Biology subjects

Rouan, L.

Publications and source records attributed to Rouan, L..

3 recordsLinked to original sources

bioRxiv2022

Combining modelling and experimental approaches to assess the feasibility of developing rice-oil palm agroforestry system

Climatic hazards affecting the main rice producing regions of Indonesia increase the risk of annual production loss and encourage the development of innovative strategies to maintain stable production. Conversion of oil palm monocultures to rice-based intercropping systems is a strategy to be considered, but relies on the existence of suitable planting management that optimizes both palm productivity while providing enough light for undergrowth rice varieties tolerant to shady conditions. This paper proposes to couple a model of light interception on virtual canopies with indoor experiments to evaluate the feasibility of developing rice-oil palm agroforestry systems. We first selected a planting design that optimized the transmitted light available for rice using a functional-structural plant model (FSPM) of oil palm. Secondly, we reproduced the light regime simulated with specific changes in the intensity and the daily fluctuation of light in controlled conditions. Three light treatments were designed to test independently the effect of daily light quantity and the effect of diurnal fluctuation on contrasted rice subpopulations. Light quantity was the main factor driving changes in plant morphology and architecture, while light fluctuation only appeared to explain variations in yield components and phenology. This study highlighted the importance of light fluctuation in the grain filling process and resource reallocation. The conservation of relative change among varieties between treatments suggests that varietal responses to low light are likely to be heritable, and that varietal screening under full light can provide clue on varietal behavior under low light. However, the identification of specific traits such as a limited expansion of leaf area and a conservation of leaf senescence under shade and high light fluctuation paves the way for selecting varieties dedicated to agroforestry systems. Further investigations including light quality and larger genotypic population to screen are discussed.

plant biology↗

bioRxiv2021

Into the range: a latitudinal gradient or a center-margins differentiation of ecological strategies in Arabidopsis thaliana?

Background and AimsDetermining within-species large-scale variation in phenotypic traits is central to elucidate the drivers of species ranges. Intraspecific comparisons offer the opportunity to understand how trade-offs and biogeographical history constrain adaptation to contrasted environmental conditions. Here we test whether functional traits, ecological strategies and phenotypic plasticity in response to abiotic stress vary along a latitudinal or a center-margins gradient within the native range of Arabidopsis thaliana. MethodsThe phenotypic outcomes of plant adaptation at the center and margins of its geographic range were experimentally examined in 30 accessions from southern, central and northern Europe. The variation of traits related to stress tolerance, resource use, colonization ability as well as survival and fecundity was determined in response to high temperature (34{degrees}C) or frost (- 6{degrees}C), in combination with response to water deficit. Key ResultsBoth evidence for a latitudinal and a center-margins differentiation was found. Traits related to the acquisitive/conservative strategy trade-off varied along a latitudinal gradient. Northern accessions presented a greater survival to stress than central and southern accessions. Traits related to a colonization-competition trade-off followed a center-margin differentiation. Central accessions presented a higher phenotypic plasticity and trait values associated with a higher colonization ability than northern and southern accessions which instead had a higher competition ability. ConclusionsIntraspecific phenotypic variation helps us understand how the distribution range has evolved in Arabidopsis thaliana, which is shaped both by climate and the population migratory history. We advocate to consider intraspecific trait variation in species range studies instead of species means only as classically done in macroecology.

ecology↗

bioRxiv2019

Role of Triose Phosphate Utilization in photosynthetic response of rice to variable carbon dioxide levels and plant source-sink relations

This study aimed to understand the physiological bases of rice photosynthesis response to C source-sink imbalances, with focus on dynamics of the photosynthetic parameter TPU (Triose Phosphate Utilization). A dedicated experiment was replicated twice on IR64 indica rice cultivar in controlled environments. Plants were grown under the current ambient CO2 concentration until heading, thereafter, two CO2 treatments (400 and 800 mol mol-1) were compared in the presence and absence of a panicle pruning treatment modifying the C sink. At two weeks after heading, photosynthetic parameters derived from CO2 response curves, and nonstructural carbohydrate content of flag leaf and internodes were measured 3-4 times of day. Spikelet number per panicle and flag leaf area on the main culm were recorded. Net C assimilation and TPU decreased progressively after midday in panicle-pruned plants, especially under 800 mol mol-1. This TPU reduction was explained by sucrose accumulation in the flag leaf resulting from the sink limitation. It is suggested that TPU is involved in rice photosynthesis regulation under elevated CO2 conditions, and that sink limitation effects should be considered in crop models.\n\nHighlightThis study provide new insights in the effect of C source-sink relationships on rice photosynthesis. TPU should be considered in photosynthesis studies under severe source-sink imbalance at elevated CO2.

plant biology↗