Location: Invasive Species and Pollinator HealthTitle: The effect of temperature on Waterhyacinth stembase regrowth
|Miskella Jr, John|
Submitted to: Journal of Aquatic Plant Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/8/2018
Publication Date: N/A
Interpretive Summary: Under controlled experimental conditions, waterhyacinth requires water temperatures greater than 10 C to initiate sprouting of leaves and stolons in the spring. A warm early spring with low flows will induce growth earlier, requiring an early response to management efforts. Colder spring weather or heavy runoff may delay sprouting and growth of waterhyacinth. Managers may wish to monitor spring water temperature as a key indicator of when nuisance plants will begin to grow.
Technical Abstract: Waterhyacinth (Eichhornia crassipes (Mart.) Solms)) stem bases were collected from sites in the Sacramento-San Joaquin Delta during the winter of 2016. The stem bases were divided into nine groups of ten. Each group of stem bases was placed in a 38.7L mesocosm at a constant water temperature with a light regime of 14 light/10 dark. Each of the mesocosms was randomly assigned one of three constant water temperatures (5C, 10C, and 15C). The number of leaves per stembase, cumulative length of leaves per stembase, the number of stolons per stembase, and the cumulative length of stolons per stembase were quantified twice per week for each stembase (n=90), beginning at 9 days after collection and continuing until 54 days after collection. Each of these growth characteristics were variable (P < 0.001) when analyzed using ANOVA (R. v3.3.2 2016) to detect differences (P = 0.05) among temperature means 54 days after collection. Mean separations of significant effects were evaluated with Tukey’s HSD test (P = 0.05). For each of these growth characteristics, there was no significant difference between 5C and 10C (P > 0.99), but there were significant difference between 5C and 15C (P < 0.001) and 10C and 15C (P < 0.001). No stolons were produced at 5C or 10C, while 10 of the 30 stembases at 15C produced stolons by 54 days (x=0.43mm (+ 0.12 mm) with a mean cumulative length of 6.00 mm + 1.71mm). Stolon growth is a key driver of waterhyacinth dispersal. With greatly reduced leaf and stolon production at 5C and 10C, waterhyacinth would disperse at a far lower rate, and would be easier to manage than the stembases exposed to 15C. Regrowth in the spring requires a water temperature of between 10C and 15C.