Gossypium lines resistant to Rotylenchulus reniformis vary in sensitivity to the herbicide fluometuron

Authors: Stetina, Salliana - Sally; Molin, William

Submitted to: Journal of Cotton Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2014
Publication Date: 9/8/2014
Citation: Stetina, S.R., Molin, W.T. 2014. Gossypium lines resistant to Rotylenchulus reniformis vary in sensitivity to the herbicide fluometuron. Journal of Cotton Science. 18:348-354.

Interpretive Summary: Reniform nematode is a microscopic worm that feeds on cotton (Gossypium hirsutum) roots and reduces crop yield. Distant relatives of cotton are resistant to reniform nematode and are being used to develop resistant cotton varieties. However, one of these resistant lines was reported to be significantly damaged when exposed to fluometuron, a herbicide commonly used in cotton production. To better understand how the reniform nematode resistant lines currently being used in cotton improvement programs respond to this herbicide, 15 of them were evaluated in the greenhouse. Of these, all four G. arboreum lines tested had higher injury ratings than commercial cotton, but two G. barbadense lines had less injury. The line G. arboreum A2-083 was the most sensitive; it showed more damage than the other resistant lines and commercial cotton in response to increasing herbicide rates. While most of the resistant lines tested were no more sensitive to the herbicide than cotton, caution should be taken when breeding with G. arboreum because this species was more prone to damage by the herbicide.

Technical Abstract: Reniform nematode (Rotylenchulus reniformis) resistance is being transferred to Gossypium hirsutum from its distant relatives. Reports of fluometuron damage to LONREN lines with nematode resistance from G. longicalyx raised concerns about introducing herbicide sensitivity from other nematode resistance sources. The research objective was to evaluate fifteen sources of reniform nematode resistance for their reaction to fluometuron three weeks after planting in a replicated greenhouse trial: two G. herbaceum accessions, four G. arboreum accessions, three G. barbadense accessions, three G. hirsutum accessions, and three G. hirsutum lines with resistance introgressed from G. barbadense (FR-05) or G. longicalyx (LONREN-1 and LONREN-2). The control genotype was G. hirsutum cultivar Deltapine 161 B2RF. Across all herbicide rates tested, mean herbicide injury ratings for G. arboreum accessions were greater than the control, while G. barbadense GB 713 and TX 110 were less. Regression analysis of herbicide rates indicated that injury increased linearly with increasing herbicide rate for all accessions, although G. arboreum A2-083 had more injury than the control. Regression analysis of herbicide rates indicated that biomass decreased linearly with increasing herbicide rate for all accessions, although G. barbadense GB 713 and Pima PHY 800 exhibited greater biomass reduction than the control. Across all herbicide rates tested, mean electron transport rates of all G. herbaceum and G. arboreum accessions and G. barbadense Pima PHY 800 were lower than the control. The relationship between herbicide rate and photosynthetic activity was curvilinear, with similar decreases in photosynthetic activity in response to increasing herbicide concentration for all lines. Increased sensitivity to fluometuron could be introduced into G. hirsutum through crosses with distantly related species, but with the exception of G. arboreum A2-083, the lines did not respond to the herbicide differently from the control.