Phytochemical management of root knot nematode (Meloidogyne incognita) kofoid and white chitwood by Artemisia spp. in tomato (Lycopersicon esculentum L.)

Abstract In vitro and screen house experiments were conducted to investigate the effectiveness of thirteen phytochemicals from Artemisia elegantissimia and A. incisa on root knot nematode, Meloidogyne incognita in tomato (Lycopersicon esculentum L.) cv. Rio Grande. A positive control (Carbofuran) and negative control (H2O) were also used for comparison. Effectiveness of phytochemicals against juveniles (J2s) mortality and egg hatch inhibition were evaluated after 24, 48 and 72 hours of incubation at three concentrations viz; 0.1, 0.2 and 0.3 mg/mL in vitro conditions. Amongst thirteen phytochemicals, Isoscopletin (Coumarin), Carbofuran and Apigenin (Flavonoid) showed the highest mortality and egg hatch inhibition of M. incognita at all intervals. Inhibition of eggs and J2s mortality were the greatest (90.0%) and (96.0%) at 0.3 mg/mL concentration. Application of phytochemicals caused reduction in number of galls, galling index, and egg masses on tomato plant and enhanced plant growth parameters under screen house conditions. Gall numbers (1.50), galling index (1.00), number of juveniles (4.83) and egg masses (4.00) were greatly reduced and plant growth parameters such as; plant height (28.48 cm), fresh (72.13 g) and dry shoot weights (35.99 g), and root fresh (6.58 g) and dry weights (1.43 g) were increased significantly by using Isoscopletin. In structure activity relationship, juveniles of M. incognita, exhibited variations in their shape and postures upon death when exposed to different concentrations of phytochemicals of Artemisia spp. The present study suggests that Artemisia based phytochemicals possess strong nematicidal effects and can be used effectively in an integrated disease management program against root knot nematodes.

摘要
本研究开展了体外试验与网室试验，以探究源自雅致蒿（Artemisia elegantissimia）和灰苞蒿（Artemisia incisa，后文简称A. incisa）的13种植物化学成分，对番茄（Lycopersicon esculentum L.）品种‘里奥格兰德’（Rio Grande）上的南方根结线虫（Meloidogyne incognita）的防治效果。试验设置阳性对照克百威（Carbofuran）与阴性对照去离子水（H₂O）用于对照比较。
在体外培养条件下，设置0.1、0.2、0.3 mg/mL三种浓度，分别孵育24、48、72小时后，评估各植物化学成分对南方根结线虫二龄幼虫（J2s）的致死活性及卵孵化抑制效果。13种供试植物化学成分中，异香豆素（Isoscopletin，香豆素类化合物）、克百威与芹菜素（Apigenin，黄酮类化合物）在各孵育时间节点下，均对南方根结线虫表现出最高的幼虫死亡率与卵孵化抑制率。在0.3 mg/mL浓度下，卵孵化抑制率与幼虫死亡率分别达到90.0%与96.0%，为所有处理中的最优水平。
网室栽培试验结果显示，施用植物化学成分可降低番茄根部的根结数、根结病情指数与卵块数量，并显著提升植株生长相关参数。其中，异香豆素处理组的番茄根结数（1.50）、根结病情指数（1.00）、二龄幼虫数量（4.83）与卵块数量（4.00）均大幅降低；同时该组植株生长参数显著提升，包括株高（28.48 cm）、地上部鲜重（72.13 g）与干重（35.99 g）、根系鲜重（6.58 g）与干重（1.43 g）。
构效关系（structure activity relationship）分析表明，经不同浓度蒿属植物化学成分处理后，南方根结线虫二龄幼虫在死亡时会出现形态与姿态的异常变化。
本研究证实，基于蒿属植物的植物化学成分具有极强的杀线虫活性，可有效应用于根结线虫的综合病害防治体系中。