Responses of Four Common Shrub Species to Different Irrigation Regimes

The impact of different irrigation regimes to Cornus sericea L. ‘Isanti’, Hydrangea arborescens L. ‘Annabelle,’ Physocarpus opulifolius (L.) Maxim. ‘Monlo’, and Salix purpurea L. ‘Nana’ were assessed. Irrigation treatments were based on percentages of evapotranspiration (ETo). Poa pratensis L. was used as a control. The shrubs were tested by being field grown (FG) and in a lysimeter using a pot in pot system (LYS). The FG shrubs had four treatments (0, 25, 50, or 100%) and the LYS shrubs had three treatments (25, 50, or 100%). Data collection included height/width, predawn leaf water potential, leaf and shoot fresh/dry weights, turf IR temperatures, soil moisture, and osmolality. As watering amounts increased for the FG Cornus, Physocarpus, and Salix, various characteristics (water potential, size, osmolality) were also positively affected. However, these three species in the 0% treatment appeared acceptable for landscape use as well. The water potential data suggest that FG Hydrangea needs more than 100% to improve growth and performance. The LYS Cornus and LYS Hydrangea adjusted their growth habits based on water availability. The LYS shrubs used water on a daily basis faster as irrigation treatments increased. Increased water use affected LYS shrub growth and more water resulted in larger shrubs.