Flowering time as influenced by nitrate fertilisation in Ruppia drepanensis Tineo

Abstract

In a laboratory experiment, Ruppia drepanensis Tineo seedlings from a brackish marsh in southern Spain were grown with and without potassium nitrate (1.4 g N m −2 week −1 added to the water column), both under nutrient-rich (clay:sand mixture) and nutrient-poor (sand) sediment conditions. Potassium nitrate fertilisation delayed flower initiation within both types of sediment, but it also resulted in increased flower abundance under nutrient-poor sediment conditions. Differences between plants in flower production were positively correlated with the above- to belowground biomass ratio. We thus propose that nutrient supply and biomass allocation should be incorporated in the age- and size-dependent models for plant reproductive effort. These models should also consider separately the induction of flowering and the production of flowers (flower abundance).