Abstract
Subsoiling is an important management practice for improving maize yield, especially for maize planted at high plant density. However, the affected physiological processes have yet to be specifically identified. In this study, field experiments with two soil tillage (CK: no-tillage, SS: subsoiling) and three planting densities (low: 45000 plants ha−1, medium: 67500plants ha−1, and high: 90000 plants ha−1) were conducted from 2010 to 2012 at Xinxiang, Henan province. Yield, canopy function, and root system were investigated to determine the associated physiological processes for improving maize production affected by soil tillage and plant density. Subsoiling significantly increased the grain yield of the low-, medium-, and high-planting densities by 6.21%, 8.92%, and 10.09%, respectively. Yield increase in the SS plots was mainly attributed to greater post-anthesis DMA and improved grain filling compared to CK plots. Greater green leaf area, leaf net photosynthetic rate, FV/Fm and ΦPSII in the SS plots were mainly contributed to enhanced dry matter production post-anthesis. This is mainly because subsoiling increased density of root dry weight in deep soil and root bleeding sap amount due to decreased the bulk density of the 0–30 cm soil profile layer. Density of root dry weight at 10–50 cm depth with SS increased by 40.68%, 32.17%, and 20.14% at low, medium, and high planting densities compared to CK, respectively, while the root bleeding sap amount increased by 17.41%, 15.82%, and 20.91%. These results indicate that subsoiling could change the root distribution and improve soil layer environment for root growth, thus maintaining a higher canopy photosynthetic capacity post-anthesis and in turn promoting DMA and yield, particularly at higher planting densities.
Highlights
Total dry matter and post-anthesis dry matter were positively and significantly correlated (r = 0.8362ÃÃÃ). These results suggest that subsoiling significantly improved both total and post-anthesis dry matter accumulation (DMA)
In the SS treatment, the average density of root dry weight at the 0–50 cm soil depth was 5.64%, 5.04%, and 1.82% greater in the LD, MD, and HD plots of the SS vs. the CK treatments. These results indicate that subsoiling significantly affected the depth distribution of the roots by promoting root penetration to the deep soil and reducing the pressure of root crowding at the soil surface, but without a significant effect on total root dry weight
These results demonstrate that subsoiling reduces the root distribution at the surface soil and promotes root growth in the deeper soil, alleviating root crowding and competition in the topsoil [16] while promoting root growth in the deeper soil layer to improve soil water and nutrient utilization
Summary
Our objectives were to: (1) assess the effects of subsoiling on soil compactness, root system distribution, and root activity; (2) determine changes in DMA, leaf area, grain filling, and photosynthetic rate; (3) and investigate physiological processes that subsoiling regulates the post-anthesis aboveground DMA and yield
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