Morphophysiological and biochemical changes of hyssop (Hyssopus officinalis L.) treated with amino acid and transpiration reducers in dry soils

Hyssop (Hyssopus officinalis L.) is a woody and perennial plant. Drought stress is one of the abiotic stresses that have the adverse effects on growth, development and other metabolic processes of the plant. In this regard, it is necessary to use targeted methods to deal with dehydration, therefore, this study was conducted based on the evaluate the rate of changes in hyssop treated with transpiration-reducing compounds such as kaolin and chitosan as well as the amino acid glycine under drought stress. This research was conducted as a factorial split plots experiment based on a completely randomized design with 3 replications, during 2016-2017 at the Agricultural and Natural Resources Center of Yazd Province. Experimental factors include the drought stress at 3 levels (25, 50 and 75% of the the available water discharge from the soil), the foliar application at 4 levels [water (control), kaolin (2.5%), chitosan (0.4 g/l) ), glycine amino acid glycine (2.5 per thousand)] and the foliar application time (vegetative and flowering, just flowering). The results showed that in the control stress treatment ( 25% of the the available water discharge from the soil), the foliar application of glycine and kaolin, increased the canopy diameter by 30.59% and 27.21%. Also the chitosan and kaolin spraying at flowering time decreased the electrolyte leakage by 6.1% and 6.3%. The highest canopy diameter was obtained on th the interaction of the control stress and glycine amino acid (619 cm2) and the lowest leakage was obtained on the interaction of control stress and the foliar application of chitosan and kaolin at flowering. The increasing drought stress until the level of 50%, increase of 4.79% in chlorophyll a and the total chlorophyll and the highest chlorophyll a, and total chlorophyll (153 and 216 mg/g FW) respectively were observed in the foliar application of control at vegetation and flowering. The increasing the amount of available water discharge to the level of 75%, a decreasing trend in the amount of leaf area (91%) dry weight (51.95%), chlorophyll a (34.64%), chlorophyll b (43.86%) and total chlorophyll (32.87%), also an increasing trend in superoxide dismutase activity (25.92%) was observed. The highest leaf area in the interaction of control stress and the foliar application of control (4947cm2) at flowering, dry weight (140.5 g/m2), chlorophyll b (69.3 mg/g FW) in the interaction of control stress and the foliar application of control and superoxide dismutase activity in the interaction of sever stress and foliar application of kaolin (0.34 (U. mg protein -1. min -1) at vegetation and flowering Was obtained. Also, the foliar application of control, kaolin and chitosan at vegetation and flowering compared to other experimental treatments had the greatest effect on chlorophyll b, canopy diameter and dry weight. Drought stress reduced the amount of morphological parameters. This decrease had less negative effects on physiological parameters, so the mentioned parameters had an increasing trend to the mild stress level and a decreasing trend was observed with the increase of dryness up to the sever level The severe stress also increased biochemical parameters. Foliar application with glycine and chitosan at vegetation and flowering was effective in increasing morphological parameters dependent on growth and foliar application of chitosan and kaolin during flowering as well as kaolin spraying during vegetation and flowering played a useful role in increasing the biochemical parameters related to the antioxidant activity of plant to. Due to the changes in the hyssop, the application of this substances can be recommended to reduce the adverse effects of stress on other medicinal plants