Plant population and row spacing effects on corn: Phenotypic traits of positive yield‐responsive hybrids

Yang

Food and Energy Security

et al. 2022

Improved canopy structure was instrumental in setting maize yield records, and yet it has rarely been examined in China. At Qitai Farm in Xinjiang, we conducted a 4‐year field experiment using China's six highest‐yielding maize hybrids sorted into three yield level groups that were grown at similar growth durations and at optimum densities. The average yield of high‐yield level (HL, 22.3 Mg ha−1) was 7.2% and 24.6% higher than that of medium‐yield level (ML) and low‐yield level (LL), respectively. For each yield level, we measured morphological traits that influence canopy structure and yield. They included plant height, ear height, ear ratio, internode length, leaf numbers, leaf angle, LOV, leaf area, and spatial density of leaf area. Among the preceding morphological traits of the three yield levels, HL’s best optimized the canopy structure, as shown by improved light distribution (19.0% light transmission at the ear) and increased light interception per unit leaf area per day (LIPA, 51.7 MJ m−2 day−1) in the canopy. In comparison, light transmission was 12.2% and 15.9% at the ear and the total LIPAs were 37.2 and 29.0 MJ m−2 day−1 at silking for ML and LL, respectively. HL had significantly longer leaf area duration and a higher photosynthetic rate, especially at the grain filling stage, and its total accumulated biomass at maturity was significantly better (by 13.9%) than LL’s. HL’s harvest index (0.54) was significantly higher than that of ML (0.52) and LL (0.48). HL’s radiation and heat use efficiencies were 2.61% and 1.37 g °C−1 day−1 m−2, both significantly greater than those of ML and LL. Therefore, optimum maize plant types can significantly improve canopy structure and increase resource use efficiency and grain yield.

Section: Discussionsupporting

confidence: 90%

Optimized canopy structure improves maize grain yield and resource use efficiency

Yang

Food and Energy Security

et al. 2022

“…This paper describes the plant population and/or row spacing effects averaged across the six hybrids. The details of individual hybrid responses and their interaction with population or row spacing are presented in a companion paper (Bernhard & Below, 2020).…”

Section: Discussionmentioning

confidence: 99%

Plant population and row spacing effects on corn: Plant growth, phenology, and grain yield

Bernhard

Below

2020

Agronomy Journal

Self Cite

The average U.S. plant population continues to increase as U.S. growers continue to push corn (Zea mays L.) grain yields higher. However, this increased plant population typically causes more intra‐row stress to the plants, potentially reducing yields. Narrower row spacings may be used to reduce the stress by increasing the plant‐to‐plant spacing within a row. The objective of this study was to evaluate the influence of plant spatial arrangement (population and/or row spacing) on corn plant growth, phenology, and grain yield. In 2017 and 2018, six contemporary commercial hybrids were planted at 94,000, 109,000, 124,000, or 139,000 plants ha−1 in 76‐ and 51‐cm row spacings at two locations in Illinois. Plant spatial arrangement affected corn growth, phenology, and grain yield. The greatest grain yield of 18.5 Mg ha−1 resulted from planting 109,000 plants ha−1 in a 51‐cm row spacing. In a 76‐cm row spacing, the minimum plant population maximized yield at 17.5 Mg ha−1. On average across plant populations, plants in a 51‐cm row spacing yielded 0.8 Mg ha−1 more than when planted in a 76‐cm row spacing. With increased plant populations, plants produced more shoot biomass, whereas root biomass was unchanged. Narrower row spacings helped mitigate crowding stress at greater plant populations by promoting phenotypic changes that consequently led to greater yield.

“…However, its HI drastically decreased under both medium and high-density conditions. It was reported that modern commercial hybrids generally have enhanced tolerance to increased planting density compared to older maize hybrids (Echarte et al 2000 ; Bernhard and Below 2020 ). DH618 is the newest cultivar of all analyzed and showed a stable high grain yield, the highest TKW and the least decrease in biomass per plant under the high-density condition (Tables 1 , 2 , Fig.…”

Section: Discussionmentioning

confidence: 99%

Improving photosynthesis to increase grain yield potential: an analysis of maize hybrids released in different years in China

Yan

Duan

et al. 2021

Photosynth Res

In this work, we sought to understand how breeding has affected photosynthesis and to identify key photosynthetic indices that are important for increasing maize yield in the field. Our 2-year (2017–2018) field experiment used five high-yielding hybrid maize cultivars (generated in the 1970s, 2000s, and 2010s) and was conducted in the Xinjiang Autonomous Region of China. We investigated the effects of planting density on maize grain yield, photosynthetic parameters, respiration, and chlorophyll content, under three planting density regimens: 75,000, 105,000, and 135,000 plants ha−1. Our results showed that increasing planting density to the medium level (105,000 plants ha−1) significantly increased grain yield (Y) up to 20.32% compared to the low level (75,000 plants ha−1). However, further increasing planting density to 135,000 plants ha−1 did not lead to an additional increase in yield, with some cultivars actually exhibiting an opposite trend. Interestingly, no significant changes in photosynthetic rate, dark respiration, stomatal density, and aperture were observed upon increasing planting density. Moreover, our experiments revealed a positive correlation between grain yield and the net photosynthetic rate (Pn) upon the hybrid release year. Compared to other cultivars, the higher grain yield obtained in DH618 resulted from a higher 1000-kernel weight (TKW), which can be explained by a longer photosynthetic duration, a higher chlorophyll content, and a lower ratio of chlorophyll a/b. Moreover, we found that a higher leaf area per plant and the leaf area index (HI) do not necessarily result in an improvement in maize yield. Taken together, we demonstrated that higher photosynthetic capacity, longer photosynthetic duration, suitable LAI, and higher chlorophyll content with lower chlorophyll a/b ratio are important factors for obtaining high-yielding maize cultivars and can be used for the improvement of maize crop yield.