Abstract: This paper deals with the manual ova hatching of Rana chinensis . It is eviden that there are three different periods in the ova eclosion. The first period is at 75～80℃of effective water cumulative temperature. The peak period is at 100～120℃. The end is at 120～140℃. The most suitabale temperature of ova eclosion is 11～13℃. In this case, the eclosion speed is 1.6～2.2, and incubation period is 9～12 days,with the rate of eclosion over 80%. Manual hatching can increase the eclosion speed of ova. It is 10%～60% higher than CK, and also 25%～100% higher than the outdoor.

Key words: cotton, salinity stress, fertilization, nitrogen utilization.