EVALUATION OF OLIVE GERMPLASM IN IRAN ON THE BASIS OF MORPHOLOGICAL TRAITS: ASSESSMENT OF 'ZARD' AND 'ROWGHANI' CULTIVARS

Iran, located in the Eastern Mediterranean, shares many geographical characteristics and common historical roots with the countries of the Mediterranean basin, which are home to the major known cultivars of olive. Iran, for its part, harbors numerous olive cultivars, whose morphological and biological characters are yet to be characterized. This is important both from commercial and nutritional points of view. Building upon earlier work and in conjunction with a molecular genetics program for molecular characterization of Iranian olive cultivars, we undertook to characterize olive germplasm of Iran on the basis of morphological characters. To reach this goal, we started our research with the study of two important cultivars in Iran, ‘Zard’ and ‘Rowghani’. This survey was performed over a one-year period. Samples were gathered from 281 (‘Zard’, 212 and ‘Rowghani’, 69) adult trees in eight regions with different ecological condition in the North of country (Roodbar, Manjil, Aliabad, Joodaki, Vakhman, Bahramabad, and Gilvan). Forty samples of flower, fruit, endocarp and leaf were collected from each tree. Multivariate statistical methods including cluster analysis and Principal Component Analysis were used for data analysis. Our preliminary results indicate a considerable variation within the traditionally recognized cultivars of olive in Iran. A more detailed assessment of morphological characters is in progress. INTRODUCTION It is believed that the olive tree originated in the Mediterranean in prehistoric times. Iran lies in the Eastern Mediterranean a part of the world that has been cradle of ancient civilizations and has been implicated as a possible place of birth for the olive tree. The early history of olive tree in Iran has been shrouded in uncertainty but we know that olive was mentioned in ancient Iranian religious hymns of two thousand years ago. The history of olive implantation in the major olive-growing region of the country (Roodbar) has been documented for the past nine hundred years (Tabatabaie, 1995). Today, Iran, with an olive crop area of 35,000 hectares and an olive oil production of 3,000 tons per year, is one of the olive-growing countries of the world. The olive gene pool in this country constitutes a potentially important subset of the olive gene pool in the world. A scientifically sound knowledge of Iranian olive varieties forms the basis of further genetic studies of Iranian olive and contributes to the worldwide drive to identify and preserve the genetic variation in olive. Traditionally, several cultivars of olive have been recognized in Iran. These cultivars are grown together in the olive-growing regions of the country. The most important of these cultivars are ‘Zard’ and ‘Rowghani’. Earlier, only limited morphological studies have been performed on Iranian olive cultivars. We attempt to investigate and further characterize these cultivars through statistical analysis of their Proc. XXVI IHC – IVth Int. Symp. Taxonomy of Cultivated Plants Ed. C.G. Davidson and P. Trehane Acta Hort. 634, ISHS 2004 Publication supported by Can. Int. Dev. Agency (CIDA) 146 morphological traits. This is part of the first comprehensive investigation of the morphological characters of olive germplasm in Iran and it is conducted in conjunction with our ongoing research program on molecular characterization of olive germplasm by use of molecular markers. MATERIALS AND METHODS Plant Material The plant specimens were collected randomly from 212 ‘Zard’, and 69 ‘Rowghani’ adult trees in eight regions with different ecological condition in the North of country (Roodbar, Manjil, Aliabad, Joodaki, Vakhman, Bahramabad. and Gilvan). Thirty-one morphological characters were measured on each individual (Table 1). Forty-organ samples from the South-facing sides of trees were characterized for each parameter according to the method prepared by the EU RESGEN CT 96/97 project, coordinated by the International Olive Oil Council (Cantini et al., 1999). Leaf, inflorescences (at the white bud stage), fruit (described when color change was complete), and endocarp were studied. Samples were collected from the mid-shoot portion of the current year’s growth from the most representative shoots at shoulder level (approximately 1.5 m from the ground). For each tree, the average for each characterized trait was used in statistical analysis. Olive plants used in this study had been propagated vegetatively. Data Analysis Qualitative and quantitative data sets were analysed separately. Quantitative variables were standardized (mean = 0, variance = 1) for numerical analysis (Manly, 1986). Qualitative data sets were scored as the presence or absence of a characters. The Euclidean distance was used as a dissimilarity coefficient for quantitative characters. Similarity value (F) was calculated between individuals for qualitative characters using Nei and Li’s (1979) and Jaccard’s (1908) methods. Similarity matrices, based on different genetic distance estimators, were compared using the Mantel matrix correspondence test (Mantel, 1976). In order to quantify intraand intercultivar relatedness, cluster analysis was performed on the total and selected characters. The methods used for these analyses were by the complete linkage method (Peeters and Martinelli, 1989) and unweighted pairgroup (UPGMA) (Benzecri, 1973). The best assessment of fit between dendrogram and original data was determined using the cophenetic correlation coefficient (Romesburg, 1984). To achieve data reduction, to clarify the relationships between two or more characters and to divided the total variance of the original characters into a limited number of uncorrelated new variables, Principal Component Analysis (PCA), (Wiley, 1981) was used. Ordination of the cultivars was performed on the first two PCA axes (Harris, 1999). Multivariate statistical analysis was performed by using NTSYS (Rohlf, 1998) and SPSS/PC (Norusis, 1999). RESULTS AND DISCUSSION High cophenetic correlation (> 0.8) obtained confirmed the efficiency of the clustering algorithms used. There was significant correlation between similarity matrices obtained using different genetic distance estimators (r = P < 0.05). We studied two important olive cultivars in Iran using morphological (quantitative and qualitative) traits and using multivariate statistical methods. This study was performed in three steps: Quantitative and qualitative characters were studied separately in cultivars of ‘Zard’ and ‘Rowghani’ cultivars. The complete sets of data on ‘Rowghani’ cultivar is shown (Fig. 1, 2 and 3). Data on ‘Zard’ cultivar is omitted in this paper due to lack of space. This survey showed that individuals from the same cultivar lie in different groups. Pattern of clustering was different with qualitative and quantitative characters (Fig. 1 and 2). However, it did not change the overall results. In other words, individuals merely moved from one group to another. Also, cluster analysis based on quantitative traits established more groups than qualitative traits, which is not surprising because