Highly Successful Adventitious Root Formation of Zamia L. Stem Cuttings Exhibits Minimal Response to Indole-3-Butyric Acid

Abstract

The influences of indole-3-butyric acid (IBA) concentrations of 0–30 mg·g−1 on the success and speed of adventitious root development of Zamia furfuracea L.f. and Zamia integrifolia L.f. stem cuttings were determined. Root formation success for both species was greater than 95%. The IBA concentrations did not influence the speed of root development for Z. furfuracea, but the Z. integrifolia cuttings that received IBA concentration of 3 mg·g−1 generated adventitious roots more slowly than the cuttings in the control group. The ending dry weights of the stems, leaves, and roots were not influenced by IBA concentration for either species. Our results indicated that adventitious root formation on stem cuttings of these two Zamia species is successful without horticultural application of IBA. Additional IBA studies are needed on the other 300+ cycad species, especially those that are in a threatened category.

Leaf Retention on Stem Cuttings of Two Zamia L. Species With or Without Anti-transpirants Does Not Improve Adventitious Root Formation

“…Moreover, most of the literature on cycad propagation is anecdotal and no data were reported to support the published recommendations. Our use of destructive sampling at the end of the studies to obtain dry weights for the purpose of quantifying plant growth has also been used in only one other study (Deloso et al., 2020).…”

“…This is the first replicated study that directly addressed the issue of leaf retention on cycad stem cuttings. We used a robust number of replications that has been used in only one other study (Deloso et al., 2020), while the number of replications was not reported for most of the past reports on cycad horticulture studies. Moreover, most of the literature on cycad propagation is anecdotal and no data were reported to support the published recommendations.…”

“…Using commercial products designed to reduce water loss from plant leaves did not influence the percentages or speed of propagation success for stem cuttings. In our previous research we detailed efforts by cycad nurseries in rural municipalities to aid in reintroduction efforts of cycads back to wild populations and supplement local farmer income (Deloso et al., 2020). Indeed, cycad conservationists in countries where these commercial products are difficult to procure need not go to the expense of trying to obtain these products.…”

“…Previous studies on cycad asexual propagation did not utilize replicated trials and more importantly did not include a control group. The first replicated trial investigating adventitious root formation on cycad stem cuttings found that a wide dose range of indole-3-butyric acid (IBA) exhibited little influence on numerous traits, including the speed of initial root formation (Deloso et al., 2020). Additionally, to our knowledge there have been no replicated trials that objectively determined the positives or negatives that result from retaining leaves on cycad stem cuttings.…”

Stem Branching of Cycad Plants Informs Horticulture and Conservation Decisions

“…This shrub-like habit can be found in several Zamia species throughout the geographic range of the genus [32] but is most common in Caribbean species such as Z. integrifolia, and Mexican species, such as Z. furfuracea, one of the most abundantly cultivated cycads in the world. Small basal stem cuttings of cycad plants are highly successful in producing adventitious roots [33][34][35]. This knowledge may be exploited to clonally propagate a female or a male tree to obtain the desired landscape objective.…”