Aims
To test the effect of zinc oxide nanoparticle (ZnO‐NP) supplementation for enhancing the efficacy of Pseudomonas fluorescens NK4 siderophore as a biocontrol agent against P. viridiflava NK2 and a plant growth promoter.
Methods and Results
Cucumber seedlings were treated with a suspension of P. fluorescens NK4 and its siderophore generated in siderophore‐inducing medium (SIM), SIM supplemented with ZnO‐NP (<100 nm) and SIM supplemented with Zn2+ ions from Zn(NO3)2. Supplementing SIM with ZnO‐NP increased siderophore secretion in P. fluorescens NK4, and irrigation of cucumber seedlings with a filtrate containing the ZnO‐NP‐supplemented siderophore increased survival, improved vegetative and root growth, and thus increased yield similar to the effects of dipping seedlings in a P. fluorescens NK4 suspension. Both P. fluorescens NK4 and its ZnO‐NP‐supplemented siderophore inhibited P. viridiflava NK2 population growth in planta.
Conclusions
The siderophore of P. fluorescens NK4 produced by ZnO‐NP supplementation can be employed as a biocontrol agent and biofertilizer.
Significance and Impact of the Study
ZnO‐NPs can boost the synthesis of siderophores, which can then be employed as biofertilizers to boost iron bioavailability in iron‐deficient soils.