Plant-parasitic nematodes parasitizing saffron in Morocco: Structuring drivers and biological risk identification

Abstract

Plant-parasitic nematodes (PPN) are the most destructive of all plant pathogens. They are an economically important group of soil pathogens, causing significant annual damages of up to 25% of world crop production. Morocco is considered to be a highly productive country for the colorant/medicinal/spice saffron (Crocus sativus L.). Taliouine and Taznakht regions are the most productive areas of this valuable neutraceutical. Due to its metabolic profile, and growth forms, saffron is susceptible to many plant diseases, including plant-parasitic nematodes (PPN). This work aims to assess the diversity of PPN communities in soils of Taliouine and Taznakht regions to facilitate understanding of links between their assemblages with biotic and abiotic parameters. Herein, nematode communities were characterized in 163 soil samples collected from 11 rural communes characterized by altitudinal gradients in Taliouine and Taznakht regions. Fifteen PPN genera belonging to 12 families were identified, among which the four genera Ditylenchus, Aphelenchoides, Pratylenchus and Helicotylenchus, potentiate serious limiting factors in saffron production. Their frequencies are respectively 92, 49, 48 and 36% in the area of Taliouine, while in Taznakht they represent 95, 69, 33, and 28% respectively. Regarding the assessment of diversity at different sites, the genus richness (R) index ranges from 2 to 10 distinct genera, whereas the Shannon diversity (H') index varies from 0.9 to 1.5 and the Evenness (E) index tends to 1. The Co-inertia analyses revealed a substantial relationship between nematode communities and soil types. Soil texture is the major factor influencing the presence and the abundance of a considerable portion of genera. Multivariate analyses (MBPLS) indicated links between humidity, rainfall, minimum temperature and PPN taxa, though maximum temperature did not have an impact. Ditylenchus, Helicotylenchus, Pratylenchus and Paratylenchus were related to the humidity and silt soil that developed in Taliouine. Aphelenchoides, Tylenchus, Tylenchorynchus and Dorylaimus were more prevalent in rainy locations and clay soils of Taznakht. Suitable nematode controlling approaches may be applied and preventative measures should be considered at nursery and field level.

Diversity and Management Strategies of Plant Parasitic Nematodes in Moroccan Organic Farming and Their Relationship with Soil Physico-Chemical Properties

“…Recently, Mokrini et al [60] emphasized that organic matter was negatively correlated with PPN patterns in Saffron. This trend was recorded in the same cropping system by Benjlil et al [99]. Organic matter accumulation in soils causes a significant decrease in nematode abundance [105,106].…”

“…On the other hand, according to our findings, nitrogen does not appear to have any attraction or depletion effect on nematodes. Benjlil et al [99] indicated that most of the genera identified in saffron (Crocus sativus L.) showed a negative association with total nitrogen (N), which can be explained by the accumulation of nitrate through nitrification that is considered to be harmful to PPNs [100,101]. Similarly, Oteifa [102] showed that the input of nitrogen to the soil had decreased drastically the population of M. incognita in beans crops.…”

Response of soil fungal communities to continuous cropping of flue-cured tobacco

“…Soil fungal community structure is obvious impacts by the soil physico-chemical properties 7 . Soil pH and enzyme activity are strongly associated with rhizosphere fungal communities as well 8 . Thus, improving the knowledge on soil fungal communities should increase our understanding of their roles in soil ecosystems.…”

Corm Rot of Saffron: Epidemiology and Management

“…Soil texture, humidity, rainfall and temperature were the major factors influencing the presence and the population of nematode genera. Ditylenchus, Helicotylenchus and Paratylenchus were reported mainly from the humid and silty soils, whereas the presence of Aphelenchoides, Tylenchus, Tylenchorynchus and Dorylaimus was significantly high in locations with regular rainfall and clay soils [92].…”

“…Tylenchus, Helicotylenchus, Pratylenchus, Hirschmaniella and Psilenchus are the nematodes genera reported from the saffron fields of Kashmir are [90], and 11 genera have been found in Spain [91]. Aphelenchoides, Ditylenchus, Pratylenchus and Helicotylenchus were reported to parasitize the saffron crop in Morocco [92]. Pratylenchus thornei, Helicotylenchus vulgaris, Aphelenchus avenae, Xiphinema sp., Tylenchus sp., Tylenchorhynchus sp.…”