Patterns of biomass allocation in Spinacia oleracea (Chenopodiaceae) across a salinity gradient: evidence for a niche separation

Spinacia oleracea var. Americana was hydroponically grown across an experimental salinity gradient ranging from 0.0 to 6.0 grams NaCl/liter nutrient medium. Twenty male, 20 female, and 20 monoecious plants were randomly harvested from each treatment where possible. Root biomass (RTA), biomass allocated to leaves and stems (VA), and reproductive biomass (RA) were determined. Male, female, and monoecious plants were shown to have significantly different patterns of RTA, VA, and RA. Moreover, the treatments influenced allocation patterns of the sexes differently, i e., a partial niche separation was observed among the sexes along the gradient with respect to RTA, VA, and RA. Additionaly, the sexes expressed different trade-offs between allocation of resources to the different tissues; most notably, under high salinity, RTA, and RA were strongly negatively correlated in females, but positively correlated in male and monoecious plants.