Bacillusvelezensis Strains for Protecting Cucumber Plants from Root-Knot Nematode Meloidogyne incognita in a Greenhouse.

Anzhela M Asaturova,Alexey V Garkovenko,Anna I Homyak,Evgeninya V Kashutina,Larisa V Yasyuk,Vladimir D Nadykta,Nikita M Sidorov,Galina A Slobodyanyuk,Ludmila N Bugaeva

doi:10.3390/plants11030275

Abstract

Meloidogyne incognita Kofoid et White is one of the most dangerous root-knot nematodes in greenhouses. In this study, we evaluated two Bacillus strains (Bacillus velezensis BZR 86 and Bacillus velezensis BZR 277) as promising microbiological agents for protecting cucumber plants from the root-knot nematode M. incognita Kof. The morphological and cultural characteristics and enzymatic activity of the strains have been studied and the optimal conditions for its cultivation have been developed. We have shown the nematicidal activity of these strains against M. incognita. Experiments with the cucumber variety Courage were conducted under greenhouse conditions in 2016–2018. We determined the effect of plant damage with M. incognita to plants on the biometric parameters of underground and aboveground parts of cucumber plants, as well as on the gall formation index and yield. It was found that the treatment of plants with Bacillus strains contributed to an increase in the height of cucumber plants by 7.4–43.1%, an increase in leaf area by 2.7–17.8%, and an increase in root mass by 3.2–16.1% compared with the control plants without treatment. The application of these strains was proved to contribute to an increase in yield by 4.6–45.8% compared to control. Our experiments suggest that the treatment of cucumber plants with two Bacillus strains improved plant health and crop productivity in the greenhouse. B. velezensis BZR 86 and B. velezensis BZR 277 may form the basis for bionematicides to protect cucumber plants from the root-knot nematode M. incognita.

Highlights

The cells of the B. velezensis BZR 86 strain are rod-shaped with rounded ends; single or paired; cells are motile; and have sizes of 2.8–4.1 × 6.6–9.4 microns
Our results demonstrated the activity of Bacillus strains against M. incognita on cucumber plants
We showed that in three consecutive years, application of two Bacillus strains in the greenhouse demonstrated that the number of galls per gram of cucumber root mass decreased by 13 times for the B. velezensis BZR 277 strain, and by 7.2 times for the B. velezensis BZR 86 strain

Summary

Introduction

Parasitic phytonematodes are among the most serious pests that negatively affect the quality of vegetables in a greenhouse [1,2]. They are obligate parasites that feed mostly on plant roots with common aboveground symptoms of stunting, yellowing, wilting, and yield losses and belowground root malformation due to direct feeding damage. These factors lead to yield losses [3]. Parasitic phytonematodes feed on many crops worldwide and they can cause enormous yield losses with an estimation of 100 billion dollars a year [4]

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Conclusion