Skip to main content
ARS Home » Southeast Area » Tifton, Georgia » Crop Protection and Management Research » Research » Publications at this Location » Publication #329868
Title: Increased size of cotton root system does not impart tolerance to Meloidogyne incognita

Author
item Davis, Richard
item CHEE, PENG - University Of Georgia
item LUBBERS, EDWARD - University Of Georgia

Submitted to: Journal of Nematology
Publication Type: Abstract Only
Publication Acceptance Date: 7/1/2016
Publication Date: 12/1/2016
Citation: Davis, R.F., Chee, P.W., Lubbers, E.L. 2016. Increased size of cotton root system does not impart tolerance to Meloidogyne incognita. Journal of Nematology. 48:312.

Interpretive Summary:

Technical Abstract: Plant tolerance or intolerance to parasitic nematodes represent a spectrum describing the degree of damage inflicted by the nematode on the host plant. Tolerance is typically measured in terms of yield suppression. Instances of plant tolerance to nematodes have been documented in some crops, including cotton, but the mechanisms of tolerance are not understood. We hypothesized that cotton plants with larger, faster-growing root systems would be more tolerant to Meloidogyne incognita because a larger root system could result in fewer nematodes per gram of root thereby reducing the parasitic load on the plant. Eleven cotton germplasm lines were selected because previous research showed their root systems (in the absence of nematodes) differed in weight, taproot length, and number of lateral branches. A field study was conducted for two years to determine whether those root system attributes were related to tolerance of the plants to M. incognita. Cotton lines were grown in a split-plot design with fumigated and nonfumigated subplots so that percentage yield loss could be calculated for each genotype. Analyses included variables that were standardized for each genotype as a percentage of the maximum (e.g., root length as a percentage of the genotype with the greatest length). Root data from previous research on these genotypes along with yield data from the current test were used to evaluate potential relationships among variables. Regression analyses showed that percentage yield loss was not related to percentage maximum weight or percentage maximum number of lateral branches. However, percentage yield loss increased as the percentage of maximum length increased, which is the inverse of what our hypothesis predicted. Perhaps nematode parasitism inhibits root elongation in seedlings and young plants which prevents plants from reaching their full rooting depth thereby resulting in a relatively greater effect on plants with the greatest potential for root length. Therefore, we conclude that cotton plants with larger root systems are not more tolerant to M. incognita.