Biology subjects

Evers, J. B.

Publications and source records attributed to Evers, J. B..

2 recordsLinked to original sources

bioRxiv2023

Branching responses to pruning in cocoa

The branching pattern of a tree determines the efficiency of light interception and carbon assimilation. Pruning can modify the branching pattern, as a result of changes in physiological and environmental conditions, and ultimately pruning can have major effects on yield. For one of the major tropical tree crops, cocoa (Theobroma cacao), very little is known about branching response to pruning. To address this knowledge gap we performed a pruning experiment on young cocoa trees in Cote dIvoire. We applied five treatments: two heading treatments (the removal of the terminal apex or 66% of a branch) and two thinning treatments (the removal of 1 or 2 primary branches) and one unpruned control. The branching pattern of the primary branches was described by the number, position, and length of lateral branches right after pruning, and the same observations were repeated after a cycle of leaf production. The probability of branching and the length of lateral branches along a primary branch, in pruned and unpruned conditions, was analyzed using generalized mixed effect models. In unpruned conditions, the probability of branch presence was higher towards the middle of the primary branches and lower at the extremes. Branch length decreased going from the base to the tip of a primary branch. After one cycle of leaf production, new branches emerged preferentially on the distal section of a branch, but probability of branch emergence was reduced by the presence of other lateral branches. Pruning increased the probability of branch emergence mostly towards the tip of a branch, with heavy heading having the strongest effect. By contrast, heavy thinning increased branch emergence also toward the base of the branch. Our results can be applied to improve formation pruning, as this may trigger branching in different part of the crown, depending on the form of pruning. Our study also assists the development of three-dimensional tree models that could further our understanding of the impact of pruning on cocoa growth and productivity.

plant biology↗

bioRxiv2021

Effects of sub-lethal single, simultaneous, and sequential abiotic stresses on phenotypic traits of Arabidopsis thaliana

Plant responses to abiotic stresses are complex and dynamic, and involve changes in different traits, either as the direct consequence of the stress, or as an active acclimatory response. Abiotic stresses frequently occur simultaneously or in succession, rather than in isolation. Despite this, most studies have focused on a single stress and single or few plant traits. To address this gap, our study comprehensively and categorically quantified the individual and combined effects of three major abiotic stresses associated with climate change (flooding, progressive drought and high temperature) on 12 phenotypic traits related to morphology, development, growth and fitness, at different developmental stages in four Arabidopsis thaliana accessions. Combined sub-lethal stresses were applied either simultaneously (high temperature and drought) or sequentially (flooding followed by drought). In total, we analyzed the phenotypic responses of 1782 individuals across these stresses and different developmental stages. Overall, abiotic stresses and their combinations resulted in distinct patterns of effects across the traits analyzed, with both quantitative and qualitative differences across accessions. Stress combinations had additive effects on some traits, whereas clear positive and negative interactions were observed for other traits: 9 out of 12 traits for high temperature and drought, 6 out of 12 traits for post-submergence and drought showed significant interactions. In many cases where the stresses interacted, the strength of interactions varied across accessions. Hence, our results indicated a general pattern of response in most phenotypic traits to the different stresses and stress combinations, but it also indicated a natural genetic variation in the strength of these responses. Overall, our study provides a rich characterization of trait responses of Arabidopsis plants to sub-lethal abiotic stresses at the phenotypic level and can serve as starting point for further in-depth physiological research and plant modelling efforts.

plant biology↗