Photosynthetic Performance of Two Wheat Varieties with Different Drought Tolerance Under Water Stress

Drought represents one of the most critical environmental constraints limiting plant growth and productivity. During early developmental stages, plants exhibit heightened sensitivity to soil water availability. In crop species such as winter wheat (Triticum aestivum L.), overcoming water deficit at the seedling stage is vital for plant establishment and achieving stable yields. Drought tolerance is therefore a primary agronomic and economic trait. Water shortage affects numerous physiological and biochemical processes, particularly photosynthesis, which is essential for plant metabolism and carbon assimilation. Under drought, plants initiate multiple adaptive responses to optimize water use efficiency while maintaining basic metabolic activity. This study aimed to evaluate the impact of drought stress on growth, chlorophyll content, and photosynthetic performance in two winter wheat varieties—Katya (tolerant) and Zora (sensitive). A controlled pot experiment was conducted in which two-week-old plants at the third-leaf stage were subjected to a seven-day drought period followed by rehydration. Chlorophyll a fluorescence, thermoluminescence, and pigment content were measured to assess photosystem II functionality and recovery potential. The results revealed distinct varietal responses: Katya maintained greater photosynthetic stability and recovery, while Zora exhibited reduced chlorophyll content and incomplete restoration. These findings underscore Katya’s superior drought resilience, crucial for sustaining wheat productivity under changing climatic conditions.