Optimum Planting Density Improves Resource Use Efficiency and Yield Stability of Rainfed Maize in Semiarid Climate

Abstract

Increasing planting density is an effective strategy for improving maize productivity, but grain yield does not increase linearly with the increase in plant density, especially in semiarid environments. However, how planting density regulates the integrated utilization of key input resources (i.e., radiation, water, and nutrients) to affect maize production is not clear. To evaluate the effects of planting density and cultivar on maize canopy structure, photosynthetic characteristics, yield, and resource use efficiency, we conducted a successive field experiment from 2013 to 2018 in Heyang County (Shaanxi Province, China) using three different cultivars [i.e., Yuyu22 (C1), Zhengdan958 (C2), and Xianyu335 (C3)] at four planting densities [i.e., 52,500 (D1), 67,500 (D2), 82,500 (D3), and 97,500 (D4) plants ha–1]. Increasing planting density significantly increased the leaf area index (LAI) and the amount of intercepted photosynthetically active radiation (IPAR), thereby promoting plant growth and crop productivity. However, increased planting density reduced plant photosynthetic capacity [net photosynthetic rate (Pn)], stomatal conductance (Gc), and leaf chlorophyll content. These alterations constitute key mechanisms underlying the decline in crop productivity and yield stability at high planting density. Although improved planting density increased IPAR, it did not promote higher resource use efficiency. Compared with the D1 treatment, the grain yield, precipitation use efficiency (PUE), radiation use efficiency (RUE), and nitrogen use efficiency (NUE) increased by 5.6–12.5%, 2.8–7.1%, and −2.1 to 1.6% in D2, D3, and D4 treatments, respectively. These showed that pursuing too high planting density is not a desirable strategy in the rainfed farming system of semiarid environments. In addition, density-tolerant cultivars (C2 and C3) showed better canopy structure and photosynthetic capacity and recorded higher yield stability and resource use efficiency. Together, these results suggest that growing density-tolerant cultivars at moderate planting density could serve as a promising approach for stabilizing grain yield and realizing the sustainable development of agriculture in semiarid regions.

Complementary effects of phosphorus supply and planting density on maize growth and phosphorus use efficiency

“…Low planting density reduces the leaf area index and the interception of photosynthetically active radiation by the canopy, resulting in a decrease in the accumulation of aboveground dry-matter ( Zhang et al., 2021 ). Consistently, we found that at low planting densities, shoot biomass accumulation and P uptake were lower than at high planting densities.…”

“…Mineral P fertilizers are critical in ensuring food security ( Nedelciu et al., 2020 ); however, P use efficiency is extremely low owing to poor P mobility ( Heuer et al., 2017 ). Although increasing planting density is a common agronomic measure for increasing P use efficiency ( Jia et al., 2018 ; Zhang et al., 2021 ), it results in reduced space for root growth. The primary mechanism for P acquisition in maize production is the morphological expansion of root systems ( Zhou et al., 2019a ).…”

Strategies for water productivity enhancement in maize—A comprehensive review

“…The furrow method is the most commonly used irrigation method for cultivating maize crops (FAO, 2016). Efficient water management and optimum plant populations (Zhang et al, 2021) are needed, which act as a key to enhancing productivity. Young seedlings, knee-high stage, flowering and grain filling are the most sensitive stages for water stress, and hence, irrigation should be ensured at these stages (Department of Agriculture, Cooperation and Farmers Welfare [DAC & FW] 2021).…”

Maize ZmWRKY28: a target to regulate shade avoidance response under high planting density

“…Optimum plant density is one of the key factors for achieving maximum yield in maize ( Zhang et al , 2021 ). An individual plant shows maximum productivity in a widely spaced plantation; however, areas of low-density cropping are prone to higher weed growth.…”