Influence of ecological variation across Pistacia altantica on fruit oil content

In the western and central parts of Iran, there are more than eight million female trees of Pistacia atlantica Desf. with approximately 20,000 tons of fruit oil production ability. In order to evaluate the influence of select ecological characteristics, fruit samples of seven P. atlantica habitats in Kurdistan (Iran) were collected in late October over two years (2013-14). Fruit oil was extracted using soxhlet extraction. The results showed a relatively small variation in oil content in fruit across plants of P. atlantica. The fruit oil content ranged from 25.4% to 28.4%, with a mean of 27.3%. Most habitats belonged to temperate and semi-arid regions, with higher longitude and altitude but less latitude and slope, higher soil electrical conductivity, total neutralizing value, organic carbon and clay, medium yearly rainfall, evaporation and sunny hours and also trees with medium ages such as Borban and Kashtar producing higher fruit oil yield than those that belonged to cool and semi-humid regions. Cluster analysis classified habitats into four distinct groups at 50% similarity; four habitats belonging to forest areas were located in the first, Borban and Kashtar in the second and third and Abdolmomen, with the coldest climate and the oldest trees, was in the fourth group. The results of principal component analysis (PCA) revealed that habitats with low fruit oil showed extreme values of PC₁ and PC₂ but ones with high fruit oil were located mainly in the central zones of the bi plot, which suggest that habitats with medium ecological conditions produce higher fruit oil.