The formation and distribution of ice within dormant and deacclimated peach flower buds

Abstract A freeze-fixation technique was used to examine the distribution of ice crystals and the pattern of freezing in peach flower buds. In dormant buds, ice crystals formed at localized sites within the bud axis and scales. Ice crystal formation disrupted tissues and mechanical injury from repetitive freezethaw cycles was apparent. There was evidence of ice formation in the floral organs of dormant buds exposed to ?25°C but none observed in buds exposed to either ?5 or ?10°C. The distribution of ice crystals was different in deacclimated buds. In addition to large ice crystals within the subtending bud axis and scales, evidence of large crystals within the developing floral organs was noted. These crystals were most prominent in the lower portions of the developing flower and peduncle, and caused a separation of the epidermal layer from adjacent cells. The distribution of ice crystals within both dormant and deacclimated peach flower buds corroborated the results of previous thermal analysis experiments.