Inoculant rhizobia suppressed root-knot disease, and enhanced plant productivity and nutrient uptake of some field-grown food legumes

Bio-protective effect of a root-nodulating Rhizobium etli strain in common bean (Phaseolus vulgaris) against Meloidogyne incognita and Radopholus similis in an in vitro autotrophic tripartite culture system

“…The observation that nodulation of the common bean root systems was significantly lower in the pre-inoculation assays with M. incognita (both trials) compared with the simultaneous inoculation assays confirmed numerous previous reports that M. incognita infection (and also R. similis as demonstrated by our study) may also affect root nodulation by rhizobia (see, for example, Huang, 1987;Sharma & Tiagi, 1990;Khan et al, 2002Khan et al, , 2018. The observation that in both assays with M. incognita and R. similis, a significantly higher number of nodules had developed on the root systems of the simultaneous inoculation assay compared with the pre-inoculation assay suggests that the simultaneous inoculation of R. etli CNPAF 512 and the nematodes may have facilitated, in one way or the other, root penetration and colonisation by the rhizobia, for instance, by rhizobia adhering to the cuticle of the nematodes when these penetrated and migrated through the roots.…”

“…Both pre-inoculation with R. etli CNPAF 512 and simultaneous inoculation significantly suppressed reproduction of the sedentary endoparasitic nematode M. incognita on common bean. This result confirms previous observations of the bio-protective suppression of M. incognita following either pre-or simultaneous inoculation of leguminous crops (chickpea, mungbean, lentil, pigeonpea) with rhizobia (Fazal et al, 1992;Khan et al, 2018). Both pre-inoculation with R. etli CNPAF 512 and simultaneous inoculation also significantly suppressed the reproduction of the migratory endoparasitic nematode R. similis on common bean.…”

“…Research on the effect of root nodulation by rhizobia on plant-parasitic nematodes and vice versa has mainly dealt with the interaction between soybean and Heterodera glycines, the soybean cyst nematode, and between a variety of leguminous crops and the most common root-knot nematode species, especially M. incognita. In most instances, root nodulation by rhizobia suppressed root galling and reproduction of M. incognita and improved plant growth (Huang, 1987;Fazal et al, 1992;Khan et al, 2018), whilst infection by M. incognita reduced either the number of nodules, their functionality or induced premature senescence of the nodules (see, for example, Baldwin et al, 1979;Huang, 1987;Khan et al, 2002Khan et al, , 2018Neeraj & Singh, 2019). Similarly, infection by Pratylenchus penetrans affected the number, weight and functionality of nodules (Elhady et al, 2020).…”

Infection of Medicago truncatula by the Root-Knot Nematode Meloidogyne javanica Does Not Require Early Nodulation Genes

“…A drop in nodule numbers in nematode-infected root system has also been observed in other legumes (e.g. Khan et al, 2018). However, results are likely to be strongly influenced by the age and nutritional status of the plant, the time of harvest and the age of the galls and nodules.…”

Microbial inoculants: reviewing the past, discussing the present and previewing an outstanding future for the use of beneficial bacteria in agriculture

“…However, there are limiting factors that restrict the use of inoculants in some areas. Biotic and abiotic stresses may affect the effectiveness of the product, making them inefficient in cases such as nutrient-poor or unbalanced soils, salinity, water stress, increasing temperatures, pests and diseases, among others (Bashan et al 2014; Das et al 2017; Khan et al 2017; Thilakarathna and Raizada 2017; Samago et al 2018). To circumvent these factors, several studies have been addressed to gain better knowledge on the intrinsic properties of PGPB, seeking at understanding their optimum growth conditions and interaction with the host plants (Flores-Félix et al 2018; Goulart-Machado et al 2018; Jiménez-Gómez et al 2018).…”