On the Artificial Germination of Pollen of Rice : VI. Protoplasmic streaming in pollen tube. : VII. The relation between temperature and protoplasmic streaming.

Abstract

The movement of the protoplasm in pollen tube is generally streaming accompanied with rotation. The movement was able to be observed at first when pollen tube reached 30YAMADA∼35μ in length for 5 minutes after setting of pollen on the media. The rate of protoplasmic streaming (μ/sec.) was measured under microscope from that time. It was found that the initial rate of streaming (5∼10 minutes after pollen setting) was very high in Japanese varieties, but it became low as the time went on. In foreign varieties, on the contrary, the rate was very low during the whole course. These results are shown in Figure 1. The results obtained under various temperature conditions are given in Figure 2. According to those, the rate of streaming increased as the temperature rose to some extent. The maximum streaming rate was recognized only at 30°C among all plots for 5∼10 minutes after pollen setting. The rotating movement of the protoplasm ceased at 40°∼45°C, and the streaming also at nearly 10°C. Changes of the streaming rate with time under different temperature conditions were examined by using two Japanese varieties (Figure 3). At 30°C the initial rate of streaming was very high, but it was then slowed down and ceased. Under 15°and 20°C conditions, the rate were always low during the whole period of the experiment. However when the temperature rose to 38°C, the rate fell between those of 30°and 15°C. In the case of 25°C condition, the intermediate values between 30°and 38°C were obtained.