To investigate the impact of zinc on the growth and yield of green gram (Vigna radiata L.) cultivated in zinc-deficient soil

Introduction

The green gram (Vigna radiata L.) is known as Mung in Hindi and Mung bean in English. It is considered the most resilient among all pulse crops. Belonging to the Leguminosae family, green gram originated primarily in India and is mainly grown across East Asia, Southeast Asia, and the Indian subcontinent. In India, it ranks third in importance for pulse crops, following pigeon pea and chickpea, based on both production and cultivation area. (Singh et al. 2017). India is the world's largest producer of green gram, accounting for over 70% of the global crop and approximately 65% of the global area and 54% of the global production. Green gram is cultivated across almost all Indian states, with major growing regions including Andhra Pradesh, Maharashtra, Orissa, Rajasthan, Gujarat, Punjab, and Uttar Pradesh. In India, green gram is grown on 3.57 million hectares, yielding a total production of 17.89 metric tonnes with a productivity of 500 kg per hectare. (Anonymous, 2021) [4] . Green gram is an short-duration legume crop with a notable amount of riboflavin and thiamine, as well as 25 per cent protein with excellent digestion (Lokhande et al. 2018) [9] . Zinc is a critical micronutrient essential for plant growth, acting as a foundation of nutrition. Soil zinc levels in pasture and forage are often low (20-30 mg kg⁻¹). Zinc is vital for enzyme function, including dehydrogenases and superoxide dismutase, and its deficiency impairs RNA and protein production, leading to low plant protein content. Foliar spraying of zinc is considered essential for enhancing green gram growth and quality. Zinc regulates plant metabolic reactions, such as chlorophyll formation, and influences plant growth hormone production, including the biosynthesis of IAA, which can increase crop yield. It also contributes to protein, nucleic acid, and seed synthesis, and regulates the balance of carbonic acid, water, and CO2 in plant metabolism (Ranpariya et al. 2017) [11] . Zinc efficiency can negatively impact the quality of harvested crops. It may also increase the plant's vulnerability to damage caused by intense light, high temperatures and fungal infections. Additionally, zinc appears to influence the plant's ability to absorb and transport water, as well as lessen the harmful effects of brief periods of heat and salt stress. The correct structure of macromolecules, iron transport systems, and cell membrane integrity all depend on zinc. Zinc sulfate can be sprayed on leaves or applied to the soil as a basal dose. Zinc is essential for the growth and development of plants, despite being needed in trace amounts. Auxins, which control growth and encourage stem elongation, are produced using it, and it is an essential part of many proteins and enzymes. It has been demonstrated that applying zinc improves growth parameters, irrespective of the dosage or technique. Zinc also increases the concentration of zinc in plant shoots when it is sprayed on leaves or incorporated into the soil (Abbas et al. 2010) [1] .

Material and Methods

The field experiment was conducted at the research field of the Department of Soil Science at the College of Agriculture, Latur, during the Kharif season of 2024-2025. to investigate the "effect of zinc application on yield, nutrient uptake and quality of green gram (Vigna radiata L.) grown on zinc-deficient soil." The field topography was uniformly leveled, well-drained and conducive to the best possible crop growth. The experimental soil had a clayey texture, a slightly alkaline reaction, low levels of available nitrogen (228.33 kg ha -1 ), available phosphorous (14.02 kg ha -1 ) and high levels of available potassium (418.14 kg ha -1 ). It was also deficient in DTPA-Zn (0.50 mg kg -1 ). According to this data, the average temperature for the cropgrowing season is 35.2°C at its highest point and 16.10°C at its lowest. The mean humidity during morning is 98.00% while mean humidity during evening is 30.86 %. The experiment was conducted using a randomized block design with three replications and eight different treatments. The treatments were as follows: T1 -(Control ), T2 -(RDF ), T3 -(RDF combined with soil application (S.A.) of ZnSO₄ at 25 kg ha -1 ), T4 -(RDF with foliar application (F.A.) of ZnSO₄ at 0.5% concentration applied at 25 and 40 days after sowing (DAS), T5 -(RDF with both soil application of ZnSO₄ at 25 kg ha -1 and foliar application at 0.5% at 25 and 40 DAS), T6 -(RDF with soil application of Grade-I micronutrient at 25 kg ha -1 ), T7-( RDF with foliar application of Grade-II micronutrient at 0.5% at 25 and 40 DAS) and T8 -(RDF with both soil application of Grade-I micronutrient at 25 kg ha -1 and foliar application of Grade-II micronutrient at 0.5% at 25 and 40 DAS). Each experimental unit measured 3.9 m by 4.0 m. Sowing was carried out using the drilling method on July 25, 2024, with a spacing of 30 cm between rows and 10 cm between plants. Recommended agronomic practices and plant protection measures were followed throughout the experiment. A fertilizer dose of 25:50:25 NPK kg ha -1 was applied according to the respective treatments. Prior to sowing, seeds were treated with rhizobium biofertilizer and SAAF fungicide, and foliar sprays of zinc and multi-micronutrients were applied as per the treatment requirements. The crop was harvested on September 8, 2024.

