Effect of Different Levels of Potassium and Boron on Growth, Productivity and Economics of Blackgram (Vigna mungo L.) under Central Plain Zone of Uttar Pradesh

Introduction

Blackgram [Vigna mungo (L.) Hepper], popularly known as urdbean, is one of the most important pulse crops cultivated extensively in tropical and subtropical regions of the world. It belongs to the family Fabaceae and occupies a prominent position among pulse crops because of its high nutritional value, short duration, adaptability to diverse agro-climatic conditions and ability to improve soil fertility through biological nitrogen fixation. Blackgram seeds contain approximately 22-26 per cent protein, 55-60 per cent carbohydrates, essential amino acids, vitamins and minerals, making it an important source of dietary protein for millions of people, particularly in vegetarian populations of South Asia. Besides human consumption, crop residues serve as nutritious livestock feed, while the crop itself contributes significantly towards soil fertility improvement through symbiotic nitrogen fixation. Pulses are often referred to as the "poor man's meat" due to their high protein content and affordability. They play a crucial role in ensuring nutritional security, improving soil health and promoting sustainable agricultural production systems. According to the Food and Agriculture Organization (FAO, 2024), pulse crops are cultivated over approximately 98 million hectares globally with an annual production exceeding 100 million tonnes. India is the largest producer, consumer and importer of pulses, accounting for nearly 25 per cent of global pulse production and about 27 per cent of world consumption. Among pulse crops, blackgram occupies a unique place because of its multiple uses and high market demand. The crop is widely used in the preparation of dal, papad, idli, dosa, vada and several traditional food products. The flour of blackgram is highly valued due to its excellent binding properties and nutritional quality. In addition to its food value, blackgram improves soil fertility by fixing atmospheric nitrogen ranging from 20 to 40 kg ha⁻¹ through symbiotic association with Rhizobium bacteria. Therefore, the crop is frequently included in cereal-based cropping systems for improving soil productivity and sustainability. India cultivates blackgram over approximately 5.5 million hectares with annual production around 3.7 million tonnes and average productivity ranging between 700 and 750 kg ha⁻¹ (DES, 2024). Despite its importance, the average productivity remains considerably lower than its genetic potential, which exceeds 1.5-2.0 t ha⁻¹ under improved management conditions. Several biotic and abiotic factors are responsible for this yield gap, including nutrient deficiencies, moisture stress, poor soil fertility, insectpest incidence and inadequate crop management practices. The major blackgram-growing states include Uttar Pradesh, Madhya Pradesh, Maharashtra, Rajasthan, Tamil Nadu, Karnataka, Andhra Pradesh and Telangana. Uttar Pradesh occupies a significant position in pulse cultivation owing to its fertile alluvial soils and favorable climatic conditions. However, productivity of blackgram in Central Uttar Pradesh remains comparatively low due to declining soil fertility and imbalanced fertilizer use. Continuous cultivation, intensive cropping systems and inadequate micronutrient supplementation have resulted in widespread deficiencies of both macro and micronutrients. Balanced nutrient management is one of the most important prerequisites for achieving higher productivity and profitability in pulse crops. Nutrient deficiencies not only reduce crop growth and yield but also adversely affect nodulation, biological nitrogen fixation and nutrient-use efficiency. Among the essential nutrients required by blackgram, potassium and boron have emerged as critical elements influencing crop growth, reproductive development and yield formation. Potassium (K) is the third major essential plant nutrient after nitrogen and phosphorus and is required in relatively large quantities by crop plants. It is often referred to as the "quality nutrient" because of its significant role in improving crop quality, stress tolerance and physiological efficiency. Potassium activates more than sixty enzymes involved in carbohydrate metabolism, protein synthesis, photosynthesis and respiration (Marschner, 2012) [18] . Potassium plays a vital role in:mRegulation of stomatal opening and closing, Maintenance of cellular water balance, Activation of enzyme systems, Photosynthesis and carbohydrate synthesis, Protein metabolism, Translocation of assimilates, Root development and nodulation, Stress resistance against drought and diseases Adequate potassium supply improves root proliferation and enhances nutrient uptake from soil. It also promotes efficient movement of photosynthates from source tissues to developing pods and seeds. In pulse crops, potassium enhances nodulation and biological nitrogen fixation by improving root growth and energy transfer processes. Deficiency of potassium results in poor vegetative growth, chlorosis of leaves, weak stems, reduced photosynthetic activity and poor grain filling. Several researchers have reported significant yield improvements in pulse crops following potassium fertilization. Mengel and Kirkby (2001) [19] observed that potassium application enhanced assimilate translocation and enzyme activity, thereby improving productivity and grain quality. Kumar et al. (2022) [5]

