Although controlled-release urea (CRU) has demonstrated higher nitrogen use efficiency compared to conventional urea, comprehensive evaluations of its multi-year continuous application on yield stability and environmental sustainability remain limited. A field experiment initiated in 2013 in the Huang-Huai-Hai Plain compared the effects of two coated ureas and conventional urea on sustainable yield, soil quality, and carbon footprint. Sulfur-coated urea achieved optimal balance among productivity, economic benefits, and environmental performance, while polymer-coated urea excelled in soil quality. The findings emphasize the importance of multi-criteria evaluation in fertilizer selection and provide scientific evidence for sustainable fertilizer management in intensive maize production systems.
- Article type
- Year
- Co-author
Open Access
Short Communication
Issue
This study aimed to explore the regulatory effects of different plant height combinations of maize varieties on the light distribution and light resource utilization of the population canopy under the soybean and maize strip intercropping pattern.
From 2023 to 2024, four maize varieties with different plant heights were used as experimental materials, including the short-stemmed varieties of MY73 and Denghai 605 (DH605), and the tall varieties of Jingke 968 (JK968) and Xianyu 1466 (XY1466), as well as the soybean variety Qihuang 34. The row configuration of maize and soybean was both 4:4. Different intercropping patterns were set, including intercropping of the same maize variety in all four rows as the control (S-MY, S-DH, S-JK, and S-XY), with 6.75×104 plants/hm2 for each of the four rows and intercropping of tall and short varieties (middle row tall variety JK968, edge row short variety MY73: MY-JK-1, MY-JK-2; middle row tall variety XY1466, edge row short variety DH605: DH-XY-1, DH-XY-2), and two types of planting densities were set, with 6.75×104 plants/hm2 for each of the four rows (MY-JK-1, DH-XY-1), 6.75×104 plants/hm2 for the middle rows, and 8.25×104 plants/hm2 for the edge rows (MY-JK-2, DH-XY-2). The plant spacing of soybean in each treatment was the same. The focus was on analyzing the effects of different intercropping patterns on the canopy structure of the population, light distribution, photosynthetic characteristics of maize and crop yield.
The combined planting of maize varieties with different plant height optimized the canopy structure, significantly improved the light transmittance of the spike layer in the maize population, increased the leaf area index and photosynthetic characteristics, and ultimately promoted the increase in total system yield. During the silk production stage, the light transmittance of the spike layer in MY-JK-1 and MY-JK-2 increased by 18.55%-88.22% compared with S-MY and S-JK, and that in DH-XY-1 and DH-XY-2 increased by 39.26%-55.77% compared with S-DH and S-XY. The net photosynthetic rate (Pn) of the four varieties (except MY73) in the tall and short plant combination pattern was all increased. Among them, the Pn of DH605 in the DH-XY-2 pattern is 6.88% higher than that of S-DH, and the Pn of XY1466 in the DH-XY-2 pattern is 10.31% higher than that of S-XY. At the same time, the maximum photochemical efficiency (Fv/Fm) and potential activity (Fv/Fo) of the spike leaf also increased. The yield of maize under the MY-JK-2 pattern increased by an average of 19.44%, 9.58% and 1.66% over two years compared with the S-MY, S-JK and MY-JK-1 patterns, respectively. The average increase of DH-XY-2 over two years was 30.20%, 14.94% and 9.21% compared with the S-DH, S-XY and DH-XY-1 patterns, respectively. The maize yield (12 536.58 kg·hm-2) and total system yield (14 001.29 kg·hm-2) under the DH-XY-2 pattern were the highest in both years.
Compared with the intercropping pattern of single maize varieties, the combined planting of maize varieties with different plant heights could optimize the canopy structure of the population, improve the light distribution of the population canopy, and increase the light transmittance of the maize ear position layer and the photosynthetically active radiation at the top of soybean. At the same time, it improved the leaf area index and photosynthetic characteristics of maize, promoted the accumulation of photosynthetic products, and ultimately increased the total system yield. With the increase of edge row density, the maize yield was further enhanced. Under the conditions of this experiment, in the eastern part of the Huang-Huai-Hai region, it was recommended to use the combined planting of short-stemmed DH605 and tall XY1466, with a middle row density of 6.75×104 plants/hm2 and an edge row density of 8.25×104 plants/hm2.
Open Access
Research Article
Issue
In maize production, the development of density-tolerant and lodging-resistant varieties has made dense planting an effective strategy for achieving high and stable yields, with superior hybrids serving as a prerequisite for successful high-density cultivation. However, the photosynthetic mechanisms underlying improved density tolerance in maize hybrids released across different eras in China remain unclear. This study investigates 40 years of breeding progress toward enhanced photosynthetic traits under varying planting densities and elucidates the physiological and ecological bases of improved density tolerance in maize hybrids. A three-year field experiment was conducted from 2019 to 2021 to compare eight major Chinese hybrids from four decadal cohorts under three planting densities: 45,000 (D1), 67,500 (D2), and 90,000 (D3) plants ha−1. At high density (D3), modern hybrids exhibited a more optimal canopy architecture and superior leaf photosynthetic performance compared to older hybrids, despite a slight reduction in specific leaf nitrogen. Notably, modern hybrids (2000s) were able to maintain higher net photosynthetic rates and photosynthetic nitrogen use efficiency (PNUE) at D3, resulting in the highest grain yield (GY), which was 118.47% greater than that of older hybrids (1970s). Leaf area duration after anthesis, total chlorophyll content, key photosynthetic enzyme activities, and maximum quantum efficiency of PSII photochemistry were all positively correlated with GY. Among these, PNUE showed the strongest correlation with grain yield and thus represents a key indicator for optimizing maize hybrids. Based on these findings, breeders should continue selecting hybrids under high-density and suboptimal conditions, focusing on optimizing population architecture and enhancing photosynthetic capacity while fine-tuning leaf nitrogen status to develop high-yielding, density-tolerant hybrids capable of sustaining long-term increases in maize grain yield.
京公网安备11010802044758号