Rising populations, dietary shifts, and shrinking arable land demand improved maize yield, stability, and quality. Climate extremes such as heat and drought reduce spikelet fertility, raise transpiration, and hinder grain filling, cutting yields. Without irrigation and fertilization, maize growth is increasingly limited. Precision agriculture (PrA) tools like SPAD, RTK, and UAVs enable monitoring of plant health, nitrogen, and soil moisture. The SPAD-502 sensor estimates chlorophyll and nitrogen non-destructively, aiding yield prediction, while UAV multispectral imaging assesses traits like phenophase, LAI, and carotenoids. PrA tools (SPAD, UAV-NDVI) effectively tracked maize response to nitrogen and irrigation under drought. Highest yields were achieved with spring basal fertilization (A120) and top-dressing at V6–V12, especially with irrigation. SPAD and NDVI strongly correlated with yield at R1 and R3, making them reliable predictors under stress. Measurements used a Minolta SPAD-502 device and UAV-NDVI with a DJI Phantom 4 Pro V2 equipped with Sentera Double 4K sensors. Data were analyzed with Duncan’s multiple range test (DMRT).