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ARS Home » Northeast Area » Kearneysville, West Virginia » Appalachian Fruit Research Laboratory » Innovative Fruit Production, Improvement, and Protection » Research » Publications at this Location » Publication #314697

Title: Susceptibility of blackberry flower parts to subfreezing temperatures

item Takeda, Fumiomi
item Glenn, David

Submitted to: International Rubus Ribes Symposium
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2015
Publication Date: 6/25/2015
Citation: Takeda, F., Glenn, D.M. 2015. Susceptibility of blackberry flower parts to subfreezing temperatures [abstract]. International Rubus Ribes Symposium. p. 82.

Interpretive Summary:

Technical Abstract: Injury of tight buds, open flowers and green fruit often occur in fruit crops in later winter to early spring frosts. In this study, freezing tolerance of ‘Triple Crown’ blackberry flowers at various maturity ranging from tight bud to green drupe stage was determined using two freezing methods. One method involved placing whole plants in a radiation frost chamber and taking plants out at selected temperatures ranging from -1 to -5 degrees C. After freeze treatments, all buds, open flowers, and green fruit were evaluated for damage and the lethal temperature50 (LT50) determined. In order, from the most sensitive flower part to the least sensitive were the interior ovary (ovule), receptacle, style, stigma, petal, filament, and anther. In the second method, thermocouple wires were inserted into tight bud, open flower, and green fruit and the chamber temperature was slowly lowered to -5 degrees C. The thermocouple readings were captured at 5 sec intervals to determine at what temperature the high temperature exotherm (HTE) occurred. In all runs, HTE occurred between -2.5 and -3.0 degrees C for all stages of reproductive development (tight bud, open flower, and green fruit). The tissues comprising the gynoecium (ovary, style, and stigma) were less tolerant to freezing than the androecium and the corolla.