Kin recognition in plants: a plea to consider competitive ability

International audienceNumerous studies have focused on plant-plant positive interactions in opposition to the classic view of predominant negative interaction between individuals (competition and niche partitioning), and concluded that kin recognition could explain the observed reduction in biomass or growth. Black poplar (Populus nigraL.) is a threatened riparian tree species growing in stressful condition in densely populated patches. We investigated the interactions in early-life stages of black poplar grown with kin (same maternal progeny) or strangers (different maternal progenies) in two experiments and measured growth and nitrogen uptake. Individuals responded differently when grown with kin compared to grown with strangers. Difference in competitive ability between maternal progenies was the most parsimonious interpretation, thus eliminating kin recognition as an explanation. This suggests that results obtained in kin studies must be carefully analyzed and that alternative interpretations, such as differences in competitive ability, must be tested before concluding to kin recognition