Enhancing maize yield, water use efficiency, and Zn content under drought stress by applying Zn-solubilizing bacteria

Mitigating drought stress is important for corn production. One way to alleviate drought stress and increase yield is to use supplementary Zn and Zn-solubilizing bacteria. The objective of this study was to investigate the effects of ZnSO 4 combined with rhizosphere bacteria on the yield, Zn uptake, relative water content (RWC), and water use efficiency (WUE) of corn under drought stress. A field experiment was conducted with sufficient irrigation, moderate stress, and the application of different combinations of ZnSO 4 and Zn-solubilizing bacteria. These combinations included four levels without Zn, with Zn applied to foliage, soil, or seed priming, and three levels of bacteria (without bacteria, Pseudomonas fluorescens , and P. aeruginosa ). Drought stress decreased RWC by 11 %, the cobs/m 2 by 9 %, and increased WUE by 5.7 % in corn. However, priming or foliar application of ZnSO 4 with both P. fluorescens and P. aeruginosa strains increased the number of cobs/m 2 by 12.5 % and the number of rows/cob by 15 %. Additionally, most methods of applying ZnSO 4 and bacteria increased the number of grains, 100-grain weight, grain yield, and WUE of corn. The results showed a 48 % and 52 % increase in 100-grain weight with the foliar application of ZnSO 4 and P. aeruginosa , respectively, under normal and drought conditions compared to the control. Soil application of ZnSO 4 without bacteria or foliar application of ZnSO 4 with P. aeruginosa enhanced grain and biological yield by 48 % and 8.9 % under drought stress, respectivly. Similarly, under sufficient irrigation, Zn seed priming with P. aeruginosa increased grain yield by 39.6 % and biological yield by 14.9 % compared with the control. Drought stress and foliar application of ZnSO 4 with P. fluorescens and P. aeruginosa increased the Zn content of corn leaves and grains. In conclusion, although drought decreased corn performance, foliar or priming of ZnSO 4 with Pseudomonas bacterial strains improved yield. • In non-stress, Zn seed priming with Pseudomonas aeruginosa yielded the highest grain yield. • Drought stress reduces RWC, yield components, grain and biological yields. • Drought stress reduced plant yield but improved water use efficiency. • Zinc sulfate along with Zn solubilizing bacteria increased yield, and Zn in corn. • Zn soil/foliar application with Pseudomonas aeruginosa increased yield under stress.