The Histology and Histochemistry of The Wound-Healing Process in Geranium Cuttings in Relationship to Basal Stem Rot Caused by Pythium Ultimum

Geraniums are largely propagated by cuttings even though new seed strains are now becoming popular. They are available as unrooted, callused redi-root (adventitious root initials just beginning to emerge) or fully rooted cuttings. Blackleg, caused by Pythium species, is a problem in geranium propagation. Cuttings of Pelargonium hortorum 'Yours Truly' were inoculated with an isolate of Pythium ultimum. Extensive basal stem rot occurred on all freshly broken cuttings. A restricted basal stem rot occurred on cuttings that had healed 1 day in soil prior to inoculation. Basal stem rot rarely occurred on cuttings that had healed 2 days or longer prior to inoculation. The wound-healing process in cuttings was studied using histological and histochemical techniques. After 1 day a distinct morphological change occurred in the cell walls of all tissues nearest the wounded surface. The cell walls became thickened due to deposition of substance in a layer around the cell wall. Histochemical tests determined this substance to be suberin. Suberin deposits were also observed in the intercellular spaces. A wound callus developed after 7-10 days. A suberized wound periderm developed after 14-21 days. Disease severity and the length of time after wound healing began were inversely correlated.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Plant Pathology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Cline, Molly Niedbalski

• Agriculture, Plant Pathology

Language dc:language

eng

Identifier

(UMI)AAI8108470

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/67450