Abstract: Bacterial wilt is one of the primary diseases of pepper grown in solar-greenhouse. In order to select an resistant rootstock and elucidate the resistant mechanism of grafted pepper，changes of disease incidence and disease index of bacterial wilt in different rootstock varieties of pepper were investigated by manual inoculation，with‘Xinfeng 2’as control. The result showed that‘Weishi’was diseased in later days，and showed the lowest disease incidence and disease index，therefore represent the highest disease resistance among the four rootstock varieties and the control. Changes of disease incidence and disease index of bacterial wilt and osmoregulation in grafted（‘Xinfeng 2’scion grafted onto‘Weishi’）and own-root plants（‘Xinfeng 2’，control）of pepper were investigated after being inoculated. The results showed that the disease incidence and disease index of grafted plants were lower than those of control. Measured on 20 d after inoculation，the disease incidence and disease index of grafted plants were lower by 33% and 43% respectively compared with the control. Before inoculation，grafted plants showed lower water content，water potential and osmotic potential，but higher bound water/free water，soluble sugar and proline content in roots and leaves，compared with the control. The water content，water potential and osmotic potential in roots and leaves of pepper plants decreased gradually after inoculation，but bound water/free water increased，the soluble sugar and proline contents increased at early stage，but decreased later. Compared with control plants，the grafted peppers showed less decreasing rates in water content，water potential and osmotic potential，and less increasing rate in bound water/free water. Soluble sugar and proline contents in leaves and roots of grafted peppers were significantly higher than those of control plants. These data indicated that graft significantly increased the bacterial wilt resistance in pepper，and is closely related to the osmoregulation.

Key words: pepper, rootstock, disease index, bound water, free water, osmoregulation