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：本研究开展离体与网室试验，探究源自雅致蒿（Artemisia elegantissimia）与裂叶蒿（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）上南方根结线虫（Meloidogyne incognita）的防控效果。试验同时设置克百威（Carbofuran）阳性对照与去离子水（H₂O）阴性对照用于对照比较。在离体条件下，设置0.1、0.2、0.3 mg/mL三种浓度，于孵育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）死亡率及卵孵化抑制的效果。在13种植物化学成分中，异香豆素（Isoscopletin，香豆素类）、克百威以及芹菜素（Apigenin，黄酮类）在所有观测时段均对南方根结线虫表现出最优的幼虫致死与卵孵化抑制效果。在0.3 mg/mL浓度下，卵孵化抑制率与幼虫死亡率分别可达90.0%与96.0%，为所有处理中的最高值。网室试验中，施加植物化学成分可显著降低番茄植株上的根结数、根结指数与卵块数，并改善植株生长指标。施加异香豆素处理后，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；植株生长指标如株高（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）均得到显著提升。在构效关系分析中，南方根结线虫二龄幼虫接触不同浓度的蒿属植物化学成分后，死亡时的形态与姿态会出现差异。本研究表明，源自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控体系中。