East-facing Helianthus annuus has maximal number and mass of kernel-filled seeds: Seed traits versus head orientation.

Q3 Agricultural and Biological Sciences
Plant-environment interactions (Hoboken, N.J.) Pub Date : 2022-06-29 eCollection Date: 2022-06-01 DOI:10.1002/pei3.10083
Péter Takács, Judit Slíz-Balogh, Dénes Száz, Gábor Horváth
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引用次数: 0

Abstract

After anthesis, the majority of mature sunflower (Helianthus annuus) inflorescences face constantly East, which direction ensures maximal light energy absorbed by the inflorescences in regions where afternoons are on average cloudier than mornings. Several theories have tried to explain the function(s) of this eastward orientation. Their common assumption is that eastward facing has certain advantages for sunflowers. In sunflower plantations, the capitulum of many plants can also face North, South, or upward. Large deviations from the conducive East direction can decrease the plant's reproductive fitness. A larger mass and number of seeds, for example, can guarantee safer seed germination and better early development of more offspring. Thus, our hypothesis was that the East facing of sunflower inflorescences ensures a larger seed number and mass compared to disoriented inflorescences. This idea was tested in a sunflower plantation, where we compared the number and mass of seeds in plants, the inflorescences of which were naturally or artificially oriented northward, eastward, southward, westward, or upward. Our study tested head diameter, seed weight, and seed number in a normal agronomic field setting being different from earlier investigations. The other difference was that we tested five head orientations and only East showed significantly increased seed weight and number. Using radiational computations, we showed that East facing ensures more absorbed light energy than other orientations, except upward. This finding can be one of the reasons for the maximal seed number and mass in East-facing sunflower capitula. Although upward-facing horizontal inflorescences absorbed maximal light energy, they had the fewest and lightest seeds probably because of the larger temperature and humidity as well as the too much sunlight, all three factors impairing the normal seed development. This study is the first that compares the seed traits of all head orientations of Helianthus annuus and proposes that the absorbed radiation could play a major role in the maximal seed number and mass of east-facing heads.

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东向的太阳花具有最大的充仁种子数量和质量:种子性状与头部朝向的关系
开花后,向日葵(Helianthus annuus)的大部分成熟花序都朝向东方,在平均下午比上午多云的地区,这个方向能确保花序吸收最大的光能。有几种理论试图解释东向花序的功能。它们的共同假设是,向东种植对向日葵有某些好处。在向日葵种植园中,许多植物的头状花序也可以朝北、朝南或朝上。大幅偏离有利的东向会降低植物的繁殖能力。例如,种子的质量和数量越大,就能保证种子更安全地萌发和更多后代的早期发育。因此,我们的假设是,向日葵花序朝东与花序朝西相比,能确保种子的数量和质量更大。我们在向日葵种植园中对这一想法进行了试验,比较了自然或人工朝北、朝东、朝南、朝西或朝上花序的植株的种子数量和质量。我们的研究在正常的农艺学田间环境中测试了头径、种子重量和种子数量,这与之前的研究不同。另一个不同点是,我们测试了五种头向,只有东向显示种子重量和数量显著增加。通过辐射计算,我们发现东向比其他方向(向上除外)吸收更多的光能。这一发现可能是向日葵头状花序朝东的种子数量和质量最大的原因之一。虽然朝上的水平花序吸收的光能最多,但它们的种子数量最少、质量最轻,这可能是因为温度和湿度较大,以及阳光太强,这三个因素都会影响种子的正常发育。这项研究首次比较了所有朝向的太阳花序的种子性状,并提出东向花序的种子数量和质量最大,吸收的辐射可能起了主要作用。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
2.70
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0.00%
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审稿时长
15 weeks
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