Effect of humic acid and salicylic acid on growth and yield of gladiolus

Introduction

Gladiolus (Gladiolus grandiflorus L.) is one of the most important commercial bulbous ornamental crops belonging to the family Iridaceae. It is widely cultivated for its attractive arrangement of spikes, brilliant colour florets and excellent vase life, making it a preferred cut flower in both domestic and international markets. The crop is valued for its wide range of colours, long flowering spikes and suitability for floral arrangements, bouquets, exhibition displays and landscape gardening. Owing to its high economic returns and year-round demand, gladiolus occupies a prominent position in the floriculture industry. Among the various cultural practices, the balanced use of plant growth promoters plays a significant role in improving vegetative growth, flowering, spike quality, corm production and post-harvest performance of gladiolus. Humic acid enhances nutrient availability, root growth, soil microbial activity and physiological processes, thereby promoting vigorous plant growth and higher flower yield. Similarly, salicylic acid acts as an important plant signalling molecule that regulates growth, flowering, photosynthesis, antioxidant activity and stress tolerance, ultimately improving flower quality and productivity. Therefore, the combined application of humic acid and salicylic acid has the potential to enhance the growth, flowering, yield, and quality of gladiolus. However, information on the optimum concentration of these biostimulants for gladiolus cultivation under the Vidarbha region of Maharashtra is limited. Hence, keeping this as a view the present research work was planned to find out suitable treatment combination for improving crop performance and flower quality.

Materials and Methods

The experiment entitled "Effect of Humic Acid and Salicylic Acid on Growth, Yield and Quality of Gladiolus (Gladiolus grandiflorus L.) cv. American Beauty" was undertaken during the Rabi season of 2025-26 at the Experimental Unit, Horticulture Section, College of Agriculture, Nagpur, Maharashtra.

The trial was conducted at Satpuda botanic graden, using a Factorial Randomized Block Design (FRBD) comprising 16 treatment combinations formed by four concentrations of humic acid (0, 500, 1000 and 1500 ppm) and four concentrations of salicylic acid (0, 100, 150 and 200 ppm), with three replications. Uniform and disease-free 4-5 cm diameter corms were selected for planting, before planting, corms were treated with 0.3% captan. Later, corms were planted at a spacing of 45 × 15 cm under recommended cultivation practices. Foliar applications of humic acid and salicylic acid were given as per the treatment, while all other cultural operations were fulfilled whenever required throughout the experiment. The recommended NPK dose of 500:200:200 kgha -1 was applied to the crop. Growth, flowering, yield and quality observations were recorded from five randomly selected plants in each experimental plot. The experimental data were analysed statistically as per method suggested by Panse and Sukhatme (1967) [9] .

Results and Discussion

Effect of humic acid Growth and flowering parameters

At 60 days after planting, humic acid significantly improved vegetative growth. The early first spike emergence (61.83 days), maximum plant height (69.38 cm), leaf area (69.90 cm²) and leaves plant -1 (15.59) were recorded in treatment 2 ml L-¹ humic acid (H₄), which were statistically at par with 1.5 ml L⁻¹ humic acid i.e H₃, (63.67 days, 66.84 cm, 68.05 cm² and 15.16 respectively). However, late spike emergence, minimum plant height, leaf area and leaves plant -1 were recorded in control treatment i.e water spray (H1). The improvement may be attributed to enhanced nutrient uptake and photosynthetic activity. Similar results were reported by Ahmad et al. (2013) [1] in gladiolus.

Yield parameters

Humic acid significantly influenced spike and corm yield attributes of gladiolus. The maximum spikes plant⁻¹ (2.58), spikes ha⁻¹ (2.17), florets spike⁻¹ (8.80) and corms plant⁻¹ (3.37) were recorded with 2 ml L⁻¹ humic acid (H₄), which were statistically at par with 1.5 ml L⁻¹ humic acid H₃ (2.52, 2.11, 8.43 and 3.24 respectively). However, minimum spike plant -1 , spike ha -1 , florets spike-1 and corms plant -1 was recorded in control treatment i.e water spray (H1). The superior performance of H₄ may be attributed to the beneficial effects of humic acid on root development and nutrient availability, which assimilate production and its translocation towards developing spikes and corms. Similar findings were reported by Iftikhar et al. (2013) [3] in gladiolus and Nikbakht et al. (2008) [7] in gerbera.

Effect of salicylic acid

Growth and flowering parameters Salicylic acid application significantly improved the vegetative growth of gladiolus. The early spike emergence (60.83 days) and maximum plant height (70.65 cm), leaves plant⁻¹ (15.59) and leaf area (69.12 cm²) at 60 DAP were recorded with 150 ppm salicylic acid (S₄), which were statistically at par with 100 ppm salicylic acid i.e S₃, (64.41 days, 68.12 cm, 15.14 and 68.05 cm², respectively). However, maximum days to spike emergence, minimum plant height, leaf area and leaves plant -1 was recorded in control treatment i.e water spray (H1). The superior performance of S₄ may be attributed to enhanced photosynthetic efficiency, nutrient uptake and cell division. Similar findings were reported by Pal et al. (2015) [8] and Kumar et al. (2012) [5] in gladiolus.

Yield parameter

Salicylic acid significantly influenced spike and corm yield attributes of gladiolus. Maximum spikes plant⁻¹ (2.51), spikes ha⁻¹ (2.17 lakh), florets spike⁻¹ (8.50) and corms plant⁻¹ (3.52) were recorded in the treatment 150 ppm salicylic acid (S₄). Spikes plant⁻¹, spikes ha⁻¹, florets spike⁻¹ and corms plant⁻¹ were statistically at par with 100 ppm salicylic acid i.e S3, (2.41, 2.08 lakh, 8.36, and 3.25). However, minimum Spikes plant⁻¹, spikes ha⁻¹, florets spike⁻¹ and corms plant⁻¹ was recorded in control treatment i.e water spray (S1). The superior performance of S₄ may be attributed to enhanced physiological activity, photosynthesis and efficient assimilate partitioning towards spikes and corms. Similar findings were reported by Pawar et al. (2018) [10] and Suresh Kumar et al. (2017) [11] .

Interaction effect

The interaction effect of humic acid and salicylic acid levels was found to be significant for growth, flowering and yield parameters of gladiolus. Foliar application of 2 ml/l humic acid with 150 ppm salicylic acid (H4S4) recorded the maximum leaves plant -1 (16.25) at 60 DAP, highest spikes hectare-1 (2.43) and maximum florets spike-1 (8.90). However, minimum leaves plant -1 , spikes ha -1 and floret spike-1 was recorded in control treatment i.e water spray (H1S1). The superior performance of this treatment combination may be attributed to the synergistic effect of humic acid and salicylic acid in enhancing nutrient availability, root growth, photosynthetic activity and assimilate accumulation. Humic acid promotes nutrient uptake and root development, whereas salicylic acid enhances photosynthetic efficiency and physiological activities. Their combined application may have resulted in better vegetative growth, efficient assimilate translocation and improved flower initiation and development, thereby increasing spike production and florets spike -1 in gladiolus.

Comparable effects was reported by Kumar et al. (2025) [6] and Khobragade et al. (2019) [4] .

Conclusion

From the present experimental trial, it is concluded that the maximum vegetative growth, flowering and yield parameters attributes were recorded under 2 ml/lit humic acid and 150 ppm of salicylic acid. The treatment combination of 2 ml/lit + 150 ppm (H4S4) was found to be superior in respect leaves plant -1 , spike hectare-1 florets spike -1 .

References

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