On the Artificial Germination of Pollen in Rice Plants. : IV. Temperature limits of pollen germination in rice varieties.

In 1953 using a rice variety "Kyoto-asahi", the same authors made observations on the effect of different temperatures on the pollen germination on artificial media. And it was found that the maximum and minimum temperatures for germination were 42∼45°C and 12∼15°C respectively. In 1954, using many varieties, similar experiments were repeated for the purpose of finding out the temperature limits for pollen germination. The applied varieties amounted 23, including 14 Japanese (6 early, 4 medium and 4 late varieties) and 9 foreign varieties. Pollen were cultured on a starch paste medium kept at various temperatures. The results were given in table 1, which showed that the maximum temperature limits were 40∼45°C and the minimum limits were 7∼14°C (Japanese varieties: 10∼14°C). Slight varietal differences were found in respect to maximum and minimum temperature limits like thus: In Japanese varieties, the maximum temperature limits in medium varieties were significantly higher than those in early and late ones. The minimum temperature limits were the highest in the early varieties and next in the late ones and the lowest in the medium varieties. Comparing foreign varieties with Japanese ones, a statistically significant difference was found in the germination of pollen at minimum temperature, the temperature limits being lower in foreign ones than in Japanese ones.