Publication Date


Advisor(s) - Committee Chair

Dr. Elmer Gray (Director), Dr. Martin J. Stone, and Dr. Todd Willian

Degree Program

Department of Agriculture

Degree Type

Master of Science


Temperate Region fruit and nut trees, and many other perennial plants, require cool winter temperatures (chilling hours) to ensure leaf and flower bud production in the following season. Temperate Regions are characterized by variable winter and spring temperatures. Failure of meeting sufficient chilling requirement results in deformed fruits, unequal maturation, and other plant deformities, thereby reducing quality and yields. Chilling requirements are expressed as number of accumulated hours within a range of approximately 32º to 45ºF or 0º to 7.2ºC. These requirements are specific for level of temperature, length of temperature period, and species and cultivar of plants. Information on chilling hour production by the diverse Kentucky environments and chilling requirements of its plants is limited. Global warming is reducing the occurrence and length of chilling conditions, thereby negatively impacting perennial fruit production (IPCC, 2014). There is increasing interest in fruit crops by the state’s producers and consumers. The Kentucky Mesonet Weather System provides temperature data, which can readily be converted to chilling units. Also, commercial nurseries are beginning to publish chilling requirement data for their fruit stocks. The present study included data collected over A 5-years period at 33 Mesonet sites. The average number of chilling hours overall years and sites was 1544, year means ranged from 1427 to 1842, sites means ranged from 1422 to 1682. Chilling hour production exceeded chilling requirements of fruit and nut crops commonly grown in Kentucky.


Agriculture | Fruit Science