Short‐term responses of leaf growth rate to water deficit scale up to whole‐plant and crop levels: an integrated modelling approach in maize

Abstract

Physiological and genetic studies of leaf growth often focus on short-term responses, leaving a gap to whole-plant models that predict biomass accumulation, transpiration and yield at crop scale. To bridge this gap, we developed a model that combines an existing model of leaf 6 expansion in response to short-term environmental variations with a model coordinating the development of all leaves of a plant. The latter was based on: (1) rates of leaf initiation, appearance and end of elongation measured in field experiments; and (2) the hypothesis of an independence of the growth between leaves. The resulting whole-plant leaf model was integrated into the generic crop model APSIM which provided dynamic feedback of environmental conditions to the leaf model and allowed simulation of crop growth at canopy level. The model was tested in 12 field situations with contrasting temperature, evaporative demand and soil water status. In observed and simulated data, high evaporative demand reduced leaf area at the whole-plant level, and short water deficits affected only leaves developing during the stress, either visible or still hidden in the whorl. The model adequately simulated whole-plant profiles of leaf area with a single set of parameters that applied to the same hybrid in all experiments. It was also suitable to predict biomass accumulation and yield of a similar hybrid grown in different conditions. This model extends to field conditions existing knowledge of the environmental controls of leaf elongation, and can be used to simulate how their genetic controls flow through to yield.

Simulating the Yield Impacts of Organ-Level Quantitative Trait Loci Associated With Drought Response in Maize: A “Gene-to-Phenotype” Modeling Approach

“…The QTL of the first population generated were assumed to control leaf elongation alone (Reymond et al 2003), whereas in a second population they were assumed to influence both leaf and silk elongation . The yield phenotype of each line was simulated using an adapted APSIM crop model (Chenu et al 2008a). A first set of simulations was carried out to determine gene-to-phenotype consequences on yield in managed drought environments with contrasting soil water contents and evaporative demands (resulting from different sowing dates and irrigation managements at Tlaltizapán, Mexico).…”

“…Chenu et al (2008a) incorporated this organ-level model (with time steps of minutes to hours) into the APSIM-Maize crop simulation model and hence captured the complex interactions of plants with their environment (e.g., the feedback of leaf growth on soil water depletion) during the entire crop cycle. For a maize hybrid, Dea, the model produced accurate predictions of leaf area, biomass, and grain yield when tested against independent data from contrasting environments (Chenu et al 2008a).…”

“…Sufficient understanding of leaf elongation has been developed to propose a physiological and genetic model of leaf elongation response to drought (see Chenu et al 2008a for additional details). Temperature, evaporative demand, and soil water deficit were identified as major environmental factors determining leaf elongation rate over periods of hours and days, whereas light and plant carbon balance had minor effects Tardieu 1996, 1997;Tardieu et al 1999;Sadok et al 2007).…”

Drought Resistance Improvement in Rice: An Integrated Genetic and Resource Management Strategy

“…Combining the probabilities for yield change with understanding of growers' tolerance for risk would help breeders to assess the desirability of incorporating a particular drought trait in cultivars to be grown at a specifi c location. A good example was recently provided by the integration of short-term physiological responses of leaf growth to drought into whole-plant and crop-level modeling in maize (Chenu et al, 2008).…”

A plastic, dynamic and reducible 3D geometric model for simulating gramineous leaves

“…We based on ADEL-maize [24], and test two hypothetic model that mimic the response to two stresses: a) leaf width is responding to local light illumination [5], and b) leaf extension rate and duration are responding to vapour pressure deficit in the air [49]. Response to light can be modeled as a stress factor affecting the r(age) curve.…”