Result and Discussion

Growth Parameters Plant height

The data revealed that the application of zinc at key growth stages had a significant effect on the plant height of green gram at 30 DAS, 45 DAS, and at harvest. Plant height varied from 29.16 to 43.40 cm at 30 DAS, 34.59 to 49.63 cm at 45 DAS, and from 38.45 to 53.12 cm at the time of harvest. The maximum plant height in green gram was observed under treatment T8, which involved the application of the recommended dose of fertilizers (RDF) along with soil application (S.A.) of Grade-I micronutrients at 25 kg ha⁻¹ and foliar application (F.A.) of Grade-II micronutrients at 0.5% concentration at 25 and 40 days after sowing (DAS). This treatment resulted in plant heights of 43.40 cm at 30 DAS, 49.63 cm at 45 DAS, and 53.12 cm at harvest. These values were statistically on par with treatment T5 (RDF + S.A. of ZnSO₄ @ 25 kg ha⁻¹ + F.A. of ZnSO₄ @ 0.5% at 25 and 40 DAS) and treatment T3 (RDF + S.A. of ZnSO₄ @ 25 kg ha⁻¹), and significantly superior to all other treatments. In contrast, the lowest plant height was recorded in the control (T1), with measurements of 29.16 cm at 30 DAS, 34.59 cm at 45 DAS, and 38.45 cm at harvest. The results are confirmative with the finding of Ajjannavar et al. (2021) [2] , Boradkar et al. (2023) [5] and Almad et al. (2020) [3] .

Number of nodulations at flowering

The data on the number of nodules per plant in green gram, as affected by zinc application and recorded during the flowering stage, are presented. During this stage, the number of nodules plant -1 ranged from 15.02 to 19.82. The highest number of nodules plant -1 (19.82) was recorded in treatment T8, which included RDF along with soil application of Grade-I micronutrients at 25 kg ha -1 and foliar application of Grade-II micronutrients at 0.5% at 25 and 40 DAS. This result was statistically similar to treatments T5 (RDF + soil application of ZnSO₄ at 25 kg ha -1 + foliar application of ZnSO₄ at 0.5% at 25 and 40 DAS) and T3 (RDF + soil application of ZnSO₄ at 25 kg ha -1 ), and significantly better than the other treatments. The lowest number of nodules plant -1 (15.02) was observed in the control treatment (T1). Similar findings were reported by Kumar et al. (2020) [8] , Boradkar et al. (2023) [5] and Meena et al. (2013) [10] .

Leaf area

Data showed that leaf area of green gram was varied from 380.47 to 518.23 cm 2 at 30 DAS and 402.27 to 554.20 cm 2 at 45 DAS. The highest leaf area, measuring 518.23 cm² and 554.20 cm² plant -1 at 30 and 45 days after sowing (DAS), respectively, was observed in treatment T8 (RDF combined with soil application of Grade-I micronutrients at 25 kg ha -1 and foliar application of Grade-II micronutrients at 0.5% at 25 and 40 DAS). This treatment was statistically on par with T5 (RDF + soil application of ZnSO₄ at 25 kg ha -1 + foliar application of ZnSO₄ at 0.5% at 25 and 40 DAS) and T3 (RDF + soil application of ZnSO₄ at 25 kg ha -1 ) and significantly outperformed the other treatments. In contrast, the lowest leaf area, 380.47 cm² and 402.27 cm² plant -1 at 30 and 45 DAS, respectively, was recorded in the control treatment (T1). Similar result was reported by Almad et al. (2020) [3] , Boradkar et al. (2023) [5] and Gowda et al. (2014) [7] .

