Response of naphthalene acetic acid (NAA) and magnesium on growth and yield of sweet corn (Zea mays L.)

Introduction

Sweet corn (Zea mays L.) has rapidly emerged as a highly lucrative, short-duration vegetable and cereal crop across various agrarian regions of India, notably gaining popularity in states like Delhi, Uttar Pradesh, Haryana, Maharashtra, Karnataka, and Rajasthan (Shankar et al., 2013) [16] . Valued for its high sugar content, tender kernels, and robust green fodder yield, sweet corn offers exceptional economic returns per unit area for Indian smallholders. However, the production of sweet corn in modern Indian agriculture faces significant bottlenecks due to intensive multi-cropping patterns, depleting micronutrient profiles in local soils, and unpredictable abiotic stressors that frequently limit the crop from reaching its true genetic potential (Islam et al., 2024) [4] . To maximize both quantitative yield attributes and qualitative economic traits, agronomic interventions using specific plant growth regulators (PGRs) and secondary macronutrients have become vital focal points in localized field research. In the contemporary agrarian economy of India, changing consumer dietary habits, accelerated industrialization of frozen and processed foods, and high domestic demand in urban centres have incentivized small and marginal farmers to rapidly adopt sweet corn cultivation. Major producing states including Karnataka, Maharashtra, Andhra Pradesh, Tamil Nadu, Uttar Pradesh, and Haryana report significant economic returns from sweet corn production compared to conventional grain crops, primarily owing to its short growth duration (75 to 90 days) which fits seamlessly into intensive multi-cropping annual rotations (Ramanjaneyulu et al., 2018) [11] . Historical records indicate that sweet corn was first cultivated by Native Americans in North America in 1779. In India, sweet corn was introduced much later as a specialty maize crop. Commercial cultivation began to expand during the 1990s and early 2000s, driven by the growth of the food processing industry, increasing urbanization, changing dietary preferences, and rising demand for fresh and processed vegetables. Today, sweet corn is cultivated in several states, including Karnataka, Andhra Pradesh, Telangana, Tamil Nadu, Maharashtra, Punjab, Haryana, and Uttar Pradesh, where it serves as a high-value crop due to International Journal of Advanced Biochemistry Research 2026; SP-10(7): 1768-1772 its short duration (75-90 days) and better economic returns compared with many traditional cereal crops (Yadav et al., 2016) [22] . India is one of the world's leading maize-producing countries. During 2024-25, maize was cultivated on approximately 11.2 million hectares, producing about 42.3 million tonnes with an average productivity of 3.78 t/ha. Although separate official statistics for sweet corn are not available, its cultivation is expanding rapidly in states such as Karnataka, Andhra Pradesh, Telangana, Tamil Nadu, Maharashtra, Punjab, Haryana, and Uttar Pradesh because of its short duration (75-90 days), high market value, and better profitability than many conventional cereal crops. Several studies have demonstrated that balanced fertilization and improved agronomic practices significantly enhance cob yield, quality, and economic returns in sweet corn (Naik et al., 2021) [8] . Therefore, optimizing nutrient management strategies, including the use of plant growth regulators and secondary nutrients such as magnesium, is essential for improving the growth, yield, and profitability of sweet corn under Indian conditions. Despite its excellent commercial potential, maximizing the productivity per unit area of sweet corn in India remains bounded by several crop-specific biological limitations and systemic soil nutrient degradations. Because sweet corn is harvested at the immature milk stage (typically 18 to 22 days post-silking), the crop demands highly aggressive and uninhibited early-stage vegetative growth, rapid leaf area expansion for optimum canopy light interception, and an uninterrupted source-to-sink photoassimilate translocation path. However, intensive cultivation sequences across major Indian farming belts have resulted in widespread exhaustion of critical primary, secondary, and micronutrient reserves in the soil profile. The continuous removal of nutrients without balanced replenishment has created widespread sub-surface nutrient limitations, severely weakened cellular expansion and reduced maize crop vigor (Kumar et al., 2020) [7] . To counter these nutritional deficits and maximize metabolic efficiency during the restricted crop cycle, modern Indian agronomical practices are increasingly focusing on fine-tuning crop physiology via external chemical interventions. Phytohormones and essential