The pot and field experiments for studying the multiplication techniques of rice TGMS lines with cold water irrigation were conducted, in which an indica rice TGMS line GD-2S with low critical temperature of fertility transition was used as experimental materials. The results suggested that: 1) It was the best to start the cold water irrigation treatment at the phase of differentiation of secondary rachis branch and spikelet primordia. But the sensitive stage of TGMS line GD-2S was during 11th day to 19th day before its heading, namely, from the differentiation of stamen and pistil primordia (phase Ⅳ ) to meiotic division of the pollen mother cell (phase Ⅵ). There seemed to exist a starting process for the rice plants to respond to cold water treatment. 2) It was suitable to be treated with cold water irrigation for about 13 d. Cold water treatment would cause the spikelets degeneration, prolong the developing process of the plants and delay the heading time. The longer the cold water irrigation or the earlier the treatment start, the more the degenerative spikelets. 3) The suitable irrigation depth was about 12cm, Just up to the growth point of the plant.