Research Gap

Although considerable research has been conducted on nutrient management in pulse crops, most studies have focused on either potassium or boron individually. Limited information is available regarding their combined effect on growth, nodulation, productivity and economics of blackgram under the agro-climatic conditions of Central Uttar Pradesh. Furthermore, the optimum combination of potassium and boron suitable for maximizing blackgram productivity under local soil conditions has not been adequately established.

Justification of the Study

The declining productivity of blackgram in Uttar Pradesh is largely associated with nutrient depletion and imbalanced fertilizer use. Potassium deficiency and boron deficiency are increasingly becoming major constraints limiting pulse productivity. Since both nutrients play critical roles in growth and reproductive development, their balanced application may substantially improve crop performance. Development of efficient nutrient management strategies involving potassium and boron is therefore essential for: Increasing blackgram productivity, Improving nutrient-use efficiency, Enhancing profitability of pulse cultivation, Maintaining soil fertility, Promoting sustainable agriculture Keeping these facts in view, the present investigation entitled "Effect of Different Levels of Potassium and Boron on Growth and Yield of Blackgram (Vigna mungo L.)" was undertaken during Kharif 2025 under the agro-climatic conditions of Kanpur, Uttar Pradesh.

Materials and Methods

The present investigation entitled "Effect of Different Levels of Potassium and Boron on Growth and Yield of Blackgram (Vigna mungo L.)" was conducted during the Kharif season of 2025 at the Students' Instructional Farm, Faculty of Agricultural Sciences and Allied Industries, Rama University, Kanpur, Uttar Pradesh, India. The experimental farm is situated in the Central Plain Zone (Agro-climatic Zone V) of Uttar Pradesh and represents the typical agro-ecological conditions of the Indo-Gangetic alluvial plains. Geographically, the experimental site is located at approximately 26.5° N latitude and 80.3° E longitude with an altitude of about 125 m above mean sea level. The region experiences a subtropical climate characterized by hot summers, humid monsoon conditions and mild winters. The field selected for the study was nearly levelled, well drained and uniform in fertility status, which ensured minimum experimental variation and better expression of treatment effects. Weather conditions prevailing during the crop growth period exerted a considerable influence on crop establishment, vegetative growth, flowering, pod development and final productivity of blackgram. During the experimental season, the maximum temperature ranged from 30 to 40°C, while the minimum temperature varied between 18 and 28°C. Relative humidity remained comparatively high during July and August due to active monsoon conditions and gradually declined towards crop maturity. Adequate and well-distributed rainfall during the vegetative phase ensured proper germination, root development and nutrient availability, whereas comparatively dry weather during reproductive and maturity stages favored flowering, pod setting and seed filling. Overall, the meteorological conditions remained conducive for blackgram cultivation and facilitated optimum crop growth. Prior to sowing, representative soil samples were collected randomly from different locations of the experimental field from a depth of 0-15 cm and analyzed using standard laboratory procedures. The soil was sandy loam in texture, slightly alkaline in reaction with a pH of 7.69 and electrical conductivity of 0.244 dS m⁻¹. The organic carbon content was 0.38 per cent. Available nitrogen, phosphorus and potassium contents were 167.78, 8.15 and 189.47 kg ha⁻¹, respectively. Thus, the soil was low in available nitrogen and phosphorus but medium in available potassium, indicating the necessity of balanced nutrient management for achieving higher productivity and sustaining soil fertility. The experiment was laid out in a Randomized Block Design (RBD) with three replications. Ten treatment combinations consisting of different levels of potassium and boron were evaluated during the course of investigation. The treatments included