THE COLLEGE of AGRICULTURAL SCIENCES Cold hardiness in peach floral buds using differential thermal analysis Ioannis Minas*, David Sterle, Horst Caspari
USDA-Plant Hardiness Zones Map Grand Junction, CO CO Fort Collins, CO
Colorado Tree Fruit Industry Crop Bearing Acreage (Acres) Total Utilized Production (Tons) Value of Utilized Production ($) Peaches 2,6 12,65 3,75, Apples 1,2 4,1 7,315, Grapes <1, >2, 4,,
Mitigating cold damage in Colorado tree-fruit
Objectives Understanding of the environmental bases for cold hardiness and damage Determine the critical, lethal temperatures of floral buds of different cultivars Development of horticultural practices and evaluation of genetic material Provide producers with accurate data on current cultivars to make informed frost control decisions (i.e., decision-support)
Oxidative browning method (standard) Following freezing, the buds are held at room temperature for 24 h at 21 o C Afterwards a longitudinal sectioning is made with a single-edged razor blade to confirm the injury of the ovary Buds with vibrant green tissue are judged as viable whereas buds with brown tissue are judged to be dead Labor intensive Not easy data handling on large samples
Differential Thermal Analysis (DTA) Monitors difference in temperature between sample and a reference thermocouple Against time or temperature While the temperature of the sample is programmed 5-6 peach buds per TEM 1 replicated TEMs plus one reference
Differential Thermal Analysis (DTA) Online data acquisition Data logger Programmable freezer 4 o C/hour
Differential thermal analysis on Peach Dormant Buds Exotherm (mv) 2 1.5 1.5 High Temperature Exotherm (HTE) Non-lethal (extracellular water freeze) Low Temperature Exotherms (LTEs) Lethal (intracellular water freeze) -5-1 -15-2 -25 Temperature ( o C)
DTA on Cresthaven floral buds 11/2/16 Exotherm (mv) 1.8.6.4.2-5 -1-15 -2-25 -5-1 -15-2 -25-5 -1-15 -2-25 -5-1 -15-2 -25-5 -5-1 -1-15 -15-2 -2-25 -25-5 -1-15 -2-25 -5-5 -1-1 -15-15 -2-2 -25-25 -5-1 -15-2 -25-5 -1-15 -2-25 -5-1 -15-2 -25-5 -1-15 -2-25 Temperature ( o C) -5-1 -15-2 -25-5 -1-15 -2-25 -5-1 -15-2 -5-1 -15-2 -5-1 -15-2 -25-25 -25 11/8/16 11/15/16 11/21/16 11/29/16 12/6/16 12/12/16 12/19/16 1/3/17 1/9/17 1/24/17 2/1/17 2/7/17 2/8/17 2/15/17 2/2/17 2/27/17 3/3/17 3/6/17 Acclimation Maximum Hardiness (Dec 12 th - Feb 1 st, 217) Deacclimation (Feb 7 nd - March 6 rd, 217)
Incubation at -2 o C overnight (12h) can reverse disappearance of low exotherms during deacclimation Exotherm (mv) 1.9.8.7.6.5.4.3.2.1 1.9.8.7.6.5.4.3.2.1-5 -5 Sierra Rich -1-15 -2-25 -1-15 -2-25 February 7, 17 No incubation Febuary 8, 17 Incubation at -2 o C overnight (12h) Temperature ( o C)
Critical temperatures for floral bud kill Temperature ( o C) -14-16 -18 4 o C/hour -2-22 1/24/217 Sierra Rich Cresthaven Red Haven Lethal Temperatures (LT, o C) Sierra Rich Cresthaven Red Haven LT 1-16.4-19.6-19.9 LT 5-21.1-22. -22.1 LT 9-22.4-22.6-23. -24.2.4.6.8 1 Cumulative probability
Red Haven peach floral buds cold hardiness Ambient temperature ( o C) Lethal temperature (LT, o C) o C 3 2 1-1 -2 T max T mean T min LT 1 LT 5 LT 9 Endo-dormancy Eco-dormancy Bud-Swell 11/1/16 12/1/16 12/31/16 1/3/17 3/1/17 Date Seasonal patterns of temperature and cold hardiness (expressed as lethal temperature, LT) for Red Haven peach floral buds 3 2 1-1 -2
Peach floral buds cold hardiness 4 o C/hour Ambient temperature ( o C) Lethal temperature (LT, o C) 3 2 1-1 -2 LT 1 LT 5 LT 9 11/1/16 12/1/16 12/31/16 1/3/17 3/1/17 Ambient temperature ( o C) Sierra Rich 3 2 1 T max T mean T min 3 3 2 2 1 1-1 -1-2 -2 Red Haven LT 1 LT 5 LT 9 Cresthaven 11/1/16 12/1/16 12/31/16 1/3/17 3/1/17 3 2 1 T max T mean T min 3 2 1-1 -2 Lethal temperature (LT, o C) -1-2 LT 1 LT 5 LT 9 T max T mean T min -1-2 11/1/16 12/1/16 12/31/16 1/3/17 3/1/17 Date
Mid-Winter Cold Damage and Inversions DTA Validation 5 ft 4 ft 6 in Temperature ( o F) 2 1-1 -24.1 o C.2-13.1 8.4 o C -18.4-1.2 o C -11.3.3 15 1 5 Wind speed (mph) 6.5 ft 6 in -2 12: AM 2:45 AM 5:3 AM 8:15 AM 11: AM Time Orchard Mesa, CO January 7 th, 217
DTA field validation 3 Sierra Rich T max T mean 3 Temperature ( o C) 2 1-1 -2 LT 1 LT 5 LT 9 T min 11/1/16 12/1/16 12/31/16 1/3/17 3/1/17 Date 2 1-1 -2 Date(s) of event Actual field damage (%) DTA Predicted Damage (%) January 7, 217 16 11 February 24-25-26, 217 23 27 March 1 and 7, 217 24 22
Peach bud cold hardiness monitoring updates http://minas.agsci.colostate.edu/tree-fruit-information/cold-hardiness/
Peach bud cold hardiness monitoring updates http://minas.agsci.colostate.edu/tree-fruit-information/cold-hardiness/
Peach bud cold hardiness monitoring updates http://minas.agsci.colostate.edu/tree-fruit-information/cold-hardiness/
Peach bud cold hardiness monitoring updates http://minas.agsci.colostate.edu/tree-fruit-information/cold-hardiness/
Conclusions DTA loses the capacity to determine ice nucleation events as bud development advances Overnight incubation at -2 o C can reverse exotherm disappearance for up to 1 month DTA is an objective measure that can accurately identify the transition from eco-dormancy to growth and development in peach floral buds Can provide reliable data for cold hardiness prediction models development (3 years data)
CSU_Pomology ioannis.minas@colostate.edu Acknowledgements Greg Litus, CSU Markus Keller, WSU Todd Einhorn, MSU Gibeaut David, OSU Western Colorado Hort. Society Colorado Ag. Experiment Station