The Study of Different Water Regimes on Photosynthetic Performance and Leaf Water [[ Status of Pistachio Trees (Pistacia vera L.)

Abstract

old trees of Akbari cultivar (Pistacia vera cv. Akbari). The water regime treatments included
20, 15.6, 10.4, and 6% of field capacity (FC) equivalent and irrigation intervals of 4, 12, 18
and 24 days. Chlorophyll fluorescence indices of photosystem 2 (PSII), photosynthetic
pigments, and leaf water status parameters were studied. Drought stress inhibited PSII activity
and induced alterations in thylakoid proteins. The results showed significant effects on
effective quantum yield of PSII (ΦPII), maximum quantum efficiency of PSII (Fv/Fm),
electron transport rate (ETR), quantum yield baseline (F0/Fm), non-photochemical quenching
(NPQ), and photoinhibition (PIHN) rate. Such changes may be due to either degradation of
photosynthesis apparatus function or photoinhibition process. From the results of the present
study, it can be concluded that exposure of pistachio trees (P. vera cv. Akbari) to an interval of
18-days (T18) may not significantly affected the parameters measured. This means that with an
increase in irrigation intervals to 16-days, compared to the traditional interval (varies from 8 to
10-days), soil may be able to provide enough moisture for the pistachio trees to complete
metabolic activities.