Date of Award

8-2014

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Plant and Environmental Science

Advisor

James E. Faust

Committee Member

Julia L. Kerrigan

Committee Member

Jeff Adelberg

Committee Member

Vijay Rapaka

Abstract

Piriformospora indica is a fungal endophyte, often called an arbuscular mycorrhizal-like fungus, that has been shown to provide benefits to plant symbionts by increasing nutrient uptake, biomass production, flower number, and disease resistance in a wide range of plant hosts. Research was carried out to investigate the ability of P. indica to improve plant production in floriculture crops. The first objective was to determine the optimal environmental conditions for growing P. indica in pure culture. Environmental conditions were optimized to produce the maximum chlamydospores for inoculum preparation (Chapter 1). These findings were used in the remaining chapters to prepare inocula for experiments. The addition of P. indica to unrooted cuttings was evaluated for enhancement of adventitious root formation (Chapter 2). Benefits of P. indica inoculation on unrooted cuttings varied between plant species, cultivars and inoculum concentration. Calibrachoa, impatiens, and petunia plants inoculated with P. indica were evaluated for growth enhancement and nutrient uptake under nitrogen and phosphorus restriction, because these are essential nutrients in greenhouse crops (Chapter 3). Our results suggested that inoculation with P. indica can enhance nitrogen uptake, biomass, and flower number of the three floriculture species tested when nitrogen was restricted, whereas only calibrachoa demonstrated benefits from inoculation with P. indica when phosphorus was restricted. Finally, five commercial biological fungicides and P. indica were evaluated for plant growth promotion and disease suppression of Phytophthora nicotianae on three petunia species. Petunia × hybrida did not respond to biological fungicide treatments for growth enhancement or disease suppression. Some biological fungicide treatments suppressed disease symptoms on Petunia grandiflora and Petunia multiflora at days 2, 6, 8 and 10 after pathogen inoculation. Improved plant growth was also dependent on host and biological control agent applied. Our results showed that inoculation of P. indica on floriculture crops can promote adventitious root formation on unrooted cuttings, enhance biomass, increase nutrient uptake, and slow down disease progression of P. nicotianae depending on inoculation levels and plant species.

Included in

Horticulture Commons

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