Date of Award

Spring 5-2019

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Master of Science (MS)

Department

Horticulture

Advisor

Stephanie E. Burnett

Second Committee Member

Bryan J. Peterson

Third Committee Member

Matthew Wallhead

Abstract

The primary method of vegetative propagation by stem cutting is to insert leafy cuttings into a solid soilless media and place the cuttings in an environment that provides moist, humid conditions to the foliage through fog or overhead intermittent mist. These systems reduce water loss through transpiration by reducing leaf temperature and provide moisture to the rooting media. However, excess water, both on the media and on the leaves can result in an increase incident of diseases. To alleviate some of these issues, research has found stem cuttings can be rooted in sub-mist systems that apply water solely to the base of cuttings without the need of an overhead mist system. With positive rooting results in these systems, including higher rooting percentage, longer roots and greater dry weight, there is limited data on how cuttings respond to being transplanted into a soilless media. In addition, while there is research reporting gas exchange measures during rooting of stem cuttings, it has focused on overhead mist. To gain insight into these inquires, two studies were conducted. The first compared the rooting and post-transplant performance of an ornamental herbaceous species, Lantana camara ‘Dallas Red’ (lantana) by stem cutting using an overhead mist (OM) and a submist system (SM). The second study compared the rooting and gas exchange measures of the woody ornamental plant Syringa pubescens ssp. patula (manchurian lilac) by stem cutting using an OM, SM, and hybrid (HY) system.

Survival of lantana in both OM and SM was 99%; cuttings in the OM produced 45% more roots than the SM. By contrast, cuttings in the SM produced roots that were 73% longer. When comparing post-transplant performance, survival rate for plants grown from cuttings propagated under overhead mist was 53%, significantly lower than the submist cuttings with a 95% survival rate. The results of most measures of growth did not differ significantly in the remaining surviving cuttings.

In the second study, rooting percentages of manchurian lilac was significantly higher in the HY system (90%), while non-significant between OM and SM, at 68% and 62%, respectively. The systems utilizing submist (HY and SM) had significantly higher root count and root length and retained most of their leaves. Photosynthetic rate differences were non-significant between systems, but in all systems increased at root emergence. Stomatal conductance also increased as roots emerged in the cuttings but was more notable in the HY and OM systems. Stomatal conductance in the SM remained relatively constant even after root emergence and was significantly lower than both the HY and SM systems.

The use of systems utilizing submist, providing intermittent mist to the basal end of the cutting, have shown to be effective alternative methods to propagating both herbaceous and woody ornamental plants, with positive rooting performance in lantana and manchurian lilac.

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