4th Annual Cal Poly Pomona Student RSCA Conference March 4, 2016 University Library, Oral Presentations from 12:45 to 5 pm Bronco Student Center (Ursa Major), Poster Session, Performance Presentation, and Reception from 4 to 6:30 pm

Lead Author: Borman Quinonez

Major: Botany

College: Science

Co-author(s): Not Applicable

Faculty Mentor(s): Dr. Edward Bobich

Presentation Type: Oral Presentation

Project Title: The Effects of Varying Concentrations of Juglone on the Germination and Seedling Success of californica, Heteromeles arbutifolia, and

Synopsis: Aim of research is to find companion plantings to with Juglans californica.

Abstract: In response to the drought many cities have started to stress to its residents the importance of conserving water (dpw.lacounty.gov); native from arid environments have been touted as a way to help individuals and municipalities can meet the water-use reductions imposed by the state. Most native plants will fare well when partnered with other native plants, especially those with which they are sympatric, but there are some plants that produce chemicals that are toxic to other plants. One such is Juglans californica ( Black Walnut), which, like other members of its genus, produces an allelopathic chemical known as juglone (5 hydroxy-1,4-napthoquinone; Cosmulescu et al. 2014). Juglans californica is a tree of a manageable size that would make a great addition to any native California landscape, but is often passed over due to the unknown effects that juglone may have on other species. The aim of our experiment is to identify companion plantings for J. californica by testing how the seed germination and seedlings of native plant species respond to exposure of different concentrations of juglone (Questad 2014). In particular, we will study the following native that can co-occur with J. californica in the walnut woodlands of Southern California: Frangula californica (Eschsch.) A. Gray (coffee berry), Heteromeles arbutifolia (Lindley) Roemer (toyon), and Prunus ilicifolia (Nutt.) Walp. (holly-leaf cherry).