potassium levels of 10, 20 and 40 kg ha⁻¹ combined with boron levels of 1.0, 1.5 and 2.0 kg ha⁻¹, along with a control treatment receiving only the recommended dose of fertilizers. Randomization of treatments within each replication was carried out to eliminate bias and improve precision of experimental observations. Blackgram (Vigna mungo L.) was used as the test crop during the investigation. A suitable high-yielding variety recommended for the agro-climatic conditions of Uttar Pradesh was selected. Healthy and certified seed was used to ensure better germination and uniform crop establishment. Sowing was carried out during the Kharif season under optimum soil moisture conditions using line sowing method. Recommended spacing and seed rate were maintained uniformly in all treatment plots to ensure optimum plant population and minimize inter-plant competition. Necessary intercultural operations such as thinning, gap filling and plant protection measures were carried out uniformly throughout the crop growth period. The recommended dose of nitrogen and phosphorus was applied uniformly to all treatments through suitable fertilizer sources. Potassium was supplied through muriate of potash (MOP), whereas boron was supplied through borax according to the treatment combinations. The entire quantity of fertilizers was applied as basal dose at the time of sowing and thoroughly incorporated into the soil to ensure proper nutrient availability during crop growth. Balanced fertilization was maintained throughout the crop season so that the effect of potassium and boron could be evaluated precisely without interference from other nutrient deficiencies. All recommended agronomic practices were adopted uniformly during the crop period. Irrigation was applied whenever required depending upon rainfall distribution and soil moisture conditions. Proper weed management practices were followed to minimize crop-weed competition during critical growth stages. Plant protection measures were undertaken as per requirement to protect the crop from insect-pests and diseases. The crop was harvested manually at physiological maturity and produce from each treatment plot was kept separately for recording observations. Observations related to crop growth, yield attributes, yield, nutrient uptake and economics were recorded systematically during the course of investigation. Growth parameters such as plant population, survival percentage, plant height, number of nodules plant⁻¹ and dry matter accumulation were recorded at different crop growth stages. Yield attributes including pods plant⁻¹, seeds pod⁻¹ and test weight were recorded at harvest. Seed yield, stover yield, biological yield and harvest index were computed using standard procedures. Plant samples collected at harvest were analyzed for nitrogen, phosphorus, potassium and boron contents using standard laboratory techniques. Nutrient uptake was calculated by multiplying nutrient concentration with corresponding dry matter yield. Economic analysis was carried out to evaluate the profitability of different nutrient management treatments. The cost of cultivation was computed on the basis of prevailing market prices of inputs and labour. Gross returns were calculated from seed and stover yields using prevailing market rates. Net returns were obtained by deducting the cost of cultivation from gross returns, while the benefit-cost ratio was calculated by dividing gross returns by total cost of cultivation. The experimental data recorded during the investigation were subjected to statistical analysis by applying the Analysis of Variance (ANOVA) technique appropriate for Randomized Block Design as described by Gomez and Gomez (1984). The significance of treatment differences was tested through the F-test at the 5 per cent level of probability. Whenever treatment effects were found significant, Critical Difference (CD) values were calculated for comparison of treatment means. Standard Error of Mean (SEm±) and Coefficient of Variation (CV%) were also worked out to assess the reliability and precision of experimental results. The statistically analyzed data were interpreted carefully for drawing valid scientific conclusions regarding the effect of potassium and boron on growth, productivity, nutrient uptake and economics of blackgram.

