The role of ACC deaminase producing bacteria in improving sweet corn (*Zea mays* L. var *saccharata*) productivity under limited availability of irrigation water

Accumulation of stress ethylene in plants due to osmotic stress is a major challenge for achieving optimum sweet corn yield under limited irrigation. Rising global temperatures exacerbate irrigation constraints. Plant growth-promoting rhizobacteria (PGPR) can enhance crop resistance and adaptability to osmotic stress and support future food security. This study evaluated the efficacy of Pseudomonas fluorescens strains on yields and physiological characteristics of sweet corn under three irrigation levels: 100% (I100, no stress), 80% (I80), and 60% (I60) of crop water requirement. Four strains (P. fluorescens P1, P3, P5/P8, and P14) and a combination of all four were tested. Severe water stress (I60) decreased chlorophyll a, chlorophyll b, total chlorophyll, Fv/Fm ratio, and nutrient uptake, and increased Fo, Fm, proline, total soluble sugars, and catalase (CAT) and peroxidase (POX) activities, resulting in reduced ear and canned seed yields. Inoculation with the four-strain combination significantly increased ear yield (44%) and canned seed yield (27%) over control. The combination treatment showed the strongest promotion, followed by P1, in reducing drought damage and improving productivity; P4/P14 showed the least improvement. In conclusion, combined inoculation with four strains is an effective approach to enhance sweet corn yield under osmotic stress.

Tayebeh Zarei, Ali Moradi, Seyed Abdolreza Kazemeini, Abdolreza Akhgar, Ashfaq Ahmad Rahi