Abstract: The yield and main economic characters of F₁ and F₂ of 4 combinations of keng rice hybrid were investigated in 1986-1988. The results indicated that the yields and main economic characters of F₁ and F₂ were close, fertility segregation did not occur in the hybrid F₂, and the segregation of its plant height and heading stage were negligible. That showed that the hybrid F₂ of these 4 combinations was utilizable. However the employed combination of hybrid F₂ was conditioned by: (l) The male sterile line employed must be gametophytic sterility;(2) The combination is possessed of strong heterosis;(3) The plant height and heading stage of the parents should be same or close;(4) The suitable cultivation techniques should be adopted, such as to add transplanting density and to give more effective management in the tillering stage, for increasing the panicles per unit area.

Key words: Keng hybrid rice, F₂ hybrid