Effects of planting patterns and sowing densities on grain-filling, radiation use efficiency and yield of maize (Zea mays L.) in semi-arid regions

The ridge-furrow rainwater harvesting system is a valuable technique for collecting runoff water and increasing radiation use efficiency to improve crop production. Field experiments were conducted over two consecutive years (2015–16) on a loess soil in semi-arid regions of China. Three different planting densities (L: 52500 plant ha−1; M: 75000 plant ha−1; H: 97500 plant ha−1) and three different planting patterns (RF: ridge and furrow rainfall harvesting system; FM: flat planting with plastic film mulching; CP: conventional planting without plastic film) were used to measure various maize characteristics. The objectives were to enhance the water use efficiency (WUE), radiation use efficiency (RUE), and promote the grain-filling process and yields of maize. The results showed that under the same densities, there was no significant differences between the average filling rate (Gmean) and the maximum filling rate (Gmax) (P>0.05) during the normal-precipitation year (2015). However, the Gmean and Gmax in the RF and FM treatments were significantly higher than the CP treatment in dry year (2016). Under the same densities, the number of grains per row, number of kernels per ear, and kernel yield per plant of RF and FM treatments were significantly higher than those of the CP treatment. These maize yield components decreased with increased planting densities under the same planting patterns. Compared to the CP treatment, the average annual grain yield under the RF and FM treatments increased by 33.4% and 30.0%, respectively. Compared to the CP treatment, the average annual RUE in the RF and FM treatments increased by 12.4% and 11.5% before silking and increased 17.7% and 14.7% after silking, respectively. Under the RF system with a middle planting density (M-RF) promoted grain-filling rate, grain yield, yield components, WUE, and RUE. Therefore, we concluded that M-RF model is the most suitable for increases maize yield and RUE in the semi-arid regions of China.