Response of phosphorus levels and bio-fertilizers on growth and yield of Pigeonpea (Cajanus cajan L)

Introduction

Pigeon pea (Cajanus cajan L.) is the world's most widely cultivated pulse crop providing adequate protein for more than million peoples in the world. After chickpea, pigeon pea is the second most important pulse crop in India. Pigeon pea has a high nutritional value because of its 22.3% Protein, 1.7% Fat, 3.5% Minerals, 1.5% Fiber and 57.6% Carbohydrate content. Apart from cooked preparations, fresh pigeon peas can also be served in salads as a diet food or can be eaten raw. Pigeon pea is one of the important pulse crop which ranks sixth in terms of area and production in the world as compared to other legumes such as beans, chickpeas and it is consumed in different ways than others. Globally, pigeon pea covers an area of 6.02 million hectares with the production of 5.32 million tonnes and the productivity of 883 kg/ha (FAO, 2022) [1] . In India, pigeon pea is grown over an area of about 4.06 million hectares with the production of 3.31 million tonnes and productivity of 814 kg/ha. Total area coverage under pigeon pea in Uttar Pradesh is 0.35 million hectares with the production of 0.36 million tonnes and the productivity of 1039 kg/ha (GOI, 2022) [2] . In early growth stage, plants may show very poor growth and exhibit nutritional disorder that make leaves and stems to change their colour. Poor plant growth and the nutritional disorder is caused by nitrogen deficiency. For that reason, plant cannot easily utilize soil nitrogen under low temperature conditions. On the other hand, it is considered that nitrogen deficiency is related to the poor nodule formation and low nitrogen fixation activity of the rhizobia in the nodules. Here, Bio-fertilizers are known to play an important role in increasing availability of nitrogen and phosphorus besides improving biological fixation of atmospheric nitrogen and enhance phosphorus availability to crop. Therefore, introduction of efficient biofertilizers such as Rhizobium, PSB through doing seed inoculation with them, may help in boosting up of production and consequently more nitrogen fixation for the crop in the soil which is poor in nitrogen. Being a legume crop, major portion of nitrogen requirement of the crop is met through biological nitrogen fixation (Khajuria et al., 2023) [3] . The main cause of this crop's low yield is insufficient and uneven fertilization, which has a negative impact on plant and soil health in addition to decreasing productivity. Because of this imbalance, shoot growth may be inhibited, resulting in dull or dark leaves. Applying fertilizers in sufficient amounts-especially phosphorus-is essential to resolving these problems. An essential plant nutrient and a crucial component of crop production is phosphorus. Because it aids in root development, contributes to the production of phosphates and phosphoproteins, and is involved in energy-fixing and -releasing activities in plants, phosphorus is a crucial mineral element for grain legumes. Ade et al. (2018) [4] observed that pigeon peas responded significantly to phosphate supplementation. In the majority of Indian soils, it is often a major limiting nutrient for plant growth. The recovery efficiency of phosphorus in crops is typically 10-30% because only a portion of the phosphorus added by fertilizers is used by the plants and a significant portion is transformed into insoluble fixed forms. Phosphorus is an important mineral element for grain legumes as it helps in root development, participates in the synthesis of phosphates and phosphoproteins and takes part in energy-fixing and releasing processes in plants. The significant response of pigeon pea to phosphate nutrition has been reported by Ade et al. (2018) [4] . It is frequently a major limiting nutrient for plant growth in most Indian soils. Only a part of the phosphorus supplemented through fertilizers is utilized by the plants and a large portion of it is converted into insoluble fixed forms, the recovery efficiency of phosphorus in crops of is generally 10-30%. Phosphorus plays a vital role in photosynthesis, respiration, energy storage, energy transfer, cell division cell elongation and several other processes within plant system (Rakshit et al., 2015) [5] . Phosphorus is a vital nutrient for pulse crops, playing a critical role in enhancing seed germination, cell division, flowering, fruiting, and the synthesis of essential compounds such as fats and starch. It supports numerous biochemical activities within the plant. Additionally, phosphorus promotes root proliferation and nodulation, which are crucial for nutrient uptake and biological nitrogen fixation. The improved yield observed in pulse crops can be attributed to phosphorus's influence on root development, energy transformation, and metabolic processes. These effects collectively lead to an efficient translocation of photosynthates towards sink development, ultimately contributing to higher crop productivity (Singh et al., 2012) [6] . Phosphorus has novel function of special importance in the process of energy storage and transfer. Response of phosphorus in pigeonpea has been reported by many researchers (Kumar et al., 2006; Singh et al., 2008) [7,8] . In India's sustainable agriculture system, bio-fertilizers-a part of integrated nutrient management-are regarded as an economical, environmentally benign, and renewable source of non-bulky, inexpensive plant nutrient augmenting fertilizers. Therefore, given the current high cost of chemical fertilizers, the role of biofertilizers takes a unique significance. The purpose of inoculating pulse seeds with phosphate-soluble bacteria and Rhizobium is to increase the quantity of these bacteria in the rhizosphere and significantly enhance the availability of N and P for plant growth. Bio-fertilizers, a component of integrated nutrient management and are considered to be cost effective, eco-friendly and renewable source of non-bulky, low cost plant nutrient supplementing fertilizers in sustainable agriculture system in India. Therefore, the role of bio-fertilizers assumes a special significance in present context of very high costs of chemical fertilizers. The seed of pulses are inoculated with Rhizobium and Phosphate solubilizing bacteria with an objective of increasing their number in the rhizosphere and substantial increase in the N and P availability for the plant growth. Rhizobium belongs to family Rhizobiaceae and is symbiotic in nature. It is a gram negative and motile bacterium with nonsporulating rods. Rhizobium incorporated in plant rhizosphere through seed treatment probably induced more amount of nitrogen fixation in nodules of plants and solubilisation of fixed nitrogen from non-available to the exchangeable pool which imparts more vegetative growth (Khajuria et al., 2023) [3]

