Trifolium (kentuckiense)
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Jonathan Kubesch Breeder, Consultant Kubesch Seed Company Spring Hill, Tennessee 37174 6148678805 jakubesch@gmail.com |
| Family Scientific Name: | Fabaceae | ||
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| Family Common Name: | Legume | ||
| Scientific Name: | Trifolium kentuckiense Chapel and Vincent | ||
| Common Synonym: | Trifolium kentuckiense | ||
| Common Name: | Kentucky clover | ||
| Ecotype: | Woodford County, Franklin County | ||
| General Distribution: |
Bluegrass region of Kentucky. Subsequent information reprinted from white paper to the Kentucky Clover Recovery Team (2018). |
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| Known Invasiveness: | Native plant. | ||
| Propagation Goal: | Seeds | ||
| Propagation Method: | Seed | ||
| ProductType: | Container (plug) | ||
| Target Specifications: | Trifolium kentuckiense (Tk) is a newly discovered and extremely endangered species found solely in two counties within the Commonwealth of Kentucky. A new species, the monitoring efforts documented small populations previously, but additionally plant material is heavily desired (Dr. Julian Campbell pers comm 2018). Given the need to increase both the number of specimens and awareness of Tk, the present study ran a simple warm germination test on a blended lot of the species to determine whether seed could be grown out into the seedling stage. This test also noted the best-case viability for wild seed under optimal conditions, as well as the opportunities for propagation in controlled environments. | ||
| Propagule Collection: | Germplasm from a 2016 mixed lot of Woodford and Franklin county populations. | ||
| Propagule Processing: |
Seed was separated from existing chaff and observed for color and external damage. 20 seed from the lot of 33 seeds were selected at random for use in the experiment. Seed was propagated in two replicates of ten seed. Each replicate was spaced evenly on a moist paper towel substrate and closed in a sandwich bag; seed was not covered with the paper towel substrate as a modification of the Ashworth protocol (Ashworth 2002). These germination replicates were used as a paired replicate for the test. Replicates were suspended vertically with tape and kept at 72 deg F (22 deg C) in a sunny west-facing window (Vet Building, Middle Tennessee Research and Education Center; Spring Hill, TN). Temperature and paper towel moisture were derived from previous work in germination testing conducted at the Ohio Seed Improvement Association on commercial clover seed. The temperature agreed with standard germination testing at 20 deg C. Germination—defined herein as the protrusion of the radicle—was measured for 7 days. Radicle length was measured over the course of the study. Counts of hard seed, imbibed (but not germinated), and germinated seed were taken 8 days into the test. At this point, due to some mold contamination, germinated seed was planted, whereas hard seed and imbibed seed were scarified and transferred to tap water sample cups; scarification was justified as per work with similar native Trifolium as well as a general germination guidelines (Kubesch 2018; Davies et al 2015). Planted seedlings grew in pulp seeding pots (Hong Kong) filled with “Cactus, Palm & Citrus” potting mix (Scotts Miracle-Gro Company, Marysville, OH). These pots went into the same west-facing windows as previously described. Description of Seed lot The original seed lot traces back to a mixture of the two known populations; labeling on the source container suggested the seed was collected in 2016 (Dr. Julian Campbell pers comm 2018). After separating remnants of the flower anatomy, the seed lot consisted of 3 seeds. Two variants were observed: a yellow and a darker brown. Two of the brown seed appeared to have already protruded their radicles and perished (Figure 1). No attempt was made to separate the color variants for the replicates, and no differences in germination were observed in the blended lots. |
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| Establishment Phase: |
Plant material was sourced as described in the Germination section of this project. Seedlings were collected from germination testing and potted up in a south facing window. In order to maintain usable plant material at the end of the study for the next stages of the project, extreme treatments and gradients were avoided. Plants were randomized and divided into two groups. Each plant was considered an experimental unit. Several plants were placed outside the south facing window for a week and retrieved when the sunlight 9 exposure started negatively affecting the plants. Experimentation was not feasible, and thus the goals of the propagation study refocused from environmental testing to simply maintaining a population. Urea (33-0-0; Tennessee Farmer’s Cooperative, LaVergne, TN) was applied at a rate of one gram per pot at a point where any starter fertilizer in the potting mix would likely be exhausted. Triple 15 (15-15-15; Tennessee Farmer’s Cooperative, LaVergne, TN) was applied at a rate of two grams per pot in a subsequent fertilization to supply the P and K absent in the potting mix. When the author relocated from the Middle TN Research and Education Center to the University of Tennessee at Knoxville, the plants were moved into a full sun, south-facing window. The watering and fertilization regime remained constant following this move from Middle TN to East TN |
