A multi-omics-based insight to decipher the nano-calcium induced enhanced chickpea (Cicer arietinum) productivity under acidic soil conditions

Chickpea ( Cicer arietinum L.) is a significant, economically important pulses crop cultivated worldwide due to its high nutritional value. Calcium (Ca), as a macronutrient, is essential for its optimal growth specifically when cultivating under acidic soil condition. However, commercially available Ca-based fertilizers, traditionally used for its remediation have inherent limitations, i.e., significant leaching, and the requirement for bulk application, high transportation cost etc. Nanotechnology-driven calcium oxide nanoparticles (CaO NPs) can offer a promising, eco-friendly, and sustainable alternative. Current evaluation was carried out to decipher the use of CaO NPs in enhancing chickpea productivity, focusing on its molecular mechanisms and environmental sustainability. CaO NPs were synthesized using a modified co-precipitation method, producing particles size of 110 nm, a zeta potential of − 43.4 mV, and an oval crystalline shape, with Ca as the core metal component, as confirmed by Dynamic light scattering (DLS), X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) respectively. Using 2 g/L lime as the standard dose and positive control, three sub-optimal doses—1/50th, 1/100th, and 1/150th of the standard concentration were applied as experimental treatments. Morphological studies demonstrated the highest germination rates, plant height, and early flowering at the 1/50th dose, highlighting its efficacy as a growth regulator. Transcriptomic studies revealed that key genes, including Calmodulin-binding transcription activator 2-like isoform X1 ( CAMTA ), Calcium-transporting ATPase 8 (plasma membrane-type) , and Tubulin tyrosine ligase-like protein 12 isoform X2 ( TTOP 12 ), were predominantly upregulated at the 1/50th dose, followed by the 1/100th dose. These findings were additionally confirmed through real-time quantitative reverse transcription PCR (RT-qPCR) analysis. Metagenomic analysis of rhizospheric soil demonstrated the environmental sustainability of CaO NPs, showing no microbial lethality and a significant increase in keystone microbial phyla such as Proteobacteria , Planctomycetes , Chloroflexi , Bacteroidota , and Firmicutes . These phyla include both nitrogen-fixing and non-nitrogen-fixing microorganisms, with the highest microbial diversity observed at the 1/100th dose, followed by the 1/50th dose. Ionic profiling revealed the highest Ca accumulation in leaves and roots at the 1/50th dose. This dosage also exhibited superior nutrient use efficiency and favorable speciation of NPK and other macro and micronutrients, including copper (Cu), iron (Fe), magnesium (Mg) and zinc (Zn). The study concluded that CaO NPs at 1/50th followed by 1/100th of the standard dose provide a sustainable alternative as Ca regulator in cultivating chickpea under acidic soil conditions.