I am culturing some orchid explants (TCL) in MS medium with PGRs for 40 days, but the plants are neither responding or dying, a yellow color is replacing the green color of explants.
This happens many a times in PTC. The explants start loosing their chlorophyll. i do not know how much Auxin u r using. High auxin content in culture restricts growth and changes the color of chlorophyll.
Please let us know that, are you trying to obtain callus or multiple shoots? If you need multiple shoot you must use higher concentration of cytokinines in combinations with little amount of Auxin. Please let me know, i might help you a bit.
Dear Nikhil, as you know, The Orchids family needs to modified media to growth in vitro, Did you prepared the proper media? may I know which species do you working on?