Drought Response of Three Ornamental Herbaceous Perennials

Abstract

Boltonia asteroides L. 'Snowbank' (Snowbank boltonia), Eupatorium rugosum L. (eastern white snakeroot), and Rudbeckia triloba L. (three-lobed coneflower) were subjected to drought for 2, 4, and 6 days during the fall and spring. Leaf gas exchange, leaf water potential, growth, and carbohydrate partitioning were measured during drought and throughout the following growing season. Leaf gas exchange of B. asteroides was not affected by drought treatment in the fall, not until day 6 of spring drought, and there were no long-term effects on growth. Transpiration and stomatal conductance of R. triloba decreased when substrate moisture decreased to 21% after drought treatment during both seasons. Assimilation of drought-treated R. triloba decreased when substrate moisture content decreased to 12% during spring but was not affected by drought in the fall. There was a decrease in the root-to-shoot ratio of R. triloba that had been treated for 4 days, which was attributed to an increase in the shoot dry weight (DW) of treated plants. Reductions in spring growth of E. rugosum were observed only after fall drought of 6 days, and there were no differences in final DWs of plants subjected to any of the drought durations. Spring drought had no effect on growth index or DW of any of the perennials. Boltonia asteroides and R. triloba had increases in low-molecular-weight sugars on day 4 of drought, but E. rugosum did not have an increase in sugars of low molecular weight until day 6 of drought. Differences in drought response of B. asteroides, E. rugosum, and R. triloba were attributed to differences in water use rates.

Evaluation of Irrigation Frequency and Quantity on Leaf Gas Exchange, Growth, and Nitrate Leaching of Coleus in a Simulated Landscape

“…Gray (blue palo verde; Stabler and Martin, 2000). Prevete et al (2000) reported similar results as coleus for Rudbeckia triloba L. (Mexican petunia). Assimilation, E, and g S were reduced after exposure to drought cycles of 2, 4, or 6 d (stress level days); however, treatments had no effect on growth indices or dry weight of Rudbeckia.…”

Influence of Substrate Water Content and Daily Light Integral on Photosynthesis, Water Use Efficiency, and Morphology of Heuchera americana

“…A N of Salvia splendens (annual salvia), Catharanthus roseus (annual vinca), petunia, and bedding impatiens also did not differ among q ranging from 0.15 to 0.32 LÁL -1 (Nemali and van Iersel, 2008). Conversely, A N of Eupatorium rugosum (eastern white snakeroot) and Rudbeckia triloba (three-lobed coneflower) was negatively impacted by q (Prevete et al, 2000). Care should be taken when comparing plant responses to prolonged, regulated deficit irrigation (as in Nemali and van Iersel, 2008) with responses in plants exposed to short-term water deficits such as Prevete et al (2000).…”

“…Conversely, A N of Eupatorium rugosum (eastern white snakeroot) and Rudbeckia triloba (three-lobed coneflower) was negatively impacted by q (Prevete et al, 2000). Care should be taken when comparing plant responses to prolonged, regulated deficit irrigation (as in Nemali and van Iersel, 2008) with responses in plants exposed to short-term water deficits such as Prevete et al (2000). Both types of water stress investigations may be valid, but they can be influenced by factors other than the current q such as the degree to which the plants acclimated to drought (Jones, 2007).…”

Drought Responses among Seven Southwestern Landscape Tree Taxa

“…Averaged over all species, control plants had 23% more leaf DW per gram of dry roots and 24% more shoot DW than drought-stressed plants ( Table 3), indicating that drought reduced foliar dry matter accumulation. In many plant species, drought decreases root growth less than shoot growth (Prevete et al, 2000;St. Hilaire and Graves, 2001).…”