Abstract: The low fertility of tetraploid tomato self-cross(4x × 4x)was studied,The comparative histological studies of the fertilization and embryogenesis of the self-crosses(2x × 2x and 4x × 4x) were reported, 1. The f requency of pollen germination was relatively low and the pollen tubes grew slowly and nonuniformly in the cross 4 x × 4x, 2 .The abnormal ovules were occasionally observed in the tetraploid before fertilization,3. fertilization proceeded normally except that the fertilization was somewhat delayed and that the percentages of ovules into which pollen tubes got was significantly low in the mating 4x × 4x,4. The developing seed of the tetraploid resembled that of the diploid very closely.5. Analysing the data on the frequency of tetraploid showed that low fertility of tetraploid was attributed to the low fertilization and embryogenesis of fertilized ovules.

Key words: Tomato (Lycopersicuri esculentunm Mill,), Tetraploid, Self-cross fertility