Abstract
The authors examined the growth of pollen tube and its varietal differences of rice plants, using Japanese and foreign varieties. The germination media for pollen were made of 5% potato starch paste containing 15% sucrose. The main results were as follows: 1) In all tests, it was found that 50∼100% of pollen used showed their germination. 2) The germination of pollen grain begun immediately after it had been set on the medium and this initial rapid growth of pollen-tube continued for 10∼20 minutes, after that the growth became very slow and ceased after 20∼30 minutes. And at last the length of pollen tube was measured to be 50∼110μ. 3) Comparing Japanese varieties with foreign ones, though no difference was found in the speed of the initial growth, the cease of pollen-tube elongation was delayed longer by 5∼10 minutes in foreign varieties. 4) The length of pollen-tube of Japanese varieties were observed to be somewhat shoter (50∼80μ) that of foreign ones (70∼110μ), and this difference was proved to be significant, statistically.
