Human population is expected to reach around 10 billion by 2050 and global food demand is projected to rise by 62% (van Dijk et al., 2021). It is estimated that, agricultural production needs to be increased by 60–70% to meet food demand of human population in 2050 (Silva, 2018). Maize is cultivated globally being the 3rd most important cereal crop after rice and wheat. Climate change significantly affects the crop production (Zhao et al., 2017). It is estimated that, climate change negatively affects maize production and decrease its yield by 24% (Jägermeyr et al., 2021). In India, it is being grown in about 9.3 m ha with a production of 30 m tons during the year 2020–21 (www.agricoop.nic.in). Kharif season accounts for about 83% of area under maize cultivation. Out of which more than 70% area is under rainfed condition.

Beneficial bacteria are extensively used to improve soil health, crop growth and yield (Srinivasarao and Manjunath, 2017; Efthimiadou et al., 2020). They extend necessary ecosystem services that help to enhance soil health and plant growth (Santos et al., 2019; Rouphael and Colla, 2020). The need for sustainable soil health and agricultural production worldwide led scientists to investigate different kinds of beneficial bacteria for their effectiveness. This has led to generation of lot of scientific evidence on beneficial interaction between plants and useful bacteria improving yield and productivity of cropping systems (Pereg and McMillan, 2015; Efthimiadou et al., 2020). Nowadays, instead of single culture combination of two or more cultures as consortia are being used to improve plant growth and development (Olanrewaju and Babalola, 2019). Use of microbial consortia improved the plant growth and yield of various crops (Saikia et al., 2018; Silambarasan et al., 2019; Jain et al., 2021). Hence, we hypothesized that, microbial consortia increase crop growth and yield of maize. Since combination of microbial cultures carries out multiple functions, which are not possible for a single species. Further, consortia are not easily get affected by environmental alterations as individual microbial cultures (Brenner et al., 2008; Lindemann et al., 2016). Bacillus and Pseudomonas species have been reported to improve growth and yield crop plants (Radhakrishnan and Lee, 2016; Costa-Gutierrez et al., 2020). Application of microbial consortium comprising of Rhizoglomus irregulare and Pseudomonas putida increased P use efficiency and maize productivity (Pacheco et al., 2021). Use of beneficial microorganisms along with farm yard manure improved maize growth (Hussain et al., 2021). Consortia of beneficial bacteria stimulated maize growth and development (Walker et al., 2012; Olanrewaju and Babalola, 2019). The bacterial isolates used in the present study were tested individually for their ability improve plant growth under pot conditions (Sandhya et al., 2009, 2011; Ali et al., 2011). The Bacillus amyloliquefaciens B17 and Paenibacillus favisporus B30 were Gram positive with irregular margin, tested positive for citrate, catalase, and oxidase activity. The former was able to produce siderophores but not the latter. The Pseudomonas putida P7 and Pseudomonas putida P45 were Gram negative and posses the PGP characteristics such as P-solubilization, synthesis of indole acetic acid, gibberellins and siderophore. Further, they were also evaluated in pot experiments for plant growth promotion in maize, sunflower and wheat under moisture stress conditions. They have increased proline, sugar and protein contents in leaves, improved relative water content (RWC) and reduced leaf water loss (LWL) of inoculated plants under moisture stress conditions (Sandhya et al., 2009, 2011; Ali et al., 2011).

Hence, the aim of the present study was to evaluate the open field effectiveness of two microbial consortia for improving yield of maize under rainfed conditions at Ballowal Saunkhri (Punjab) having sub-humid (Hot dry) climatic conditions.

Beneficial microorganisms have been used to improve growth and yield of wheat (Kumar et al., 2014), sunflower (Alami et al., 2000), chickpea (Ogola et al., 2021), maize (Chahal et al., 2022), okra (Manjunath et al., 2016), and many other crops. The microbial technologies offer ecofriendly and affordable means for sustainable soil health and crop production (Kumar et al., 2014; Manjunath et al., 2016). Plant associated microorganisms help to improve plant growth and development through mobilization, solubilization and transformation of plant nutrients, production of plant hormones, exopolysaccharides and regulation of biochemical compounds like sugars and proline.

