Classification of Some Iranian Pomegranate (Punica granatum) Cultivars by Pollen Morphology Using Scanning Electron Microscopy
2009
Varasteh, Feryal (Tarbiat Modares University, Tehran, Iran) | Arzani, Kazem (Tarbiat Modares University, Tehran, Iran), E-mail: [email protected]
Pollen grains from 14 pomegranate (Punica granatum) cultivars were examined using scanning electron microscopy. Pollen grains were observed and photographed at 3,000x for whole grains and at 20,000x for exine patterns. The polar (P) and equatorial axis (E) of grains, P/E ratios, distances between the two furrows, and width of the pollen grain ridges were measured. The results indicated that the mean polar axis ranged between 22.63-25.86 ㎛, while the mean equatorial axis ranged between 12.69-14.47 ㎛. Two groups were identified according to the polar axis and equatorial axis. Mean values of the P/E ratio varied from 1.75-1.94. In addition, pollen grains were placed in prolate (elliptical) shape group based on the P/E ratio. The studied cultivars were classified into four groups according to distance between furrow edges and into two groups according to width of ridges. All studied cultivars showed a similar foveolate ornamentation pattern. Correlation coefficients calculated between different traits of pomegranate pollen grains indicated that there were positive and significant correlations between polar axis and equatorial axis (r = 0.675), polar axis and distance between furrow edges (r = 0.908), and P/E ratio and distance between furrow edges (r = 0.671). The projections of the loadings defined by the first two principal components allowed grouping of pomegranate cultivars. Cluster analysis of the studied cultivars indicated the estimated relations between the studied cultivars, which were classified into the three main different groups. The cluster analysis partially confirmed the results of principal component analysis on the cultivars. Hence, pollen morphology characteristics can be used for pomegranate cultivar identification.
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