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The present study evaluated the effect of nanochitosan in combination with plant growth promoting rhizobacteria (PGPR), PS2 and PS10 on maize growth. The PGPR were earlier recognized as Bacillusspp. on the basis of 16S rDNA sequencing. The observation revealed enhanced plant health parameters like seed germination (from 60 to 96.97%), plant height (1.5-fold increase), and leaf area (twofold). Variability in different physicochemical parameters (pH, oxidizable organic carbon, available phosphorous, available potassium, ammoniacal nitrogen and nitrate nitrogen) was observed. Activities of soil health indicator enzymes (dehydrogenase, fluorescein diacetate hydrolysis and alkaline phosphatase) were also enhanced 2 to 3 fold. Plant metabolites with respect to different treatments were also analyzed using gas chromatography–mass spectroscopy (GC–MS) and the result revealed an increase in the amounts of alcohols, acid ester and aldehyde compounds. Increase in organic acids indicates increased stress tolerance mechanism operating in maize plant after treatment of nanochitosan.

Pesticides belonging to pyrethroid group are widely used in agricultural fields to check pest infestation in different crops for enhanced food production. In spite of beneficial effects, non-judicious use of pesticides imposes harmful effect on human health as their residues reach different food materials and ground water via leaching, percolation and bioaccumulation. Looking into the potential of microbial degradation of toxic compounds under natural environment, a cypermethrin-degrading Bacillussp. was isolated from pesticide-contaminated soil of a rice field of Distt. Udham Singh Nagar, Uttarakhand, India. The bacteria degraded the compound up to 81.6 % within 15 days under standard growth conditions (temperature 32 °C pH 7 and shaking at 116 rpm) in minimal medium. Analysis of intermediate compounds of biodegraded cypermethrin revealed that the bacteria opted a new pathway for cypermethrin degradation. GC–MS analysis of biodegraded cypermethrin showed the presence of 4-propylbenzoate, 4-propylbenzaldehyde, phenol M-tert-butyl and 1-dodecanol, etc. which was not reported earlier in cypermethrin metabolism; hence a novel biodegradation pathway of cypermethrin with Bacillussp. strain SG2 is proposed in this study.

The role of plant growth-promoting rhizobacteria along with nanochitosan on maize productivity remains unexplored. In the present study we report the effect of nanochitosan and PGPR on growth, productivity and mechanism(s) involved in defence response in Zea maysunder field conditions. Application of nanochitosan (50 mg L−1) along with plant growth-promoting rhizobacteria enhanced seed germination, plant height, root length, leaf area, fresh and dry weight of shoot and root, chlorophyll, carotenoids, total sugar and protein content upto 1.5–2 fold over control in maize after 60 days of the field experiment. Treated maize plants also showed enhanced level of defence-related biomolecules like phenolic compounds (103%), catalase (60.09%), peroxidase (81.57%) and superoxide dismutase (76.50%) over control. Level of phenols and sugar content in maize plants enhanced which was analysed by GC–MS (Gas chromatography–mass spectrometry). Significant increase in cob length, cob weight/plot, grain yield/plot and 100 grain weight was observed in treated maize plants over control. As per the results, the combination of nanochitosan and plant growth-promoting rhizobacteria was reported to improve the health and yield of maize. The interaction can be further studied in field trials for improvement in agriculture production.

Bio-inoculants play an important role for sustainable agriculture. Application of nanocompounds in the agriculture sector provides strength and is reported to enhance crop production but the combined effect of nanocompounds and plant growth-promoting rhizobacteria on plants has not been studied much. Therefore, the present study was planned to observe the effect of two plant growth promotory Bacillusspp. along with nanozeolite on maize under field conditions using a randomized block design. Combined treatment of nanozeolite and bio-inoculants promoted plant height, root length, fresh and dry weight of shoot and root, chlorophyll, carotenoids, total sugar, protein and phenol contents in maize significantly over control. Enhanced level of catalase, peroxidase, superoxide dismutase, phenols, alcohols and acid-esters in treated plants over control showed their role in stress management. An increase of 29.80% in maize productivity over control was reported in the combined treatment of Bacillussp. and nanozeolite. Our results indicate that the application of bio-inoculants with nanozeolite showed a positive response on the health and productivity of maize plants. Hence, these may be used to enhance the productivity of different crops.