Diversified impact of mycorrhizal inoculation on mother plants and daughter ramets in the clonally spreading plant Hieracium pilosella L. (Asteraceae)

Abstract

Resource allocation studies of clonal plants whose individuals form networks of interconnected ramets are very challenging. In addition, the presence of mycorrhizal fungi may further modify resource allocation. In this study, we sought to determine whether the impact of mycorrhizas on resource allocation occurs throughout the entire ramet network. The optimal division of resources is decisive for the potential ecological and evolutionary success of an individual. The study was carried out under uniform conditions on Hieracium pilosella (L.) networks with the same age. Data related to growth and reproduction were collected from the total of 47 mother plants and 210 daughter ramets that they generated. The differences between AMF-inoculated and non-inoculated plants with respect to continuous variables were tested using a one-way ANOVA. Mother plants that were inoculated with a mycorrhizal fungus displayed lower belowground dry biomass than the non-inoculated plants. The presence of the fungus did not affect the allocation of resources to other examined traits of the mother plants. The daughter ramets formed by the fungus-inoculated plants had larger rosette diameters and produced more inflorescence heads than did the non-mycorrhizal daughter ramets. In our study, the positive effect of mycorrhizas on resource allocation was observed only in the next vegetatively produced generation. The distribution of resources is a dynamic process and, from an evolutionary standpoint, it cannot be approached as a mere balance of benefits and losses observed at a given time point.