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  • Author or Editor: Glen A. Davis x
  • HortScience x
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Abstract

The freezing behavior of peach [Prunus persica (L.) Batsch] flower buds was influenced by the temperature at which ice formation was initiated. Buds seeded with ice just below 0°C were more likely to exhibit deep supercooling, and water in the primordia would supercool to lower temperatures than in unseeded excised flower buds. This effect was not always expressed and varied with the stage of acclimation. Researchers using differential thermal analysis to estimate bud hardiness will need to evaluate this effect. Seeding specimens with ice may be warranted to obtain results comparable with field conditions.

Open Access

A seasonal study was conducted to assess the freezing injury of `Boskoop Giant' black currant (Ribes nigrum L.) samples from Oct. 1991 through Mar. 1992. Buds were subjected to either differential thermal analysis (DTA) or one of a series of temperatures (0 to -36C). Freeze injury was then assessed either visually or with TTC. Results indicated that black currant floral buds have multiple low-temperature exotherms (LTE). Freeze injury in intact buds could not be visually quantified because of the lack of visible browning, nor assayed with TTC reduction. Excised floral primordia incubated in TTC, however, developed colored formazan following exposure to nonfreezing and sublethal freezing temperatures, but remained colorless when exposed to lethal temperatures. The percentage of floral primordia that were colored and colorless were tabulated and a modified Spearman-Karber equation was used to calculate the temperature at which 50% of floral primordia were killed (T50 The T50 temperature was correlated with the temperature at which the lowest LTE was detected (R2 = 0.62). TTC reduction assay using excised floral bud primordia was a good indicator of viability in frozen blackcurrant buds. Chemical name used: 2,3,5-triphenyltetrazolium chloride (TTC).

Free access