In our new post, Curtis Lubbe from the Institute of Botany, Czech Academy of Sciences, Czech Republic, presents his latest work ‘Trash or Treasure: Rhizome conservation during drought’. Curtis discusses the wonders of the rhizome, elucidates his research on senescence, and shares some lovely whimsical drawings of plants.
About the paper
Many herbaceous perennial plants use rhizomes (stem-derived belowground storage organs) to store resources, grow, spread, and fuel and coordinate recovery after seasonal or recurrent disturbances. These are complex and dynamic structures built from units—internodes flanked by nodes from which new roots, buds, and branches may form—and in annual increments. These annual increments vary in persistence, and, after some time, these tissues die and decompose into the soil, potentially with lots of carbohydrates. Unfortunately, this process of rhizome senescence is little understood, as is the quantity of carbon released by this process. Unlike aboveground leaf litter, we cannot inherently see this process, nor is there any identifiable relationship to when during the year this occurs. Therefore, we must be clever if we want to see what is happening to these belowground organs and the release of carbon.
Many experiments have tested the role of rhizome connectivity in the movement of resources between ramets (rooting units that could potentially live as separate individuals), but not for the purpose of studying senescence. There are also numerous studies on decomposition and litter formation, but very few of these study rhizomes and those that do lack the comparisons between treatments that would provide valuable data on the senescence process. To assess the amount of carbohydrates moved from (or retained within) senescing rhizomes, we used a split-pot drought experiment inspired by these studies. For eight different species of rhizomatous herbs, specimens were placed in pots with one compartment containing the young and actively growing end of the rhizome, and the other had the older end. For all treatments, we watered the young end of the rhizome, but for half of the plants we stopped watering the old end of the plant. Plants were harvested several times during the growing season, and we measured biomass, fine root traits, and storage carbohydrate type and concentration for each individual compartment. This was done in order to finally have a comparison of these different stages within the life of a rhizome annual increment.
About the research
In a study carefully designed and carried out to study rhizome senescence, the rhizomes did not senesce—at least not sufficiently or due to the drought treatment. This was somewhat disheartening and means we need to find new ways to study rhizome senescence. It also means that these plants—exposed to heterogeneous drought conditions and the opportunity to lose the aging portion of their rhizomes—instead preserved both the rhizome and effectively all its storage carbohydrates, even in the same proportions regarding different types. Because they are complicated and hidden belowground, rhizomes are frequently overlooked. Some have even suggested that rhizomes and their carbohydrate storage is generally used for little more than to contain excess carbon assimilated when other factors (such as nutrients) are limiting growth.
This preservation of the rhizome lets us see that for a diverse range of species (regarding phylogeny and functional traits) from mesic temperate habitats, the rhizome and its carbohydrate storage are valuable resources to be saved and maintained, even under stress when it is just easy to relocate entirely to a more resource-rich location.
About the author
The intersection between organisms and the world around them is all about problem solving, so for me, ecology is about understanding how plants survive all these different problems (freezing temperatures, heat, shovels, etc.) with a certain assortment of tools, based on their morphology, anatomy, physiology, and biochemistry. It can feel like solving a mystery, or potentially like watching a drama (sometimes a horror movie). I really enjoy these glimpses into plant life and am frequently inspired to interpret them in assorted art forms.
Aside from ecology, I have an arts background and make ink illustrations for my science communication and outreach, and for my own amusement. I also make small ceramic sculptures. I do not just make visual art but have also begun writing about how people interpret images and the objects around them.
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