College of Photonics, National Yang Ming Chiao Tung University, No.301, Sec. 2, Gaofa 3Rd Rd., Guiren District, Tainan City, 71150, Taiwan.
Sci Rep. 2022 Nov 18;12(1):19864. doi: 10.1038/s41598-022-24451-8.
Mikania micrantha is an exotic and aggressive species that can reproduce asexually and sexually through its germinative stem and its featherlike seeds. Present weeding methods cannot effectively or economically control the spread of Mikania micrantha. In this article, we propose a method to suppress the growth and spread of Mikania micrantha by applying a high-energy laser beam to penetrate its stem. The threshold penetrating optical intensity is 3.1 W/mm. To optimize the damage to the inner tissue of the stem, which includes the vascular bundle and medulla for transporting organic nutrients, water, and inorganic salt, the absorption spectrum of the tissue and laser beam size are analyzed. According to the absorption spectrum of the tissue and growth mechanism of Mikania micrantha, a 455 nm blue laser is used as an irradiated light source. A single beam with two different beam sizes or two laser beams with the same beam size is used to optimize the stem damage. By the time the cumulative energy reaches 15 Joules for a single laser beam with dimensions of 0.81 mm × 0.74 mm, the inner tissue will be damaged 97.5%. We perform laser irradiation on the fresh Mikania micrantha grown hydroponically, with the result that all samples withered in 30 days. Therefore, using the method before the flowering season of Mikania micrantha can effectively inhibit its reproduction.
微甘菊是一种外来的、具有侵略性的物种，它可以通过其生殖茎和羽毛状的种子进行无性和有性繁殖。目前的除草方法无法有效地或经济地控制薇甘菊的传播。在本文中，我们提出了一种通过高能激光束穿透其茎来抑制薇甘菊生长和传播的方法。茎穿透的光学强度阈值为 3.1 W/mm。为了优化对茎内组织的损伤，包括运输有机养分、水和无机盐的维管束和髓，分析了组织的吸收光谱和激光束尺寸。根据组织的吸收光谱和薇甘菊的生长机制，我们使用 455nm 蓝光作为辐照光源。使用两种不同光束尺寸的单光束或两种相同光束尺寸的激光束来优化茎的损伤。当单束激光的累积能量达到 15 焦耳，尺寸为 0.81mm×0.74mm 时，内部组织将被破坏 97.5%。我们对水培生长的新鲜薇甘菊进行了激光辐照，结果所有样本在 30 天内枯萎。因此，在薇甘菊开花季节之前使用这种方法可以有效地抑制其繁殖。
