Trait-based characterisation of cover plants' light competition strategies for weed control in banana cropping systems in the French West Indies

Cover plants can be used as an ecological tool to manage weeds through competition for shared resources. Assessing the abilities of a large number of different plant species to compete for light remains difficult. Our aim was to characterise the light competition strategies of a range of species on the basis of a small number of traits related to both acquisition of light and interference abilities, to help farmers choose the most suitable cover plant species for banana cropping systems. Using a trait-based approach, we identified and measured the most representative plant morphological and functional traits to characterize the light acquisition strategies of 21 plant species including banana, cover plants, and weed species. We identified trade-offs between plant traits and light acquisition strategies. We identified light competition strategies by taking into account the aboveground interference abilities of plants as defined by their growth habit. There was a wide range of variations between species for all the traits. Two main trade-offs were identified: resource acquisition vs. conservation and carbohydrates investment in height vs. leaf area. Five traits selected in a multivariate analysis explained 80% of the variability of light acquisition strategies in our panel of species. These were related to plant morphology (height and plant crown width), light conversion efficiency (specific leaf area), carbohydrate allocation (aboveground leaf area ratio), and carbohydrates demand (aboveground biomass). The growth habit and the light acquisition strategies were related. The characterisation of plant species using functional traits enabled us to hypothesise three light acquisition strategies shaped by interference abilities in four light competing strategies. We propose a new method to characterise and distinguish species through their ability to acquire light and to interfere aboveground with their neighbours. (Résumé d'auteur)