Presentation Title

Effects of juglone on the germination of Southern California native and invasive plant species

Start Date

November 2016

End Date

November 2016

Location

HUB 302-58

Type of Presentation

Poster

Abstract

The Southern California black walnut, Juglans californica, is an endemic, native deciduous tree that commonly occurs in chaparral, coastal sage scrub, riparian communities, and woodlands throughout San Bernardino and Los Angeles Counties. Juglans californica, as well as other species in the genus Juglans produce the compound juglone (5 hydroxy-1,4-napthoquinone), which has been shown to inhibit the growth of understory plant species due to an allelopathic effect; however the effects of juglone have not been studied in California plant communities. We examined how juglone affects the germination of several invasive and native species including: Bromus diandrus, Bromus madritensis, Brassica nigra, Hirschfeldia incana, Carduus pycnocephalus, Silybum marianum, Deinandra fasciculata, Amsinckia intermedia, Phacelia distans, and Diplacus longiflorus. Seeds were sown in groups of 100 in petri dishes. They were exposed to 4mL of five concentrations of juglone: 0mM, 0.01mM, 0.05mM, 0.1mM, and 0.5mM, with four replicates per concentration. Germination was monitored daily and average radicle length was measured weekly. Juglone had an effect on seed germination for all tested species. Nine of the ten species showed a significant decline in germination mainly between the higher concentrations of 0.1mM and 0.5mM. Seed germination for D. fasciculata increased significantly when exposed to juglone concentrations up to 0.1mM. Radicle length was significantly affected in five of the ten species by juglone at concentrations between 0.05 and 0.5mM. The affected radicles were visibly smaller, and often appeared necrotic. Future native species to be tested include Artemisia californica, Pseudognaphalium californicum, and various other commonly occurring herbaceous and woody species.


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Nov 12th, 1:00 PM Nov 12th, 2:00 PM

Effects of juglone on the germination of Southern California native and invasive plant species

HUB 302-58

The Southern California black walnut, Juglans californica, is an endemic, native deciduous tree that commonly occurs in chaparral, coastal sage scrub, riparian communities, and woodlands throughout San Bernardino and Los Angeles Counties. Juglans californica, as well as other species in the genus Juglans produce the compound juglone (5 hydroxy-1,4-napthoquinone), which has been shown to inhibit the growth of understory plant species due to an allelopathic effect; however the effects of juglone have not been studied in California plant communities. We examined how juglone affects the germination of several invasive and native species including: Bromus diandrus, Bromus madritensis, Brassica nigra, Hirschfeldia incana, Carduus pycnocephalus, Silybum marianum, Deinandra fasciculata, Amsinckia intermedia, Phacelia distans, and Diplacus longiflorus. Seeds were sown in groups of 100 in petri dishes. They were exposed to 4mL of five concentrations of juglone: 0mM, 0.01mM, 0.05mM, 0.1mM, and 0.5mM, with four replicates per concentration. Germination was monitored daily and average radicle length was measured weekly. Juglone had an effect on seed germination for all tested species. Nine of the ten species showed a significant decline in germination mainly between the higher concentrations of 0.1mM and 0.5mM. Seed germination for D. fasciculata increased significantly when exposed to juglone concentrations up to 0.1mM. Radicle length was significantly affected in five of the ten species by juglone at concentrations between 0.05 and 0.5mM. The affected radicles were visibly smaller, and often appeared necrotic. Future native species to be tested include Artemisia californica, Pseudognaphalium californicum, and various other commonly occurring herbaceous and woody species.