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United States Department of Agriculture

Agricultural Research Service

Research Project: BIOLOGICALLY BASED INTEGRATED MANAGEMENT OF INVASIVE AQUATIC AND RIPARIAN WEEDS

Location: Exotic and Invasive Weeds Research

Title: Variation in Arundo Donax Stem and Leaf Strength: Implications for Herbiovry

Authors
item Spencer, David
item Tan, Wailun -
item Whitehand, Linda

Submitted to: Aquatic Botany
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: March 5, 2010
Publication Date: May 19, 2010
Citation: Spencer, D.F., Tan, W., Whitehand, L.C. 2010. Variation in Arundo Donax Stem and Leaf Strength: Implications for Herbiovry. Aquatic Botany. 93(2):75-82.

Interpretive Summary: There is little information about giant leaf or stem strength which can be applied to predict potential interactions with biological control agents. We determined leaf and stem strength for plants collected at different locations and times. Leaf strength showed important changes depending on the sampling date, sampling location, type of leaf sampled, and position within the leaf where the measurement was taken. In general leaf strength was greater near the base of the leaf and decreased with distance away from the base; leaf strength changed as the growing season progressed; and first year leaves had leaf strength values about 25% greater than leaves produced on stems greater than 1 year old. Mean stem strength decreased by approximately 6.8 % from one leaf position to the successive leaf position moving in the direction of the shoot tip. These results suggest that assessment of plant material used in testing the survival and efficacy of potential biological control agents in quarantine, should include measures of both plant physical attributes so that they can be compared to conditions found in the open environment.

Technical Abstract: One aspect of a plant’s resistance to herbivory is determined by the physical properties of its leaves and stems. There is little information about Arundo donax leaf or stem strength which can be applied to predict potential interactions with herbivores, nor how these physical properties might interact with nutritional characteristics of the plant. We determined leaf and stem strength for A. donax from plants grown in geographic areas and at different times within their growing cycle. Mean leaf strength for plants collected within California was 1.72 N and ranged from 0.36 N to 6.32 N, based on 1170 individual determinations. For leaves collected at 30 sites within four states between July 11 and 20, 2007, mean leaf strength was 1.58 N based on 936 determinations. Values ranged from 0.24 N to 4.90 N. Overall, leaf strength showed statistically significant changes depending on the sampling date, sampling location, type of leaf sampled, and position within the leaf where the measurement was taken. In general leaf strength was greater near the base of the leaf and decreased with distance away from the base; leaf strength changed as the growing season progressed; and first year leaves had leaf strength values about 25% greater than leaves produced on stems > 1 year old. Stem strength and stem wall thickness were strongly correlated (Kendall’s Tau b = 0.92, P < 0.0001, N=26). Linear regression indicated that mean stem strength decreased by approximately 6.8 % (95% confidence limits 5.8 to 7.7%) from one node to the successive node progressing from the stem base to the shoot tip. These results have implications for the impact of insect herbivores used as biological control agents against A. donax.

Last Modified: 7/24/2014
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