Ice nucleation, freezing injury, and colonization of 'Totem' strawberry flowers with ice-nucleation-active (INA) bacteria

• Published in: Journal of the American Society for Horticultural Science Vol. 123; no. 2; pp. 234 - 238
• Main Authors: Warmund, M.R, English, J.T
• Format: Journal Article
• Language: English
• Published: 01-03-1998
• Subjects: AGUA; CONGELACION; CONGELATION; DANOS POR LA HELADA; DEGAT DU AU GEL; EAU; FLEUR; FLORA MICROBIANA; FLORE MICROBIENNE; FLORES; FLOWERS; FRAGARIA ANANASSA; FREEZING; FROST DAMAGE; MICROBIAL FLORA; PSEUDOMONAS SYRINGAE; SUPERVIVENCIA; SURVIE; SURVIVAL; TEMPERATURA; TEMPERATURE; WATER
• ISSN: 0003-1062; 2327-9788
• DOI: 10.21273/jashs.123.2.234

INA bacteria were isolated from primary flowers of 'Totem' strawberry (Fragaria xananassa Duch.) plants that had been previously inoculated with strain Cit 7 of Pseudomonas syringae van Hall or noninoculated to determine their relationship to ice-nucleation temperature and floral injury. Mean ice-nucleation temperature of inoculated and noninoculated flowers was -2.2 and -2.8 degrees C, respectively. Primary flowers of noninoculated plants survived lower temperatures than those of inoculated plants. In another experiment, noninoculated plants were misted with sterile deionized water and incubated for 0, 12, 24, 36, or 48 hours at 25 degrees C day/10 degrees C night, and naturally occurring INA bacteria were isolated from primary flowers. INA bacterial densities increased exponentially with increasing incubation period. The critical wetness period for INA bacteria to establish a sufficient density to increase the likelihood of floral injury at -2.5 degrees C was 24 hours. Longer wetness periods resulted in higher INA bacterial densities but did not increase the floral mortality rate. Thermal analysis demonstrated that the ice nucleation temperature was associated with strawberry floral injury. Thus, low temperature survival of flowers was adversely affected by moisture for greater than or equal to 24 h due to the presence of a sufficient density of INA bacteria to incite ice formation and floral injury