Moisture Relations of Peach Buds During Winter and Spring

In overwintering flower buds of ‘Redhaven’ peach [Prunus persica (L) Batsch], seasonal changes in the supercooling point were correlated significantly with seasonal changes in water content of the whole flower bud and its parts, the flower primordium within the flower bud and the vascular traces just below the flower primordium. Both the supercooling point and the water content of the whole flower bud and its parts were correlated significantly with the 2- and 5-day mean air temperature preceding collection. Controlled-temperature studies with ‘Siberian C’ and ‘Redhaven’ revealed that the water content of the flower primordium and vascular traces and not that of the whole flower bud was critical to the level of supercooling attained. Supercooling of the flower primordium appeared to be related directly to its water content. Water content of the vascular trace appeared to be important during the initial stages of freezing for preventing spread of the ice boundary into supercooled regions of the flower primordium. Water content of the 2 critical tissues appeared to be determined by migration from and to these tissues during freezing and thawing. During freezing, water was lost from the flower primordium and vascular traces by migration to the flower bud scales which appeared to act as an ice sink. After prolonged exposure to freezing outdoors, water was also lost to the exterior of the flower bud. After thawing, the flower primordium and vascular traces regained water content by transfer from the ice sinks within the flower bud and sources external to the flower bud. Loss of flower bud hardiness occurred during storage at 0°C for 10 days, which was not due to change in water content of the flower bud or its parts. The excised flower buds of the hardier ‘Siberian C’ supercooled to a lower temperature than excised flower buds of the less hardy ‘Redhaven’ at equivalent water content.

mentioning

confidence: 84%

Relationship of Air Temperature to Water Content and Supercooling of Overwintering Peach Flower Buds

Quamme

1983

“…The freeze resistances of peach and sweet cherry flower buds (23,28) and Vitis buds (25) changed over time in response to the preceding temperature exposure. In 1923, Johnston (15) noticed that the freeze resistance of peach flower buds and their water contents were inversely related. More recently, both water content and extent of deep supercooling of Rhododendron (12) and peach (33) flower primordia have been found to change with air temperature.…”

mentioning

confidence: 99%

Effects of Temperature on the Deep Supercooling Characteristics of Dormant and Deacclimating Sweet Cherry Flower Buds

Andrews¹,

Proebsting²

1987

Seasonal changes in the temperature of the median low-temperature exotherm (LTE50) of dormant sweet cherry (Prunus avium L. cv. Bing) flower buds were significantly correlated with the preceding minimum air temperature in the orchard and the water content of the flower primordia. When buds were exposed to temperatures just below the high temperature exotherms, water migrated from the primordia to the bud scales. Under these conditions, the LTE50 decreased almost 5°C during the first day, but only 1°/day thereafter. The minimum LTE50 was near −32° after the buds were frozen for 10 days. Thawing buds at 0° or above increased the LTE50 about 1°/hr, to −20° to −21°. The LTE50 did not increase above these temperatures until the buds were exposed to 20° for 1-2 days following the completion of rest. During deacclimation, both the LTE50 and temperature range of the low temperature exotherms (LTEs) increased. These changes were accompanied by fluctuations in the capacity of the flower buds to exhibit deep supercooling, expressed as the fraction of an LTE produced per flower primordium (LTE/primordium). Even on days when the LTE/primordium was low, the temperature required to injure 50% of the flower primordia was similar to the LTE50.

“…Fruit bud and wood cold hardiness have been inversely cor related with plant cell sap moisture indices (5,14,15,16). Increases in susceptibility to freeze injury occur when cells have large central vacuoles, indicative of relatively large amounts of water (14).…”

Section: Resultsmentioning

confidence: 99%

“…of fruit/m. Although bloom in the sprinkled trees was delayed by Apple response to chemical control of weeds in the orchard has been investigated for more than 15 years (5). These studies employed either total orchard floor treatment or some form of directed basal application such as strips or spots.…”

Section: Resultsmentioning

confidence: 99%

Effects of Evaporative Cooling during Dormancy on ‘Redhaven’ Peach Wood and Fruit Bud Hardiness1

Bauer

Chaplin

Schneider

et al. 1976

‘Redhaven’ peaches (Prunus persica L. Batsch) were sprinkled from the end of rest, January 22, 1975, until the time check trees reached full bloom, April 18, 1975. Sprinkling delayed bloom by 15 days. Energy models predicted bloom one day before it occurred in the check trees. Wood temperatures were lowered as much as 6.5°C in sprinkled trees, but no significant difference in wood cold hardiness was observed. Sprinkled fruit buds were more cold hardy than non-sprinkled fruit buds until early March. Non-sprinkled buds were more cold hardy than sprinkled fruit buds in late March. Sprinkling reduced the number of viable buds/m by late March. Analyses of total and reducing sugars and protein showed no significant difference.