Utilisation of single and multiple species cover crops for the suppression of soil-borne nematodes of Narcissus

Chekanai, V. (2025) Utilisation of single and multiple species cover crops for the suppression of soil-borne nematodes of Narcissus. Doctoral thesis, Harper Adams University.

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Abstract

Ditylenchus dipsaci, Pratylenchus penetrans, and Aphelenchoides subtenuis parasitise Narcissus. Cover crops reduce plant parasitic nematodes through several mechanisms, including non/poor host, allelopathy and trap cropping. This study assessed the impact of cover crops on plant parasitic nematodes associated with Narcissus and beneficial nematode communities. Several cover crops were tested under greenhouse conditions for their host suitability to P. penetrans, and ten were rated as poor hosts (Chapter 3). Four selected cover crops (French marigold, oilseed radish, alfalfa and forage chicory) were tested in three field experiments (Chapter 6). The abundance of Pratylenchus spp., fungivorous and bacterivorous nematodes, was monitored before planting, three months after planting and six weeks post-incorporation. All cover crops significantly reduced Pratylenchus spp. and increased the abundance of fungivorous and bacterivorous nematodes (Chapter 6). The impact of cover crops on soil nematode communities and soil food web indices was assessed using High-throughput Sequencing targeting the 18S rRNA gene (Chapter 7). Cover crop treatments did not impact beta diversity; therefore, no adverse effects on nematode communities. To better understand how cover crops reduce P. penetrans, in vitro assays were conducted to assess the nematodes' behavioural responses after exposure to root exudates (Chapter 4). Root exudates from forage chicory and alfalfa did not affect the behaviour of P. penetrans. Finally, in vitro assays were conducted to test the nematicidal potential of three different brassica isothiocyanates against P. penetrans (Chapter 5). Benzyl was the most toxic (LD50=3.2 μg ml-1), 2-Phenylethyl (LD50=5.2 μg ml-1) was the second and lastly Allyl (LD50=9.9 μg ml-1). Collating the results of the experimental work in this PhD thesis strongly suggests that French marigold, oilseed radish, forage chicory, and alfalfa are potential options for managing Pratylenchus spp. in Narcissus fields without deleterious effects on non-target nematodes. Moreover, P. penetrans is associated with various cash crops grown in the UK; therefore, these cover crops could become part of integrated nematode management and in rotations to confer agroecosystem services, such as improved soil fertility.

Item Type:	Thesis (Doctoral)
Divisions:	Agriculture and Environment (from 1.08.20)
Depositing User:	Mrs Susan Howe
Date Deposited:	10 Jun 2025 15:13
Last Modified:	10 Jun 2025 15:13
URI:	https://hau.repository.guildhe.ac.uk/id/eprint/18222

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