Investigating Water Requirements of Select, Field-grown Tree Species in a Semi-arid Climate

Abstract

Recent droughts and depleted water tables across many regions have elevated the necessity to irrigate field-grown (FG) nursery trees. At the same time, ordinances restricting nursery irrigation volume have been implemented, often without regard to plant water requirements. This research investigated growth of seven FG tree species (Acer buergeranum, A. campestre, A. × freemanii `Autumn Blaze', A. truncatum, Quecus muehlenbergii, Q. polymorpha, and Q. robur) subjected to three reference evapotranspiration (ETo) irrigation regimes (100%, 60%, and 30% ETo) in a semi-arid climate. During Spring 2002, nine containerized (11.3 L) trees of each species were field planted in a randomized block design. Each year trees were irrigated through a drip irrigation system. During the first growing season, all trees were irrigated at 100% ETo. Irrigation treatments began Spring 2003. Growth data (shoot elongation and caliper increase) were collected at the end of the 2003 growing season. Species growth data were subjected to analysis of variance. If treatment differences were found, means were separated by Fisher's least significant difference. Shoot growth was influenced by irrigation regime for each species except A. campestre and Q. robur. For each of the five remaining species, the greatest shoot growth increase was generally not associated with the greatest irrigation regime. In a similar manner, caliper increase was influenced by irrigation regime for each species. The 100% ETo irrigation regime produced the greatest caliper increase for A. buergeranum, A. truncatum, Q. polymorpha, and Q. robur. For remaining species, the greatest caliper increase was generally not associated with the greatest irrigation regime.