Results and Discussion

Effect of Potassium and Boron Levels on Growth Parameters of Blackgram

Growth parameters are considered important indicators of crop performance because they directly reflect the influence of nutrient availability on physiological, biochemical and metabolic activities of plants. Potassium

Effect on Plant Height

Plant height is an important growth parameter reflecting the overall physiological status and nutrient availability within the plant system. The data presented in [19] , Marschner (2012) [18] , Sharmila et al. (2020), Kumar et al. (2022) [5] and Verma et al. (2023), who observed significant increases in plant height of pulse crops following potassium and boron fertilization.

Effect on Number of Nodules Plant⁻¹

Nodulation is one of the most important characteristics of leguminous crops because it determines the efficiency of biological nitrogen fixation. The data revealed that potassium and boron significantly influenced nodule formation in blackgram.

The maximum number of nodules plant⁻¹ (31.4) was recorded under T₉, followed by T₈ (29.6) and T₇ (28.2). The control treatment recorded the lowest nodulation (16.6 nodules plant⁻¹). The increase in nodulation under higher potassium and boron levels may be attributed to enhanced root growth, improved energy transfer processes and better nitrogen metabolism. Potassium promotes root proliferation and carbohydrate supply to nodules, while boron improves cell division and nodule development.

The treatment T₉ recorded nearly 89. 16

Discussion

The present investigation clearly demonstrated that balanced application of potassium and boron significantly improved growth parameters of blackgram. Higher plant population, greater survival percentage, increased plant height, enhanced nodulation and greater dry matter accumulation were observed under treatments receiving higher levels of potassium and boron. Among all treatments, T₉ (40 kg K ha⁻¹ + 2.0 kg B ha⁻¹) consistently recorded superior performance for all growth parameters. The beneficial effect of potassium may be attributed to its role in enzyme activation, osmotic regulation, photosynthesis and assimilate translocation, whereas boron contributed through improved cell division, sugar transport, reproductive development and nutrient utilization. The combined application of these nutrients created favorable physiological conditions that enhanced root growth, nutrient uptake and biological nitrogen fixation, ultimately resulting in vigorous crop growth. The findings of the present study corroborate the reports of Mengel and Kirkby (2001) [19] , Marschner (2012) [18]

Effect of Potassium and Boron Levels on Yield Attributes and Yield of Blackgram

Yield is the ultimate expression of various physiological, biochemical and metabolic processes occurring within the crop throughout its growth period. Yield attributes serve as important determinants of final productivity because they directly influence seed formation, grain filling and biomass accumulation.

Potassium and boron are known to play crucial roles in photosynthesis, assimilate translocation, enzyme activation, pollen viability, fertilization and seed development. Therefore, balanced application of these nutrients significantly influences reproductive growth and final crop yield.

The experimental results revealed that different levels of potassium and boron exerted a significant influence on yield attributes and yield of blackgram. Higher levels of potassium and boron improved flowering, pod setting, seed development and translocation of assimilates towards reproductive organs, resulting in superior yield performance.

Effect on Test Weight

Test weight reflects seed size, density and grain filling efficiency. Significant differences in test weight were observed among different treatments. The highest test weight (42.4 g) was recorded under T₉, followed by T₈ (41.0 g) and T₇ (40. [19] , Marschner (2012) [18] , Kumar et al. (2022) [5] , Singh et al.

Effect on Seed Yield

Seed yield represents the most important economic parameter and is the cumulative effect of all growth and yield-contributing characters. Among all treatments, T₉ recorded the maximum seed yield of 15.28 q ha⁻¹, which was significantly superior to all other treatments. The lowest seed yield (7.62 q ha⁻¹) was recorded under control treatment.

Effect on Stover Yield and Biological Yield

Stover yield and biological yield followed trends similar to seed yield. The highest stover yield (29.56 q ha⁻¹) and biological yield (44.84 q ha⁻¹) were recorded under T₉, while the lowest values were observed under control treatment. The increase in biomass production may be attributed to greater leaf area development, enhanced photosynthetic efficiency and improved nutrient uptake under higher potassium and boron levels. Increased biomass accumulation reflects superior crop growth and efficient utilization of available resources. Compared with control, T₉ recorded: 65.51% higher stover yield, 76.00% higher biological yield Similar findings have been reported by Rahman et al.

