他家受粉及び2, 3の自家不和合性打破処理がブドウ‘ピオーネ’の雌ずい中での花粉管伸長に及ぼす影響

Abstract

The major cause of poor sets of normal seeded berries in ‘Pione’ grapes is that most of the pollen tubes are inhibited from growing further at the basal part of the style or the upper part of the ovary. To clarify whether this inhibition is due to self-incompatibility or not, we conducted several pollination tests and heat treatments on prebloom and blooming flower clusters.1. Reciprocal pollination tests using pollen of ‘Muscat of Alexandria’, ‘Campbell Early’ and ‘Benizuiho’, where a number of pollen tubes grow in their pistils, showed that the number of pollen tubes growing into each part of ‘Pione’ pistils was not greater than in selfed ones. The percentage of set of seeded berries and average seed number were also not increased by cross pollination. Pollen tube growth in those three cultivars, on the other hand, was inhibited to some degree, depending on the cultivar, when crossed by ‘Pione’ pollen.2. Repeated self pollinations every 6 hours for 2 days did not improve pollen tube growth in ‘Pione’ pistils. Pollinating every 2 hours, however, increased the number of tubes reaching the style and upper and middle parts of an ovary, though their further growth into micropyles was not affected. The set of seeded berries was also not improved by repeated pollinations.3. Bud pollination (3 days before anthesis or earlier) and delayed pollination (4 days after or later) did not enable pollen tubes to grow into the styles or ovaries of ‘Pione’ pistils. Following pollination one day before or 2 days after anthesis, pollen tubes grow into the pistils as with pollination at anthesis.4. Heat treatments such as 40, 45, and 50°C for 5, 15, and 30 seconds or 30 minutes on pre-bloom or blooming ‘Pione’ flower clusters did not increase the number of pollen tubes reaching each part of the pistils.5. From these results, we conclude that the inhibition of pollen tube growth in ‘Pione’ pistils may be caused by some other mechanism than that of self incompatibility.