Recurrent Half‐Sib Family Selection for 2,4‐D Tolerance in Red Clover

Abstract

Low profit potential as well as environmental residue and toxicology concerns make it difficult for chemical companies to develop and register herbicides for forage crops. Selection of forages with tolerance to currently labeled herbicides may be an alternative. The objective of this research was to develop a 2,4‐D [(2,4‐di‐chlorophenoxy) acetic acid] tolerant red clover (Trifolium pratense L.) population, using recurrent half‐sib family selection. A 20 000 plant base population of equal parts of ‘Nolins’, ‘Kenstar’, and a Florida population (QC5) was sprayed with 1.12 kg ha−1 2,4‐D and 63 individuals were selected and intercrossed. Four cycles of half‐sib family selection were conducted with from 63 to 276 families evaluated in a cycle. Family selections were based on mean visual top and root damage scores using a 1 to 5 visual rating scale. Four cycles of recurrent selection increased levels of 2,4‐D tolerance in red clover by approximately 35% with an average change of 0.30 score units per cycle. The narrow‐sense heritability of the 2,4‐D tolerance trait was near 50% and inbreeding depression was apparently minimal. These results showed that significant progress has been made and that future progress leading to economically valuable field tolerance should be possible.

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

“…Both a greenhouse and a field experiment were conducted to evaluate the progress made from the initial four cycles of half‐sib family selection program conducted to increase levels of 2,4‐D tolerance in red clover. Methods for these experiments were described in Taylor et al (1989).…”

“…1 shows the process in a flow chart. These four selection cycles were conducted as part of a doctoral research project (Taylor et al, 1989). After this project, two additional cycles of recurrent phenotypic selection were conducted, but records of exact selection percentages in each cycle were not kept.…”

“…he previously published results of Taylor et al (1989, Table 3) compared plant response 21 d ater herbicide application at four rates of the four selection cycles and the beginning population. heir results showed a signiicant reduction in plant damage symptoms of Cycle 4 at the 1.1 kg ha -1 herbicide application rate in a greenhouse experiment compared with Cycle 0 with a rating of 3.7.…”

2,4-D Past, Present, and Future: A Review

“…For some time, researchers have been attempting to incorporate resistance to 2,4-D into desirable plants that are normally sensitive either through selective breeding (Devine et al 1975;Munoz et al 2015;Taylor et al 1989) or biotechnology (Bayley et al 1992;Charles et al 2007;Wright et al 2010). The objectives were generally to allow use of 2,4-D on the crop of interest or incorporate greater tolerance to low rates occurring from off-target movement.…”

Registration of ‘Barduro’ Mid‐Dormant Red Clover

“…Primary methods for breeding red clover have been either recurrent mass selection or recurrent half‐sib selection (Taylor and Quesenberry, 1996), and these methods are easily applied to both selection for dormancy response (Quesenberry et al, 1993) and RKN response (Quesenberry et al, 1989). It has also shown that these methods can be successfully used for selection for 2,4‐D tolerance (Taylor et al, 1989) and for plant regeneration from callus tissue culture (Quesenberry and Smith, 1993; Quesenberry et al, 1996).…”