secondary nutrients applied as foliar sprays or targeted soil updates provide a precise, high-efficiency pathway to adjust crop ontogeny. Exogenous crop regulation aims to shift biochemical priorities away from standard baseline survival mechanisms toward upgraded structural growth, elevated chlorophyll retention, and better reproductive ear configurations. Among these biochemical stimulants, Alpha-Naphthalene Acetic Acid (NAA) a robust synthetic auxin analog and Magnesium (Mg), an absolute structural backbone of the photosynthetic machinery, present a highly promising interactive strategy for optimizing sweet corn growth and fresh cob yield parameters (Thavaprakaash et al., 2019) [20] . Naphthalene Acetic Acid (NAA) is a synthetic plant growth regulator belonging to the auxin class, which plays a multifaceted regulatory role in plant ontogeny, morphogenetic expressions, and cellular homeostasis. When applied exogenously at crucial phenological stages such as late vegetative growth or knee-high stages NAA diffuses rapidly across the cuticle to alter internal hormonal balances. At the cellular level, NAA activates plasma membrane-bound proton pumps, leading to localized acidification of the cell wall. This process, biochemically described by the Acid Growth Hypothesis, breaks down structural cross-links within cell wall polysaccharides, enabling internal turgor pressure to drive cell elongation and division (Singh et al., 2017) [18] . In sweet corn, this hormone-driven cellular expansion leads to visible morphological changes. Field trials conducted across varying sub-humid environments in India demonstrate that optimizing NAA application rates significantly increases structural plant height, stem thickness, and the Leaf Area Index (LAI). A larger, more active green canopy improves the crop's Net Assimilation Rate (NAR) and Crop Growth Rate (CGR), ensuring the accumulation of rich vegetative dry matter during the early growth phases. Furthermore, NAA improves the vascular development of the root network, increasing the volume of soil the plant can access and enhancing its capacity to draw mobile and immobile nutrients from the rhizosphere (Paramasivan et al., 2020) [9] . Beyond vegetative architecture, NAA alters the reproductive dynamics of sweet corn by managing metabolic source-sink pathways. Auxins establish strong physiological 'sinks' at the site of reproductive organs by upregulating the expression of sugar transporter proteins and cell wall invertase enzymes. Consequently, exogenously applied NAA helps direct mobile sucrose and carbohydrates away from standard structural reserves straight into the developing cob. In Indian sweet corn systems, this precise movement reduces the rate of tip-barrenness, minimizes premature kernel abortion, and ensures optimal grain-filling across the entire cob length. This results in uniform cob size, high single-ear weight, and superior marketable green yield (Sharma & Agarwal, 2019) [17] . Magnesium is crucial for sweet corn production, influencing both yield and grain quality (Rani et al., 2022) [12] stated in their research that soil acidity is a major reason for low productivity in most of cultivated soils. In India, more than 45 million hectares of land is acidic and Karnataka is one among the several states where the acidic soils are spread over a large area. Out of total cultivated area of 104 lakh hectares in Karnataka, 12.3 lakh hectares of land is acidic. On most acid soils, there are several limiting factors for plant growth, including toxic levels of Al, Mn, and iron (Fe), as well as deficiencies of some essential elements, such as phosphorus (P), nitrogen (N), potassium (K), calcium (Ca), Mg, and some micronutrients such as Mo and B, low microbial activity, poor fertility, and low crop yields. To meet the demands of calcium and magnesium, as well as to create favorable conditions for better uptake of other essential nutrients, liming is an important management practice in the acid soils helping in raising the pH and base saturation of the soil and inactivation of iron, aluminium and manganese in the soil solution and minimizing phosphate fixation by iron. Simultaneously, sustaining high-density maize systems requires addressing secondary nutrient deficiencies, where Magnesium is frequently under-applied in Indian fertilizer regimens. Magnesium serves as the absolute structural center of the chlorophyll molecule, making it completely indispensable for light absorption, carbon fixation, and maintaining peak photosynthetic rates throughout the short vegetative phase of sweet corn. When external stresses or nutrient imbalances restrict Mg concentration within the leaves and roots, cellular energy systems face oxidative stress, resulting in poor root growth and reduced nutrient absorption (Ullah et al., 2022) [21] .

