Pistachio is one of the most important horticultural crops in Iran. Selection of suitable genotypes, resistant to unfavorable environmental and soil conditions and diseases, are important for increasing yield efficiency and the acreage of this important crop. The aim of this research was to evaluate wild pistachio species and genotypes native to Iran and also to determine any relationships that exist according to their phenotypical characteristics. A total of 11 pistachio types in situ from Kerman and Fars provinces and ex situ from the Iranian Pistachio Research Institute (IPRI) were used during the research. Thirty-one morphological characteristics (17 quantitative and 14 qualitative) were evaluated based on the pistachio descriptor (IPGRI). Results from simple correlation analyses showed significant positive and negative correlations in certain important characteristics. Nut thickness and weight were in significant correlation with the size (dimensions) of the leaves and terminal leaflets. Factor analysis was used to determine the effective characteristics and the number of main factors. For each factor loading a value of more than 0.65 was judged as being significant. Effective characteristics were categorized into seven main factors that contributed to 94% of the overall variance. Leaf and nut characteristics were defined mainly by the first factor contributing to 40% of the total variance. Pistachio genotypes were clustered based on seven factors and at a similarity distance of 10, these were further divided into three sub-clusters each consisting of genotypes belonging to species P. vera L., P. khinjuk Stocks. and P. atlantica Desf. Based on the results, P. khinjuk was located between the other two species, but resembled P. atlantica more than P. vera.

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The mechanism of osmoprotectant action on photosynthesis process is still not well known, especially under salt stress. The objective of this study was to evaluate and explain the effect of glycine betaine (GB) on photosynthetic efficiency and other physiological parameters of cucumber plants grown under salinity stress. Our results indicated that salinity decreased chlorophyll and carotenoids content, Ca 2+ and K + concentrations, and quantum yield parameters, such as probability that a trapped exciton moves an electron in to the electron transport chain beyond QA, quantum yield of electron transport from QA to QB in PSII, quantum yield of reduction of end electron acceptors in PSI, performance index for the photochemical activity, total performance index for the photochemical activity, trapping per reaction centers, and other parameters related to primary photochemical reactions of PSII. However, the exogenously applied GB increased most of tested parameters including the total soluble carbohydrate, proline and GB content, and Ca 2+ and K + concentrations, under salt stress. We suggest that GB can play an essential role as regulator to improve photosynthetic efficiency and thus yield of cucumber plants under salt stress conditions. At the level of photosynthesis process, the application of exogenous GB indirectly enhanced the performance of the photosynthetic machinery of cucumber plant due to the reduction of the dissipated light energy, as heat, and the increase of primary reactions of photosynthesis efficiency. Abbreviations: Chl -chlorophyll; DM -dry mass; ET0/RC -electron transport flux per RC; F0 -minimal fluorescence yield of the dark-adapted state; Fm -maximal fluorescence of the dark-adapted state FM -fresh mass; Fv -maximal variable fluorescence; Fv/Fm -maximal quantum yield of PSII photochemistry; GB -glycine betaine; PIabs -performance index for the photochemical activity; PItot -total performance index for the photochemical activity; RC -reaction center; SM -normalized area (related to the number of electron carriers per electron transport chain); TChl -total chlorophyll; TR0/RC -trapped energy flux per RC; TSC -total soluble carbohydrate; VI -relative variable fluorescence at I-step (30 ms after the start of actinic light pulse); VJ -relative variable fluorescence at J-step (2 ms after the start of actinic light pulse); ΦDo -quantum yield of energy dissipation; φET20 -quantum yield of electron transport from QA to QB in PSII; ΦPo -maximum quantum yield of primary PSII photochemistry; ΦRE10 -quantum yield of reduction of end electron acceptors in PSI; Ψ0 -probability that a trapped exciton moves an electron in to the electron transport chain beyond QA.