Cyanobacterium-based silver nanoparticles are considered not only as an efficient nano-nematicide but also as a bio-stimulant material for plant growth. They could be employed as a part of an integrated program for controlling some plant diseases. In this study, silver nanoparticles (Ag-NPs) were biosynthesized from aqueous extract of the cyanobacterium, Nostoc sp. PCC7524. Full characterization of the biosynthesized Ag-NPs was monitored by UV-vis spectroscopy, transmission electron microscopy, X-ray diffraction pattern, Zeta sizer, and Fourier transform infrared spectroscopy. In vitro assay against the root-knot nematode Meloidogyne javanica showed that Ag-NPs significantly decreased egg hatching of M. javanica at different applied concentrations (3, 6, 12, 25, and 50%, v/v). Fifty percent of Ag-NPs induced the highest reduction percent (94.66%). Moreover, Ag-NPs and AgNO3 significantly increased the percentages of larval mortality of the second-stage juveniles (J2) with concentration and time-dependent responses. Ag-NPs or AgNO3 at 2.4 ml/l, 24 h, completely inhibited the growth of J2 compared to 23% inhibition using aqueous cyanobacterial extract (ACE). In vivo effect of Ag-NPs on faba bean-infected plant under greenhouse conditions was achieved by treating soil with three different concentrations of 1, 2, and 3 ml/kg soil over two consecutive seasons. Ag-NPs significantly reduced root galling from 39.6 to 78.7% and J2 population in the soils from 32.2% to 86.7% in the 2018 season and from 21.9 to 78.1% and 40.0 to 81.0% in the 2019 season, respectively. Moreover, 3 ml/kg soil of Ag-NP treatment showed statistically comparable effects to that of vydate nematicide but with remarkable enhancement of faba bean growth parameters as compared to those of vydate or AgNO3 treatments in the two seasons. The considerable in vitro and in vivo nematicidal potential of the cyanobacterium-based Ag-NPs, besides their bio-stimulant effect on plant growth, makes them feasible for the biological control of M. javanica.

中文翻译：

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银纳米颗粒的绿色生产、对爪哇根结线虫的杀线虫活性评价及其对蚕豆生长的影响

基于蓝藻的银纳米粒子不仅被认为是一种有效的纳米杀线虫剂，而且被认为是一种植物生长的生物刺激材料。它们可以用作控制某些植物病害的综合计划的一部分。在这项研究中，银纳米粒子 (Ag-NPs) 是从蓝藻 Nostoc sp. 的水提取物生物合成的。PCC7524。通过紫外-可见光谱、透射电子显微镜、X 射线衍射图、Zeta 粒度仪和傅立叶变换红外光谱对生物合成的 Ag-NP 进行全面表征。针对根结线虫爪哇根结线虫的体外测定表明，Ag-NPs 在不同应用浓度（3、6、12、25 和 50%，v/v）下显着降低了爪哇线虫的卵孵化。50% 的 Ag-NPs 诱导的还原百分比最高 (94.66%)。此外，Ag-NPs 和 AgNO3 显着增加了具有浓度和时间依赖性反应的第二阶段幼鱼 (J2) 的幼虫死亡率百分比。与使用蓝藻水提取物 (ACE) 的 23% 抑制相比，Ag-NPs 或 AgNO3 以 2.4 ml/l、24 小时完全抑制 J2 的生长。Ag-NPs 在温室条件下对蚕豆感染植物的体内作用是通过连续两个季节用三种不同浓度的 1、2 和 3 ml/kg 土壤处理土壤来实现的。在 2018 年和 2019 年，Ag-NPs 显着减少了土壤中的根磨损率从 39.6% 到 78.7% 和 J2 种群从 32.2% 到 86.7% 和从 21.9 到 78.1% 和 40.0% 到 81.0%。而且，3 ml/kg 土壤的 Ag-NP 处理显示出统计上与 vydate 杀线虫剂相当的效果，但与两个季节的 vydate 或 AgNO3 处理相比，蚕豆生长参数显着提高。除了对植物生长的生物刺激作用外，基于蓝藻的 Ag-NPs 在体外和体内具有相当大的杀线虫潜力，使它们可用于 M. javanica 的生物控制。