(2011), Marschner (2012) [18] , Kumar et al.

Effect on Harvest Index

Harvest index represents the efficiency of conversion of biological yield into economic yield. Although slight differences were observed among treatments, harvest index remained statistically non-significant. The highest harvest index (34.12%) was recorded under T₈, closely followed by T₉ (34.07%). The lowest harvest index (29.91%) was observed under control treatment. The relatively stable harvest index indicates that potassium and boron primarily enhanced total biomass production and grain yield simultaneously rather than altering partitioning efficiency.

Discussion

The present investigation clearly demonstrated that balanced application of potassium and boron significantly enhanced yield attributes and yield of blackgram. The superior performance of T₉ (40 kg K ha⁻¹ + 2.0 kg B ha⁻¹) may be attributed to improved physiological efficiency, enhanced nutrient uptake, greater nodulation, better photosynthetic activity and efficient assimilate translocation towards reproductive organs. Potassium enhanced enzyme activation, photosynthesis and carbohydrate movement, while boron improved pollen viability, fertilization and seed development. Their synergistic interaction ultimately resulted in greater pod formation, improved seed filling and higher grain yield. The findings are in close conformity with those reported by Mengel and Kirkby (2001) [19] , Marschner (2012) [18] ,

Effect of Potassium and Boron Levels on Economics of Blackgram

Economics is one of the most important criteria for evaluating the practical feasibility and adoption of any nutrient management technology under field conditions. Although certain nutrient combinations may enhance crop productivity, their adoption by farmers largely depends upon the profitability generated from the investment made. Therefore, an economic analysis was carried out to assess the effect of different levels of potassium and boron on cost of cultivation, gross return, net return and benefit-cost ratio of blackgram cultivation. The economic performance of different treatments is presented in Table 3. The economic analysis clearly revealed that potassium and boron application significantly influenced profitability of blackgram cultivation. Although the cost of cultivation increased slightly with increasing levels of potassium and boron due to additional expenditure on fertilizers, the increase in crop productivity more than compensated for the additional investment, resulting in substantially higher economic returns. Among all treatments, T₉ (40 kg K ha⁻¹ + 2.0 kg B ha⁻¹) recorded the highest gross return (₹1,22,240 ha⁻¹), net return (₹83,040 ha⁻¹) and benefit-cost ratio (3.12). The superiority of this treatment was mainly attributed to its higher seed yield, greater biomass production and improved marketable produce. The treatment generated approximately 197 per cent higher net return compared with the control treatment. The higher profitability under T₉ indicates that balanced application of potassium and boron substantially improved resource-use efficiency and economic productivity. Potassium enhanced photosynthetic activity, assimilate translocation and grain filling, whereas boron improved flowering, fertilization and seed development. The combined effect of these nutrients ultimately resulted in greater seed yield and higher monetary returns. The treatment T₈ (40 kg K ha⁻¹ + 1.5 kg B ha⁻¹) also recorded comparatively higher economic returns with a gross return of ₹1,15,360 ha⁻¹, net return of ₹76,760 ha⁻¹ and benefitcost ratio of 2.99. This was closely followed by T₇ (40 kg K ha⁻¹ + 1.0 kg B ha⁻¹), which recorded a net return of ₹72,720 ha⁻¹ and B:C ratio of 2.91. These findings clearly indicate that increasing potassium levels substantially improved profitability of blackgram cultivation. On the other hand, the control treatment recorded the lowest gross return (₹60,960 ha⁻¹), net return (₹27,960 ha⁻¹) and benefit-cost ratio (1.85). The lower profitability under control was mainly due to poor growth, lower pod formation, reduced seed yield and inferior nutrient-use efficiency resulting from inadequate nutrient availability. The increase in gross return under higher potassium and boron levels may be attributed to improved yield attributes such as pods plant⁻¹, seeds pod⁻¹ and test weight, which ultimately contributed towards higher seed yield. Since seed yield is the major determinant of economic return in blackgram cultivation, treatments producing superior yield generated significantly greater profitability. The benefit-cost ratio followed a trend similar to gross and net returns. The highest B:C ratio of 3.12 was recorded under T₉, indicating that every rupee invested in crop production generated a return of ₹3.12. Such a high benefit-cost ratio demonstrates the economic viability and practical suitability of balanced potassium and boron fertilization under the agro-climatic conditions of Central Uttar Pradesh. Overall, the economic analysis clearly demonstrated that balanced application of potassium and boron significantly improved profitability of blackgram cultivation. Among all treatment combinations, application of 40 kg K ha⁻¹ along with 2.0 kg B ha⁻¹ (T₉) proved most economical and profitable, producing the highest gross return, net return and benefit-cost ratio. Therefore, this treatment may be recommended for maximizing productivity and profitability of blackgram under the agro-climatic conditions of Central Uttar Pradesh.