In the present investigation, seed + soil application of microbial consortia 1 and 2 recorded significantly higher grain as well as straw yield of maize as compared to uninoculated control (Table 3). This may be due to beneficial effects exerted by the microbial consortia on maize plants. The bacteria used in the present study viz., Pseudomonas putida P7 + Paenibacillus favisporus B30 (Microbial consortia 1) and Pseudomonas putida P45 + Bacillus amyloliquefaciens B17 (Microbial consortia 2) were previously tested for plant growth promoting characteristics. They were able to produce phytohormones such as IAA, solubilize phosphorus, synthesize exopolysaccharides (EPS) and increased proline, sugar and protein contents in leaves under moisture stress conditions. Also improved relative water content (RWC) and reduced leaf water loss (LWL) of inoculated plants (Sandhya et al., 2009, 2010, 2011; Ali et al., 2011). Both seed as well as soil application might have resulted in providing more inoculum for improved colonization as compared to seed or soil application alone. Fitriatin et al. (2021) reported that, seed and soil application of biofertilizers improved growth of maize compared to single method of application.

Kaur and Reddy (2014) evaluated phosphate-solubilizing bacteria such as Pantoea cypripedii and Pseudomonas plecoglossicida at three different agroclimatic regions and reported that, these two bacteria significantly improved the phosphorous (P) uptake, soil organic carbon, activity of soil enzymes, grain yield of maize and wheat at three agroclimatic regions. Notable increase in maize productivity under field conditions was observed due to the use of microbial consortium which resulted in improved phosphorus use efficiency (Pacheco et al., 2021). Likewise, IAA producing bacteria promoted plant growth through improved root growth leading to increased water and nutrient uptake (Mantelin and Touraine, 2004; Myo et al., 2019). Inoculation of plant growth promoting bacteria viz., Pseudomonas spp. and Azotobacter spp. in maize significantly improved leaf area and relative water content as compared to uninoculated control under moisture stress conditions (Osama et al., 2020). Seed treatment of maize with Pseudomonas fluorescens strain 153 caused enhancement in proline content and improved the tolerance of plants to water deficit stress conditions (Ansary et al., 2012). Proline helps to maintain osmotic potential of cell, scavenge reactive oxygen species, stabilizes proteins and cell membrane leading to prevention of electrolytes leakage (Chun et al., 2018). EPS producing Pantoea aglomerans NAS206 improved root colonization, soil aggregation and thereby moisture stress tolerance of wheat (Amellal et al., 1998). In the present study, dryspells of 09–19 days duration were observed during the cropping seasons. Application of microbial consortia 1 and 2 resulted in relatively higher soil moisture content at flowering stage as compared to uninoculated control (Figure 1). This may be attributed to improved water holding capacity as a consequence of increased soil aggregation due to exopolysaccharide synthesis ability of bacteria used in the consortia. Inoculation of wheat with EPS producing microbial consortia consisting of Planomicrobium chinense strain P1 and Bacillus cereus strain P2 significantly improved the soil moisture availability as well as chlorophyll, sugar and leaf protein contents under rainfed conditions at different locations (Khan and Bano, 2019). Further, significant increase in rain water use efficiency was recorded due to seed + soil application of microbial consortia 1 and 2 as compared uninoculated control (Figure 2).

Evaluation of microbial consortia under field conditions for 3 years suggested that, both microbial consortia 1 (Pseudomonas putida P7 + Paenibacillus favisporus B30) and microbial consortia 2 (Pseudomonas putida P45 + Bacillus amyloliquefaciens B17) significantly increased yield and economics of kharif maize under rainfed conditions at Ballowal Saunkhri (Punjab) having sub-humid (Hot Dry) climatic conditions. Since microbial consortia are ecofriendly and affordable, they can be conveniently used to improve maize production under rainfed farming.

The original contributions presented in the study are included in the article/Supplementary material, further inquiries can be directed to the corresponding author.

MM, GC, SY, and KG: designed research. AK: performed research. MM and AK: analyzed data. MM, NJ, and KS: wrote the manuscript. VS, MS, and MP: resources. All authors contributed to the article and approved the submitted version.