Investigating the main and interactive effects of vapour pressure deficit, soil water deficit, warmer temperatures and elevated CO2 on cotton growth and physiology

Abstract

Climate change factors such as rising temperature, atmospheric carbon dioxide concentration [CO2] and increased drought frequency and intensity have been shown to affect cotton physiology and productivity. To investigate the effect of climate change on cotton, we divided our study into two parts, of which the first study focused on the effect of vapour pressure deficit (VPD) and soil water deficit (SWD) on stomatal response and the second study focused on the effect of increased temperature (TE) and elevated [CO2] (CE) on cotton growth and physiology. We conducted both experiments in an environmentally controlled glasshouse to imitate the projected drier, warmer and increased [CO2] conditions. Our goal was to use cotton to improve the understanding of the physiological and growth response of C3 crops to changing climate. Our study expands the understanding of how VPD affected plant physiology by separating temperature and RH and whether SWD has a role in altering this relationship. We found that rising VPD reduced gs, A and E. However, the key finding of this study was that SWD decreased gs and rising VPD exacerbated this reduction. We also found that SWD did not affect the relationship between VPD components and that each VPD component can affect plant physiology, either individually or combined. The results further indicated that the reduction in RH had a stronger effect on gs than temperature, regardless of soil water content. In addition, the stomatal model indicated that WUE in well-watered cotton was reduced at high temperature at given VPD levels. The SWD treatment did not alter plant hydraulic status, but significantly reduced height and number of nodes. This type of study should be further investigated as it has the potential to further our understanding of crop adaptation to drier and warmer climates, particularly in dry-land irrigation cotton farming systems.

Date of Award	2019
Original language	English