Extension Growth of Impatiens glandulifera at Low Irradiance: Importance of Nitrate and Potassium Accumulation

Abstract

It is concluded that accumulation of NO(3)(-) in place of organic molecules in stems is an important mechanism allowing I. glandulifera to achieve substantial height at low irradiance.

The biology of invasive alien plants in Canada. 9. Impatiens glandulifera Royle

“…In both open and shady areas the adaxial surface had a higher density of stomata than the abaxial surface (Beerling and Perrins 1993 Beerling and Perrins 1993). The concentration of organic and inorganic compounds was found to differ in areas with contrasting amounts of sunlight (Andrews et al 2005). Leaf and stem NO 3 ( levels were negligible at 50Á100% irradiance and potassium, malate 2( and sugars, respectively, accounted for 33.2Á50.1%, 19.3Á20.8% and 2.0Á2.6% of total osmoticum in stems (Andrews et al 2005).…”

“…The concentration of organic and inorganic compounds was found to differ in areas with contrasting amounts of sunlight (Andrews et al 2005). Leaf and stem NO 3 ( levels were negligible at 50Á100% irradiance and potassium, malate 2( and sugars, respectively, accounted for 33.2Á50.1%, 19.3Á20.8% and 2.0Á2.6% of total osmoticum in stems (Andrews et al 2005). At irradiance levels of 2Á10%, NO 3 ( concentrations were four to eight times greater in stems than leaves; Andrews et al (2005) concluded that these high concentrations in the stems enabled I. glandulifera to reach heights up to 3 m even at low light levels, with NO 3…”

“…Plants from shaded sites had a higher maximum biomass likely due to increased leaf area ratio, but plants from open areas had a higher maximum relative growth rate (Beerling and Perrins 1993). The increased concentration of nitrate in plants from shaded sites gives the plants a competitive advantage and allows them to reach great heights (Andrews et al 2005).…”

AFestschriftin honour of Professor John A. Raven

“…He concluded, for example, that photon and water savings can be made with nitrate assimilation in comparison with nitrogen fixation but this is dependent on site of nitrate assimilation (root or shoot) and mechanism of pH regulation. Subsequent work has altered some of the stoichiometries used by Raven (1985) but recent revisions of the calculations indicate that they are an underestimate by only a few percent at most, and that the order of costs is unaltered as a function of pathway or site of nitrogen assimilation or the mechanism of pH regulation (Andrews et al , 2005(Andrews et al , 2009a A further area is that of how the earliest embryophytic plants functioned in their early-and mid-Palaeozoic environment (Raven 1977(Raven , 1993(Raven , 1995(Raven , 2002Raven and Edwards 2001). Here, John has considered the evolution of important extant higher plant features such as roots, long-distance transport processes, intercellular gas spaces, cuticle and stomata.…”

“…One of us was fortunate enough to have had John as a lecturer at undergraduate level, as a Ph.D. supervisor, and then to have worked with him over the following 25 years building on some of his earlier work (e.g. Andrews et al 1984Andrews et al , 1999Andrews et al , 2005Andrews et al , 2009aRaven et al 2004Raven et al , 2005a. We highlight two areas of John's current research -firstly, 'Interactions among resources in the growth of phytoplankton', and secondly, 'The potential for photosynthesis on other planets'.…”