Analysis of nitrogen seed reserves of ten tree species of the tropical dry forest

• We studied the functional diversity in the partitioning of N inside seeds.
• We studied ten tree species from five families in a tropical dry forest.
• The species tested had differential distributions of seed N-containing compounds.
• The N concentration was positively correlated with the amino acid concentration.
• We studied the ecological role of N reserves.

Nitrogen is a component of many seed reserve compounds, which play a remarkable role during germination and have great value for predators. A predefined coefficient factor is used to determine the protein concentration from the seed nitrogen concentration. However, this calculation may not reflect the variety of nitrogen compounds present in seeds and their ecological role. Understanding how the seed nitrogen content is distributed between amino acids and proteins will help explain how nitrogen compounds are involved in seed metabolism. We studied the heat-stable protein and total amino acid concentrations in ten tree species in a tropical dry forest in northwest Mexico. The seed nitrogen concentrations formed a continuum in the studied species. The total amino acid concentration was positively correlated with the nitrogen concentration. During germination, a differential decrease in the nitrogen, total amino acid, and heat-stable protein contents was detected among the species. Functional diversity in the partitioning of nitrogen inside seeds is discussed.