Answer:
It will be higher in the summer.
Step-by-step explanation:
Usually, the winter season is more harsh a weather on leaves than summer because it is wet season and thus has less sunlight and this means there will be less photosynthesis reactions and therefore it means the partial pressure will be lesser here unlike in the summer when it is a more warm and dry weather with sunlight where photosynthesis reactions will be more favorable to occur.
Thus, CO2 which is a great component of photosynthesis is used more in the summer and as such the partial pressure in the summer will be higher.