Results of Breeding for Tolerance to 2,4‐D in Birdsfoot Trefoil¹

Abstract

To develop a weed control system for birdsfoot trefoil (Lotus corniculatus L.) utilizing an effective, inexpensive, and relatively safe herbicide, 2,4‐D, a recurrent selection program was undertaken to breed a strain of trefoil tolerant to this herbicide. We believe that this is the first report of the successful use of recurrent selection to develop herbicide tolerance.A series of tests established that five cycles of field selection had been effective in developing a strain substantially more tolerant to 2,4‐D than commonly used trefoil cultivars. After 2,4‐D treatment, green weight of the lowest yielding progeny line of the tolerant strain was five times that of ‘Viking.’ Survival percentage of the resistant strain was significantly higher than Viking, ‘Empire,’ ‘Mansfield,’ ‘Granger,’ and ‘Tana.’ Fresh and dry weight, plant N composition, and surface wax accumulation were significantly less affected by 2,4‐D in the tolerant strain. Evidence is presented that the 2,4‐D tolerant strain is resistant to the 2,4‐D homologs as well as the parent compound. It was suggested that evaluation of early seedling growth during exposure to herbicides in petri dish culture may prove to be both an effective and efficient screening device in breeding programs to develop tolerance to specific herbicides.

Phytotoxicity of 2,4-D and 2,4-Dichlorophenol to Red Clover (Trifolium pratense)

“…Traditionally, such plant breeding projects have been conducted using conventional techniques such as recurrent selection (10). Devine et al (7) developed a line of birdsfoot trefoil (Lotus corniculatus L.) tolerant to 2,4-D; five cycles of selection resulted in a significant increase in 2,4-D tolerance levels. Faulkner (9) developed a line of perennial ryegrass (Lolium perenne L. # 3 LOLPE) tolerant to paraquat (1,1'dimethyl-4,4T5ipyridinium ion).…”

Registration of ‘FL24D’, a Red Clover Selected for Tolerance to 2,4-D Herbicide

“…However, the clovers often experience significant seedling stage weed competition while being highly sensitive to 2,4‐D. Previous research in birdsfoot trefoil ( Lotus corniculatus L.) (Devine et al, 1975) showed progress through five cycles of recurrent selection for tolerance to 2,4‐D herbicide. Given the above, we initiated a program to select for 2,4‐D tolerance in red clover with a recurrent selection strategy.…”

Tolerance of Birdsfoot Trefoil (Lotus corniculatus) to 2,4-D

“…Most legumes, including birdsfoot trefoil, are susceptible to 2,4-D, but birdsfoot trefoil is more tolerant than many other legumes. Recognition of this fact led to development of a 2,4-D-tolerant selection of trefoil, T-68, from the Viking variety using the technique of recurrent selection (5). Mor phologically, T-68 is similar to Viking.…”

“…Blacklow and Linscott (1) reported that absorption was essentially the same in both varieties, but slightly more 2,4-D is bound in nonalcohol-soluble components in T-68 than in Viking. Devine et al (5) noted that T-68 has twice the surface wax and cuticle of Viking, and the waxes differ in quality. Swanson and Tomes (12) compared T-68 with 'Leo', a Canadian trefoil, and found regeneration of T-68 in tissue culture after 2,4-D treat ment slower than Leo regeneration.…”