Susceptibility of Blackberry Tissues to Freezing Injury after Exposure to 16C

Abstract

Abstract Experiments were performed on ‘Cherokee’ blackberry (Rubus sp.) floral buds and cane tissue collected from field plantings on 12 Jan. and 18 Feb. 1987 to determine the susceptibility of floral primordia, phloem, and xylem to freezing injury after exposure to 16C for 0, 4, 12, 24, or 48 hr. Before rest completion in January, floral primordia, phloem, and xylem subjected to 16C were hardier than those tissues tested in February when rest was completed. Floral primordia and cane tissues dehardened slowly with time at 16C before rest completion. After rest was completed, the rate of deacclimation of floral primordia and xylem increased. Some blackberry canes were subjected to two thawing episodes at 16C for 4 hr. In January, phloem and xylem of canes thawed twice were as hardy or hardier than those tissues in samples thawed once. Conversely, two thawing episodes in February resulted in greater xylem injury than a single episode, but two episodes did not affect the hardiness of the phloem. The number of thawing episodes did not affect floral bud hardiness at either sampling date.