Morphology and discrimination features of pollen from Italian olive cultivars (Olea europaea L.)

Pollen morphology of 14 cultivars of Olea europaea subsp. europaea var. europaea was analysed in order to discriminate main pollen types. The cultivars were selected from the most spread and early flowering crops grown in Italy. Morphometric parameters were observed on acetolysed pollen by means of light microscopy and scanning electron microscopy. Polar axis (P), equatorial diameter (E), P/E ratio, maximum distance between colpi in mesocolpium, distance between the apices of two colpi, exine thickness, maximum length of lumina in mesocolpium and in apocolpium, and exine reticulum thickness in mesocolpium have been measured. According to P and E, the 14 olive cultivars of this study can be divided into the three groups of small (P: 21.75 mu m, E: 22.55 mu m; Manna' and Tonda di Cagliari'), large (P: 25.1 mu m, E: 26.1 mu m; Pescarese' and Rotondella di Sanza') and medium size (P: 23.49 mu m, E: 24.54 mu m, Carolea', Grossa di Cassano', Giarraffa', Nocellara messinese', Nocellara del Belice', Santagatese', Intosso', Maiatica di Ferrandina', Nostrale di Fiano Romano', Santa Caterina'). Maximum length of lumina and exine thickness are useful parameters for further distinction of olive pollen groups, since these parameters are able to provide a specific pollen profile for each cultivar.