Plant structure and early growth in coriander: Effect of light and temperature indoors

Introduction

Coriander (Coriandrum sativum L.) is one of the commonly used annual herbaceous plants in global cuisines, valued for its aromatic flavor (Mandal and Mandal, 2015) [2] . It belongs to the family Apiaceae. Remarkably, the entire coriander plant is edible. Coriander is extensively grown in India as compared to other countries. India is the largest producer, importer and exporter of coriander in the world. In India, it is widely grown in Rajasthan, Karnataka, Telangana, Andhra Pradesh, Gujarat, Madhya Pradesh, Tamil Nadu, Uttar Pradesh and Bihar. Rajasthan (58%) leads in the production of coriander seed, followed by Madhya Pradesh (15%). It was estimated that the area under the cultivation of coriander was found to be 6.2 million hectares with approximately 8.29 million metric tons of production. Coriander is used as a traditional remedy for treating various disorders in the medicine systems of many civilizations (Sahib et al., 2013) [3] . Coriander is rich in vitamins (vitamin A, vitamin B2 and vitamin C) and minerals (Shahwar et al., 2012) [4] . It was reported that coriander extract contains anti-inflammatory, anti-diabetic, anti-lipidemic, anticarcinogenic, cytoprotective, vasoprotective, cardioprotective and neuroprotective activities (Laribi et al., 2015) [6] . Coriander is also known for its antioxidant properties viz., flavonoids, terpenoids, phenolic compounds (rutin and chlorogenic acid), β-carotene and linolenic acid (Hwang et al., 2014) [5] . These secondary metabolic compounds concentration is an important index for the assessment of quality. Overall, coriander is regarded as a functional food ingredient having medicinal and economic importance. The demand for fresh and high-quality vegetables, including coriander is growing widely in large cities. A plant factory with artificial growing conditions enables the production of vegetables inside cities with higher productivity, which can satisfy specific quality demands in plant growth and accumulation of secondary metabolites (Kozai and Niu, 2016) [7] . The growth and development of plants, and accumulation of secondary metabolites are mostly affected by environmental factors like air temperature, light, carbon dioxide concentration, etc. Under controlled environmental conditions, the cost for electrical energy essential for providing artificial lighting accounts about 28% of the total operational costs (Kozai and Niu, 2016) [7] . Hence, augmenting PPFD (photosynthetic photon flux density) is an important thing to improve the plant production. Additionally, plant growth and development are affected by temperature, which significantly affects the growth and various physiological processes viz., water uptake, mineral uptake, photosynthesis, metabolic absorption, and accumulation of bioactive compounds (Yan et al., 2012). Light is the most important resource that affects the morphology, development and bioactive chemical composition of plants. Several researchers have indicated that photoperiods improve photosynthesis, growth and secondary metabolites viz., sugars, proteins and phenols (16-19). Providing insufficient light checks photosynthesis process in mesophyll of leaf, while excessive light may alter the photosynthesis process by weakening photosynthetic tissues and cell membranes. The quality, intensity, and distribution of light, regulate highly complex effects on plant physiology. The quality of light affects the expression of genes that are associated with growth and development by stimulating signal cascades of photoreceptors, such as phytotropins, cryptochromes and phytochromes. Red and blue lights are the most efficient and dominant wavelengths because the absorption spectrum of chlorophyll in plants is most considerable in the red part of the spectrum (660 nm) and blue part of the spectrum (450 nm). Phytochromes mainly absorb R light, which has the highest quantum yield of CO2 fixation plays a significant role in developing photosynthesis. Hence, it is required to balance photoperiod and light intensity to augment crop yields. With customizable spectral qualities, intensities and ecofriendliness, LEDs (light emitting diodes) in plant factories have resulted in revolutionary changes under controlled environmental conditions for improving growth and development of plants by influencing their morphology, physiology, and photosynthetic characteristics (Gomez and Izzo, 2018) [9] . Also, LED lights reduce pests and precludes the necessity to apply pesticides and ensures the crop safety. Hence, growing coriander in plant factories can improve the productivity and enhance its food safety. Therefore, incorporating coriander into plant factories can enhance its yield and food safety and increase its industrial disease output. The application of LEDs ranges from the advanced replacement of incandescent lights used in the management of photoperiod (Craig and Runkle, 2013) [11] , up to the replacement of highpressure sodium (HPS) lamps and fluorescent lamps for providing supplemental lighting in controlled environmental conditions (Olle and Virsile, 2013) [10] . Additionally, temperature is another important factor which significantly affects the growth and development of plants. It also affects various physiological processes viz., water uptake, mineral uptake, photosynthesis, metabolic absorption, and accumulation of bioactive compounds (Al-Rawahy et al., 2019). Hence, keeping in view the above facts, the present study has been conducted with the objectives to know the effect of light on flowering in coriander, and to study the effect of temperature on growth and yield in coriander.

