Resource manipulation through experimental defoliation has legacy effects on allocation to reproductive and vegetative organs in Quercus ilex
Résumé
Background and Aims In plants, high costs of reproduction during some years can induce trade-offs in resourceallocation with other functions such as growth, survival and resistance against herbivores or extreme abioticconditions, but also with subsequent reproduction. Such trade-offs might also occur following resource shortageat particular moments of the reproductive cycle. Because plants are modular organisms, strategies for resource allocationto reproduction can also vary among hierarchical levels. Using a defoliation experiment, our aim was totest how allocation to reproduction was impacted by resource limitation.• Methods We applied three levels of defoliation (control, moderate and intense) to branches of eight Quercusilex trees shortly after fruit initiation and measured the effects of resource limitation induced by leaf removal onfruit development (survival, growth and germination potential) and on the production of vegetative and reproductiveorgans the year following defoliation.• Key Results We found that defoliation had little impact on fruit development. Fruit survival was not affected bythe intense defoliation treatment, but was reduced by moderate defoliation, and this result could not be explainedby an upregulation of photosynthesis. Mature fruit mass was not affected by defoliation, nor was seed germinationsuccess. However, in the following spring defoliated branches produced fewer shoots and compensated for leafloss by overproducing leaves at the expense of flowers. Therefore, resource shortage decreased resource allocationto reproduction the following season but did not affect sex ratio.• Conclusions Our results support the idea of a regulation of resource allocation to reproduction beyond theshoot scale. Defoliation had larger legacy effects than immediate effects.
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