*of the Division of Botany, Indian Agricultural Research Institute, and presently Additional Agricultural Commissioner with the Govt. of India.
Indian Agricultural Research Institute, New Delhi
Several colchicine treatment methods were tried in berseem and senji, which are important fodder plants under irrigated and rainfed conditions respectively. In berseem, immersion of snoots of 4-day old seedlings in 0.1 per cent colchicine for 8 hours at room temperature gave the highest percentage of total tetraploids (30 per cent). Treatment of whole seedlings with 0.05 per cent colchicine for 8 hours at room temperature gave the highest percentage of mixoploids (63.5 per cent). Senji responded best to whole seedling treatment with 0.05 per cent colchicine for 4 and 8 hours at room temperature. The optimum age of seedlings for the whole seedling as well as shoot immersion treatments was found to be 4 days. The different variables involved in standardising a suitable colchicine treatment method are discussed and it. is pointed out that the proper after-care of colchicine treated seedlings is of great importance for ensuring the success of the treatment.
