Effect of planting density and pattern on maize yield and rainwater use efficiency in the Loess Plateau in China

Abstract

We conducted a two-year field research to evaluate the effect of three planting densities (L: 52,500, M: 75,000 and H: 97,500 plants ha−1) and three different planting patterns (RF: ridge with plastic film mulching; FM: flat planting with plastic film mulching; and CP: conventional planting without mulching) on maize yield. Results showed that, at each planting density, average topsoil temperature (5–25 cm) was improved under FM and RF, relative to CP, before silking. This resulted in earlier emergence and accelerated plant development. Compared to CP, RF significantly increased soil water storage (SWS) at the end of the fallow season and provided non-limiting water conditions for early seedling growth. During the growing season, when rainfall was more abundant, RF prevented evapotranspiration (ET); thereby, favouring SWS. Furthermore, when rainfall was scarce, RF provided the crop with additional soil moisture, which resulted in increased ET. Under RF and FM, the two-year average grain yield increased by 33.4% and 30%, respectively; while, water use efficiency (WUE) increased by 34.2% and 27.5%, respectively; similarly, rainwater use efficiency (RUE) increased by 35.6% and 32.1%, respectively. In a normal year (2015), grain yield, WUE and RUE, significantly increased as planting density increased from low to moderate; but not in a dry year (2016). Under such conditions, no significant differences were observed in grain yield, WUE or RUE among planting density treatments within the same planting pattern. Under moderate planting density, the two-year average final aboveground dry matter, grain yield, WUE and RUE in RF increased by 14.7%, 31.8%, 31.9% and 34.1%, respectively, compared to CP. Therefore, we conclude that RF is the most suitable planting pattern under moderate planting density for increasing maize yield in the Loess Plateau in China.