Cover: Thirteen-day-old wheat (Triticum aestivum L., cv. USU-Apogee) growing in zeoponic substrate with microporous tube irrigation (ZPT) (foreground) and recirculating hydroponics (background). Zeoponic substrate and microporous tube irrigation have been developed for use in controlled environment life support systems in space-based applications. Environmental conditions (24-h photoperiod, 1700 μmol m⁻²s⁻¹ photon flux, and continuous 23°C temperature) favoring rapid development in a bioregenerative life support system were used in this comparison of the ability of ZPT and hydroponic culture to deliver water and nutrients to wheat. See Steinberg et al., "Wheat Response to Differences in Water and Nutritional Status between Zeoponic and Hydroponic Growth Systems," p. 353-360. Photo credit:Susan Steinberg, Lyndon B. Johnson Space Center, NASA, Houston, TX.