Materials and Methods

The experiment was carried out at the Research farm of the Department of Agronomy, School of Agriculture Science, Technology & Research, Sardar Patel University, Balaghat (M.P.). The experiment was conducted in a randomised complete block design, factorial concept with three replications. Different phosphorus levels and biofertilizers will be allocated to the plots according to the treatments. The seed rate used as 20 kg/ha for sowing with 60.0 x 20.0 cm row-to-row and plant-to-plant distance. The experiment involved twelve treatment combinations to evaluate the effects of varying phosphorus levels and seed inoculations with biofertilizers on crop performance. The treatments included: T1control with no phosphorus and no inoculation (P₀ BF₀), T2 -control with Rhizobium @ 10 g/kg seed (P₀ BF₁), and T3 -control with Phosphate Solubilizing Bacteria (PSB) @ 10 g/kg seed (P₀ BF₂). At 40 kg P₂O₅/ha, treatments included T4 -without inoculation (P₁ BF₀), T5 -with Rhizobium (P₁ BF₁), and T6 -with PSB (P₁ BF₂). At 50 kg P₂O₅/ha, the treatments were T7 -without inoculation (P₂ BF₀), T8with Rhizobium (P₂ BF₁), and T9 -with PSB (P₂ BF₂). At the highest level, 60 kg P₂O₅/ha, the treatments included T10 -without inoculation (P₃ BF₀), T11 -with Rhizobium (P₃ BF₁), and T12 -with PSB (P 3 BF 2 ). This structured design enabled the assessment of the individual and combined effects of phosphorus and biofertilizer treatments on plant growth, nutrient uptake, and yield. The gross and net plot size was 5.00 m x 3.00 m and 4.50 m x 2.10 m, respectively. The fertiliser grades were applied as per the treatments. All the other agronomic practices were applied uniformly to all the treatments. The experiment will consist of the following factors along with their respective levels.

