Effects of gamma-ray treatment on Cannabis sativa pollen viability

The viability and the in vitro germination capability of hemp pollen (cv. Carmagnola) were studied. Viability tests were based on the microscopic observation of the fluorescence of loaded fluorescein diacetate (FDA), while, for germinability tests, five different media were tested. The effects of irradiation with 7-rays on pollen viability and germination and on seed set were also studied, at three different irradiation doses (20, 60 and 100 krad). The results show that in one of the media tested, about 85-90% of the pollen grains are viable and able to germinate in control samples, and that while viability measured by FDA test is not affected by increased 7-ray doses, the pollen in vitro germinability drops to about one-half of the controls at the maximum "y-ray dose employed, 100 krad. Seed set of hemp plants pollinated with the irradiated pollen dropped to less than 1% of that of plants pollinated by untreated pollen for the higher dose used. The different media suitable for in vitro germination of hemp pollen, and the observed lack of correspondence between viability and germination capacity tests are discussed.