Study of morphological diversity in some olive genotypes of Gorgan region

Local genotypes and wild species are regarded as national genetic resources of plants in each country and much effort should be made to preserve and prevent their extinction. Given that Iran is one of the origin area of olive in the world, identifying and protecting the olive resources, identifying the old orchards and organizing the genotypes have special importance.

In this study, 32 genotypes were evaluated using morphological markers according to the standard methods of the International Olive Council, which was approved by the Seed and Plant Registration and Certification Institute. This method comprises 33 morphological traits for leaf, stone and fruit. Of these, 11 quantitative traits and 22 qualitative attributes were studied. Quantitative traits were determined in 30 fruits and stones and 15 leaves. The cluster analysis, grouping and factor analysis and principle component analysis were performed.

The results showed that there were some significant differences at 0.1% probability level among the genotypes studied in terms of fruit weight, fruit length, fruit diameter, fruit length to diameter ratio and flesh percentage and stone weight, stone length, stone diameter, and stone length to diameter ratio.. The highest fruit weight was observed in genotype I7 (3.88 g). The highest fruit lengths were in genotypes B13 (25.28 mm) and F1 (25.15 mm). The highest fruit diameter was in genotype I7 (16.48 mm). The highest stone weight was seen in genotypes G4 (0.95 g) and the highest stone length was related to F1 (21.55 mm). The genotype F12 had the highest leaf length (65.66 mm), but did not have any significant difference with genotype D2, F9, D10, A12 and A10. The genotype F12 had the highest leaf width (14.77 mm). In evaluating the qualitative traits of fruit, most genotypes had symmetrical shape and about one third of genotypes were partly symmetric, while there was not seen any asymmetric shape among genotypes. Correlation analysis showed that there is a significant correlation between the majorities of measured traits. According to the results, the highest correlation was observed between stone weight and stone diameter (r = 0.86). In cluster analysis, 32 genotypes were divided into six main clusters in the distance of 0.68. Based on the factor analysis, the data of this study have four main factors, in which justified about 91% of the total variance. Analysis of the principle component confirmed the existence of high morphological variability among the genotypes.

According to the results of this study, there was a highly genetic diversity among olive genotypes located in Hashemabad Gorgan, therefore they could be promising genotypes in propagation programs, breeding, and development of olive commercial orchards and cultivar selection in Golestan province.