Reaction of some selected soybean varieties (Glycine max (L) Merril) to root - knot nematode infection
Two-year screen-house studies to evaluate the reaction of five soybean varieties (TGX – 1987 – 34F, TGX -1987 – 38F, TGX – 1987 – 95F, TGX – 1986 -3F, TGX – 1985 – 8F) to root – knot nematode, Meloidogyne incognita, were conducted in the Faculty of Agriculture, University of Ilorin. Forty experimental pots containing pasteurized soil were used. Twenty pots were inoculated each with approximately 3,000 eggs of M. incognita while the other twenty which did not receive any treatment served as control. The experimental set up was a completely randomized design having each treatment replicated four times. Results showed that all the varieties were susceptible to M. incognita at varying degrees. While plant height of nematode inoculated varieties were significantly (P=0.05) lower than the un-inoculated plants, among the same varieties, there were significant differences in the number of branches of inoculated and non inoculated plants between different and among the same varieties. There were varietal differences in terms of seed weight which represented actual yield. Generally, the un-innoculated plants gave significantly higher yield than inoculated ones. Root gall infestation rated the same level for all the five varieties. However, variety TGX-1985 – 8F exhibited superior characteristics over the other four varieties because it showed higher level of tolerance to nematode infestation judging from its performance and yield. From the study, it can be deduced that the use of nematode resistant/tolerant Soybean varieties be adopted in the management of root- knot nematode infestation. It is one of the cheapest and safest control methods that pose no form of hazard to man and the environment. In nematode endemic ecological zones, TGX-1985 – 8F is therefore recommended as it proved to contain some specialized genes that conferred a higher level of tolerance against root- knot nematode, Meloidogyne incognita.
Key Words: Glycine max, root – knot nematode, Dominant loci, Mi – 1.2, leucine zipper and R genes.