Pecan Cold Hardiness Determined by Differential Thermal Analysis

Abstract

Our objectives were to 1) Determine acclimation and deacclimation patterns of buds and stems of four pecan cultivars in Mississippi and 2) to determine the relationship between cold hardiness, based on DTA, and tissue injury, based or viability tests. Stem critical temperatures for September showed that `Hughes' was slower in acclimating than `Jackson'. Maximum hardiness for all cultivars occurred in January, except for `Desirable', which reached maximum hardiness in December but started deacclimating in January. Deacclimation for the remaining cultivars started in February. Bud critical temperatures for September and October also show that `Hughes' was slower in acclimating compared to the remaining cultivars. Maximum bud hardiness for `Desirable' occurred in December, with the remaining cultivars reaching maximum hardiness in January. Bud deacclimation for all cultivars occurred in March. The LD50 for the tetrazolium and electrolyte leakage tests occurred at about –32 and –30C, respectively. In buds, LT50 for the tetrazolium test was –18C. The LT50 electrolyte leakage and browning test was –20C.