| Two drought-tolerant California native plant species (a nonselected
from of Ceanothus griseus var. horizontalis, C. griseus
var. horizontalis 'Santa Ana', a nonselected form of Rhamnus californica,
and R. californica 'Eve Case') and a widely planted non-native landscape
species (Photinia fraseri) received the same total volume of water
(63.8% ET0) over a 14 week period in one of four irrigation treatments
(water applied daily, every three days, every five days, or every seven
days). Each irrigation treatment also received one of three rates of nitrogen
application (0, 20 g N/m2 [0, 180, and 360 lb. N/A]). The irrigation
frequencies or fertilization rates had few significant effects on plant
growth and survival. Selection of a cultivar of R. californica has
resulted in increased growth rates and aesthetic quality, but has also increased
susceptibility to root pathogenic fungi. |