Optimizing Plant Density and Row Spacing Enhances Growth, Yield and Quality of Waxy Maize on the Loess Plateau

Abstract

Waxy maize (Zea mays L. ceratina) is extensively cultivated and exhibits substantial market demand in China; however, its yield and quality improvement remain constrained by relatively underdeveloped cultivation techniques. Optimizing plant density and row spacing is critical to improving the yield and nutritional quality of waxy maize, yet their combined effects remain insufficiently explored. A split-plot design evaluated two plant densities, i.e., 5.25 × 10⁴ plants ha^-1 (PD_5.25) and 6.75 × 10⁴ plants ha^-1 (PD_6.75), and three row configurations, i.e., 80 + 40 cm wide-narrow rows (RS_8-4), 100 + 20 cm wide-narrow rows (RS_10-2) and conventional 60 + 60 cm equal rows (RS_6-6). This study aims to identify the optimal cultivation configuration for waxy maize in the Loess Plateau region. Results showed that the RS_8-4 configuration maximized agronomic traits, dry matter accumulation, and yield relative to RS_6-6 and RS_10-2 treatments. Specifically, RS_8-4 reduced the insertion angle of the lower ear leaf by 12.4% (p < 0.05) and ear height by 8.3% while increasing yield by 19.86-20.00% compared to RS_6-6 and RS_10-2 treatments. At fresh-market maturity, dry matter accumulation under RS_8-4 treatment increased significantly by 34.0% with higher plant density. Under PD_6.75, RS_8-4 boosted dry matter by 29.8% and 39.4% versus RS_6-6 and RS_10-2, respectively. Under the RS_8-4 and PD_6.5 configurations, dry matter accumulation reached 13.56 t ha^-1 and a yield of 9.94 t ha^-1 was achieved in 2022. In summary, the combination of the PD_6.75 density and the RS_8-4 row spacing configuration achieved the optimal yield for the 'Jinnuo 20' cultivar in the Loess Plateau region. This approach provides a scalable planting framework for high-yield waxy maize production in the area, while demonstrating that optimized plant density and row spacing represent not only a key technical measure for enhancing productivity but also a core agronomic strategy for improving resource-use efficiency.

Keywords: nutritional quality; plant densification; purple waxy maize; row spacing configuration; yield components.

Figure 1

Location of the experimental site.

Figure 2

Daily mean air temperature (DMAT) and precipitation during waxy maize growing seasons in 2021 and 2022.

Figure 3

Agronomic traits and leaf insertion angle of waxy maize under different plant densities and row spacing configurations. PH, plant height. EH, ear height. EHC, ear height coefficient. UL, insertion angle of upper ear leaf. EL, insertion angle of primary ear leaf. LL, insertion angle of lower ear leaf. SD, stem diameter. Different lowercase letters indicate significant differences among treatments at p < 0.05.

Figure 4

The LAI under different plant densities and row spacing treatments at the silking and fresh-market maturity stages. LAI, Leaf Area Index. R1, Reproductive stage 1. FM, Fresh market maturity. Different lowercase letters indicate significant difference among treatments at p < 0.05. ** indicates significant differences between PD_5.25 and PD_6.75 treatments at p < 0.01.

Figure 5

The LAD under different plant densities and row spacing treatments during emergence to silking (VE–R1) and the silking to fresh-market maturity (R1–FM) stage. LAD, Leaf Area Duration. VE, Vegetative emergence. R1, Reproductive stage 1. FM, Fresh-market maturity. Different lowercase letters indicate significant difference among treatments at p < 0.05. ** indicates significant differences between PD_5.25 and PD_6.75 treatments at p < 0.01.

Figure 6

Effects of plant density and row spacing configurations on kernel nutritional quality of waxy maize. (I-1,II-1) indicate grain fat content data in 2021 and 2022, (I-2,II-2) indicate grain reducing sugar content data in 2021 and 2022, (I-3,II-3) indicate grain soluble content data in 2021 and 2022, (I-4,II-4) indicate grain sucrose content data in 2021 and 2022, (I-5,II-5) indicate grain vitamin C content data in 2021 and 2022. Different lowercase letters indicate significant differences among treatments at p < 0.05. **, significant differences among treatments at p < 0.01.