TITLE:
Functional Analysis of Air Temperatures as Related to Chilling Requirements of Perennial Fruit Crops
AUTHORS:
Yao Xue, Sai Pavan Adigarla, Sravya Patil Bagli, Elmer Gray
KEYWORDS:
Chilling Hours, Diurnal Temperatures, Chilling Metrics, Global Warming
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.9 No.4,
March
7,
2018
ABSTRACT: After more than two centuries of observation and
research on chilling requirements of perennial fruit crops, there remain
unresolved aspects concerning relationships between chilling condition and
ambient air temperatures. The purpose of this ongoing study was to further
explain association between chilling temperature and plant functions: growing,
chilling, and freezing. Temperature data consisted of 5-year averages for 50
Mesonet weather sites randomly located throughout Kentucky. Based upon the
Chilling Hours Model analysis, available chilling hours exceeded requirements
of commonly grown perennial fruit crops. In the extended study, max and min
daily temperatures were processed separately permitting their comparisons
within plant functional classes. Nearly twice as many min as max temperature
days were included within the chilling class function. Most consecutive days of
chilling temperatures ranged from 1 to 3 days and were more clustered with min
than max temperatures. Using multiple-year averages especially when the
temperatures were near freezing point, resulted in a high percentage of
individual years with freezing temperatures that were not reflected in the
group average. Separating max and min temperatures in functional classes
permitted greater focus on critical temperature-chilling relations. Within the
chilling range, impact of min on chilling was nearly twice that of max.
Contrariwise, widely reported research literature confirms that global warming
has greater influence on min than on max or mean temperatures.