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：本研究开展体外实验与网室实验，以探究雅致蒿（Artemisia elegantissimia）与裂叶蒿（A. incisa）来源的13种植物化学成分对番茄（Lycopersicon esculentum L.）品种‘里奥格兰德’上的南方根结线虫（Meloidogyne incognita）的防治效果。本研究设置阳性对照（克百威（Carbofuran））与阴性对照（去离子水（H₂O））用于对照比较。在体外条件下，设置0.1、0.2、0.3 mg/mL三种浓度梯度，于孵育24、48、72小时后，评估各植物化学成分对根结线虫二龄幼虫（J2s）死亡率及卵孵化抑制率的影响。在13种植物化学成分中，异瑞香素（Isoscopletin，香豆素类）、克百威以及芹菜素（Apigenin，黄酮类）在所有孵育时段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。当浓度为0.3 mg/mL时，卵孵化抑制率与幼虫死亡率均达到最高，分别为90.0%与96.0%。网室实验条件下，施用植物化学成分可降低番茄植株上的根结数、根结指数与卵块数，并提升植株生长相关参数。其中施用异瑞香素后，根结数（1.50）、根结指数（1.00）、二龄幼虫数量（4.83）与卵块数（4.00）均大幅降低；同时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），以及根系鲜重（6.58 g）与干重（1.43 g）。在构效关系分析中，暴露于不同浓度蒿属植物化学成分的南方根结线虫二龄幼虫在死亡时会表现出形态与姿态的变化。本研究表明，基于蒿属植物的植物化学成分具有优异的杀线虫活性，可有效应用于根结线虫的综合病害防治方案中。