&lt;b&gt;Adventitious rooting of mature &lt;I&gt;Cycas micronesica&lt;/I&gt; K.D. Hill (Cycadales: Cycadaceae) tree stems reveals moderate success for salvage of an endangered cycad&lt;/b&gt;

2018

horts

Large stem cuttings were removed from Cycas micronesica K.D. Hill trees and used for asexual propagation to more fully understand resource factors that influence adventitious root formation success. Healthy source trees had received insecticide protection from ubiquitous Aulacaspsis yasumatsui Takagi infestations and unhealthy source trees had suffered from chronic A. yasumatsui infestations. Nonstructural carbohydrates were quantified from stem tissues at the base of each 1-m cutting, and induction of adventitious roots was attempted using field soil as the medium. Carbohydrate concentrations were increased in healthy, protected tree cuttings above those in unhealthy, infested tree cuttings. The relative increase was greatest in the hexoses, intermediate in sucrose, and least in starch. The total nonstructural carbohydrate concentration in cuttings of infested trees was 54% of that of protected trees, and the sugar/starch quotient of infested trees exceeded that of protected trees. Asexual propagation success was 30% for the unhealthy tree cuttings and 100% for the healthy tree cuttings. These manipulative experiments confirm that chronic A. yasumatsui herbivory of C. micronesica trees reduces stem carbohydrates and decreases asexual propagation success. The results indicate that the use of large cuttings from unhealthy C. micronesica trees to rescue tree populations from construction sites is not a wise conservation decision in habitats where A. yasumatsui herbivory has been uncontrolled. Protocols for future rescue operations designed to transplant C. micronesica trees from construction sites may be improved by this new knowledge.

Section: Resultsmentioning

confidence: 99%

“…The propagation protocols followed those of Marler and Cruz (2017). All leaves and debris were removed from the apex.…”

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Stem Carbohydrates and Adventitious Root Formation of Cycas micronesica following Aulacaspis yasumatsui Infestation

2018

horts

“…The use of large C. micronesica stem cuttings as propagules was evaluated to determine if the approach could be employed to rescue trees from construction sites on Guam [ 10 ]. Low to moderate success rates were realized due to the compromised health status of the CAS-infested trees.…”

Section: Introductionmentioning

confidence: 99%

Axial and Radial Spatial Patterns of Non-Structural Carbohydrates in Cycas micronesica Stems

2018

Plants

Self Cite

The pachycaulous stem of arborescent cycad species exhibits unique traits and has received limited research. To date, nothing is known about the axial and radial spatial patterns of non-structural resources within cycad stems. Cycas micronesica K.D. Hill stem tissue was collected from apical and basal axial positions of ca. 100-cm tall plants to serve as two axial regions; and from pith, vascular, and cortex tissues to serve as three radial regions. Starch and four free sugars were quantified. These stems contained more starch than any of the individual sugars, and sucrose concentration exceeded that of fructose and glucose, which exceeded that of maltose. Total non-structural carbohydrate was least in basal vascular tissue (225 mg·g−1) and greatest in apical pith tissue (379 mg·g−1). Axial differences in NSC concentrations were negligible but radial differences were substantial. These results combine with past research to validate the non-woody cycad stem contains copious nonstructural resources available for deployment to ephemeral sinks during critical times of need.

Stem CO₂ efflux of Cycas micronesica is reduced by chronic non-native insect herbivory

Plant Signaling & Behavior

2020

Self Cite

Carbon dioxide efflux (E s ) from the base of Cycas micronesica K.D. Hill stems was quantified in four locations containing healthy populations and in one location with populations threatened by non-native insect herbivores in order to determine the influence of reduced plant health on E s . Minimal variation of E s occurred among the four locations with healthy plants, and E s ranged from 1.68 to 1.79 µmol•m −2 •s −1 . The threatened in situ populations were on the island of Guam, where recent invasions of non-native insects have caused epidemic plant mortality, and the E s was 0.59 µmol•m −2 •s −1 . This is the first known report of E s for any cycad species, and the values for the unique pachycaulous stem form fit in the lower half of the range of published E s for woody trees. The results illuminate the potential for using E s to screen in situ C. micronesica populations to identify the individual trees with the greatest likelihood of surviving conservation measures.