¹M.Sc. student, Plant Pathology Section, College of Agriculture, Kolhapur (MH), India.                      

  ²Assistant Professor & Associate Professor, Plant Pathology Section, 

College of Agriculture, Kolhapur (MH), India.          

  ³Assistant Professor of Agricultural Botany, College of Agriculture, Kolhapur (MH), India.                      

Biofertilizers play an important role in increasing nutrient availability to crop plants. They are environmentally, cost effective and ecofriendly sustainable source. Biofertilizers, as opposed to chemical fertilizers, support long-term soil health, enhance the soil's physical, chemical, and biological properties, and lessen their negative environmental effects (Pahalvi et al., 2021). Similarly, biofertilizers also enhance soil chemical properties by promoting the nitrogen fixation process (Chaurasia et al., 2024a). Furthermore, by dissolving insoluble phosphates, phosphorus-solubilizing bacteria in biofertilizers increases phosphorus availability (Arif et al. 2017). Groundnut is an important oilseed crop in India occupying first position in terms of area and second in terms of production after soybean. In India, Groundnut is considered the "king  of  oilseeds".  This  oil  seed crop is primarily found in tropical and subtropical regions, and  is also  known as  peanut, earthnut, monkey  nut  and  poor  men's  cashew  nut.  The global  area,  production  and  productivity  of groundnut  is  29.7 million  ha,  50.8 million tonnes and  17.1  quintal  ha-1,  respectively.  China is the world's largest producer  of  groundnut  with  4.6 million ha  area, 17 million tonnes production and productivity of 37.0 quintal ha-1 followed by India. Groundnut  covers  an area  of 4.8  million ha with production of 9.9 million tonnes and productivity of 20.6  quintal  ha-1 in  India  during  2019 -20 (Anonymous, 2020). It plays a major role in bridging the vegetable oil deficit in the country. Groundnuts provide essential nutrients to the human body, in the form of proteins, carbohydrates, fats, vitamins, minerals and fiber. Groundnut is great and economical source of nourishment. In the prevention of diseases or some immune-based disorders in human can be prevented by the consumption of protein-rich foods like groundnut which provides energy-rich nutrients and bioactive compounds which regulates the human immune system.

In groundnut P, K and N is vital for plant growth and yield parameters. Phosphorus is  considered  a crucial mineral fertilizer  for the  flourishing production of the crop (Hasan  et. al., 2021). The requirement of phosphorus in nodulating legumes is higher as compared to non-nodulating crop as it plays significant role in nodule formation and fixation of atmospheric nitrogen (Brady & Well 2002). Phosphorus determines plant reproductive efficiency and plays a vital role in growth and development of groundnut crop (Savani & Sarji 1995). Legumes often need phosphorus for good seed formation (Asiedu et al., 2000). So, the PSB is more important which solubilize phosphorous by secreting organic acids. These acids lower the pH & bring dissolution of bound phosphate (Subba Rao, 1993). Another important element is Potassium which is considered one of the primary nutrients responsible for quality of ground nut crop. Also adequate  potassium   supply   is essential  for   proper  pod  development,  kernel filling   and   maintaining   high   oil   quality (Sanadi et al., 2008). KMB is very important which convert the insoluble or mineral structure K compounds into soluble form in soil as a soil solution and make them available to plants (Zeng et al., 2012). KMB are effective in releasing K from inorganic and insoluble pools of total soil K through solubilization (Archana et al., 2013, Meena et al., 2015, Saha et al., 2016). The inoculation with KMB produced benefical effect on growth of different plants (Ahmad et al., 2016, Bakhshandeh et al., 2017). Furthermore, by introducing a range of advantageous microorganisms such as nitrogen-fixing bacteria and fungi biofertilizers increase microbial diversity and foster a more resilient and dynamic soil microbiome (Odoh et al., 2020). By promoting disease resistance in plants, improved nutrient cycling, and healthy soil, this all-encompassing strategy supports sustainable agricultural methods (Ghimirey et al., 2024c).

Hence good balance between chemical and biological fertilizers should be used to achieve both quality and quantity in groundnut production. The present investigation was designed and results were put forth.

A field experiment was conducted at Rajarshee Chhatrapati Shahu Maharaj Collge of Agriculture, Kolhapur (Maharashtra, India) during the summer season of the year 2023. Seeds of Phule Unnati variety was treated with lignite based powder formulation of efficient bacterial inoculum of PSB and KMB @ 250 g per 10 kg seeds. During seed treatment, 10% jaggery solution was used as an adhesive. Chemical fertilizers were applied, as per the treatments. The cultural operation like irrigation, weeding were uniformly carried out to all the treatments. All the data obtained was statistically analyzed by using the Panse and Sukhathe (1985) procedure.

Fifteen root and rhizospheric soil samples were collected from different villages of Kolhapur district. Isolation was carried out on Pikovaskays medium for PSB and Aleksandrov’s medium medium for KSB. Out of eight isolates, four of phosphorus solubilizing bacteria (PSB) and remaining four of potash mobilizing bacteria (KMB) were obtained. All the obtained isolates of PSB and KMB were identified on the basis of morphological and biochemical tests. Efficient strain of PSB (PSB-2) and KMB (KMB-2) used for field experiment.

A. Effect on growth parameter

Plant height and branches per plant were recorded after 90 days are presented in Table 1. The results indicated that the treatment T11, Commercial strain of PSB and KMB + RDF observed highest plant height (38.90 cm) at par with T9, PSB + KMB + R.D. of N + 75% P2O5 and K2O (37.68cm). Lowest plant height was observed in T1, PSB (27.16 cm). 