Yield and yield attributes Number of pods plant -1 and Number of grains pod -1

The data revealed that the highest number of pods plant -1 (29.95) was observed in treatment T8 (RDF + soil application of Grade-I micronutrient at 25 kg ha -1 + foliar application of Grade-II micronutrient at 0.5% at 25 and 40 DAS). This was statistically on par with treatment T5 (RDF + soil application of ZnSO₄ at 25 kg ha -1 + foliar application of ZnSO₄ at 0.5% at 25 and 40 DAS) and treatment T3 (RDF + soil application of ZnSO₄ at 25 kg ha - 1 ) and significantly better than the remaining treatments. The lowest number of pods plant -1 (25.08) was recorded in treatment T1 (Control). Likewise, the highest number of seeds pod -1 (13.85) was recorded in treatment T8 (RDF + soil application of Grade-I micronutrient at 25 kg ha -1 + foliar application of Grade-II micronutrient at 0.5% at 25 and 40 DAS). This value was comparable to that in treatment T5 (RDF + soil application of ZnSO₄ at 25 kg ha -1 + foliar application of ZnSO₄ at 0.5% at 25 and 40 DAS) and treatment T3 (RDF + soil application of ZnSO₄ at 25 kg ha -1 ), and significantly higher than in the other treatments. The lowest number of seeds per pod (10.72) was found in treatment T1 (Control) in green gram. Similar findings were reported by Gidaganti et al. (2019) [6] , Banoth et al. (2022) and Boradkar et al. (2023) [5] .

It was clearly noted that application of zinc showed beneficial effect on grain yield as compared to control. The seed yield of green gram ranged between 865.38 kg ha -1 to 1408.12 kg ha -1 . The highest seed yield (1408.12 kg ha -1 ) was achieved with treatment T8, which involved the application of RDF along with soil application of Grade-I micronutrients at 25 kg ha -1 and foliar application of Grade-II micronutrients at 0.5% at 25 and 40 days after sowing (DAS). This yield was statistically on par with treatment T5 (RDF + soil application of ZnSO₄ at 25 kg ha -1 + foliar application of ZnSO₄ at 0.5% at 25 and 40 DAS) and treatment T3 (RDF + soil application of ZnSO₄ at 25 kg ha -1 ) and significantly higher than all other treatments. In contrast, the lowest seed yield (865.38 kg ha -1 ) was observed under treatment T1 (Control). These results are in line with Gidaganti et al. (2019) [6] , Ajjannavar et al. (2021) [2] and Boradkar et al. (2023) [5] .

The data showed that the straw yield of the green gram crop increased with the application of zinc, ranging from 1371.79 to 1976.50 kg ha⁻¹. The highest straw yield (1976.50 kg ha⁻¹) was observed in treatment T8 (RDF combined with S.A. Grade-I micronutrient at 25 kg ha⁻¹ and F.A. Grade-II micronutrient at 0.5% applied at 25 and 40 DAS). This yield was statistically similar to treatment T5 (RDF with S.A. of ZnSO4 at 25 kg ha⁻¹ and F.A. of ZnSO4 at 0.5% applied at 25 and 40 DAS) and treatment T3 (RDF with S.A. of ZnSO4 at 25 kg ha⁻¹), but significantly higher than all other treatments. In contrast, the lowest straw yield (1371.79 kg ha⁻¹) was recorded in treatment T1 (Control). The results explained above are in close conformity with the findings of Almad et al. (2020) [3] , Meena et al. (2013) [10] and Boradkar et al. (2023) [5] .

Acknowledgement

We sincerely thank the College of Agriculture, Latur, Vasantrao Naik Marathwada Krishi Vidyapeeth, Parbhani for providing financial support and infrastructure facilities that made this work possible.

Conclusion

1. Green gram crops fertilized with RDF combined with S.A.

Grade-I micronutrient at 25 kg ha⁻¹ and F.A. Grade-II micronutrient at 0.5% applied at 25 and 40 days after sowing showed improved growth parameters such as plant height, leaf area and number of nodules plant -1 . This treatment was found to be comparable to the application of RDF with S.A. of ZnSO₄ at 25 kg ha⁻¹ plus F.A. of ZnSO₄ at 0.5% at 25 and 40 DAS, as well as RDF with S.A. of ZnSO₄ at 25 kg ha⁻¹. 2. The application of RDF combined with S.A. Grade-I micronutrient at 25 kg ha⁻¹ and F.A. Grade-II micronutrient at 0.5% at 25 and 40 days after sowing resulted in a significantly higher number of pods plant -1 , grains pod -1 , seed yield plot -1 , seed yield hectre -1 , straw yield plot -1 and straw yield hectare -1 . This treatment was found to be comparable to the RDF + S.A. of ZnSO₄ at 25 kg ha⁻¹ + F.A. of ZnSO₄ at 0.5% applied at 25 and 40 DAS, as well as RDF + S.A. of ZnSO₄ at 25 kg ha⁻¹ alone. 19.48 T4: RDF + F.A. of ZnSO4 @ 0.5 % 25 and 40 DAS.

