Decoding nematode system harmful to rice in Red River Delta
Unlike pests and diseases that can be easily identified in the fields, nematodes are almost an “invisible enemy” of rice plants. They are only about 0.5–1 mm long, as slender as a thread, and live hidden in the soil or penetrate the roots, stems and leaves of plants, silently absorbing nutrients and destroying plant tissues. Globally, plant-parasitic nematodes are classified among the most dangerous pests to crops, causing an estimated 12.3% loss in crop production each year. For rice, numerous studies have shown that nematodes can reduce yields by 10–25%, depending on the harmful species and ecological conditions.
Stemming from practical requirements, the task under Vietnam Academy of Science and Technology’s Institute-level Basic Investigation Programme, entitled “Investigation and assessment of plant-parasitic nematodes on rice plants in the Red River Delta” (task code: UQĐTCB.07/24-25), led by Associate Professor, PhD Trinh Quang Phap and the research team from the Institute of Biology, was carried out to clarify the picture of nematode species harmful to rice in this area.
The researchers conducted numerous field surveys in six provinces in the Red River Delta, collecting hundreds of soil and rice-root samples from fields. Subsequently, each specimen was extracted, observed under a microscope and combined with DNA analysis to accurately identify the “identity” of each species. Based on these research data, a relatively comprehensive picture of the plant-parasitic nematode system on rice in the Red River Delta has, for the first time, been elucidated.
As a result, the research team recorded 48 species of plant-parasitic nematodes. In particular, the team discovered two species new to science, Hirschmanniella namdinhensis and Aphelenchoides vinhphucensis, while also recording, for the first time, three species of nematodes parasitic on rice in Vietnam. The three species with the greatest potential to cause damage to rice in the Red River Delta are Hirschmanniella oryzae, H. mucronata and the root-knot nematode Meloidogyne graminicola. At the same time, the team found that changes in cultivation practices, particularly the shift from traditional flooded fields to alternate wetting and drying irrigation, could create conditions for certain nematode groups to adapt and increase.
Symptoms of rice plants parasitised by Meloidogyne graminicola
Based on the research findings, the team developed a complete scientific dataset for 10 important rice-parasitic nematode species, incorporating identification characteristics, microscopic images, DNA data and distribution information. On this basis, the team compiled an identification handbook, developed a distribution map of the main harmful species, established a reference specimen collection for identification, and prepared a pest risk assessment report.
Distribution map of important rice nematodes in the Red River Delta (based on the distribution map of rice-growing areas in the Red River Delta by author Do Minh Phuong, Department of Digital Transformation and International Cooperation, Ministry of Agriculture and Environment)
Based on the data collected, the team also proposed sustainable pest management solutions, combining adjustments to cultivation practices, appropriate water management and increased use of biological products to limit the development of nematodes.
The results of the task have been published in four international articles included in the Science Citation Index Expanded (SCIE) and one domestic article. The research team also registered 18 DNA sequences of harmful nematode species in the GenBank database, contributing to the integration of Vietnamese research data into the international reference system.
Translated by Tuyet Nhung
Link to Vietnamese version
