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ARS Home » Pacific West Area » Logan, Utah » Forage and Range Research » Research » Publications at this Location » Publication #177854
Title: MORPHOLOGICAL AND PHYSIOLOGICAL PLASTICITY OF ISATIS TINCTORIA: RESPONSES TO CONTRASTING LIGHT, SOIL-NITROGEN, AND WATER

Author
item Monaco, Thomas
item Johnson, Douglas
item CREECH, J - PURDUE UNIVERSITY

Submitted to: Weed Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/20/2005
Publication Date: 11/1/2005
Citation: Monaco, T.A., Johnson, D.A., Creech, J.E. 2005. Morphological and physiological plasticity of isatis tinctoria: responses to contrasting light, soil-nitrogen, and water. Weed Research 45:1-7.

Interpretive Summary: We evaluated the magnitude of morphological and physiological plasticity in response to contrasting above and below ground resources for the invasive weed, Isatic tinctoria L. (dyer's woad). Plants were grown under low and high levels of light (shade [50% of ambient] and full sun), soil water (50 and 100 ml day-1), and soil nitrogen (N) (0 and 20 mg N kg-1 soil) in 8-L pots in 63-day greenhouse experiments conducted during winter and spring. We did not reject the hypothesis that I. tinctoria has relatively less plasticity in response to nutrient addition than to variable light and soil water, and that plasticity is highly pronounced for traits that favor efficient capture of resources in heterogeneous light and water environments. Soil-N enrichment did not increase any of the growth variables (e.g., shoot and root dry mass, shoot:root ratio, leaf area, specific leaf area) or leaf gas exchange variables (photosynthetic rate and stomatal conductance) in either experiment. In contrast, variable water and light greatly altered growth allocation and physiology in ways that improve growth and persistence in shaded, more productive settings where competitive exclusion by other species may limit soil resource availability. We discuss the potential mechanisms whereby greater plasticity in response to water and light relative to soil-N may be associated with a series of adaptations that favor the ability to tolerate and colonize harsh, nutrient-poor conditions as well as confront environmental variability in light and water that exists when plants invade intact, more productive sites.

Technical Abstract: We evaluated the magnitude of morphological and physiological plasticity in response to contrasting above and below ground resources for the invasive weed, Isatis tinctoria L. (dyer's woad). Plants were grown under low and high levels of light (shade [50% of ambient] and full sun), soil water (50 and 100 ml day-1), and soil nitrogen (N) (0 and 20 mg N kg-1 soil) in 8-L pots in 63-day greenhouse experiments conducted during winter and spring. We did not reject the hypothesis that I. tinctoria has relatively less plasticity in response to nutrient addition than to variable light and soil water, and that plasticity is highly pronounced for traits that favor efficient capture of resources in heterogeneous light and water environments. Soil-N enrichment did not increase any of the growth variables (e.g., shoot and root dry mass, shoot:root ratio, leaf area, specific leaf area) or leaf gas exchange variables (photosynthetic rate and stomatal conductance) in either experiment. In contrast, variable water and light greatly altered growth allocation and physiology in ways that improve growth and persistence in shaded, more productive settings where competitive exclusion by other species may limit soil resource availability. We discuss the potential mechanisms whereby greater plasticity in response to water and light relative to soil-N may be associated with a series of adaptations that favor the ability to tolerate and colonize harsh, nutrient-poor conditions as well as confront environmental variability in light and water that exists when plants invade intact, more productive sites.