Materials and method

This experiment was carried out during kharif 2025 at Crop Research Farm, Department of Agronomy, SHUATS, Prayagraj, (U.P), to check the Response of Naphthalene Acetic Acid (NAA) and Magnesium on Growth and Yield of Sweet corn. The experimental field soil was sandy loam with less availability of nitrogen. The experiment was laid out in randomised block design consisting of ten treatment viz T1 (NAA-20 ppm + Mg-20 kg/ha), T2 (NAA-20 ppm + Mg-25 kg/ha), T3 (NAA-20 ppm + Mg-30 kg/ha), T4 (NAA-40 ppm + Mg-20 kg/ha), T5 (NAA-40 ppm + Mg-25 kg/ha), T6 (NAA-40 ppm + Mg-30 kg/ha), T7 (NAA-60 ppm + Mg-20 kg/ha), T8 (NAA-60 ppm + Mg-25 kg/ha), T9 (NAA-60 ppm + Mg-30 kg/ha), T10 (N-P-K -120-60-40 Kg/ha). Which were replicated thrice. 20 kg/ha seed of Sweet corn variety Sugar 75 the spacing adopted was plant to plant 45 cm and row to 15 cm according to the treatment details and the seeds were drilled at 4-5 cm depth in the net plot area 3m x 3m on 31st July 2025. The observation on growth parameters i.e. Plant height (cm), Plant dry weight (g),were recorder whereas yield attributing parameters i.e. Number of cobs/plant, Number of grains/row, Number of grain rows/cob, Cob length, Cob yield (kg/ha), Grain yield (kg/ha) and Harvest Index (%) from the net plot area these observation were recorded. The cob and stover yield were taken for the net plot of 1m2. Harvest Index(%) was calculated by using this formula (economic yield /Biological yield) x 100 and extrapolated to a per-hectare basis. The recorded data were analysed statically by ANOVA technique. The maximum plant height observed in T5 [NAA-40 ppm + Mg-25 kg/ha] is due to the synergistic interaction between Naphthalene Acetic Acid and Magnesium. NAA stimulates crucial proton pump activity to promote rapid cell wall elongation and vertical inter nodal expansion, while the application of Magnesium ensures maximum chlorophyll core synthesis and ATP production to structurally fuel this growth. Consequently, this optimal balance of exogenous plant growth regulators and essential secondary nutrients maximizes the vegetative architecture of the sweet corn. Similar findings regarding the positive influence of exogenous NAA applications on accelerating cell elongation and improving overall plant vegetative height were also reported by Deb and Sinha (2024) [3] .

Results and discussion

Plant dry weight

At 80 DAS, there was significant difference among the treatments, the maximum plant dry weight (151.98 g) was obtained in T5 [NAA-40 ppm + Mg-25 kg/ha]. However, T6 [NAA-40 ppm + Mg-30 kg/ha] was statistically at par with T5 [NAA-40 ppm + Mg-25 kg/ha]. The maximum plant dry weight observed in T₅ [NAA-40 ppm + Mg-25 kg/ha] may be attributed to the synergistic effect of Naphthalene Acetic Acid and Magnesium on cellular metabolism and photosynthetic efficiency. NAA promotes rapid cell division and elongation, resulting in enhanced vegetative growth and biomass accumulation, whereas magnesium, being the central component of chlorophyll, improves photosynthetic activity, carbohydrate synthesis and translocation of assimilates. The combined application of optimum NAA and magnesium therefore enhanced dry matter production throughout the crop growth period. Consequently, this balanced interaction between plant growth regulator and essential nutrient maximized the overall growth performance of sweet corn. Similar findings regarding the positive influence of NAA and magnesium on dry matter accumulation and vegetative growth in maize were also reported by Rao et al,. (2021) and Sankaralingam and Malarvizhi (2021) [13,15] .