This might be due to adequate supply of nutrients required for optimum growth and development of groundnut plants under different treatments.  This finding is in agreement with that of Tsegaye (2022) and Ghosh et al. (2022). The nitrogen helps the cells of the apical meristem to enlarge. Apical meristem helps in shoot growth which affects plant growth. Microbial secretion of organic acid might help in improving soil condition required for better root proliferation. Better availability of nutrients like nitrogen, phosphorous and potassium at early stages helped for synthesis of biomolecules, protein metabolism leading to more plant height (Chaudhary et al., 2019) & similar results were found by Singh et al. (2002) in soyabean. This  finding  is  in  agreement  with  that  of  Tsegaye  (2022)  and Ghosh  et  al.  (2022).

The result about no. of branches specified that treatment T11, Commercial strain of PSB and KMB+RDF showed maximum (22.40) branches per plant which was statistically found at par with treatment T9, PSB +  KMB + R.D. of N +75% P205  and K2O (21.68), T10 PSB + KMB + R.D. of N+50% P2O5 and K2O (21.68) and T7, PSB + RDF (21.58). This results shows similarity with Singh (2007) in soyabean crop increases in branches per plant up to 16.

B. Yield characters

Number of pods per plant. Results revealed that treatment T11, Commercial strain of PSB and KMB + RDF showed maximum pods number per plant (43.56) which was statistically found at par with treatment T9, PSB + KMB +R.D. of N + 75% P2O5 and K2O (42.30). This might be due to improvement in vegetative structures for nutrient absorption and photosynthesis as a result of KSB and other microorganisms application.

This finding conforms with the Kamboj et al. (2023) which reported increased matured pod yield in groundnut due to P application (Chaudhary et al., 2019). This results were found similarity with Sagervanshi et al. (2014) in soyabean, Parmar et al. (2016) who observed 20% no. of pods per plant due to PSB application.

Table 1: Effect of Phosphate Solubilizing Bacteria and Potash Mobilizing Bacteria on growth and yield parameters.

Yield. Result depicted in Table 1,  revealed that treatment T11, Commercial strain of PSB and KMB + RDF showed maximum groundnut yield (35.58 q/ha) statistically found at par with treatment T9, PSB+  KMB+ R.D. of N +75% P205  and K2O (35.12q/ha). Lowest yield was observed in treatment. T2, KMB (16.92 q/ha). This is might be the effect of micro organisms which solubilize the nutrient which helped for optimum growth higher yield (Chaudhary et al., 2019). These results are in accordance with the finding of Dwivedi et.al (1999) in Soyabean, Bansal (2009) in Mungbean, Sulochanamma and Reddy (2007) in vigna radiata.

Effect of efficient Phosphate solubilizing bacteria (PSB) and Potash mobilizing bacteria (KMB) on available N, P, K of groundnut (Kg/ha) 

The effect of efficient Phosphorus solubilizing bacteria (PSB) and potash mobilizing bacteria (KMB) on available N, P, K of groundnut. are presented in Table 2. The results specified that N, P, K of groundnut. of groundnut was increased significantly when seeds were treated with Phosphorus solubilizing bacteria (PSB) and potash mobilizing bacteria (KMB) biofertilizers.

The results stated that maximum available Nitrogen of groundnut was observed in treatment T11, Commercial strain of PSB & KMB +RDF showed maximum available N of groundnut (163.07 kg /ha) which was statically found at par with treatments T9, PSB + KMB+ R.D. of N + 75% P2O5 & K2O R. D. of N (162.72 kg /ha) and treatment were T7, PSB+RDF (161.07kg /ha). Lowest germination was observed in treatment T2, KMB (131.07 kg/ha) while rest of the treatments exhibited available of groundnut in range of 133.80-160.90 kg/ha.

The results stated that maximum available Phosphorus of groundnut. was observed in treatment T11, Commercial strain of PSB & KMB + RDF showed maximum available Phosphorus of groundnut. (20.00 kg /ha) which was statically found at par with treatments T9, PSB + KMB + R.D. of N + 75% P2O5 & K2O R. D. of N (19.90 kg /ha) and treatment were T5 KMB + 75% Potassium + Rec. Dose of N and P (19.20 kg /ha) T7, PSB+RDF (18.99kg /ha) treatment T6 KMB + R.D. of N & P2O5 + 50% K2O (18.87kg/ha). 

Lowest available Phosphorus was observed in treatment T2, KMB (15.90 kg/ha), while rest of the treatments exhibited available Phosphorus of groundnut. in range of 16.76 to 17.90 kg/ha. 

The results indicated that, maximum available Potassium of groundnut was observed in treatment T11, Commercial strain of PSB & KMB +RDF showed maximum. available Potassium (260.99 kg /ha) which was statically found at par with treatments T9, PSB + KMB + R.D. of N + 75% P2O5 & K2O R. D. of N (259.87 kg /ha) and treatment were T7, PSB + RDF Lowest germination was observed in treatment T2, KMB (245.50 kg/ha) while rest of the treatments exhibited available of K groundnut. in range of 246.70 to 251.99 kg/ha Similar results were found by Singh et al. (2002) in groundnut and Dwivedi et al., (1999) in faba bean. They found that increase in available N due to quick supply of available nutrients through fertilizers. 

Table 2: Effect of efficient Phosphate solubilizing bacteria (PSB) and Potash mobilizing bacteria (KMB) on available N, P, K of groundnut (Kg/ha).