Residual effect of potash, iron and zinc on growth and yield of chickpea

Introduction

The role of balanced fertilization in sustaining crop productivity has become increasingly important in modern Indian agriculture. Among essential nutrients, potassium (K) and trace elements like iron (Fe) and zinc (Zn) are gaining renewed attention due to their multifaceted contributions to plant health and soil fertility. Overreliance on conventional NPK fertilizers, without adequate supplementation of micronutrients, has led to the emergence of secondary and micronutrient deficiencies, particularly in the coarse-textured and intensively cultivated soils of North Gujarat. Potassium enhances physiological efficiency by regulating water balance, activating key enzymes, and facilitating assimilate transport, while also helping plants withstand environmental stresses. Iron plays a central role in energy transfer and photosynthetic pathways, whereas zinc is indispensable for growth hormones, enzyme systems, and reproductive development in plants. Chickpea (Cicer arietinum L.), one of the most important pulse crops in India, serves as a major source of dietary protein, particularly in vegetarian diets. It holds a prominent place in India's pulse production, with Gujarat being a significant contributor in terms of area and yield. Chickpea not only improves soil fertility through biological nitrogen fixation but also fits well into crop rotations, especially in rainfed and semi-arid regions. However, suboptimal nutrient management particularly deficiencies of potassium, iron, and zinc poses a major constraint to achieving higher productivity and better seed quality. Therefore, integrated nutrient management practices that include both macro-and micronutrients are essential for enhancing chickpea yield, improving soil health, and supporting sustainable agriculture in the region. extractable iron (Fe), medium in available nitrogen, phosphorus, sulphur, and DTPA-extractable manganese (Mn) and zinc (Zn), and high in DTPA-extractable copper (Cu). The electrical conductivity (EC) of the soil was within the normal range, indicating no salinity hazard. A recommended dose of fertilizer (RDF) comprising 12.5:25:25 kg N:P₂O₅:S ha⁻¹ was uniformly applied to the groundnut crop in all treatments.

Results and Discussion

Number of pods per plant and pod weight per plant of chickpea

The data presented in Table 1 revealed that the residual application of potash, iron and zinc significantly improved the number of pods per plant and pod weight per plant of chickpea during both the years and on pooled basis. Among the potassium levels, residual application of 50 kg K ha⁻¹ (K₂) recorded the highest number of pods per plant (39.70 pooled) and pod weight per plant (18.02 g pooled), followed by 25 kg K ha⁻¹ (K₁), while the lowest values were recorded under the control (K₀). The improvement may be attributed to the role of potassium in enhancing photosynthesis, enzyme activation, carbohydrate translocation and efficient partitioning of assimilates towards reproductive organs, resulting in better pod formation and development. Similar findings were reported by Goud et al. (2014) [4] , Jat et al. (2017) [5] , and Patel et al. (2018) [8] . Similarly, residual application of 30 kg Fe ha⁻¹ (Fe₂) produced the maximum number of pods per plant (40.16 pooled) and pod weight per plant (17.95 g pooled), followed by 15 kg Fe ha⁻¹ (Fe₁). This beneficial effect could be due to the involvement of iron in chlorophyll synthesis, electron transport, nitrogen metabolism and biological nitrogen fixation, which enhanced photosynthetic activity and assimilate production, thereby increasing pod setting and pod growth. Similar observations were made by Patil et al. (2007) [9] , Yadav et al. (2020) [14] , and Chauhan et al. (2024) [2] . Among the zinc treatments, 16 kg Zn ha⁻¹ (Zn₂) recorded the highest number of pods per plant (39.55 pooled) and pod weight per plant (18.07 g pooled), which was statistically at par with 8 kg Zn ha⁻¹ (Zn₁) for number of pods per plant.

The positive response to zinc may be attributed to its role in auxin synthesis, enzyme activation, protein synthesis and improved nutrient uptake, leading to better flower retention, pod development and accumulation of photosynthates in pods. Supporting evidence comes from Ranparia (2001) [11] , Elayaraja and Singaravel (2012) [3] . The interaction effects of potash, iron and zinc as well as their interactions with years were found to be nonsignificant for both the characters studied, indicating that the residual effects of individual nutrients remained consistent over the two years of experimentation. Overall, the residual application of 50 kg K ha⁻¹, 30 kg Fe ha⁻¹ and 16 kg Zn ha⁻¹ proved most effective in improving the yield attributes of chickpea.

Seed and Stover yields of chickpea

The data presented in Table 2 indicated that the residual application of potash, iron and zinc significantly influenced the seed and stover yields of chickpea during both the years as well as on pooled basis. Among the potassium levels, the residual application of 50 kg K ha⁻¹ (K₂) recorded the highest seed yield (1574 kg ha⁻¹) and stover yield (2622 kg ha⁻¹), followed by 25 kg K ha⁻¹ (K₁), while the lowest yields were obtained under the control (K₀). The increase in yield may be attributed to the residual availability of potassium, which enhanced photosynthesis, enzyme activation, assimilate translocation and water-use efficiency, thereby promoting better growth and dry matter accumulation. Similar results were reported by Goud et al. (2014) [4] , Jat et al. (2017) [5] , and Patel et al. (2018) [8] . Residual application of 30 kg Fe ha⁻¹ (Fe₂) significantly produced the highest seed yield (1507 kg ha⁻¹) and stover yield (2511 kg ha⁻¹), followed by 15 kg Fe ha⁻¹ (Fe₁). The improvement in yield could be due to the role of iron in chlorophyll synthesis, electron transport, respiration and biological nitrogen fixation, which enhanced photosynthetic efficiency and nutrient utilization, resulting in higher biomass production and seed yield. Similar results were reported by Yadav (2002) [13] , Kumar et al. (2006) [7] , Patil et al. (2007) [9] and Thakur et al. (2010) [12] . Similarly, the residual application of 16 kg Zn ha⁻¹ (Zn₂) recorded the maximum seed yield (1513 kg ha⁻¹) and stover yield (2519 kg ha⁻¹), followed by 8 kg Zn ha⁻¹ (Zn₁), whereas the lowest yields were observed under Zn₀. The beneficial effect of zinc may be attributed to its involvement in enzyme activation, auxin synthesis, protein metabolism and improved nutrient uptake, leading to enhanced vegetative growth, dry matter production and efficient translocation of photosynthates to developing seeds. Similar findings also reported by Kulhare et al.

(2014) [6] , Ankesh et al. (2023) [1] , Polara et al. (2010) [10] . The interaction effects among potash, iron and zinc, as well as their interactions with years, were found to be nonsignificant for both seed and stover yields, indicating that the residual effects of individual nutrients remained consistent across the two years of study. Overall, the residual application of 50 kg K ha⁻¹, 30 kg Fe ha⁻¹ and 16 kg Zn ha⁻¹ proved most effective in enhancing the productivity of chickpea.

Summary and conclusion

The experimental results revealed that the residual application of potash, iron and zinc significantly improved the growth, yield attributes and productivity of chickpea.

Residual application of 50 kg K ha⁻¹, 30 kg Fe ha⁻¹ and 16 kg Zn ha⁻¹ recorded the highest number of pods per plant, pod weight per plant, seed yield and stover yield over the lower levels and control. The interaction effects among nutrients and with years were non-significant, indicating a stable and consistent residual response across both years.

Overall, the study concludes that the residual application of 50 kg K ha⁻¹, 30 kg Fe ha⁻¹ and 16 kg Zn ha⁻¹ is beneficial for enhancing the productivity of chickpea under the given experimental conditions.

References

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