Evaluation of the effect of putrescine and brassinosteroid on induction of drought tolerance and physiological changes in basil plant (Ocimum basilicum L.)

Drought stress is one of the important environmental factors in arid and semi-arid regions of the world that causes a number of physiological and metabolic changes in plants. Drought stress causes the formation of reactive oxygen species in plant chloroplasts and also causes peroxidation of membrane lipids and destruction of cell membranes. In this regard, an experiment aimed at investigating the role of growth regulators, putrescine and brassinosteroids on the control of oxidative stress and physiological changes in water deficiency tolerance in basil in the form of factorial split-plot in a randomized complete block design with three replications in The research farm of the Faculty of Agriculture of Ilam University was implemented during 2017-2018 crop seson. Experimental treatments included drought stress at three levels (40, 80 and 120 mm evaporation from Class A evaporation pan) as the main agent and putrcin foliar application at three levels (zero, 0.5 and 2 mM) and solution. Brassinosteroid spraying was performed at three levels (zero, 0.5 and 2 μM) factorially in subplots. According to the results obtained in this study, the amount of chlorophyll a and b, total flavonoids and CO2 concentration under the stomata in the treatment of application of 2 mM follicle application of putricin and 2 μM brassinosteroid compared to the control treatment (no foliar application) And brassinosteroids) in the conditions of non-drought stress 74.06, 64.07, 45.68 and 19.5%, in moderate stress 61.4, 33.9, 3.6 and 10.3% and in severe drought stress 1 62.68, 68.6, 33.1 and 15.7% showed an increase. The rate of photosynthesis decreased under drought stress, but the treatment of 0.5 mM putrescine and 2 μM brassinosteroid compared to the control treatment (lack of foliar application of putricin and brassinosteroid) in moderate and severe drought stress increased by 76.59 and 83.33%, respectively. Photosynthesis rate. Application of foliar application of 2 mM putrescine and 0.5 μM brassinosteroid reduced ion leakage under all levels of drought stress. The percentage of essential oil in the treatment (concentration of 2 mM putrescine and 0.5 μM brassinosteroid) in severe drought stress, moderate drought stress and lack of drought stress, respectively, 66.5, 39.5 and 50% compared to the control treatment (no solution) Spraying of putrescine and brassinosteroids was increased. In general, it seems that consumption of high concentrations of putrescine and brassinosteroids (2 mM putrescine and 2 μM brassinosteroids) in drought stress conditions can improve the physiological parameters of basil.