Climatic factors such as vapor pressure (the capacity of the air to hold water at a given temperature, which is used to calculate relative humidity) influence crop growth, including how much moisture from the plant is needed for transpiration, Transpiration is important to regulate leaf temperature which influences photosynthesis and crop growth. This study showed that changes in vapor pressure affected the level of stress a plant regardless of the level of soil moisture highlighting the need for irrigation scheduling to reflect both factors. Quantifying these effects is also important where future climate change predictions suggest lower humidity and higher temperature which will increase the evaporative demand on crop