Year of Publication


Degree Name

Master of Science (MS)

Document Type

Master's Thesis


Agriculture, Food and Environment


Plant and Soil Sciences

First Advisor

Dr. Michael Barrett


A red clover (Trifolium pratense) population (UK), from a cross between the cultivar Kenland and a 2,4-D tolerant population (Florida), was recurrently selected for 2,4-D tolerance with evaluations after the 6th, 7th, and 8th selection cycles. All UK populations were more 2,4-D tolerant than Kenland. The 2,4-D tolerance following the 6th selection cycle was similar to the Florida population and tolerance was increased following 7 and 8 cycles of selection by removing plants showing 2,4-D injury and doubling the rate of 2,4-D used for selection.

Yield and forage quality were evaluated in UK and Kenland. Forage quality measurements included acid detergent fiber (ADF), neutral detergent fiber (NDF), and crude protein (CP). The UK population had improved yield and NDF.

The potential role of 2,4-D uptake, translocation, and metabolism in the red clover tolerance to the herbicide was evaluated by following behavior of 14C 2,4-D in UK and Kenland 8, 24, 48 and 72 hours after treatment. Plants were partitioned into the treated leaf, untreated shoot, and roots. There was less parent 2,4-D and more 2,4-D metabolites in all sections of UK at all sample times, indicating that enhanced 2,4-D metabolism in UK is likely the basis for tolerance in this population.