An improved method for artificial hybridization in annual Medicago species

An improved technique for successful artificial hybridization in annual medic (Medicago spp.) is described. Using a previously reported method, only four out of seven species were successfully crossed, with the percentage of success ranging from 3 to 22%. Initial modifications to this technique gave a 7-8 fold increase in the successful crossing rate in M. murex and M. polymorpha medic, from 9 to 64% with M. murex and from 10 to 82% with M. polymorpha. Further modifications to the technique resulted in a success rate of 100% in both species. The numbers of seeds per pod obtained from crosses in both species were also increased by using the modified techniques compared to the established method. Selection of larger, more mature flowers, differences in flower cutting position, as well as post pollination position were the main modifications which accounted for the greatly improved success rate. The modified technique was subsequently applied successfully to obtain for the first time inter-specific crosses involving M. polymorpha x M. murex, M. polymorpha x M. sphaerocarpos, M. murex x M. sphaerocarpos, M. solerolii x M. littoralis/M. truncatula hybrid, M. solerolii x M. tornata, and M. littoralis/M. truncatula hybrid x M. sphaerocarpos.