[Objective] The purpose was to study and analyze the difference of Peiai 64 S fertility expression in two different climatic regions, Hainan and Hunan in 2010, and confirm the suitable region for its production of hyb...[Objective] The purpose was to study and analyze the difference of Peiai 64 S fertility expression in two different climatic regions, Hainan and Hunan in 2010, and confirm the suitable region for its production of hybrid seeds. [Method] Eight sowing times were designed, March 20 and 30, April 10 and 30, May 15, June 1, 10 and 20, respectively in Changsha of Hunan. Thirteen sowing times were designed in Hainan, January 28, February 12 and 27, March 14 and 29, April 13 and 28, May 13 and 28, June 12, July 1, 12 and 27, respectively. Peiai 64S was gradually managed and recorded heading stage during cultivation, and the effects of different climate influencing factors, such as daily mean temperature, daily maximum temperature, daily minimum temperature, duration of day at 0-25 d before heading （namely pollen mother cell meiophase）, on pollen fertility were analyzed to confirm sensitive periods of light and temperature. [ResuLt] There was a big difference in sensitive period among the same cytoplasmic male sterile （CMS） in different climatic regions. The sensitive period of Peiai 64S was in first four phases, phases V, VI, VII, VIII （0-13 d） in Changsha of Hunan, which was in last four phases, phases I, II, III, IV （13-25 d） in Haikou of Hainan. Under natural conditions, Peiai 64S pollen sterility rate were all more than 99.5% and seed-setting rates all less than 0.5% in Haikou, so production of hybrid seeds was safe. Its pollen sterility rate was 21.3%- 100.0% in Hunan, so its security coefficient of hybrid seeds production was lower than that in Hainan. [Conclusion] The security coefficient of hybrid seeds production of CMS Peiai 64S is lower than that in Hainan.展开更多
In the urban labor market, the rural labor force can choose whether to become self- employed or work for wages depending on their stock of human capital and local labor market conditions. A simple Mincer earnings regr...In the urban labor market, the rural labor force can choose whether to become self- employed or work for wages depending on their stock of human capital and local labor market conditions. A simple Mincer earnings regression shows that the rate of return to schooling for wage earners is two percentage points higher than that for the self-employed. After correcting for bias in sample selection, the expanded Mincer earnings equation estimated the rate of return to schooling for wage earners at between 5.3 and 6.8 percent. From the standpoint of training, we found that the simplest form of training, short-term training and formal training played an important role in promoting migrant workers’ repeat mobility. However, the simplest form of training did not have a significant effect on earnings,whereas short-term and formal training played an important determining role in this respect. Moreover, rights protection issues such as wage arrears also had an important effect on migrant workers’ repeat mobility. In handling heterogeneity and endogenous educational variables among migrant workers, the authors found that the years of schooling of the parents of migrant workers were not an ideal instrumental variable.展开更多
文摘[Objective] The purpose was to study and analyze the difference of Peiai 64 S fertility expression in two different climatic regions, Hainan and Hunan in 2010, and confirm the suitable region for its production of hybrid seeds. [Method] Eight sowing times were designed, March 20 and 30, April 10 and 30, May 15, June 1, 10 and 20, respectively in Changsha of Hunan. Thirteen sowing times were designed in Hainan, January 28, February 12 and 27, March 14 and 29, April 13 and 28, May 13 and 28, June 12, July 1, 12 and 27, respectively. Peiai 64S was gradually managed and recorded heading stage during cultivation, and the effects of different climate influencing factors, such as daily mean temperature, daily maximum temperature, daily minimum temperature, duration of day at 0-25 d before heading （namely pollen mother cell meiophase）, on pollen fertility were analyzed to confirm sensitive periods of light and temperature. [ResuLt] There was a big difference in sensitive period among the same cytoplasmic male sterile （CMS） in different climatic regions. The sensitive period of Peiai 64S was in first four phases, phases V, VI, VII, VIII （0-13 d） in Changsha of Hunan, which was in last four phases, phases I, II, III, IV （13-25 d） in Haikou of Hainan. Under natural conditions, Peiai 64S pollen sterility rate were all more than 99.5% and seed-setting rates all less than 0.5% in Haikou, so production of hybrid seeds was safe. Its pollen sterility rate was 21.3%- 100.0% in Hunan, so its security coefficient of hybrid seeds production was lower than that in Hainan. [Conclusion] The security coefficient of hybrid seeds production of CMS Peiai 64S is lower than that in Hainan.
文摘In the urban labor market, the rural labor force can choose whether to become self- employed or work for wages depending on their stock of human capital and local labor market conditions. A simple Mincer earnings regression shows that the rate of return to schooling for wage earners is two percentage points higher than that for the self-employed. After correcting for bias in sample selection, the expanded Mincer earnings equation estimated the rate of return to schooling for wage earners at between 5.3 and 6.8 percent. From the standpoint of training, we found that the simplest form of training, short-term training and formal training played an important role in promoting migrant workers’ repeat mobility. However, the simplest form of training did not have a significant effect on earnings,whereas short-term and formal training played an important determining role in this respect. Moreover, rights protection issues such as wage arrears also had an important effect on migrant workers’ repeat mobility. In handling heterogeneity and endogenous educational variables among migrant workers, the authors found that the years of schooling of the parents of migrant workers were not an ideal instrumental variable.
