Cyclic Microirrigation in Container-grown Landscape Plants Improves Plant Growth and Water Conservation

Abstract

Four tree (Acer rubrum L., Ulmus alata Michx., Quercus virginiana Mill, and Lagerstroemia indica L.) and two landscape shrub species (Rhododendron indicum L. ‘Formosa’ and Elaeagnus pungens Thunb.) were grown in 10-liter (#3) polyethylene containers. Plants were irrigated with overhead impact sprinklers (control) or with individual low volume spray stakes. Microirrigated treatments consisted of same or double volume per day per container as controls applied as one to three cyclic subvolumes. Shrub growth was seldom influenced by irrigation treatment. Xeric tree species (U. alata and Q. virginiana) grew as well with single volumes applied in 2 cycles as double volumes applied in 3 cycles; both produced significantly larger trees than the control. Mesic species (A. rubrum and L. indica) irrigated with double volumes in 3 cycles produced the largest trees that were significantly larger than single volume microirrigated or control trees. Growth of single cycle, single volume trees (overhead and microirrigation) was equivalent; thus, growth effects were due to cycling, not microirrigation. With commercially representative container spacings used, superior trees were produced with cycled microirrigation using 25% (xeric) or 50% (mesic) of the water volume per area applied through the overhead sprinkler. Further aspects of irrigation requirements and water efficiency are discussed.