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| Active Growth Phase: |
Plants responded to urea readily and quickly. Chlorotic symptoms were much more visible than expected, though no conventional signs of P and K deficiencies arose. The plants continued to grow vigorously through a 98 day period from May 25 to August 31, 2018. Unfortunately, the plants completely senesced in the last week of the growth period (Table 2). The attempted lighting experiment led to a 66% fatality in the outside group, which might lend further credence to light exposure mortality. Plants achieved at least a V5 or V6 stage during the growth period. No floral structures developed throughout the course of the period, and the growth points put out leaves in regular intervals. The roots—during an examination—were few, but quite long, penetrating the bottom of the peat pots. Despite the intrusion of the observation, the plants seemed no worse for the wear, contrary to earlier observations regarding the sensitivity of the root structure (Dr. Julian Campbell pers comm 2018). The plants behaved similarly to greenhouse specimens of running buffalo clover. |
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| Other Comments: |
Trifolium kentuckiense is a severely endangered native clover known only to two counties in central Kentucky. As a consequence of its perilous state in the wild, efforts to rear plants to maturity in the lab and greenhouse are imperative to better understanding the agronomic and ecological factors affecting the species. An additional benefit of these efforts includes the increase in known plants as well as a supply of plants that will not directly harm the wild populations. Compared to cultivated Trifolium, and even to previous germination tests in native Trifolium, Tk has limited germination success (Erica Sustar 2017). Seed quality, age, and life history might all contribute to this limited success. Additional evaluation of these different aspects of germination success is warranted, especially in future attempts to produce plant material. As a species with only two small populations, drift likely exerted more force on allele frequencies than selection. As such, seed may be genetically predetermined to fail (Kubesch 2018). In agronomic and physiological realms, the seed set may be low due to currently unknown pollinator dynamics. Seed is known to germinate precociously on the inflorescence, and the seed germinated may be a part of this early starting seed. A scarification requirement has not been observed as exists in Trifolium stoloniferum, but for the purposes of seed increase, scarification might help rescue more embryos (Kubesch 2018). A stratification requirement should not be needed, as seed is produced in spring and plants are generally growing following the May flowering period (Dr. Julian Campbell pers comm 2018). The future of Tk, both in the field and as a species, will require getting wild seed to proceed through this crucial life history stage. Given the challenges of Tk in germinating under ideal conditions, propagating plants to generate more seed will continue to be a challenge. Seed collection in the wild may be disastrous to the two wild populations, and should be done in a sparing manner until cultivated seed stock might be produced. |
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| References: |
Ashworth, S. 2002. Home Germination Testing. Seed Savers Exchange, Decorah, IA Barker, D. 2018. Personal communication Campbell, J. 2018. Personal communication Chapel, K.J. and M.A. Vincent. 2013. Trifolium kentuckiense (Fabaceae, Papilionoideae), a new species from Franklin and Woodford counties, Kentucky. Phytoneuron 2013-63: 1–6. Kubesch, J. 2018. Propagation of a native endangered clover. Report to the Kentucky Clover Recovery Team. Kubesch, J. 2018. Edaphic and morphological factors affecting running buffalo clover (Trifolium stoloniferum) ecology. Undergraduate Thesis. http://hdl.handle.net/1811/84873. Ohio State University, Columbus, OH Davies, R., di Sacco, A., and Newton, R. 2015. Germination testing: procedures and evaluation. Royal Botanic Gardens, Kew, United Kingdom Sustar, E. 2017. The Effects of Scarification on Germination Rates on Running Buffalo Clover. Independent Study Project, unpublished. Ohio State University, Columbus, OH. |
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Citation:
Kubesch, Jonathan Omar Cole. 2019. Propagation protocol for production of Container (plug) Trifolium kentuckiense Chapel and Vincent Seeds Kubesch Seed Company Spring Hill, Tennessee. In: Native Plant Network. URL: https://NativePlantNetwork.org (accessed 2024/04/24). US Department of Agriculture, Forest Service, National Center for Reforestation, Nurseries, and Genetic Resources.
