Morphological plasticity of submerged macrophytePotamogeton wrightiiMorong under different photoperiods and nutrient conditions

Abstract

The morphological plasticity of the submerged macrophyte Potamogeton wrightii under different nutrient conditions and photoperiods was measured in a laboratory controlled experiment for 70 days in Japan. Six treatments were used in this experiment (3 × 2 factorial design with three replications) which consisted of three photoperiods and two nutrient conditions. Both photoperiod and nutrient condition had a pronounced effect on shoot and leaf morphology in P. wrightii. New shoot recruitment, and the length of main and new shoots gradually decreased with shortening photoperiod under both nutrient treatments. Plants under an 8 h photoperiod and high nutrient levels generated significantly more dead leaves (7.42 leaf·shoot −1 ) and decomposed shoots (1.3 shoots·pot −1 ) than plants under other treatments. Under short photoperiods (12 and 8 h) plants failed to produce flowering spikes in both nutrient conditions. In high nutrient conditions, P. wrightii produced shorter shoots, fewer leaves with shorter and narrower laminas, and smaller petioles compared with plants in the low nutrient condition. This may be adaptive under high nutrient conditions because it lowers foliar uptake and, thus, nutrient toxicity.

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“…Some develop acclimation mechanisms or adaptations, allowing then to extract resources from adjacent environments. Phenotypic plasticity might include the environmentally dependent expression of phenotypes that alter physiological processes or morphology, and the morphological plasticity in aquatic plants is often considerable (Sultana et al, 2010). The relative importance of roots and shoots for nutrient uptake may vary between environments (Barko and James, 1998;Eugelink, 1998).…”