This experiment was conducted to gather basic information necessary for CO₂ gas treatment to be a economical and practical method for selfed seed production in self-incompatible radish inbreds is replacing the Labour-consuming bud pollination method. Three inbreds possessing different Level of self-incompatibility were treated with five different concentrations of CO₂, five different interval between pollination and CO₂ treatment, and Eve different duration of treatment in three seperate experiments, respectively.
The results were as follows:
1. CO₂ treatment seemed to be effective in overcoming self-incompatibility in radish inbreds, but it appeared to be harmful in pod setting in other pollination where the self-incompatibility was not involved.
2. Optimum concentration of CO₂ varied with the level of self-incompatibility the inbred possessed. The inbred with stronger self-incompatibility required higher concentration of CO₂.
3. Under the same concentration of CO₂, the weaker self-incompatible inbreds, the more selfed seeds were produced.
4. Regardless of the degree of self-incompatibility the most effective time for CO₂ treatment was 2 hours after pollination.
5. For all inbreds studied, the most effective duration of CO₂ treatment was 2 hours.
6. CO₂ treatment was found to have no harmful effect on seed weight and rate of seed germination. However, seed dormancy appeared to he broken down by CO₂ treatment.
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