ORIGINAL ARTICLE

Evaluation of Water Stress Tolerance in Advanced Breeding Lines of Durum and Bread Wheat Using ¹³C

Dry matter (DM), nitrogen uptake (TN) along with water (WUE) and nitrogen (15NUE) use efficiencies in twelve advanced breeding lines (ACSAD) and two varieties (Cham1&6) of durum (DW) and bread (BW) wheat grown under well water (I1) and water stress conditions (I2) were evaluated using ¹⁵N and Δ¹³C. Water stress decreased Δ¹³C in all studied genotypes. The extent of the decrease in Δ by stress was relatively higher in BW (-1.08‰) than DW (-0.8‰). Cham1 (DW) exhibited the highest DM, TN, NUE, WUE and Δ¹³C values under I1, indicating its suitability to be grown under irrigated conditions. However, ACSAD1261 (DW) seemed to be a promising line to be grown in semi arid areas due to higher values in the aforementioned criteria under I2. For BW, the highest DM of ACSAD59 under I1 may suggest its suitability to be grown under well irrigated conditions. However, DM of ACSAD883 and 1115 were not affected by watering regime. Additionally, due to the high DM of Cham6 and ACSAD1135 in both watering regimes, and because of the decrease in Δ¹³C values under stress, it can be suggested that they could be suitable for both irrigated and water stress conditions. Since Δ¹³C values were affected by wheat genotype and watering regime as a result of the effects on the balance between stomatal conductance and carboxilation, it cannot be relied, completely, upon this technique to select drought tolerant genotypes. Therefore, we suggest that using Δ¹³C along with agro-physiological parameters are better selection criteria for water stress tolerance in breeding programs than when used separately.