Growth and phosphorus productivity of non-mycorrhizal Pinuspinaster seedlings: Comparison of three populations and seven full-sib families within a population

Abstract

Growth and nutrition of hydroponically cultivated pine seedlings (Pinus pinaster Ait.) were investigated at various phosphorus (P) availabilities. P was added either with free access or at a relative addition rate of 0.02 and 0.04 day⁻¹. Laboratory observations were compared with adult growth performances in the field in two sets of experiments: the first with three contrasting populations, the second with seven full-sib families within a population. Significant differences in P productivity (growth rate per unit P in the plant) and in maximal relative growth rate were observed in both experiments, but correlation with adult performances was restricted to populations. Selection for nutrient-related traits would thus be possible, but understanding of the relationship between growth and nutrition needs further evaluation. The minimum P concentration in the seedlings supporting maximum growth ([P]optimum) varied from 2.2 to 3.8 mg g⁻¹ DM, which is in agreement with values obtained in other species. The root/shoot ratio increased with P limitation, with a marked tendency for the population with the highest adult height performance. Inversely, within families, seedlings identified as the best performers for adult growth invested more biomass in shoots than in roots with P stress.

Keywords:

• Genotypes
• maritime pine
• steady-state growth

Acknowledgments

The authors are grateful to N. Yahaya, C. Lambrot and J. L. Grange for P analyses and technical handling on the growth units. The investigations were supported by grants from the European Union (FAIR5 CT97-3454: “Exploitation of Nutrient Efficiency in Forest Tree Breeding”, NUTRIGEN).