Effects of Soil Tillage and Canopy Optimization on Grain Yield, Root Growth, and Water Use Efficiency of Rainfed Maize in Northeast China

Lin Piao,Wanrong Gu,Ming Zhao,Ming Zhan,Jialei Xiao,Congfeng Li,Ming Li,Cougui Cao

doi:10.3390/agronomy9060336

Abstract

Elucidating the mechanisms underlying the relationships between root growth and water use efficiency is important for achieving full yield potential. We conducted a field experiment with maize under high planting density (105,000 plants ha−1) in 2013 and 2014. Four treatments were implemented: traditional cultivation, root optimization cultivation, canopy optimization cultivation, and shoot–root optimization cultivation. Compared to the treatments involving rotary tillage, subsoil tillage significantly improved the soil structure and promoted soil water storage. Moreover, the distribution of roots was significantly deeper under shoot–root optimization cultivation than traditional cultivation treatment. Shoot dry matter and leaf area were slightly higher under the plant growth-regulator treatments than that under the other treatments. Thus, relative to the shoot–root optimization cultivation treatment, the root optimization cultivation and canopy optimization cultivation treatments reduced the shoot–root area ratio by 8% and 4%, respectively, and these reductions were significantly lower than the reduction under the traditional cultivation treatment (16%). Rainfall storage can be enhanced by improving tillage practices, promoting root growth (particularly at depths >20 cm), promoting access to water, and regulating plant growth by the foliar spraying of ECK (ethylene-chlormequat-potassium). This approach has the potential to achieve highly efficient resource utilization without additional inputs, thereby increasing yield.

Highlights

China uses 5% of the planet’s water and 7% of its arable land resources to feed 20% of the global population [1]
Porosity, field moisture capacity (FMC), and permanent wilting percentage (PWP) in each layer were significantly higher under the subsoil tillage treatments than that under the rotary treatments (Figures 1 and 3, whereas there were no significant differences in moisture between the two tillage treatments (Figure 1)
Our results agree with previous findings demonstrating that subsoil tillage significantly improves soil physical properties, including soil bulk density (BD), moisture, FMC, and PWP

Summary

Introduction

China uses 5% of the planet’s water and 7% of its arable land resources to feed 20% of the global population [1]. Yield increases in maize (Zea mays L.), the most important crop globally, have been achieved mainly by maximizing planting density [3,4]. The precipitation resources are generally sufficient to meet the water demands for maize production, but due to overexploitation and improper mechanical manipulation of Agronomy 2019, 9, 336; doi:10.3390/agronomy9060336 www.mdpi.com/journal/agronomy. Agronomy 2019, 9, 336 the soil, an increase in the depth of the highly compacted layer under the topsoil has been observed in recent years [6]. This compaction obstructs the infiltration of precipitation and limits the extension of roots. Studies have indicated that the maize yield under rainfed conditions was 5% lower than that under irrigated maize conditions in the 1980s and 10%–20% lower in the 2000s, and that currently, 40% of maize fails to receive sufficient water to attain its yield potential [11]

Methods

Results

Discussion

Conclusion