Effects of Extended Photoperiod and Light Quality on Growth of Carpinus caroliniana, Fagus grandifolia and Gymnocladus dioicus Seedlings

Abstract

Abstract Although Carpinus caroliniana (American hornbeam), Fagus grandifolia (American beech), and Gymnocladus dioicus (Kentucky coffeetree) have considerable landscape merit, they are not readily available in nurseries. Little research has been conducted on the cultural preferences of these species during nursery production. This study tested the effects of light quality and extended photoperiod on these species. Container-grown seedlings were subjected to three light treatments: 18-hour photoperiod using high pressure sodium lights (HPS), 18-hour photoperiod using incandescent lights (INC), and natural light and daylength (NAT). After 14 weeks, stem height of F. grandifolia seedlings was greatest for HPS light and least for NAT light. After 8 and 12 weeks, light source had no impact on stem heights of C. caroliniana. In 1997, stem height and caliper of G. dioicus were greatest using HPS light. In a repeat of the G. dioicus, experiment in 1998, HPS and INC light treatments resulted in greater stem height, caliper, and shoot and root dry weight compared to NAT treatment. The increase in height of seedlings under the HPS and INC treatments compared to the NAT treatments resulted from a greater number of seedlings that produced a second flush of growth under the HPS and INC treatments.