevity traits and the consistent superiority of M₃ highlights the role of organic-rich media in extending blooming and flowering duration, confirming that optimal light-substrate management is essential for maximizing both yield and post-harvest quality in heliconia (Naik et al., 2019; Linares-Gabriel et al., 2020).
 
Transpiration rate, photosynthetic efficiency and pigment composition
 
Physiological and biochemical traits of Heliconia psittacorum × H. spathocircinata ‘Golden Torch’ were significantly influenced by environment (E), growing media (M) and their interaction (M × E). Transpiration rate was higher under open conditions (E₁; 5.54 mmol H₂O m^-2 s^-1) than 50% shade (E₂; 3.24 mmol H₂O m^-2 s^-1; CD_0.05 = 0.12) as stated in Table 5, due to increased leaf temperature and vapour pressure deficit (Broschat and Donselman, 1983; Sharma et al., 2019), while M₃  recorded the highest transpiration (4.49 vs M₁: 4.26), indicating improved root activity; however, shade consistently moderated water loss across media. In contrast, photosynthetic rate was significantly higher under shade (21.24 µmol CO₂ m^-2 s-1) than open conditions (13.11 µmol CO₂ m^-2 s^-1; CD_0.05 = 0.54), suggesting reduced photoinhibition and improved carbon fixation efficiency (Naik et al., 2019; dos Santos et al., 2024). Among media, M₂ (17.55) and M₃ (17.00) outperformed others, likely due to enhanced nutrient availability (Lopp and Sammul, 2017), with significant interaction effects showing amplified benefits under shade. Carotene content was higher under shade (3.07 mg g^-1 vs 2.53 mg g^-1; CD_0.05 = 0.05), reflecting protective acclimation (dos Santos et al., 2024; Zhang et al., 2025) and was maximized in M₃ (2.90 vs M₁: 2.66), particularly under M₃ × E₂ (Ribeiro et al., 2024). Similarly, chlorophyll content increased significantly under shade (6.82 mg cm^-2 vs 5.09 mg cm^-2; CD_0.05 = 0.27), indicating enhanced light-use efficiency (Naik et al., 2019; Linares-Gabriel et al., 2020), with highest values in M₃  (6.30) followed by M₂ (5.82) and maximum accumulation under M₃ × E₂. Overall, shade improved photosynthesis and pigment accumulation, while organic-rich media (especially M₃) enhanced physiological efficiency, demonstrating strong interactive effects of light and substrate on heliconia physiology.


 
Correlation analysis
 
The correlation analysis among the studied traits revealed several significant relationships (Fig 1). Number of leaves showed a significant positive correlation with the number of flowers per clump (r = 0.519), indicating that plants with more leaves tend to produce a higher number of flowers. However, the number of leaves exhibited a significant negative correlation with days to flowering (r = -0.506), suggesting that plants with a higher number of leaves tend to flower earlier. Leaf area was significantly and positively correlated with days to flowering (r = 0.732), duration of flowering (r = 0.727) and inflorescence length (r = 0.687), indicating that plants with larger leaf area tend to flower later and maintain flowering for a longer duration with longer inflorescences. On the other hand, leaf area showed a significant negative correlation with vegetative to flowering shoot ratio (r = -0.55).


       
Vegetative to flowering shoot ratio showed a significant negative correlation with number of flowers per clump (r = -0.676), suggesting that a higher proportion of vegetative shoots may reduce flower production. Days to flowering exhibited significant positive correlations with duration of flowering (r = 0.721) and inflorescence length (r = 0.587), indicating that genotypes that flower later tend to have longer flowering duration and longer inflorescences. Duration of flowering also showed a strong positive correlation with inflorescence length (r = 0.834), implying that plants with longer inflorescences tend to maintain flowering for a longer period. The traits such as leaf area, duration of flowering and inflorescence length play an important role in influencing flowering behaviour and may serve as useful selection criteria in breeding programs aimed at improving floral traits.

Collectively, shaded conditions significantly reduced transpiration while enhancing photosynthetic rate, chlorophyll concentration and carotenoid content, thereby improving physiological efficiency and stress tolerance. Open conditions, although associated with higher water loss, favoured faster growth and earlier flowering, as discussed previously. Among the growing media, M₃  consistently supported superior physiological performance, highlighting the importance of substrate optimisation in heliconia cultivation. These findings corroborate earlier reports that emphasise the role of moderate shade and organic-rich root environments in enhancing physiological resilience and floral quality in tropical ornamental crops.

The authors express their sincere gratitude to the Faculty of Agricultural Sciences, Siksha ‘O’ Anusandhan (Deemed to be University), Bhubaneswar, Odisha, for providing the necessary facilities, infrastructure and technical support to carry out the present investigation. We are also thankful to the faculty members and staff of the department for their valuable guidance, cooperation and assistance during the course of the study. The authors duly acknowledge all those who have directly or indirectly contributed to the successful completion of this research work.

The authors declare that there are no conflicts of interest regarding the publication of this article. No funding or sponsorship influenced the design of the study, data collection, analysis, decision to publish, or preparation of the manuscript.