Results and Discussion

Phosphorus is a key macronutrient essential for vital physiological processes in plants, including energy transfer (ATP), cell division, and early root development (Mengel et al., 2001) [9] . In the present study, increasing phosphorus levels from 0 to 60 kg P 2 O 5 /ha significantly enhanced the growth of pigeonpea (Cajanus cajan), as evident in parameters such as plant height, number of branches, and overall plant vigour. Plants under the control treatment (P 0 ) showed restricted growth due to phosphorus deficiency, which limited root proliferation and nutrient absorption (Hinsinger, 2001) [10] . Higher phosphorus levels, particularly at 60 kg P 2 O 5 /ha (P 3 ), resulted in robust vegetative growth due to improved root activity and nutrient uptake, confirming the findings of Singh et al. (2012) [11] and Fageria et al. (2011) [12] , who reported similar growth enhancement in legumes under adequate phosphorus supply. Phosphorus application significantly influenced the yield and its components in pigeonpea, including pods per plant, seeds per pod, and 100-seed weight. These improvements are attributed to phosphorus's critical role in enzyme activation and energy metabolism during the reproductive stages (Fageria et al., 2011) [12] . The highest yield was obtained with the application of 60 kg P 2 O 5 /ha, indicating that sufficient phosphorus availability enhances flowering, pod setting, and grain filling. Lower phosphorus levels led to poor yield performance due to impaired nutrient use efficiency (Tiwari et al., 2014) [13] . These results are supported by Singh et al. (2012) [11] , who found a direct relationship between increasing phosphorus rates and higher grain yield in pigeonpea, making phosphorus management an essential factor in sustainable legume production. Phosphorus plays a vital role in protein synthesis by enhancing nitrogen assimilation and supporting various biochemical pathways (Fageria et al., 2011) [12] . In pigeonpea, seed protein content increased steadily with higher phosphorus levels, with the highest protein concentration recorded at 60 kg P 2 O 5 /ha. This is due to improved nitrogen fixation and efficient nutrient uptake, which are facilitated by better root development under phosphorus-rich conditions (Singh et al., 2012) [11] . Tiwari et al. (2014) [13] also reported that phosphorus promotes enzymatic and metabolic activities necessary for amino acid and protein formation in legumes. Therefore, adequate phosphorus not only boosts productivity but also improves the nutritional quality of pigeonpea seeds. Biofertilizers such as Rhizobium and Phosphate Solubilizing Bacteria (PSB) have proven beneficial in improving pigeonpea growth and yield by enhancing nutrient availability. Rhizobium aids in atmospheric nitrogen fixation, supplying an essential nutrient for plant growth, while PSB increases the bioavailability of phosphorus in the rhizosphere by solubilizing bound phosphate (Gaur, 1990; Kumar et al., 2013) [14,15] . Application of these biofertilizers resulted in better plant height, branching, and yield parameters when compared to uninoculated controls. Singh et al. (2014) [16] found that biofertilizerinoculated pigeonpea exhibited significantly higher biomass and grain yield. Additionally, Bhattacharyya et al. (2012) [17] reported synergistic effects when biofertilizers were combined with chemical phosphorus, highlighting their potential in sustainable nutrient management. The use of Rhizobium and PSB also positively influenced the protein content of pigeonpea seeds. Rhizobium increased nitrogen availability through fixation, promoting greater protein synthesis, while PSB enhanced phosphorus-mediated metabolic functions critical to amino acid formation (Kumar et al., 2013) [15] . The combined inoculation significantly improved seed protein levels over the control, corroborating findings by Singh et al. (2014) [16] and Bhattacharyya et al. (2012) [17] . Economically, biofertilizers offer cost-effective solutions by reducing the dependency on expensive chemical fertilizers. According to Tiwari et al. (2014) [13] , phosphorus application, especially in combination with biofertilizers, improved net returns and benefit-cost ratios in pigeonpea farming. Hence, the integration of biofertilizers not only supports yield and protein enhancement but also contributes to sustainable and profitable cultivation practices (Singh et al., 2016) [18] .

Conclusion

The application of phosphorus at 60 kg P₂O₅ ha⁻¹ consistently demonstrated significant positive effects on the growth, yield attributes, and productivity of pigeon pea. This level of phosphorus led to the highest plant height across all growth stages (40, 80, and 120 DAS), the maximum number of branches and root nodules per plant, and the most favorable yield components including pods per plant, seeds per pod, and 1000-grain weight. Consequently, it resulted in the highest grain and stover yields, along with improved harvest index and protein content. Economically, the 60 kg P 2 O 5 ha -1 treatment yielded the greatest gross monetary return (GMR), net monetary return (NMR), and benefit-cost (B:C) ratio, underscoring its agronomic and financial viability for pigeon pea cultivation. Similarly, the use of biofertilizer BF 2 (PSB @ 10 g/kg seed) significantly enhanced plant growth and yield parameters. This treatment promoted better plant height and branching, and achieved higher grain and stover yields compared to other biofertilizer treatments. Although Rhizobium @ 10 g/kg seed recorded a slightly higher harvest index and protein content, BF 2 was superior in overall yield performance. In terms of economics, Rhizobium inoculation resulted in higher GMR, NMR, and B:C ratio, indicating its potential for cost-effective cultivation. Thus, the integrated use of phosphorus at 60 kg P 2 O 5 ha -1 and biofertilizer seed treatment, particularly PSB or Rhizobium, can be recommended for optimising growth, yield, and profitability in pigeon pea production. Therefore, phosphorus @ 60 kg/ha and biofertilizer BF 2 (PSB @ 10 g/kg seed) should be opted for to achieve a higher production of pigeon pea crop in the existing agroclimatic conditions of Balaghat.

References

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18. How to cite this article: Jitendra, Bisen J, Turkar D. Response of phosphorus levels and bio-fertilizers on growth and yield of Pigeonpea (Cajanus cajan L). International Journal of Research in Agronomy. 2026;9(9):1186-1189. doi: https://www.doi.org/10. 33545/2618060X.2026.v9.i9p.6668 International Journal of Research in Agronomy https://www.agronomyjournals.com 26180618, 2026, 9(9), Downloaded from https://www.doi.org/10.33545/2618060X.2026.v9.i9p.6668 by International Journal of Research in Agronomy on [26/09/2026]. See the Terms and Conditions (https://www.agronomyjournals.com) for rules of use; OA articles are governed by the applicable Creative Commons License