INVITRO POLLEN GROWTH AND MELON POLLEN GERMINATION (CUCUMIS-MELO L) AFTER GAMMA-IRRADIATION

The effects of several factors (dose-intensity) of gamma irradiation on the germination ability and pollen growth in vitro of the Cucumis melo L. type Cantaloup Charentais cv. "vedrantais" pollen are quantified. The level of germination is determined by a manual count using a binocular microscope. The morphometric characteristics of the pollen tube are evaluated by image analysis. The automated nature of the evaluation method permits a rapid processing of a large number of samples and, therefore, good reliability in the established comparisons. Relatively high doses of irradiation (1.6 kGy) are needed to reduce the level of germination. Nevertheless, doses greater than 0.5 kGy are sufficient to reduce pollen tube growth rates. The maximum length of pollen tubes is affected only by doses greater than 2.5 kGy. The lethal dose is around 4 kGy. The high radioresistance of this pollen is confirmed by the high LD50 (3 kGy) value.