Biodiversity study of several superior hazelnut (Corylus avellana L.) genotypes in Fandogloo on the basis of some fruit and environmental characteristics

Fandogloo habitat, the largest gene pool of hazelnuts, is located in the Northwest of Iran. A combination of climatic variation and consecutive sexual propagation have produced a very rich genetic diversity among local hazelnuts in this gene pool. The goal of this research was to conduct a biodiversity analysis of hazelnuts in Fandogloo habitat using a correlational study among variables, principle component analysis and cluster analysis. Meanwhile, probable relationships between the studied variables of hazelnuts and their growing location were also evaluated. Twenty superior genotypes were selected out of 70 primarily studied genotypes and labelled in 2014-2015 on the basis of important morphological and phonological traits. Ten variables regarding nut and kernel dimension and phytochemical compositions (oil, protein, and carbohydrates percentages of kernels and the amount of Taxol in mature leaves) were evaluated. In order to study the environmental effects, five environmental traits including the means of annual rainfall and temperature, elevation above sea level, number of frosty days, and soil pH were evaluated for each sampling place. The statistical analysis was done with SPSS 16. According to descriptive statistics, the highest coefficient of variance (C.V.) values belonged to nut thickness (26.31%), and nut weight (24.41%), while the lowest C.V. values belonged to frosty days (1.53%), and soil pH (1.83%). There was a strong correlation between nut length and kernel percentage (r = 0.943, P<0.01) and a negative correlation between Taxol and kernel thickness (r = -0.519, P<0.05) and kernel percentage (r = -0.524, P<0.05). There was a negative correlation between soil pH and annual precipitation (r = -0.838, P<0.01) while elevation above sea level was positively correlated with annual precipitation (r = 0.481, P<0.01). Annual rainfall had a negative correlation (r = -0.495, P<0.05) with kernel ratio. Principle component analysis showed that the first five principle components (PCs) accounted for 70.85% of the total variation. Cluster analysis produced a dendrogram with two main clusters. The genotypes classified in group II were located in a higher elevation than the group I genotypes. This study showed a significant genetic diversity among the hazelnuts of Fandogloo habitat, which is of great value for breeding programmes. The diversity observed within hazelnuts in Fandogloo is related rather to their genetic variation than the impact of environmental conditions. However, among environmental properties, elevation above sea level had more effects on genotype attributes in comparison with other environmental factors. Hemmed in by tall mountains with a cold climate, Fandogloo has become one of the unique gene pools of hazelnut in Iran. The nuts of the studied genotypes in Fandogloo were smaller, globular with relatively high kernel ratio than hazelnuts from other habitats in Iran. Although none of the studied genotypes are potentially eligible to be introduced as a new cultivar, but they may be crossed with commercial cultivars in order to produce new hazelnut cultivars compatible with the harsh climatic conditions of Fandogloo.