1a.Objectives (from AD-416)
Screen dormant alfalfa germplasm for resistance to blue alfalfa aphid (Acyrthosiphon kondoi) and stem nematode (Ditylenchus dipsaci) and release germplasm.
1b.Approach (from AD-416)
Plant selected dormant germplasm in greenhouse for determination of resistance to blue aphid. At the same time, screen large numbers of plants from Columbia Basin College germplasm for selection purposes. Score resistance reaction according to standard tests using known non-dormant resistant varieties as resistant checks. If dormant resistant plants are identified, cross in greenhouse, test and reselect. If no resistance is identified in dormant germplasm, cross with resistant non-dormant germplasm in the greenhouse. Screen seed from dormant germplasm for resistance and plant in the field to select for class four dormant plants. Recombine in greenhouse for germplasm release.
Standard tests developed for screening and testing for stem nematode have failed to produce resistant varieties that will perform well in the field. Recurrent field selection is a good indication that field selection may be better suited than standard screening procedures that have been in use for over 30 years with little or no progress. Columbia Basin College (CBC) will plant experimental varieties selected from infested fields for stem nematode to evaluate progress for resistance. Additional selections will be made from the field for seed increase and testing. Germplasm will be released based on test results. At the same time a greenhouse screening procedure will be developed that will allow more time for infection of all plants. More precision is necessary for progress toward higher levels of resistance.
Documents SCA with Columbia Basin College.
Four alfalfa lines have been identified with potential resistance to stem nematode. These are currently being evaluated in the field for long-term resistance to the nematode while also being used for seed increase. Survival data from stem nematode infection is also being collected on additional selected alfalfa varieties. As the project is still in its infancy, no data have yet been collected on alfalfa germplasm resistant to the Blue alfalfa aphid.
The agreement was established in support of Objective 1 of the in-house project, the goal being to screen alfalfa for resistance to biotic stresses that reduce harvest yields.
This project was monitored via visits, email, and phone calls with the cooperator.