18.58 T5: RDF + S.A. of ZnSO4 @ 25 kg ha -1 + F.A. of ZnSO4 @ 0.5 % at 25 and 40 DAS.

19.69 T6: RDF + S.A. Grade-I micro-nutrient @ 25 kg ha -1 .

18.43 T7: RDF + F.A. Grade-II micro-nutrient @ 0.5 % at 25 and 40 DAS. 17.93 T8: RDF + S.A. Grade-I micro-nutrient @ 25 kg ha -1 + F.A. Grade-II micro-nutrient @ 0.5 % at 25 and 40 DAS. 1132.48 1634.62 T7: RDF + F.A. Grade-II micro-nutrient @ 0.5 % at 25 and 40 DAS.

1087.61 1559.83 T8: RDF + S.A. Grade-I micro-nutrient @ 25 kg ha -1 + F.A. Grade-II micro-nutrient @ 0.

References

1. Abbas G, Abbas Z, Aslam M, Malik AU, Hussain F. Effects of organic and inorganic fertilizers on mungbean (Vigna radiata L.) yield under arid climate. Int J Plant Sci. 2010;2(4):94-98.
2. Ajjannavar DB, Yadahalli VG, Sarwad IM, Patil SB. Growth and yield of chickpea (Cicer arietinum L.) and soil fertility as influenced by micronutrients and bio-fertilizers in vertisols. J Farm Sci. 2021;34(4):404-409.
3. Almad SR, Pandit SR, Rachappa V, Dodamani BM, Ananda N. Growth, yield and economics of pigeonpea as influenced by biofortification of zinc and iron. Int J Curr Microbiol Appl Sci. 2020;9(2):3088-3097.
4. Anonymous. Annual report on pulses. Agric Stat Glance [Internet]. 2021 [cited 2025 Sep 24]. Available from: www.dacnet.nic.in/ean
5. Boradkar SG, Adsul PB, Tribhuwan AR, Shelke MS. Effect of iron and zinc application on soil properties, nutrient uptake and yield of green gram (Vigna radiata L.) in Inceptisol. Indian J Agric Allied Sci. 2023;9(1):1-6.
6. Gidaganti A, Tarence T, Smriti R, David AA. Effect of different levels of micronutrients on crop growth and yield parameters of green gram (Vigna radiata L.). Int J Chem Stud. 2019;7(3):866-869.
7. Gowda KM, Halepyati AS, Koppalkar, Satyanarayaro. Response of pigeonpea (Cajanus cajan L. Millsp.) to application of micronutrients through soil and foliar spray macronutrients on yield, economics and protein content. Karnataka J Agric Sci. 2014;27(4):460-463.
8. Kumar R, Abrar YB, Kumar M, Bhusan A, Singh K. Growth, nodulation and yield of black gram (Vigna radiata L.) as influenced by sulphur and iron under sandy loam soil. J Pharmacogn Phytochem. 2020;6(5):1474-1477.
9. Lokhande PB. Effect of phosphorus and zinc on growth, yield, nutrient uptake and quality of green gram (Vigna radiata L.) in Inceptisol [Master's thesis]. Parbhani: Vasantrao Naik Marathwada Krishi Vidyapeeth; 2018. Phytochemistry. 9(3):614-616.
10. Meena KK, Meena RS, Kumavat SM. Effect of sulphur and iron fertilization on yield attributes, yield and nutrient uptake of mungbean (Vigna radiata L.). Indian J Agric Sci. 2013;83(4):472-476.
11. Ranpariya VS, Polara KB, Hirpara DV, Bodar KH. Effect of potassium, zinc and FYM on content and uptake of nutrients in seed of summer green gram (Vigna radiata L.) and post-harvest soil fertility under medium black calcareous soil. Int J Chem Stud. 2017;5(5):1055-1058.
12. Singh P, Yadav KK, Meena FS, Singh B, Singh R. Effect of phosphorus and sulphur on yield attributes, yield and nutrient uptake of mungbean (Vigna radiata L.) in central plain zone of Punjab, India. Plant Arch. 2017;17(2):17561760.