Ponkan mandarin (Citrus reticulata Blanco) is one of the most important commercial cultivars of mandarin orange in China. This study reports an improved and efficient protocol for in vitro plant regeneration of Ponkan mandarin. Epicotyl segments, which were cut longitudinally into two halves, were used as explants. The shoot regeneration frequency was significantly increased by longitudinal cutting. A 100% shoot regeneration frequency and 13.2 shoots per explant were obtained when cultures were maintained in darkness for 20 d before being transferred to light conditions, with bud induction by indirect organogenesis. A 72.5% shoot regeneration frequency and 7.8 shoots per explant were obtained when explants were incubated under a 16-h light photoperiod continuously with buds differentiating directly from the cutting wound surface. The optimal medium for shoot formation was Murashige and Tucker basal medium supplemented with 2 mgL −1 BA and 30 gL −1 sucrose both under light conditions. The addition of the auxin NAA reduced the frequency of regeneration. A "filterpaper bridge" technique was used for rooting in this study. The basal portion of regenerated shoots was dipped into 1,000 mgL −1 IBA solution for 15 min before placement on a filter-paper bridge that was maintained in 1/2 MS liquid medium supplemented with 10 gL −1 sucrose. Eighty percent of the shoots rooted, and an average of 2.0 roots per shoot were achieved. Survival rate through acclimatization was 100%.

This paper investigates the determinants and the time pattern of the subjective well-being of private business owners. We find that both personal and enterprise-level factors have a significant influence on subjective status of private business owners. Meanwhile, we find supportive evidence of Easterlin paradox among Chinese private entrepreneurs: both personal income and operating revenue enhance subjective status in a certain period, but subjective status declines as time goes by, even as incomes continue to rise. A further Oaxaca-Blinder decomposition suggests that the competition and provincial factors are the keys to explaining the paradox. Finally, we try to verify the positive effect of political connection on entrepreneurs' subjective status to provide some helpful advice for the government.

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