Yield Parameters Number of cobs per plant

The statistical analysis reveals that the varying treatment combinations exerted a highly significant influence on this specific prolificacy trait. There was significant difference among the treatments, significantly higher number of cobs per plant (1.66) was recorded with the application of T5 [NAA-40 ppm + Mg-25 kg/ha]. However, T6 [NAA-40 ppm + Mg-30 kg/ha] was found statistically at par with T5 [NAA-40 ppm + Mg-25 kg/ha]. Significant and maximum number of cobs/plants was observed with NAA (40 ppm), the efficient nutrient application enhanced the better root development and biomass production, resulted in increasing number of cobs per plant. Similar results were also reported by Alam and Sadat (2019) [1] . Application of NAA resulted in a maximum number of grain row/cob, possibly due to its effect on enhancing cell division during early spikelet initiation, while magnesium contributed to improved nutrient use efficiency during reproductive differentiation. Similar findings were also reported by Potarzycki (2011) [10] .

Number of grain row/cob

Number of grains/rows

The statistical observations demonstrate that the treatment variables generated a highly distinct and significant impact on kernel retention along the row. Maximum number of grains/row (37.46) was recorded with the application of T5 [NAA-40 ppm + Mg-25 kg/ha]. However, T6 [NAA-40 ppm + Mg-30 kg/ha] was found statistically at par with T5 [NAA-40 ppm + Mg-25 kg/ha]. The significant increase in grains per row could be attributed to the minimized ovule abortion mediated by NAA application. Similar findings were also reported by (Ullah et al., 2022), and (Revilla et al., 2021) [14,21] .

Cob length

There was significant difference among the treatments, significantly higher cob length (18. The elongation of the cob length might be due to the cell elongation property of auxin coupled with the metabolic energy provided by magnesium. Similar findings were also reported by Khan et al. (2025) [6] .

The statistical variance highlights that the integration of growth regulators and secondary macronutrients profoundly influenced final harvest weight. There was significant difference among the treatments, significantly higher cob yield (9.53 t/ha) was recorded with the application of T5 [NAA-40 ppm + Mg-25 kg/ha]. However,T6 [NAA-40 ppm + Mg-30 kg/ha] was found to be statistically at par with T5 [NAA-40 ppm + Mg-25 kg/ha]. The maximum cob yield under optimal NAA and Mg levels might be due to the synchronized enhancement of both chlorophyll content and sink strength, optimizing the allocation of photosynthates toward economic parts. Similar findings were reported by Choudhary et al., (2013) [2] .

The analysis of variance reveals that the vegetative structural development responded significantly to the distinct treatment combinations. There was significant difference among the treatments, significantly higher stover yield (19. This increase in stover yield is likely attributed to magnesium's foundational role in the central core of chlorophyll molecules coupled with auxin-induced lateral root expansion, which together accelerated vegetative dry matter accumulation. Similar observations were documented by Jeet et al., (2012) [5] .

Harvest Index (%) Significantly higher numerical harvest index (33.4%) was recorded with the application of T6 [NAA-40 ppm + Mg-30 kg/ha] and the minimum value (30.5%) was observed in Control (RDF) -[N-P-K -120-60-40 kg/ha] and there was no significant difference between the treatments.

Conclusion

Competing interests

Authors have declared that no competing interests exist.

