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United States Department of Agriculture

Agricultural Research Service

Title: Estimating Arundo Donax Ramet Recruitment Using Degree-Day Based Equations

Authors
item Spencer, David
item Ksander, Gregory

Submitted to: Aquatic Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 9, 2006
Publication Date: November 1, 2006
Citation: Spencer, D.F., Ksander, G.G. 2006. Estimating arundo donax ramet recruitment using degree-day based equations. Aquatic Botany. 85:282-288.

Interpretive Summary: Arundo donax L. is a tall perennial reed that has invaded riparian zones where it changes important ecosystem properties. The ability to predict plant growth is an important step to integrated management. We sought to determine if nitrate levels in soil water or temperature played key roles in regulating shoot emergence. Contrary to results from studies on seed germination, sprouting of giant reed rhizomes was not influenced by nitrate level. Temperature played a more important role in regulating shoot emergence. We used this information in combination with ramet emergence data from plants grown outdoors at Davis, California to develop degree-day equations for three separate groups of shoots that emerged during a single growing season. When compared to ramet emergence from different plants in different years, there was very good agreement between predicted and actual shoot emergence indicating that these equations provide a realistic representation of processes involved in shoot emergence. This is an important step in developing integrated management plans for this invasive plant species.

Technical Abstract: Invasive plant species significantly alter ecosystem structure and function. Arundo donax is an invasive weed of California riparian zones. Once established, it spreads by clonal expansion, which is dependent on the production of new shoots (ramets) from rhizomes. We performed experiments to test the hypotheses that temperature (7, 8, 14, 16, or 20 C) and nitrate concentration (0, 0.3, 0.6,1.2, 2.4, 3.6, 4.8, 6.0 mg/l nitrate) regulated the initiation of ramet production. No ramets emerged from rhizome sections at 7 C or 8 C, but ramets emerged at 14 C, 16 C, and 20 C. Neither time to ramet emergence nor the number of ramets that emerged was influenced by nitrate level in the watering solution. We used the above results in combination with ramet emergence data from plants grown outdoors at Davis, California to develop degree-day equations for three separate ramet cohorts. When compared to ramet emergence from different plants in different years, there was very good agreement between predicted and actual ramet emergence indicating that these equations provide a realistic representation of processes involved in ramet emergence. This is an important step in developing integrated management plans for this invasive plant species.

Last Modified: 8/1/2014
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