Physiological and biochemical changes in Moroccan barley (Hordeum vulgare L.) cultivars submitted to drought stress

Abstract

Barley (Hordeum vulgare L.) is the second most consumed and cultivated cereal by the Moroccan population. However, it is predicted that frequent drought periods, caused by climate change, can cause problems in plant growth. Thus, the selection of drought-tolerant barley cultivars is essential to ensure the security of barley's needs. We aimed to screen drought stress tolerance in Moroccan barley cultivars. We tested the drought tolerance of nine Moroccan barley cultivars ('Adrar', 'Amalou', 'Amira', 'Firdaws', 'Laanaceur', 'Massine', 'Oussama', 'Taffa', and 'Tamellalt') based on physiological and biochemical parameters. Drought stress was applied by maintaining field capacity at 40% (90% for the control), and plants were randomly arranged in a greenhouse at 25 °C under natural light conditions. Drought stress decreased relative water content (RWC), shoot dry weight (SDW), and chlorophyll content (SPAD index), but significantly increased electrolyte leakage, hydrogen peroxide, malondialdehyde (MDA), water-soluble carbohydrates, and soluble protein contents, as well as catalase (CAT) and ascorbate peroxidase (APX) activities. High levels of SDW, RWC, CAT, and APX activities were recorded in 'Firdaws', 'Laanaceur', 'Massine', 'Taffa', and 'Oussama', which can be interpreted by high drought tolerance. On the other hand, 'Adrar', 'Amalou', 'Amira', and 'Tamellalt' showed higher values of MDA and H₂O₂ content, which can be linked with drought sensitivity. Physiological and biochemical parameter changes are discussed in terms of barley's tolerance to drought. Tolerant cultivars could be a good background for barley breeding in areas known for the alternative of long dry spells.

Keywords: Barley; Drought stress; Drought tolerance; Hordeum vulgare; Physiological parameters.

Fig. 1

Means values of Shoot dry weight (a), relative water content (b), electrolytes leakage (c), and SPAD value (D) of barley varieties under optimal irrigated conditions (Control) and drought stress. Values indicate the mean (±SE) of n = 3. Scores with the same letter are not significantly different at P = 0.05.

Fig. 2

Means values of proline (a), total soluble sugars (b), and proteins (c) contents of barley varieties under optimal irrigated conditions (Control) and drought stress. Values indicate the mean (±SE) of n = 3. Scores with the same letter are not significantly different at P = 0.05.

Fig. 3

Means values of catalase (CAT) activity (a) and ascorbate peroxidase (APX) activity (b) of barley varieties under optimal irrigated conditions (Control) and drought stress. Values indicate the mean (±SE) of n = 3. Scores with the same letter are not significantly different at P = 0.05.

Fig. 4

Means values of H2O2 (a) and Malondialdehyde (b) contents of barley varieties under optimal irrigated conditions (Control) and drought stress. Values indicate the mean (±SE) of n = 3. Scores with the same letter are not significantly different at P = 0.05.

Fig. 5

Biplot of principal component analysis for physiological responses in nine barley Moroccan cultivars. Shoot dry weight. RWC: Relative water content. EL: Electrolytes leakage. MDA: Malondialdehyde. TSS: Total soluble sugars. CAT: Catalase activity. APX: Ascorbate peroxidase activity.

Fig. 6

Dendrogram for agglomerative hierarchical cluster analysis based on physiological characteristics under drought stress of leaves of nine barley Moroccan cultivars.