Abstract
Marginal superiority is a common phenomenon in crops, and is caused by the competitiveness of individual plant for resources and crop adaptability to crowded growth conditions. In this study, in order to clarify the response of marginal superiority to maize morphology and plant-density tolerance, field experiments without water and nutrition stress were conducted at Qitai Farm in Xinjiang, China, in 2013–2014 and 2016–2019. The results showed that no more than three border rows of all the cultivars had marginal superiority under high density, about 90% of all the cultivars had no more than two border row that had marginal superiority and a significant negative correlation was observed between marginal superiority and population grain yield (first border row: y = − 2.193x + 213.9, p < 0.05; second border row: y = − 2.076x + 159.2, p < 0.01). Additionally, marginal superiority was found to have a significant positive relationship with plant density (first border row: y = 6.049x + 73.76, p < 0.01; second border row: y = 1.88x + 95.41, p < 0.05) and the average leaf angle above the ear (first border row: y = 2.306x + 103.1, p < 0.01). These results indicated that the smaller the leaf angle above the ear, the weaker the marginal superiority and the higher the grain yield. It suggests that the magnitude of marginal superiority in the border rows can be an indicator for plant-density tolerance under high density. What’s more, cultivars with small leaf angle above the ear can be selected to weaken the marginal superiority and improve grain yield under high plant density. Conversely, cultivars with a large leaf angle above the ear can be selected to achieve higher individual yield in intercropping systems with no more than four rows alternated with other crops.
Highlights
Marginal superiority is a common phenomenon in crops, and is caused by the competitiveness of individual plant for resources and crop adaptability to crowded growth conditions
The results of the analysis of variance (ANOVA) between individual yields in different border rows showed that there was no significant difference after the third border row for any cultivars in any experimental year, and about 90% of all the cultivars that there was no significant difference after the second border row
The average individual yield from the fourth to the sixth border row was regarded as the individual yield of the inner row, and the individual yield of the first border row, second border row, and third border row were divided by this mean value, respectively, to calculate the marginal superiority (Eq 1) in each of these rows
Summary
Marginal superiority is a common phenomenon in crops, and is caused by the competitiveness of individual plant for resources and crop adaptability to crowded growth conditions. Previous studies have shown that these morphological traits can contribute to high grain y ield[6,27], such as lower plant height and ear height, and small leaf angle, which can weaken the competitiveness of individual plants and allow each individual plant to use resources more effectively[12,28]. Both the plant density and plant type may affect the marginal superiority. The main objectives were to clarify: (1) how many rows have marginal superiority under high plant density and high grain yield; (2) the relationship between marginal superiority and population density and grain yield; (3) the relationship between marginal superiority and plant type and grain yield
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