You can try the following protocol as we do. We usually use 0.3-0.4% of colchicine solution. The haploid plant for doubling is usually 3-4 tillers. During colchicine treatment, it is better use flowing air in solution. After transplant, we usually spray water on plants three to four time each day because DH plant is very weak. The temperature keep at 15 to 20 oC for DH plant. I just mention key points or skills for preventing DH plant from death. If you have any question, please let me know.