【作者】 潘雷；

【导师】 陈树人；

【作者基本信息】 江苏大学 ， 机械设计及理论， 2008， 硕士

【摘要】 杂草是作物的大敌。随着公众对生态环境及食品安全的关注度日益增加,取代传统化学除草剂的物理除草方法逐渐得到了广泛深入的研究。物理除草可以有效减少除草剂对环境及作物的污染,对改善生态环境、保证食品安全以及维护人类健康都有重要的意义。本文主要研究低功率CO₂激光的除草效果,试验台主体由LASY-12 CO₂激光器和TS8618振镜组成,可发射出最大功率为12W、波长为1060nm的激光。对稗草、婆婆纳及大巢菜三种杂草的茎秆进行九种不同激光剂量下的除草试验,结果表明,当激光剂量大于12J/mm时,激光可以直接切断两片真叶期和四片真叶期稗草的茎秆,前者在14天后死亡,而后者的其余部分可继续存活,与未被激光作用的同期稗草相比,可获得最高84.5%、最低78%的相对干重损失;当激光剂量大于3J/mm时,激光可对两片真叶期和四片真叶期的婆婆纳带来致死作用;激光在切断子叶期和真叶期的大巢菜茎秆后,其仍可以在根部附近延伸出新的茎秆继续生长,激光对其再生长的影响效果并不显著,说明CO₂激光除草也具有一定的局限性。以大巢菜和婆婆纳种子为研究对象,分别使用五种剂量的激光对其进行1秒的照射。使用15.28J/mm²剂量的激光不能完全碳化大巢菜种子,作用后的种子仍然可以进行玻璃化转变,但种子已经不能正常发芽,而婆婆纳的种子则随着激光剂量的增加,其发芽率迅速下降。试验表明,利用CO₂激光照射在杂草种子上也可以起到一定的除草效果。基于以上实验,可将CO₂激光除草机理分为局部机理和整体机理,局部机理即激光直接作用的部分,包括激光对生物体的各种生物效应;整体机理指激光间接作用的部分,杂草受激光的高温高热作用后,受作用处组织的酶和蛋白质受到破坏,直接影响养分在茎秆中的运输,进而影响杂草的顶端分生组织的再生长。当杂草顶端分生组织的再生长受到抑制后,杂草的再生长也会受到明显的抑制或延缓,甚至产生致死作用。本论文为CO₂激光除草技术的探索研究提供了前期研究数据,具有一定的学术意义和参考价值。更多还原

【Abstract】 Weeds always do harm to crops. With the increasing concerns about ecological environment and food security of the public, more and more physical weeding methods to take the place of using chemical herbicides have been given extensive and in-depth research. Physical weeding can effectively reduce the side-effects of herbicides, improve the ecological environment, increase food security and safeguard human health.This article mainly research on the effect of low-power CO₂ laser with the LASY-12 laser which is powered by the Access Laser Company and can launch a bouquet of laser with the maximum power of 12 W and the wavelength of 1060 nm. Weeds of three species, echinochloa crusgalli, veronica polita and vicia sativa were irradiated with nine different doses. The experiments showed that when the dose is larger than 12J/mm, the laser can directly cut the stems of echinochloa crusgalli which are in the terms of two true-leaves and four true-leaves, and the former will die 14 days later while the latter can survive with the maximum relatively dry weight loss of 84.5% and the minimum of 78% corresponding to the echinochloa crusgalli which is not irradiated by the laser. When the dose is larger than 3J/mm, the laser can directly cut the stems of veronica polita which are in the terms of two true-leaves and four true-leaves too and both of them will die 14 days later. The vicia sativa can survive even under the maximum does of 12J/mm with the stems being cut; new stems will grow up nearby the root, which shows that there is also limitation of using CO₂ laser to control the weeds.And the seeds of vicia sativa and veronica polita are also irradiated by five different dose of laser. The experiment shows that even the maximum dose of 15.28J/mm² can not cause full carbonation effect to the vicia sativa, glass transition can occur although the seeds have been irradiated, but the seeds can not germinate normally. The experiment shows that irradiating the seeds of the weeds can also kill the weeds. Based on the former experiment, the mechanism of CO₂ laser weeding can be divided into the partial mechanism and the overall mechanism. The partial mechanism means the course while the weeds are being irradiated by the laser with several kinds of laser biological effects occurring. The overall mechamsm means that, when the stems of the weeds were hurt by the laser with high-temperature heat, the transportation of nutrients in the stems will be destroyed, then the regrowth of the apical meristem will also be destroyed, so this means the irradiation of laser will indirectly prevent or hold the weed from regrowth, and it even kills the weed.The research can provide some prophase data for CO₂ laser weeding, which has significant science meanings and reference value.更多还原