Study on nutrient stress tolerance of nine Taraxacum microspecies with a contrasting mineral ecology by cultivation in a low nutrient flowing solution

Abstract

1990. Study on nutrient stress tolerance of nine Taraxacum microspeeies with a contrasting mineral ecology by cultivation in a low nutrient flowing solution. -Physiol. Plant. 79: 389-399.Growth and mineral status of 9 Taraxacum miicrospecies were studied under mineral stress conditions, using a flowing solution of low nutrient concentration. Relative growth rate of (whole) plant dry weight, leaf area, and (whole) plant tissue water were used to describe growth. For 4 microspeeies, specific uptake rates of NOj, H2PO4", K+, Mg-* and Ca'* were investigated. The applied nutrient condition clearly discriminated between the studied Taraxacum mierospecies. With respect to relative growth rate, 3 groups of microspeeies could be distinguished: T. nordsledtii > T. lancidens, T. adamii, T. kollandicum, T. taeniatum > T. sellandii, T. eudontum, T. ekmanii, T. ancistrolobum. These categories coincided well with the mineral ecology of the microspeeies, going from infertile tO' fertile sites. T. nordstedtii, a microspeeies of infertile sites, was most efficient in absorbing NO^, HjPOi^and K*. T. sellandii and T. eudontum, both occurring in fertile grasslands, showed poor uptake performances for all studied ions. In all Taraxacum microspeeies studied, except T. eudontum, internal N conceBtration appeared to limit growth. Efficiencies in N use, at sub-optimal internal N concentrations, varied with the mineral habitat of the microspeeies studied. T. nordstedtii, from infertile sites, and 7". sellandii, from fertile sites, were established as high and low extremes, respectively.