Introduction: Drought is one of the major abiotic stresses that drastically reduces crop yield throughout the world. Being precursor of glutathione biosynthesis and involvement in other metabolic processes, cysteine (Cys) has been shown to alter growth and development in plants. In this context, we investigated Cys-induced physicochemical alterations in oat (Avena sativa L. var. Scott and var. F-411) plants under drought stress.
Methods: There were two levels of drought stress, i.e., control (100% field capacity) and drought (50% field capacity) and three levels of foliar application of Cys, i.e., 0, 10, and 20 mM. Experimental design was completely randomized block design.
Results: Drought stress significantly decreased growth parameters, chlorophyll (Chi) contents, while increased leaf membrane permeability (MP), ascorbic acid (AsA), and activity of catalase (CAT) and peroxidase (POD) enzymes. Foliar application of varying Cys levels significantly increased root fresh weight, root length, photo synthetic pigments (chl. a and b), AsA contents in var. Scott, and shoot length, total free amino acids, total phenolics and free proline contents in var. F-411.
Discussion: Of the two oat varieties, var. Scott proved better in root fresh weight, root length, chl. a and b contents, and total phenolic contents, while var. F-411 was higher in the values of shoot length, MP (%), total free amino acids, and free proline contents. Thus, on the basis of strong root system, total phenolics, and more photosynthetic contents (chl. a and b contents), var. Scott could be grown under semi-arid environments than that of var. F-411.
Keywords: cysteine; drought; glycinebetaine; growth; oat plants.
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