Coordinated Adaptive Phenotyping for Improving Soil Water Acquisition and Utilization

Advancing technologies are enhancing phenotyping efforts aimed at identifying superior crop traits for improving water deficit stress resilience. However, much of the current phenotyping approaches disregard the coordination of both above- and belowground traits that is required to acquire and utilize soil water for improving agronomic yield loss from water deficit stress. This research aimed to develop an in situ approach to quantify the coordination between peanut (Arachis hypogaea L.) root system architecture (RSA), soil water depletion (SWD), and transpiration rates in a field setting. We utilized a series of soil wetting and drying cycles and quantified daily SWD across 10 cm soil depth increments at 61, 68, 75, 82, 89, and 96 days after planting (DAP). Mid-morning transpiration fluxes were measured on the days of SWD quantification. A positive relationship was observed between the total SWD and mid-morning transpiration for both genotypes (R²=0.61 for COC 041; R²= 0.67 for TUFRunner^TM ‘511’) when considered across all sampling dates, indicating that this SWD method was valid for assessing relative crop water uptake. Despite variations in genotypic RSA, SWD zones among the different genotypes where similar for each measurement date. However, the zones of depletion were dependent on the overall soil water content conditions. For example, when soil water content was high following irrigation, approximately 74% of the quantified SWD occurred in the top 30 cm of soil; under soil drying conditions 67% of the SWD occurred from 30-60 cm of soil depth. Relating daily volumetric soil water content (VSWC) to mid-morning transpiration fluxes provided evidence that the COC 041 genotype had a greater susceptibility to reduced transpiration rates resulting from soil drying. The results of this research suggest that trait selection for improving soil water deficit tolerance in the U.S. humid peanut production environment should concentrate on the trait coordination between above- and belowground phenotypes specifically adapted to either irrigated or dryland hydrologic scenarios.