The use of chlorophyll fluorescence indices to identify environmental stresses (drought and salinity) in leaves of Mutica Pistachio (Pistacia mutica L.)

High temperature, high radiance, low vapor pressure, and lack of precipitation in most months characterize arid ecosystems. Under these conditions, tree crops such as pistachio suffer from drought combined with salinity stress. In order to investigation effects of combined salinity and drought stress on function of photosynthetic apparatus, Mutica pistachio (Pistacia mutica) seedlings were subjected to four osmotic stress treatments (induced by NaCl and polyethylene glycol) including: control, low osmotic stress, moderate osmotic stress and high osmotic stress. Thus, chlorophyll fluorescence parameters such as F0, Fm,Fv,Fʹm,Fʹ0,Fʹm,Fʹv, Fs,F0 /Fm,Fv/ Fm,Fv/F0,Fʹv/Fʹm, ΦPSII,ETR and qP were measured and calculated. Significant alterations in F0 and Fm were just observed at high osmotic stress that show injure to photon transfer process from antenna to reaction centers. Likewise, a significant reduction in Fv/ Fm at high osmotic stress depicted light photooxidation in photosystem II. Significant increase in F0 / Fm ratio at high osmotic stress appeared a suffering in functional performance of photosystem I. Significant alterations in ΦPSII and NPQ (as decrease and increase, respectively) showed a high non-photochemical dissipation of light energy in photosynthetic apparatus. Significant decrease in qP initiated at moderate osmotic stress and reached to the lowest at high osmotic stress. This reduction implies that light use efficiency by the plants has reduced. This investigation proved that the both groups of chlorophyll fluorescence parameters (dependent and independent) have an important role to study the effects of environmental stresses on photosynthetic apparatus.