Drought Stress Effects on the Aerial Part Physiology and Macronutrient Uptake in Pear (Pyrus communis L.) Scion-Rootstock Combinations

Drought is a major abiotic stress in arid and semi-arid areas. This study examines how drought stress and different rootstocks affect aerial part physiology and macronutrient uptake in two seedlings of pear cultivars, 'Dargazi' and 'Louise Bonne,' grafted onto 'Dargazi' and 'Pyrodwarf' rootstocks. Treatments were well-watered as control (۱۰۰% Field Capacity, FC), moderate (۶۰% FC), and severe drought (۳۰% FC). Drought stress decreased the Root-to-Shoot weight ratio (R/SH), Leaf Relative Water Content (LRWC), Soluble Protein (SP), Photosynthetic Nitrogen Use Efficiency (PNUE), leaf osmotic potential (Ψs), Leaf potassium (LK+), Root Calcium (RCa۲+), Root Nitrogen (RN), Stomatal aperture (SA), net photosynthetic rate (An), transpiration rate (E), stomatal conductance (gs), and instantaneous carboxylation Efficiency of Rubisco (EiC) in all scion-rootstock combinations. Under drought stress, levels of proline (Prol), Glycine Betaine (GB), Total Soluble Carbohydrate (TSC), root potassium (RK+), leaf calcium (LCa۲+), leaf nitrogen (LN), leaf and root phosphorus (P) increased. 'Dargazi' as the cultivar or rootstock showed better instantaneous Water Use Efficiency (WUEi), Nitrogen Utilization Efficiency (NUtE), and Nitrogen Uptake Efficiency (NUpE), with higher LN, LNO۳−, LNH۴+, Prol, and Ψs under severe stress. 'Louise Bonne' had higher amounts of R/SH weight ratio, Total Nitrogen Accumulation (TNA), leaf and root nitrate reductase activity (NRA),  An, intracellular carbon dioxide concentration (Ci), E, and root nitrate (RNO۳−) under moderate stress. 'Pyrodwarf' rootstock demonstrated the highest TNA and RCa۲+ under moderate stress conditions. These results indicated that 'Dargazi' demonstrated better tolerance under severe stress, while 'Pyrodwarf' and 'Louise Bonne' were more effective under moderate stress conditions.

کلیدواژه ها:

Abiotic stresses ، Osmolytes ، Photosynthesis ، Scion-rootstock interaction.