Diversity and incidence of plant-parasitic nematodes associated with saffron (Crocus sativus L.) in Morocco and their relationship with soil physicochemical properties

Abstract

SummarySaffron (Crocus sativus) fields in Morocco’s Taliouine and Taznakht regions were surveyed between January and April 2018 to study the diversity and incidence of plant-parasitic nematodes and assess the effects of soil physicochemical properties on the nematodes. Fourteen nematode genera were identified in soil and root samples collected from 66 saffron fields. The most common plant-parasitic nematodes in the Taliouine region were Pratylenchus spp. and Helicotylenchus spp. In the Taznakht region, the most common nematodes were Pratylenchus spp., Tylenchorhynchus spp. and Ditylenchus dipsaci. Nematodes, particularly Pratylenchus spp. and Ditylenchus spp., were abundant and frequent throughout the region. Several nematode genera were significantly associated with soil texture and mineral content, indicating that soil properties play an important role in plant-parasitic nematode communities. This description of plant-parasitic nematode assemblages associated with saffron fields in Morocco and their relationship with soil physicochemical properties provides a starting point from which appropriate nematode management strategies can be implemented.

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

“…In this current study, four species of Pratylenchus, viz. P. penetrans, P. thornei, P. neglectus, and P. crenatus were found, which was in agreement with what has been previously reported in organic farming in Germany [13], the United States [63,64], as well as in conventional wheat and saffron cultivations in Morocco [16,60]. Pratylenchus penetrans has a broad host range of more than 400 different plants, as the most damaging species [65].…”

“…Helicotylenchus vulgaris was also an important nematode in Southern Morocco, affecting 40.2% of the sampled organic farms with a population density of up to 7 nematodes per 100 cm 3 of soil. In previous studies, H. vulgaris was recorded in around 59% and 30% of the sampled Moroccan saffron fields of Taliouine and Taznakht, respectively [60], and 6.5% of the organically grown vegetable fields in Germany [13]. In another study, Adam et al [14] reported the presence of Helicotylenchus spp.…”

“…was present in significantly more bean and onion sites than tomato and other aromatic and medicinal sites, given that both organic bean and onion growers practiced rotation with cereals, which are considered as preferred hosts of this genus [13]. Moreover, this genus poses a serious threat to cereal and saffron production in Morocco [59,60] and species of Pratylenchus have been reported to form disease complexes with a large number of soil-borne fungi, thus causing root disease [61]. Population densities of Pratylenchus spp.…”

“…The thermal conductivity in sandy soils is considerably higher than soils with high clay contents, which may be the reason behind their significant relationship with PPN patterns. In a recent study, Mokrini et al [79] indicated that several identified PPNs (Helicotylenchus spp., Rotylenchulus spp., Longidorus spp., Criconemoides spp., Paratylenchus spp., and Xiphinema spp.) have a strong association with some soil granulometry (soil textures) in raspberry (Rubus idaeus) based on their abundance.…”

“…was significantly attributed to calcium content. Mokrini et al [60] highlighted a strong affiliation between PPNs and soil mineral contents (Ca, Cu, K, Mn, and Zn) in saffron. Moreover, numerous studies have demonstrated the strong relationship between soil minerals (particularly Fe, P, and Mg) and nematode species distribution in some organic crops [76,93].…”