Materials and Methods

The study entitled "Plant Structure and Early Growth in Coriander: Effect of Light and Temperature Indoors" was carried out during the academic year 2025-2026 at the Urban Kisaan Research and Development Unit, Hyderabad, in academic coordination with the Department of Horticulture, School of Agricultural Sciences, Malla Reddy University.

Treatment details

Experimental Details

The experiment was carried out in completely randomized design (CRD) comprising seven treatments with three replications. Each treatment consisted of 21 plants arranged on NFT (Nutrient Film Technique) stand. Plants were established in an alternate pattern to maintain uniform plant density. Planting was undertaken during the second week of November, and all recommended cultural practices were uniformly followed across treatments. In each replication, five plants per treatment were randomly selected and tagged for recording observations. The recorded data were used to compute mean values based on the observations obtained from the tagged plants. Plant height is an important indicator of vegetative growth and reflects the plant's response to environmental conditions, particularly light quality and temperature in controlled cultivation systems. Significant differences in plant height were observed among the treatments throughout the experimental period, indicating the influence of the tested environmental factors. At 10 DAT, plants grown under T 4 (2 Blue:1 Red LED with an 18-hour photoperiod) attained the greatest height (14.41 cm), followed by T 2 (2 Red:1 Blue LED with an 18-hour photoperiod) at 13.74 cm, whereas the control (T 1 ) recorded the lowest value (11.03 cm). The same pattern was maintained at 20 DAT, with T 4 producing the tallest plants (20.43 cm), followed by T 2 (19.26 cm), while the control measured only 15.49 cm. By 30 DAT, T 4 continued to outperform all other treatments, reaching a maximum height of 25.72 cm, followed by T 2 (24.65 cm) and the temperature treatment T 7 (18-20°C), which recorded 23.63 cm. The control treatment consistently exhibited the lowest plant height (21.10 cm). The improved growth observed under T 4 may be associated with the synergistic effect of a blue-enriched light spectrum and an extended photoperiod, which likely enhanced photosynthetic efficiency and stimulated vegetative development. In addition, both temperature treatments (T 6 and T 7 ) produced taller plants than the control, suggesting that optimized thermal conditions also contributed positively to plant growth. Overall, the findings indicate that the combination of 2 Blue:1 Red LED light with an 18-hour photoperiod was the most effective treatment for promoting plant height, demonstrating the importance of integrating appropriate light spectra and temperature management to maximize coriander growth under indoor cultivation systems.

Results and Discussion

Plant height 10, 20 and 30 days

Graphical representation of plant height at 10, 20 and 30 DAS Leaf length of coriander varied considerably among the different light spectra and temperature treatments across the observation period. At 10 DAT, the maximum leaf length was recorded in T 3 (2R:1B + 16 h photoperiod) with 11.10 cm, closely followed by T 2 (2R:1B + 18 h photoperiod) with 10.35 cm, indicating that red-dominant light promoted rapid leaf elongation during the early growth stage. The minimum leaf length was observed in T 4 (2B:1R + 18 h photoperiod) with 6.58 cm. At 20 DAT, T 3 continued to produce the longest leaves (16.06 cm), followed by T 2 (14.68 cm) and the control (13.00 cm), whereas the shortest leaves were again recorded under T 4 (10.20 cm). However, by 30 DAT, the control treatment (T 1 ) exhibited the greatest leaf length (17.53 cm), followed by T 2 (16.28 cm), while all other treatments recorded comparatively shorter leaves ranging from 11. Root length was markedly influenced by the different light spectrum and temperature treatments, indicating that environmental conditions played an important role in underground growth and root development. Among all treatments, T 6 (24-26°C temperature) produced the longest roots (12.50 cm), followed by T 7 (18-20°C temperature) with 11.86 cm, suggesting that temperature regimes had a stronger influence on root elongation than light quality alone. Among the LED treatments, T 4 (2B:1R + 18 h photoperiod) recorded the greatest root length (10.80 cm), followed by T 2 (2R:1B + 18 h photoperiod) with 10.66 cm. Moderate root lengths were observed in T 3 (2R:1B + 16 h photoperiod) and T 5 (2B:1R + 16 h photoperiod), measuring 10.26 cm and 10.20 cm, respectively. The shortest roots were recorded under the control treatment (T 1 ) with 9.97 cm. The superior performance of the temperature treatments indicates that maintaining an appropriate thermal environment enhanced cell division and elongation in root tissues, resulting in improved root growth. Furthermore, the slightly better performance of the 18-hour photoperiod over the 16-hour photoperiod among LED treatments suggests that prolonged light exposure may indirectly support root development through increased photosynthate production.

Number of leaves at 10, 20 and 30 DAS

Overall, the findings demonstrate that both temperature management and optimized light conditions contribute to improved root growth, with temperature exerting a greater influence on root elongation under controlled environment cultivation.

Graphical representation of root length (cm) of coriander

References

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