Investigation the effect of humic acid on some morphhophysiological and biochemical ‎characteristics of almond rootstocks under salinity stress

Choosing suitable feed sources remove the problems of salinity from the plant. For this purpose, an experiment as factorial was conducted in a RCBD with three replications at the University of Mohaghegh Ardabili during 2015-16. The first factor was humic acid (HA) application at four levels: (0, 2.5, 5 and 7 kgha-1), the second factor was salinity at four levels: (0, 60, 120 and 180mM NaCl) and the third factor was two-years old almond rootstocks seedling at two levels (GF677 and GN15). Results showed that with increasing salinity, root/stem dry weight increased, especially in GF677, Na+ and Cl– and SI increased, especially in GN15 and SLA, K+ and N, leaf osmotic potential, gs, Pn and T were decreased, especially in GN15. Carbohydrates increased to 120mM NaCl, especially in GF677 and then decreased. GF677 with an increase in HA up to 5 kgha-1, in the salinity of 180mM NaCl, with the highest root/stem dry weight and SLA, the lowest Na+ and Cl-and the highest K+and N of leaf had the highest leaf osmotic potential (-1.9MPa) and carbohydrate (86.92 mg gFW-1) compared to other rootstocks. The highest gs (0.53 mmol m-2s-1) and Pn (18.73 μmolCO2 m-2s-1) were found in GF677, 2.5 kgha-1 HA and 0 mM NaCl. With increasing HA, in these conditions, the SI decreased, especially in GF677. Therefore, GF677 was evaluated as the most tolerant rootstock for salinity and 2.5 and 5 kgha-1HA was evaluated as the most appropriate levels for affecting almond rootstocks.