Abstract
Background and Objectives
Olive (Olea europaea) is compatible with Mediterranean and Mediterranean-like climates. Due to its high adaptability to different environmental conditions, this plant has adapted well to the varied climates in the world. It has extensively been cultivated in some regions of Iran to the extent that some cultivars do not have any identification. Therefore, a genotype/variety may be classified under several names and several varieties under a single name. Also, lack of garden information, re-naming of imported cultivars, and non-standard morphological traits for naming has led to fundamental problems in the pomology industry. Accordingly, it is necessary and inevitable to eliminate these ambiguities and accurately identify different olives’ genotypes in Iran. Hense, the first step in identifying the genotype is morphological identification. To this aim, the present research was conducted to investigate the genetic diversity and the relationship between the olive trees cultivated in some of the cities of Khuzestan through exploring morphological traits.
 
Materials and Methods
This study was conducted in Indica, Baghmalek, Izeh, and Lali in 2015-2016. Fifty genotypes were collected from the orchards of the Andika, Baghmalek, Izeh and, Lali. The morphological traits of fruit, stone, and leaf were measured according to the IOOC guidelines and the Seed and Plant Certification and Registration Institute for Research (2007) guidelines. The variance analysis of the traits was performed using SAS 9.1 software as a nested design. Cluster analysis was used for the determination of the degree of relationship between genotypes. The main components and biplot analysis were used to reduce the number of variables.
 
Results
The results showed that there was a wide range of morphological variations among genotypes. Factor and principal components analysis showed that 12 components could justify 87.7% of the variation among genotypes. The first component explained 13.42% of the total variance. In this factor, fruit length (0.63), fruit width (0.61), fruit weight (0.61), stone shape (-0.7), stone width (0.66), stone length (-0.44), and leaf length (0.5) had a high coefficient. Moreover, traits such as length and width of fruit, stone and leaf, stone and leaf shape, curvature of leaf, stone number grooves, fruit base in position A, stone weight, stone surface in position B,  stone symmetry in position A, fruit size of lenticels, stone distribution of grooves, stone symmetry in position B, were the most important traits in genotyping and grouping of the cities studied. Based on the results of cluster analysis, the genotypes were divided into six distinct groups.
 
Discussion
In general, it was found that most of the genotypes in Baghmalek city are located in a separate cluster. In contrast, several genotypes in Lali, Izeh, and Indica are situated in a single cluster, which can be due to atmospheric differences in precipitation rates in these cities. Izeh, Lali, and Indica have lower temperatures and more atmospheric precipitation than Bagmalek. This important difference can cause the genotypes of these cities to be different compared to Baghmalek city.