Variation in reproduction and pathogenicity of geographic isolates of Rotylenchulus reniformis on soybean

Document Type

Article

Publication Date

6-1-2011

Abstract

Known incidence of Rotylenchulus reniformis in Louisiana increased from 3 parishes in 1961 to 11 parishes in 1985 to all 21 of the major soybean producing parishes in 2010. Comparative reproduction and pathogenicity of isolates of Rotylenchulus reniformis from Alabama, Arkansas, Hawaii, Louisiana, Mississippi and Texas on soybean was evaluated in microplot trials. Prior to initiation of microplot trials, ten populations of each geographic isolate were derived. Reproduction of the single egg-mass (SEM) populations of each geographic isolate were evaluated in greenhouse studies with Deltapine 4331 soybean by assessing the numbers of vermiform stages in soil and eggs per gram of root tissue 60 days after inoculation. On the basis of these trials, each repeated once, one SEM population of each of the six isolates was selected for use in microplot trials. Averaged over the two trials, SEM populations selected for use in microplot trials and their respective reproduction values (R, where R = Pf/Pi) and numbers of eggs per gram of root were: AL-7 (R = 3.5, eggs = 1,082); AR-4 (R = 26.7, eggs = 2,186); HI-1 (R = 30.2, eggs = 1,624); LA-3 (R = 30.2, eggs = 1,656); MS-2 (R = 43.9, eggs = 5,215) and TX-5 (R = 55.4, eggs = 4,329). Data from full-season (126 day) microplot trials, averaged over 2 years, showed significant differences (Tukey's HSD test (P ? 0.05%)) among isolates of reniform nematode in both reproduction and pathogenicity. Dry plant weight at harvest averaged 273.3 g for the non-inoculated control. All isolates except the ones from HI and TX produced root weights at harvest that were reduced significantly below that of the control. With the exception of the MS-2 isolate, harvest weights for plants inoculated with AR-4 were significantly lower than those from the other four geographic regions. Relative to the control, numbers and dry weights of pods per plant at harvest were reduced significantly by all reniform nematode isolates except those from AL and HI.

Publication Source (Journal or Book title)

Nematropica

First Page

12

Last Page

22

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