Effect of synthetic compounds on growth, physiological traits and yield of pearl millet (Pennisetum glaucum L.) under heat stress conditions
Abstract
Pearl millet (Pennisetum glaucum L.) is an important cereal crop grown in arid and semi-arid regions of India. High temperature stress during reproductive stages adversely affects crop productivity. A field experiment was conducted during 2025 at the Centre for Millets Research, Deesa to evaluate the effect of synthetic compounds on morpho-physiological traits and yield of pearl millet under heat stress conditions. The experiment was laid out in a split plot design with four replications. Three sowing dates were assigned to main plots, namely D1 (second week of February), D2 (first week of March) and D3 (second week of March), while eight foliar spray treatments of synthetic compounds were assigned to subplots. The results revealed that sowing during the first week of March (D2) significantly increased plant height (178.26 cm), leaf area (1000.21 cm² plant⁻¹), dry matter accumulation (14.23 g m⁻²) and SPAD value (61.73). Among foliar spray treatments, application of salicylic acid @100 ppm recorded significantly higher growth parameters and yield attributes including earhead length (25.66 cm), test weight (13.41 g), grain yield (4375 kg ha⁻¹) and stover yield (7526 kg ha⁻¹). The study indicates that optimum sowing time combined with foliar application of salicylic acid improves heat stress tolerance and productivity of pearl millet.
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Introduction
Pearl millet (Pennisetum glaucum L.), commonly known as bajra, is one of the most important coarse cereals cultivated in tropical and semi-arid regions of India. It serves as a staple food and fodder crop due to its ability to withstand drought and poor soil fertility conditions. India produces approximately 9.13 million tonnes of pearl millet from 7.38 million hectares with an average productivity of 1237 kg ha⁻¹, with Rajasthan, Gujarat, Haryana, Madhya Pradesh and Maharashtra being the major producing states. High temperature stress is a major abiotic factor limiting crop productivity in arid and semi-arid regions. Climate projections indicate that global temperatures may increase by 1-3.4 °C by the end of the century, resulting in more frequent episodes of heat stress during crop growth stages. Application of certain synthetic compounds such as potassium nitrate (KNO₃), calcium chloride (CaCl₂) and salicylic acid (SA) has been reported to enhance plant tolerance to abiotic stresses by regulating physiological and biochemical processes. Foliar application of these compounds may improve plant growth, membrane stability and yield under stress conditions. Therefore, the present investigation was conducted to evaluate the effect of different synthetic compounds and sowing dates on morpho-physiological traits and yield of pearl millet under heat stress conditions.
Materials and Methods
Experimental site
The field experiment was conducted during the summer season of 2025 at the Centre for Millets Research, Deesa, Sardarkrushinagar Dantiwada Agricultural University, Gujarat.
Experimental design
The experiment was laid out in a split plot design with four replications.
Main plot treatments (Date of sowing)
D1-Second week of February D2-First week of March D3 -Second week of March Sub plot treatments (Foliar spray of synthetic compounds) T1-Potassium nitrate @ 1% T2-Potassium nitrate @ 3% T3-Calcium chloride @ 6 mM T4-Calcium chloride @ 12 mM T5-Salicylic acid @ 100 ppm T6-Salicylic acid @ 300 ppm T7-Water spray (control) T8 -Absolute control Foliar sprays were applied at booting and anthesis stages.
Crop details
Results and Discussion
Effect of sowing date on growth and physiological parameters Sowing date significantly influenced the growth and physiological traits of pearl millet. Sowing during the first week of March (D2) resulted in significantly higher plant height, leaf area, dry matter accumulation and SPAD value compared with other sowing dates. The improved growth under this sowing time may be attributed to favourable temperature conditions during vegetative and reproductive phases of crop growth. Optimum temperature promotes better photosynthetic activity, leaf expansion and assimilate accumulation which ultimately enhances biomass production.
Higher leaf area under D2 sowing contributed to increased interception of solar radiation and enhanced photosynthetic efficiency. The increased SPAD value indicates higher chlorophyll content, which directly improves photosynthetic rate and biomass accumulation. Similar results were reported by Yadav et al. (2012) [4] and Gupta et al. (2015) [3] , who observed that optimum sowing time significantly improves growth and physiological performance of pearl millet under semi-arid conditions. The results clearly indicate that delayed sowing exposes the crop to higher temperature stress during reproductive stages, leading to reduced physiological efficiency and lower biomass accumulation.
Effect of synthetic compounds on morpho-physiological parameters
Foliar application of synthetic compounds significantly improved morpho-physiological parameters of pearl millet under heat stress conditions. Among the treatments, salicylic acid @ 100 ppm (T5) recorded the highest plant height, leaf area, dry matter accumulation and SPAD value. Salicylic acid acts as a signalling molecule in plants and plays an important role in stress tolerance by regulating physiological and biochemical processes. It enhances antioxidant activity, improves membrane stability and maintains chlorophyll content under stress conditions. This leads to better photosynthetic efficiency and improved plant growth. The increase in dry matter accumulation observed under salicylic acid treatment may be due to improved photosynthesis and efficient translocation of assimilates from source to sink. Similar findings were reported by Hayat et al. (2010) [1] and Khan et al. (2015) [2] , who reported that foliar application of salicylic acid significantly improves growth and physiological traits of crops under abiotic stress conditions.
Effect on yield and yield attributes
Yield attributes such as earhead length, girth of earhead, number of effective tillers per plant and seed setting percentage were significantly influenced by sowing date and foliar spray treatments. The highest grain yield and stover yield were recorded under salicylic acid @ 100 ppm, which may be attributed to improved physiological efficiency and better reproductive development. Salicylic acid improves pollen viability, seed setting and assimilate partitioning, which ultimately leads to higher grain yield. Higher test weight under salicylic acid treatment indicates improved grain filling due to better translocation of photosynthates during the reproductive stage. Similar results were reported by Singh et al. (2018) [5] and Rao et al. (2017) [6] who reported that exogenous application of salicylic acid enhances yield and yield components in cereal crops under stress conditions.
References
- Hayat S, et al. Role of salicylic acid in plant responses to environmental stresses. Plant Signaling and Behavior. 2010.
- Khan MIR, Fatma M, Per TS, Anjum NA, Khan NA. Salicylic acid-induced abiotic stress tolerance. Environmental and Experimental Botany. 2015.
- Gupta S, et al. Temperature stress and productivity of pearl millet. Journal of Plant Physiology. 2015.
- Yadav OP, et al. Pearl millet production and management under arid environments. Indian Journal of Agronomy. 2012.
- Singh R, et al. Influence of plant growth regulators on growth and yield of pearl millet. Indian Journal of Agricultural Sciences. 2018.
- Rao SS, et al. Effect of salicylic acid on growth and yield of cereal crops. Crop Research Journal. 2017.
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