Drought Stress Effect on Physiological Parameter and Amino Acids Accumulations in Canola

This experiment was conducted to investigate of drought effect on some physiological parameters and amino acids accumulation in two canola cultivars (SLM046 and Cooper; tolerance and sensitive to water stress, respectively). The experiment was carried out during two growth phase (stem elongation and flowering stage) using irrigation levels consisting of irrigation after 80 mm evaporation from class “A” pan as control, no irrigation from stem elongation stage and flowering stage. The results showed that water stress significantly diminished seed yield, stomata conductance, chlorophyll a and b, carotenoid content and soluble protein content in leaves of both cultivars. Also antioxidant enzyme activity (catalase, peroxidase and ascorbate peroxidase) were enhanced with drought stress at stem elongation stage, but peroxidase and ascorbate peroxidase activity were decreased at flowering stage. The amino acids of Tryptophane, serine, glutamine and α-amino butyric acid showed highest abundance of total amino acids at stem elongation stage, also glutamine, isoleucine, serine and histidine revealed highest amount of total amino acids at flowering stage. An increase in contains most of amino acids in response to drought stress at flowering stage was observed. The significant accumulation of aspartic acid, asparagines, glutamine, lysine, cysteine, tryptophan and phenylalanine under drought at elongation stage, and significant accumulation of glutamine, glycine, thyrosine, methionine, phenylalanine and isoleucine under drought at flowering stage were observed in the drought-tolerant SLM046, whereas no were showed the significant accumulation of amino acids in the drought-sensitive Cooper under drought. Thus it can conclude that tolerance of genotypes to drought stress is closely associated with their accumulation of free amino acids.