Cotton leaves in dry soil have higher photosynthesis in the morning but lower in the afternoon compared to leaves in moist soil. The midday drop in photosynthesis is mainly due to factors other than stomata in dry conditions, while in moist conditions, it's due to both stomatal and non-stomatal factors. Water use efficiency is higher in dry soil, but photosynthesis rate is lower. There is no photoinhibition in either condition, and cotton can handle midday depression of photosynthesis even with high soil moisture.