Protein:RNA ratios and N:P stoichiometry of “pygmy” and normal pines: A test of the growth-rate hypothesis

The growth-rate hypothesis suggests that the N:P stoichiometry of fast-growing organisms is low due to a large investment in P-rich ribosomal RNA to support protein synthesis. I analysed the balance of protein and RNA, and nitrogen and phosphorus, in the leaves of field-sampled Pinus contorta and P. muricata that were growing at different rates due to edaphic factors. I also moved "pygmy" individuals of both species from poor soils to nutrient-rich greenhouse pots and compared their protein:RNA and N:P ratios before and after the change to their growth rate and nutrient status. Although nutrient content, protein, and RNA content increased in faster-growing plants, data from the stoichiometric ratios did not conclusively support the growth-rate hypothesis.