Hormonal Correlates of Seedling Growth of Two Vallisneria Species Grown at Different Current Velocities

Abstract

Seedling survival and growth of two common Vallisneria species in China, Vallisneria natans and Vallisneria spinulosa were quantified experimentally for current velocities from 0 to 40 mm/s. At the same time, changes in the concentrations of three hormones (IAA, ZR, and GA 3 ) in the leaves were compared to identify how current velocity influenced the two Vallisneria seedlings growth discrepantly. All plants survived in all treatments and showed positive growth. The most rapid growth for both species was found at the velocity of 10 mm/s. Although V. spinulosa showed faster growth than V. natans at the beginning of the experiment, there was no significant difference on final biomass. Higher IAA and ZR contents were measured in seedlings of both species grown under low current velocity. The time reaching the maximum for IAA and ZR was just around the time of a maximum seedling growth rate. IAA and ZR contents were positively correlated with growth rate. However, GA 3 was negatively associated with growth rate and more GA 3 in V. natans seedlings was induced by high current velocity.

Influence of flow turbulence on growth and indole acetic acid and H2O2 metabolism of three aquatic macrophyte species

“…The differences in plant growth among the treatments throughout the experimental period were analyzed with repeated measures analysis of variance (RM-ANOVA). The experimental data on hormone concentration in the plants were logarithmically transformed to ensure the normal distribution of data (Ke and Li 2006;Puijalon et al 2008). The homogeneity of variance test and Levene's check for equality of variances were performed on the data sets to verify the assumption of homogeneity of variances prior to performing a one-way ANOVA to check for significant differences (P \ 0.05) among the plants exposed to different turbulent conditions.…”

“…Indole acetic acid (IAA) is one of the major growth hormones related to shoot elongation and cell division. To our knowledge, the only study carried out on the correlation between hormones and the impact of current velocity on aquatic macrophytes was done on two Vallisneria species (Ke and Li 2006). It was observed that the IAA concentration was reduced in plants of both species exposed to current velocities ranging from 10 to 40 mm s -1 .…”

“…Though some of these modifications reduce damage to mature plants, plants in the early stages of growth are more vulnerable to damage (Doyle 2001), as the benefit of canopy formation is not yet available. Watermovement-induced mechanical stress may have a major impact on the survival of winter buds, turions or seedlings, which grow as individuals (Doyle 2001;Ke and Li 2006). Plant hormones play a major role in the regulation of developmental processes and in signaling networks involved in responses to biotic and abiotic stress (Bari and Jones 2009).…”

“…Plant hormones play a major role in the regulation of developmental processes and in signaling networks involved in responses to biotic and abiotic stress (Bari and Jones 2009). The response of aquatic plants to turbulence may also induce changes in plant hormones, though this has not been thoroughly explored (Ke and Li 2006). Indole acetic acid (IAA) is one of the major growth hormones related to shoot elongation and cell division.…”

The effect of flow turbulence on growth, nutrient uptake and stable carbon and nitrogen isotope signatures inChara fibrosa

“…However, water movement does not necessarily enhance nutrient uptake; it can inhibit plant physiological processes becoming a stress to the plants. Reduction of growth, variations of growth hormone concentration and development of oxidative stress have been observed when plants are exposed to flow and/or turbulence (Ke and Li, 2006;Ellawala et al, 2011aEllawala et al, , 2011b. In addition, reduction of the rate of photosynthesis, metabolism and reduction of nutrient uptake have also been observed in many aquatic plants, when they are exposed to water movement of any kind (Madsen et al, 1993;Ellawala et al, 2011a) and some authors hypothesized that this is a result of thigmomorphogenic effect (Madsen and Sondergaard, 1983).…”