Physiological and Biochemical Responses of GF677 (Peach and Almond Hybrid) Rootstock to In Vitro Drought Stress

Physiological and biochemical responses of GF677 rootstock (Prunus persica L × P. amygdalus Batsch) to drought stress induced by polyethylene glycol (PEG-6000) were studied in the solid and liquid medium. This research was conducted using completely randomized design (CRD). Plantlets of GF677 rootstock were subcultured into the Murashige and Skoog (MS) proliferation medium containing 1 mg l-1 BA (6-Benzyladenine) and 0.1 mg l-1 NAA (naphthaline acetic acid) in four drought levels 0 (control), 10, 20 and 30% polyethylene glycol to study the effect of drought stress. After six weeks results showed that drought levels in the solid and liquid medium had a significant effect on all of measured parameters. Antioxidant enzymes activity (catalase and peroxidase), total protein content, proline content and soluble sugars significantly increased in the solid and liquid medium. Increasing of total protein content, proline content and soluble sugars in the liquid medium was more than solid medium. Soluble sugars had non-significant increasing in the different levels of drought in the solid medium. Leaf chlorophyll index was decreased by increasing drought levels. Leaf chlorophyll reduction in the solid medium was more than liquid medium. Generally, drought stress in both medium (solid and liquid), lead to activate defense mechanisms of GF677 rootstock such as antioxidant systems, osmoregulation by proline and soluble sugars and increasing protein synthesis and this increasing was more in liquid medium. Therefore, it concluded that drought stress in the liquid medium is more effective and more accurate in the study of plant tolerance to drought stress.