PJB-2018-638
THE IMPACTS OF DIFFERENT WATER REGIMES ON PHOTOSYNTHETIC PERFORMANCE AND LEAF WATER STATUS IN PISTACHIO TREES (PISTACIA VERA L.) UNDER FIELD CONDITIONS
Abolfazl Ranjbar
Abstract
Soil water deficiency is one of the most important environmental stresses that limit plant growth and crop production. Measurement of chlorophyll fluorescence parameters is considered as an important approach to evaluate safety of photosynthetic apparatus. In the present study, we investigated the effects of drought stress, imposed through three water-regime treatments (75%, 50%, and 25% FC), on chlorophyll fluorescence indices of PSII, photosynthetic pigments, and leaf water status parameters in Pistacia vera trees. Drought stress inhibits PSII activity and induces alterations in thylakoid proteins. Our results revealed significant alterations in the effective quantum yield of PSII, electron transport rate, quantum yield baseline, non-photochemical quenching, and photoinhibition rate. Such changes may be due to either degradation of photosynthesis apparatus function or photoinhibition process. In conclusion, the present examination showed that nut pistachio trees are tolerant to drought stress as judged by leaf pigment content, photosynthetic performance demonstrated through measured and calculated fluorescence variables and leaf water status indices. With respect to all the parameters investigated in the current study, it seems that PSII activity in P. vera trees is efficiently protected.
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