DROUGHT STRESS EFFECTS ON APETALA2 (AP2) GENE EXPRESSION, PHYSIOLOGICAL, AND YIELD TRAITS OF MAIZE (ZEA MAYS L.).

Maize (Zea mays L.) field experiments commenced during crop season 2022 at the Experimental Farm, Al-Mahnawiya, Extension Training Center, Babylon, Iraq. The study examined the impacts of water stress tolerance on four maize cultivars' AP2 gene expression, physiology, and yield. The experiment used a randomized complete block design (RCBD) with a split-plot arrangement and three replications. Four irrigation treatments applied on the main plots comprised 1) full irrigation (control), 2) withholding irrigation during elongation (Gs-V7), 3) non-irrigation during grain-filling (Gs-R2), and 4) suppressing irrigation during both elongation and grain-filling (Gs-V7+R2). The subplots included four maize cultivars: Furat, Dijlah, ZP, and Konsens. The results showed that withholding water during maize plants' elongation stage (GS-V7) significantly reduced leaf water and chlorophyll content. However, withholding irrigation increased peroxidase and catalase enzyme concentrations significantly. Suppressing irrigation at the elongation stage (GS-V7) and the elongation and grainfilling stages (GS-V7+R2) resulted in a considerable drop in cycle threshold (CT) values, with average CT values of 31.68 and 31.69 cycles, respectively. The AP2 gene expression and CT values indicated a negative correlation. The study found that the AP2 gene increases maize's water stress tolerance, and the gene expression in maize cultivar "Furat" confirms this. Maize cultivar Furat achieved recommendations for cultivation in desert regions because of its superior ability to survive and adapt. [ABSTRACT FROM AUTHOR]