Optimizing Plant Density and Plastic Film Mulch to Increase Maize Productivity and Water-Use Efficiency in Semiarid Areas

Increasing crop productivity in semiarid areas is essential for ensuring future food security. We hypothesized that crop yield could be increased by using plastic film mulching to reduce evaporation and increase plant density. A 3-yr field experiment was conducted on the Loess Plateau of China to evaluate the effects of soil temperature and water content on maize (Zea mays L.) grain yield (GY) and water-use efficiency (WUE). Film mulching promoted maize growth and development by increasing the soil temperature and water content, particularly during the early growth season. At harvest, the mulched treatments had higher kernel numbers per ear (KN) and greater 1000-kernel weight (KW) than non-mulched treatment. Furthermore, mulching allowed the optimum plant population to be increased from 65,000 to 85,000 plants ha(-1). Compared with mulching for the entire growing season, removing the film at the silking stage decreased the plant senescence rate and slightly increased the final KN and KW, thus further increasing the GY by 0.6 to 1.2 Mg ha(-1). Although the WUE showed no significant difference among the three mulched treatments (34.0-47.2 kg ha(-1) mm(-1)), these values were markedly higher than that in the non-mulched treatment (20.3-29.6 kg ha(-1) mm(-1)). We conclude that film mulching together with increased plant density can increase semiarid maize yields and water-use efficiency.