Relationship Between Growth Parameters, Yield Attributes, Yield and Economics

The present investigation revealed a strong positive relationship between growth parameters, yield attributes, yield and economic returns of blackgram. Treatments that produced higher plant height, greater nodulation and increased dry matter accumulation also recorded superior yield attributes such as pods plant⁻¹, seeds pod⁻¹ and test weight. These improvements ultimately resulted in higher seed yield and profitability. Application of potassium and boron enhanced photosynthetic activity, nutrient uptake and assimilate translocation, leading to vigorous crop growth. Improved vegetative growth increased the production and accumulation of photosynthates, which were subsequently translocated to reproductive organs. Consequently, higher pod formation, better seed development and greater grain filling were observed under higher levels of potassium and boron. A positive correlation was observed between plant height and seed yield (r = 0.92), nodules plant⁻¹ and seed yield (r = 0.95), and dry matter accumulation and seed yield (r = 0.97). Similarly, pods plant⁻¹ exhibited a strong positive association with seed yield (r = 0.98), indicating that improvement in yield attributes directly contributed towards higher productivity. These relationships clearly demonstrate that improvements in growth and yield attributes under balanced potassium and boron fertilization ultimately translated into higher productivity and profitability of blackgram.

Conclusion and Recommendations Conclusion

The present study revealed that different levels of potassium and boron significantly influenced the growth, yield attributes, yield and economics of blackgram. Application of potassium and boron improved plant height, nodulation, dry matter accumulation, pods plant⁻¹, seeds pod⁻¹ and test weight, which ultimately resulted in higher seed and stover yields. Among the various treatments, application of 40 kg K ha⁻¹ + 2.0 kg B ha⁻¹ (T₉) proved superior by recording the highest growth parameters, yield attributes, seed yield (15.28 q ha⁻¹), stover yield (29.56 q ha⁻¹) and biological yield (44.84 q ha⁻¹). The same treatment also produced the highest gross return (₹1,22,240 ha⁻¹), net return (₹83,040 ha⁻¹) and benefit-cost ratio (3.12). The enhanced performance under this treatment may be attributed to improved photosynthetic activity, better nutrient uptake, efficient assimilate translocation, enhanced reproductive development and improved source-sink relationship. Thus, balanced application of potassium and boron was found essential for maximizing productivity and profitability of blackgram under the agro-climatic conditions of Central Uttar Pradesh.

Recommendation

Based on the findings of the present investigation, it may be recommended that application of 40 kg potassium ha⁻¹ along with 2.0 kg boron ha⁻¹ should be adopted for blackgram cultivation under the Central Plain Zone of Uttar Pradesh to obtain higher yield and economic returns. Further research may be conducted under different agro-climatic conditions and cropping systems to validate the findings and develop location-specific nutrient management recommendations for sustainable blackgram production.

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