Relating stomatal conductance and surface area with evapotranspiration induced suction in a heterogeneous grass cover

Evapotranspiration was determined to be hydrological effect which induces suction. Evapotranspiration induced suction governs the slope stability, ground water recharge and runoff. This study focuses on suction induced in root zone of mix grass used in green infrastructure. Most of the previous studies focused on evapotranspiration induced suction less than 100 kPa measured using tensiometers. However, for investigating the drought condition, it is essential to obtain suction data greater than 100 kPa. It was noted that the response of plant parameters such as stomatal conductance and surface area were not considered holistically evapotranspiration induced suction. The main objective of this study is to investigate relationship among evapotranspiration induced suction, stomatal conductance and surface area for a mix grass species used in green infrastructure subjected to drought stress (corresponds to suction > 100 kPa). Stomatal conductance was observed to increase up to suction (6 ± 1 kPa) corresponding to volumetric field capacity. Thereafter, large decrease (more than 90%) in stomatal conductance was found with an increase in suction. Stomatal conductance was found to be 0 at 2431 kPa (i.e., wilting point). Change in normalized surface areas of mix grass was found to be relatively low (within ±15%) with an increase in suction up to 138 kPa. However, beyond 138 kPa, it varied drastically (by 31–68%) with an increase in suction from 138 kPa to 3642 kPa. Two new relationships i.e., Stomatal conductance characteristic curve (SCCC) and surface area characteristic curve (SACC) were proposed. Therefore, the relationships developed in current study help to analyze the performance of green infrastructure accurately.