In the desert, lots of water! Forget anything else, and you may have spend an umcomfortable night, but at least you won't die. Forget the water, and you will die!
Due to knee injuries, my backpacking days are probably over. These days it is mostly day hikes, and 100+ mile per day trips on the dirt bikes or ATV's. My basic kit that I always carry no matter what is a Gortex jacket, poncho, Emerson CQC-13, Ruger SP101, basic survival kit (fire starter, signal mirror, light multi-tool, etc.), basic first aid, toilet paper, and an appropriate amount of water. As the weather gets colder and/or we head into the mountains, add in layers of clothing to suit the conditions. Actually, on the bikes and ATV's, you are already wearing a helmet, chest protector, gloves, motocross pants and boots, so you just need an insulation layer underneath (various weights of long underwear) when it turns cold.
