Electrolyte Leakage Assay Capable of Quantifying Freezing Resistance in Rose Clover

Abstract

Rose clover (Trifolium hirtum All.) is a winter annual legume with potential for increased use as a forage crop in Texas, Oklahoma, and the southern U. S. region. However, there is a need for rose clover with improved winter growth, extended seasonal forage production, and improved winter survival to increase the usefulness of this legume as a reseeding forage crop. The objectives of this study were to: (i) develop screening methods to measure freezing resistance; and (ii) discriminate freezing stress resistance differences in selected germplasm, both in controlled and field conditions. An electrolyte leakage (EL) test performed on young leaves (YL) at −14°C temperature for 60 min proved to be the most efficient for detecting both acclimation and cultivar differences in rose clover freezing tolerance. Under the climatic conditions prevalent during the experiment, the rates of acclimation and deacclimation were the same for three cultivars that were tested under controlled conditions and in the field. ‘Overton R18’ exhibited a general trend toward a higher level of freezing tolerance than ‘Kondinin’ or ‘Hykon’, both under controlled conditions and field testing. The experimental lines TX‐B97 and TX‐B29 had the apparent ability to respond rapidly to cold field conditions by reversing the deacclimation process. Other clover entries changed their rate of deacclimation in response to cold temperature but not as rapidly as TX‐B97 and TX‐B29.