Increasing the Planting Uniformity Improves the Yield of Summer Maize

Crop production is oft en affected by resource limitations, especially water in semiarid areas. This study was conducted to identify whether the changes in inter and intra row spacing could improve soil water availability and radiation interception for maize (Zea mays L) through adjusting spatial distribution of root systems and canopy morphology. A 6-yr field study (2011-2016) was conducted to examine the impacts of five planting patterns on summer maize growth and yields in the North China Plain (NCP), which included two narrow-wide row spacings (20-100 cm, R20-100; 40-80 cm, R40-80), two equal-row spacings (60 cm, R60; 50 cm, R50) and equidistance both in row spacing and in plant distance in a row (38 cm, R38). The results showed that the more uniform planting increased the active soil volume taken by root system, therefore, increased the soil water availability to plants under limited water supply condition. The more uniform planting also increased the light capture at vegetative stages which accelerated the biomass accumulation of the crop. Grain yield was 6% higher under R38 than that of R20-100 in a very wet season up to 25% higher in a very dry season. The improvement in yield was related to the increased ear numbers per area at harvest in dry seasons and the increased kernel numbers per ear in wet seasons. Reducing inter-row spacing and increasing intra-row spacing had positive impacts on the yield of summer maize related to either the increased seedling establishment or the increased seed numbers per ear.