Variación genética y efecto de la disponibilidad de nutrientes en las defensas constitutivas e inducidas de Pinus pinaster Ait.

Résumé

[EN]: Maritime pine (Pinus pinaster) is a species of vital importance to the economy and ecology of Mediterranean and Atlantic forests. In the last decades, several breeding programs for maritime pine in Iberian Peninsula were started looking forward to improve growth, stem form and branching characteristics. Previous field studies in progeny x fertilization trials of the Galician breeding program reported an important genetic variation in the resistance to the phloem-feeder Hylobius abietis which causes large juvenile mortality in several conifer species in Europe. Moreover, this insect fairly preferred fertilized pines, especially with calcium phosphate, regarding unfertilized plants. These results gave us the opportunity to test how fertilization with phosphorus (P, the limiting nutrient in Galician forest soils) and genotype affect the constitutive and induced mechanisms of defence, and fitness costs associated to their production. According to several ecological theories, increases in resource availability for plants could decrease the resource allocation to defences, but no information is available about the relative contribution of constitutive and induced defences to the overall resistance of juvenile pine trees.