The role of growth regulators, embryo age and genotypes on immature embryo germination and rapid generation advancement in tomato (Lycopersicon esculentum Mill.)
One of the most important problem of tomato breeders is lengthy seed to seed cycle in a breeding program. In vitro techiques provide a lot of advantages for breeders. The objective of this work was to determine the effect of growth regulators and immature embryo age on embryo germination and rapid generation advancement in different tomato genotypes. For this purpose, four different tomato genotypes were used. Immature embryos were derived from fruits 20, 24, 28, 32 and 36 days after pollination. Fruits were left on the plant to mature as control (conventional breeding cycle). MS, MS + 0.1 mg/l kinetin, MS + 0.1 mg/l IAA and MS + 0.1 mg/l kinetin + 0.1 mg/l IAA were used as growth regulators. Growth regulators and genotypes resulted in nonsignificant effect on germination rate and rapid generation advancement, but embryo age resulted in significant effect. Germination rate from immature embryos ranged between 55.22 and 100%. Twenty eight (28) and thirty two (32) days old embryos gave the best germination rate. Days from pollination to flowering, shortened between 53,36 and 63,96 days in comparison with the conventional breeding cycle. This study showed that using immature embryo technique in tomato breeding offers more generation per year when compared to conventional breeding practice.
Key words: Growth regulators, immature embryo culture, embryo age, tomato, kinetin, IAA, shortened breeding cycle.