Influenece of cotton root system size on tolerance to Rotylenchulus reniformis

Authors: GALBIERI, RAFAEL - Universidade Federal De Mato Grosso; Davis, Richard; KOBAYASTI, LEIMI - Universidade Federal De Mato Grosso; ALBUQUERQUE, MARIA - Universidade Federal De Mato Grosso; BELOT, JEAN - Instituto Mato-Grossense Do Algodao (IMAMT); ECHER, FABIO - Instituto Mato-Grossense Do Algodao (IMAMT); BOLDT, ALBERTO - Instituto Mato-Grossense Do Algodao (IMAMT)

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/31/2018
Publication Date: 10/3/2018
Citation: Galbieri, R., Davis, R.F., Kobayasti, L., Albuquerque, M., Belot, J., Echer, F., Boldt, A. 2018. Influenece of cotton root system size on tolerance to Rotylenchulus reniformis. Plant Disease. 102:2473-2479. https://doi.org/10.1094/PDIS-09-17-1424-RE.
DOI: https://doi.org/10.1094/PDIS-09-17-1424-RE

Interpretive Summary: The ability of a crop to minimize yield loss despite parasitism by a nematode is called tolerance. The factors that influence the ability of cotton to be tolerant to parasitism by the reniform nematode were evaluated. For 12 cotton genotypes, reniform nematode reproduction and total length of the root system were measured under greenhouse conditions, and the relationship of those variables to yield loss caused by the nematode in infested fields was evaluated. Values for nematodes per gram of root and root length were standardized by setting the genotype with greatest value as 100% and then calculating a percentage for each genotype. There was significant variability among genotypes in yield loss, resistance, and root length. Mean yield loss for the genotypes ranged from 10.4% to 43.2%. There was a significant linear relationship in which the percentage yield loss caused by the reniform nematode could be estimated using a combination of total root length and the number of nematodes per gram of root, both expressed as a percentage of the maximum (the equation was: Yield Loss (%) = 16.1258 - 0.1918*(% maximum root length) + 0.3728*(% maximum eggs + vermiform/g of roots). We conclude that tolerance to the reniform nematode in cotton is influenced by the size of the root system and the parasitic load on the plant (nematodes per gram of root). Management approaches that increase root growth may lower the parasitic load, thereby reducing losses in cotton to the reniform nematode.

Technical Abstract: The factors that influence the ability of cotton to minimize yield loss despite parasitism by Rotylenchulus reniformis (i.e., tolerance) were evaluated. For 12 cotton genotypes, R. reniformis reproduction and total length of the root system were measured under greenhouse conditions, and the relationship of those variables to yield loss caused by R. reniformis in infested fields was evaluated. Values for nematodes per gram of root and root length were standardized by setting the genotype with greatest value as 100% and then calculating a percentage for each genotype. There was significant variability among genotypes in yield loss, resistance, and root length. Mean yield loss for the genotypes ranged from 10.4% for IAC 26RMD to 43.2% for IMACD 5675B2RF. The least nematode reproduction was on IAC 26RMD, which had 49.6% of the reproduction on the susceptible check, Deltapine 16. The genotype with the shortest total root length was 34% less than the genotype with the greatest length. There was a significant linear relationship between percentage yield loss caused by R. reniformis and root length and nematodes per gram of root, both expressed as a percentage of the maximum, represented by the following equation: Yield Loss (%) = 16.1258 - 0.1918*(% maximum root length) + 0.3728*(% maximum eggs + vermiform/g of roots). We conclude that tolerance to R. reniformis in cotton is influenced by the size of the root system and the parasitic load on the plant (nematodes per gram of root). Management approaches that increase root growth may lower the parasitic load, thereby reducing losses in cotton to R. reniformis.