Embryo culture studies in interspecific crosses between Arboreum and Hirsutum cotton

For the embryo culture studies in crosses between G. arboreum & G. hirsutum cotton, the immature hybrid embryos of four crosses viz. AKH-4 x LRA-5166, AKH-4 x AKH-081, AKA-8401 x LRA-5166 and AKH-081 excised 12, 15, 20 & 25 days after pollination (DAP) were used. They were cultured on BT & MS media supplemented with various concentrations & combinations of auxins, cytokinins & gibberelins. The embryos cultured at 20 DAP showed best response when the immature hybrid embryos were sequentially transferred in five different BT media. The cross AKH-4 x AKH-081 yielded maximum number of plantlets on BT media. With MS medium fortified with 1.5 mg/l IAA. 0.5 mg/l KIN and 250 mg/l CH, only one plantlet developed. In other combinations of MS media, no plantlet was obtained. Among all the cross combinations, AKA-8401 x AKH-081 showed relatively better response to all the media (BT & MS) used in study. In case of plantlets developed from immature hybrid embryos, maximum survival was observed in the hardening treatment M2S3 (transferring the plantlets to sterile distilled water for 6h and then to trays/polybags containing potmix & covering them with polythene sheet and keeping open).