TITLE:
Assessing Chilling Conditions by Sites and Years for Perennial Fruit Production in Kentucky
AUTHORS:
Yao Xue, Sai Pavan Adigarla, Venkata Sravani Reddy Seethi, Elmer Gray
KEYWORDS:
Climate, Weather, Global Warming, Plant Dormancy
JOURNAL NAME:
American Journal of Plant Sciences,
Vol.7 No.10,
July
22,
2016
ABSTRACT: Temperate regions of the world are characterized by seasonal warm and
cool temperature. Cool temperature enables the plant to undergo physiological
processes essential for flowering and fruit bearing in the following season.
Failure of environments to provide chilling conditions required for the fruit
cultivar results in deformed leaves, fruits, or barren trees. The present study
was conducted to assess production and distribution of chilling hours in
Kentucky environments. Weather data were provided by Kentucky Mesonet system
for 50 counties over a 5-year period. A chilling unit is defined as a clock
hour in which air temperature is between 0°C and 7.2°C. Temperature
readings in this range were recorded from September through April. Average
number of chilling hours observed in the study was 1556 overall, and ranged
from 1463-1680 for sites, and 1473-1842 for years. Estimated chilling hours
were more variable for years than for sites. Consistency of chilling results was
high when measured by linear correlation and relative standard deviation
statistical procedures. Accumulated chilling hours at the sites reached
approximately 1000 by mid-January thereby meeting the requirements for many
fruit crops. At that point, plants would be ready for bud break and become
subject to freezing damage. The results indicated that chilling exceeded
requirements for most Kentucky crops. This margin of excess has both negative
and positive value. First, the plants become more vulnerable to freezing damage
before winter weather is completed. The higher risk could be mitigated by
growing cultivars with longer chilling requirements. Second, since warming has
been shown to decrease chilling production, the margin of chilling hours could
provide time for adjusting horticultural enterprises in Kentucky to global
warming. Additional understanding of relationships between environments and
chilling will contribute to perennial fruit production in temperate regions of
the world.