References

1. Alam MS, Sadat MA. Impact of plant growth regulators on reproductive attributes and prolificacy of sweet corn (Zea mays var. saccharata). Journal of Agricultural Crop Science. 2019;14(3):201-212.
2. Choudhary RS, Jat NL, Yadav SS. Effect of plant growth regulators and nutrient management on yield attributes and yield of sweet corn (Zea mays var. saccharata). Indian Journal of Agronomy. 2013;58(2):214-218.
3. Deb P, Sinha D. Effect of plant growth regulators on the early growth of tissue cultured banana plants (cv. Grand Naine). Environment Conservation Journal. 2024;25(1):409-419.
4. Islam MS, Islam MR, Hasan MK, Hafeez ASMG, Chowdhury MK, Pramanik MH, Iqbal MA, Erman M, Barutcular C, Konuşkan Ö, Dubey A, Kumar A, Sabagh AE. Salinity stress in maize: Consequences, tolerance mechanisms, and management strategies. OBM Genetics. 2024;8(2):1-41.
5. Jeet S, Singh JP, Bohra JS. Effect of fertility levels and plant growth regulators on growth, yield and quality of sweet corn (Zea mays L.). Indian Journal of Agricultural Sciences. 2012;82(8):701-705.
6. Khan A, Hussain M, Ahmad S. Effect of potassium and foliar naphthalene acetic acid application rates for enhancing yield and phenological components of maize hybrids. Kashf Journal of Multidisciplinary Research. 2025;2(10):62-74.
7. Kumar A, Meena RN, Singh RK. Micronutrient and secondary nutrient dynamics in intensive maize-based cropping systems of Northern India: A review. Indian Journal of Agronomy. 2020;65(3):245-256.
8. Naik BSS, Sharma SK, Choudhary R, Yadav SK, Jat G, Prajapath B S. Effect of FYM and silicon on productivity of organic sweet corn. Indian Journal of Agricultural Sciences. 2021;91(11):1660-1664.
9. Paramasivan M, Malathi P, Srinivasan K. Influence of synthetic auxins on root morpho-architecture and nutrient uptake pathways in sweet corn. Madras Agricultural Journal. 2020;107(7-9):312-318.
10. Potarzycki J. Influence of magnesium fertilization on topcross hybrids of maize (Zea mays L.) yield components. Plant, Soil and Environment. 2011;57(12):565-571.
11. Ramanjaneyulu AV, Srinivas A, Kishore M. Growth, yield and economics of sweet corn (Zea mays L. var. saccharata) as influenced by planting density and nutrient management options in semi-arid tropics of Telangana. Journal of Research PJTSAU. 2018;46(1):12-21.
12. Rani SS, Sudhir K, Nalina CN, Prakash HC, Veeranagappa MC, Shankara MH. Maize yield response to application of calcium, magnesium and boron on acidic soil. International Journal of Environment and Climate Change. 2022;12(11):29802988.
13. Rao KS, Singh S, Chandra KR, Dawson J. Effect of nitrogen and foliar application of naphthalene acetic acid (NAA) on growth and yield of baby corn (Zea mays L.). International Journal of Plant & Soil Science. 2021;33(22):55-61.
14. Revilla P, Anibas CM, Tracy WF. Sweet corn research around the world 2015-2020. Agronomy. 2021;11(3):534.
15. Sankaralingam P, Malarvizhi P. Effect of graded levels of magnesium on dry matter production and yield of maize cultivated in soils of maize growing tracts in Pudukkottai district of Tamil Nadu. Madras Agricultural Journal. 2021;108(4-6):220-223.
16. Shankar LG, Ganpat LS, H KJ. Performance of baby corn (Zea mays L.) as influenced by spacing, nitrogen fertilization and plant growth regulators under subhumid condition in Rajasthan, India. African Journal of Agricultural Research. 2013;8(12):1100-1107.
17. Sharma R, Agarwal S. Plant growth regulators as tools for crop intensification and sink optimization in sweet corn production. Indian Journal of Agricultural Research. 2019;53(4):410-416.
18. Singh MK, Tiwari A, Gautam P. Physiological responses of sweet corn (Zea mays L. var. saccharata) to application of alpha-naphthalene acetic acid (NAA) and gibberellic acid. Journal of Pharmacognosy and Phytochemistry. 2017;6(5):2134-2138.
19. Suryavanshi PK, Naga SR, Choudhary R. Effect of plant growth regulators on growth, yield and quality of sweet corn (Zea mays L. var. saccharata) under semiarid conditions of Rajasthan. Annals of Agricultural Research. 2021;42(3):291-298.
20. Thavaprakaash N, Velayudham K, Santhi R. Effect of crop geometry, intercropping systems and growth regulators on yield attributes and yield of sweet corn (Zea mays L. var. saccharata). Indian Journal of Agronomy. 2019;64(2):201-207.
21. Ullah A, Zeng F, Tariq A, Asghar MA, Saleem K, Raza A, Naseer MA, Zhang Z, Noor J. Exogenous naphthaleneacetic acid alleviated alkalinity-induced morpho-physio-biochemical damages in Cyperus esculentus L. var. sativus Boeck. Frontiers in Plant Science. 2022;13:1018787.
22. Yadav OP, Prasanna BM, Yadava P, Jat SL, Kumar D, Dhillon BS, Solanki IS, Sandhu JS. Doubling maize (Zea mays) production of India by 2025: Challenges and opportunities. Indian Journal of Agricultural Sciences. 2016;86(4):427-434.