It is predicted that future increases in yield potential will rely largely on improved biomass production boosted by higher radiation use efficiency (RUE).
Major improvement in photosynthetic capacity and/or efficiency will be required to maximize RUE. One strategy for increasing photosynthetic capacity is to increase canopy photosynthesis, including photosynthesis in leaves situated at different strata of the canopy. However, relatively little is known about genetic diversity for the photosynthetic rate of leaves below the flag leaf and their contribution to final biomass, probably due to the amount of time needed to make these measurements.
A useful proxy for measuring photosynthesis is to measure stomatal conductance using a porometer. In previous studies, a positive correlation between yield and stomatal conductance in the flag leaf was observed. To date, information regarding stomatal conductance and stomatal density at the different canopy strata and their regulation in response to environment in wheat is scarce. Given their importance, a clear opportunity exists to genetically improve crops for stomatal behavior through increased understanding of their distribution along the canopy, their response to environment, and through exploitation of genetic diversity.
Stomatal conductance and leaf porosity will be studied along the canopy strata with the goal of identifying genetic variation associated with radiation use efficiency in different environments (irrigated and heat) where increasing RUE is a target for increasing yield in wheat.
The candidate will conduct research at CIMMYT’s experiment station in the Yaqui Valley (Northwest Mexico, Ciudad Obregon) during a period of 5 months (from February to June). The candidate will spend an additional month (July) at CIMMYT headquarters (in Texcoco) working with the data and performing statistical analysis for publication.
During the period in Cd. Obregon, the candidate will work with genotypes that have contrasting canopy architecture under irrigated and heat (late sowing) conditions. Stomatal conductance and leaf porosity will be measured at booting initiation and during grain-filling at different canopy strata (flag leaf, leaf 2, leaf 3 and leaf 4). These measurements will be included in growth and RUE analysis.
The candidate must be able to work in the field under high temperature conditions (up to 40°C) and have a basic knowledge of statistical analysis.