Abstract Biofumigation is a soil sterilization technique using isothiocyanates (ITCs) generated from naturally occurring glucosinolates (GLs, thioglucosides) in members of Brassicaceae. Efficacy of biofumigation on plant-parasitic nematodes could be affected by the way biofumigant crops are terminated. The objective of this research was to determine biofumigant crop termination method suppressive to Meloidogyne spp. and Rotylenchulus reniformis on zucchini (Cucurbita pepo). Three field trials were conducted where ‘Sodbuster’ oil radish (OR; Raphanus sativus) and ‘Caliente 199’ brown mustard (MS; Brassica juncea) were grown as biofumigant crops and subjected to various termination methods. In the first trial (Trial I), OR and MS were each terminated by: 1) clipping off shoots at soil line and covering residues with woven weed mat in no-till (NT); 2) macerating shoots followed by tilling (MT); and 3) MT plus covering with black plastic (MTBP). In the second and third trials (Trials II and III), MS was terminated by: 1) NT; 2) MT; or 3) MTBP, in the same way, described in Trial I; 4) macerating shoots in no-till (MNT); 5) MNT plus covering residues with black plastic (NTBP); and tilling without prior tissue maceration (T). A bare ground (BG) control was included in each trial. Brown mustard MTBP suppressed soil populations of Meloidogyne spp. (Trial I-III) or R. reniformis (Trial I), reduced severity of root galls (Trial I-II) and increased zucchini canopy (Trials I and III) (P ≤ 0.05). None of the OR treatments suppressed Meloidogyne spp. and R. reniformis, but MT and MTBP reduced severity of root galls and increased zucchini canopy (Trial I). When soil glucose and sulfate were analyzed as indicators of biofumigation efficacy, sulfate depicted biofumigation efficacy in the order of MTBP > MT > T, higher than in no-till treatments (NT, MNT, and NTBP) and BG. A similar trend in the glucose was observed only when toluene (methylbenzene) was added immediately to soil samples to arrest microbial degradation of glucose. In summary, Meloidogyne spp. were sensitive to biofumigation than R. reniformis. Biofumigation effect was stronger with MS than OR, and MTBP was the most suppressive treatment on the targeted nematodes. Soil sulfate was more stable in the soil than glucose, thus a good indicator of biofumigation.

中文翻译：

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生物熏蒸作物终止方法对抑制植物寄生线虫的影响

摘要 生物熏蒸是一种土壤消毒技术，它使用异硫氰酸酯 (ITC)，异硫氰酸酯 (ITC) 从芸苔科成员中天然存在的硫代葡萄糖苷（GL，硫代葡萄糖苷）产生。生物熏蒸对植物寄生线虫的功效可能会受到生物熏蒸作物终止方式的影响。本研究的目的是确定抑制根结线虫的生物熏蒸作物终止方法。西葫芦（Cucurbita pepo）上的 Rotylenchulus reniformis。进行了三项田间试验，其中将“Sodbuster”油萝卜（OR；Raphanus sativus）和“Caliente 199”棕芥菜（MS；Brassica juncea）作为生物熏蒸作物种植，并采用各种终止方法。在第一次试验（试验 I）中，OR 和 MS 分别通过以下方式终止：1）在土壤线上剪下枝条并在免耕（NT）中用编织的杂草垫覆盖残留物；2) 浸渍芽后耕作 (MT)；和 3) MT plus 黑色塑料覆盖层 (MTBP)。在第二个和第三个试验（试验 II 和 III）中，MS 被终止：1）NT；2) 吨；或 3) MTBP，与试验 I 中描述的方式相同；4) 免耕浸渍芽 (MNT)；5) MNT 加上用黑色塑料 (NTBP) 覆盖残留物；和耕种没有事先组织浸渍 (T)。每个试验中都包括裸地 (BG) 对照。褐芥菜 MTBP 抑制了根结线虫的土壤种群。（试验 I-III）或 R. reniformis（试验 I），根瘿的严重程度降低（试验 I-II）并增加西葫芦冠层（试验 I 和 III）（P ≤ 0.05）。没有一种 OR 治疗抑制根结线虫属。和 R. reniformis，但 MT 和 MTBP 降低了根瘿的严重程度并增加了西葫芦冠层（试验 I）。当将土壤葡萄糖和硫酸盐作为生物熏蒸功效的指标进行分析时，硫酸盐按 MTBP > MT > T 的顺序描述了生物熏蒸功效，高于免耕处理（NT、MNT 和 NTBP）和 BG。仅当立即将甲苯（甲苯）添加到土壤样品中以阻止葡萄糖的微生物降解时，才观察到葡萄糖的类似趋势。总之，根结线虫属。比 R. reniformis 对生物熏蒸敏感。MS 的生物熏蒸效果比 OR 强，MTBP 是对目标线虫抑制作用最强的处理方法。土壤硫酸盐在土壤中比葡萄糖更稳定，因此是生物熏蒸的良好指标。仅当立即将甲苯（甲苯）添加到土壤样品中以阻止葡萄糖的微生物降解时，才观察到葡萄糖的类似趋势。总之，根结线虫属。比 R. reniformis 对生物熏蒸敏感。MS 的生物熏蒸效果比 OR 强，MTBP 是对目标线虫抑制作用最强的处理方法。土壤硫酸盐在土壤中比葡萄糖更稳定，因此是生物熏蒸的良好指标。仅当立即将甲苯（甲苯）添加到土壤样品中以阻止葡萄糖的微生物降解时，才观察到葡萄糖的类似趋势。总之，根结线虫属。比 R. reniformis 对生物熏蒸敏感。MS 的生物熏蒸效果比 OR 强，MTBP 是对目标线虫抑制作用最强的处理方法。土壤硫酸盐在土壤中比葡萄糖更稳定，因此是生物熏蒸的良好指标。