1a.Objectives (from AD-416)
Deployment of nematode resistant carrots to U.S. growers and seed industry.
1b.Approach (from AD-416)
We have discovered multiple genetic sources of nematode resistance in carrot germplasm. In this project we will confirm the strength of the resistance, intercross best resistance, produce ample seed for extensive field testing, and release best resistance to the public, especially growers and seed companies. We will also evaluate horticultural quality including field performance traits (color, shape, uniformity) and consumer quality (flavor and nutritional value), hold field days for the carrot production community, and confirm genetic models of resistance in mapping populations.
Root-knot nematodes cause significant levels of economic loss for U.S. carrot growers. Field and greenhouse trials to produce seed for nematode screening were evaluated this past year with the purpose of identifying new sources of resistance. One source of genetic resistance was discovered from a Brazilian carrot a decade ago, but additional genetic resistance will be useful. Carrots were evaluated in the greenhouse and in infested fields. Diverse seed sources were grown in duplicate on Meloidogyne incognita infested soil and on Meloidogyne javanica infested soil with adjacent susceptible check rows throughout both fields. Several of the newer inbreds from sources performed well, and roots were selected for seed increase. Several intercrosses among these sources of resistance are being made to examine the genetics of resistance in these new sources. Intercrosses of resistance with nematode susceptible good-flavored, long carrots adapted for production in California are under development. Several selections have excellent resistance and suitable length, smoothness and flavor. Seed production from the field trials was established for seed production in collaboration with industry cooperators to provide adequate seed for larger scale testing. Project monitored by regular meetings and e-mail discussions of progress.