Leaf water status and biochemical adjustments as a mechanism of drought tolerance in two contrasting wheat (Triticum aestivum L.) varieties

Understanding the water relationship and biochemical changes in response to drought can aid in drought tolerance in wheat, which is critical for future yield stability. The current study investigated the mechanisms of drought tolerance in wheat, considering water relations, biochemical properties, and yield of two wheat varieties: drought-susceptible BARI Gom 25 and drought-tolerant BARI Gom 26. Drought decreased relative water content (RWC), leaf water potential (LWP), xylem exudation rate (XER), leaf chlorophyll content, flag leaf phosphorus (P), and grain yield. Conversely, drought stress increased various osmolytes: proline, soluble sugar, malondialdehyde (MDA), and flag leaf potassium ion (K+). Under drought conditions, BARI Gom 26 outperformed BARI Gom 25 in terms of LWP, RWC, and XER. However, drought increased the electrolyte leakage (EL) and MDA in BARI Gom 25. BARI Gom 26 had higher proline concentration, soluble sugar accumulation, cell membrane integrity, chlorophyll concentration, and K+ in drought conditions than BARI Gom 25. These responses were most noticeable during the reproductive stages. However, BARI Gom 26 could compensate for drought-induced reductions in agronomic parameters, including grain yield, by maintaining superior osmotic adjustment in the leaves, as evidenced by increased proline, MDA, cell membrane stability, and K+ accumulation.