|Rumbaugh, M - USDA-ARS, RETIRED|
Submitted to: Journal of Nematology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 27, 1994
Publication Date: N/A
Interpretive Summary: Approximately 86% of the 153 million ha of rangelands in the Intermountain Region of the western United States are considered to be in less than good condition, producing approximately 60% of its potential. Nitrogen, an essential constituent of protein necessary for cell protoplasm, must be in an available form for all flora organisms. Symbiotic relationship exists between nitrifying bacteria, Rhizobium spp. and the family Leguminosae that enrich the soil with nitrogen for use by all plants including the legumes. Legumes are not only beneficial for making atmospheric nitrogen available for other plants, but aid in land reclamation and are used as a energy supply for wildlife and livestock. The objective of this study was to determine the host-parasite relationships of different population and inoculum levels of M. hapla and M. chitwoodi on Leguminosae species. In the greenhouse, all Leguminosae species, except for Lathyrus sp., were hosts to Meloidogyne chitwoodi and the three populations of M. hapla. There were, however, genetic differences with seed lots of most susceptible species to all nematode populations. Since resistance is the major means of controlling Meloidogyne spp., plant accessions differed enough to provide sources of resistance for genetic improvement.
Technical Abstract: Legumes of the genera Astragalus (milkvetch), Coronilla (crownvetch), Lathyrus (pea vine), Lotus (birdsfoot trefoil), Medicago (alfalfa), Melilotus (clover), Onobrychis (sainfoin), Trifolium (clover), and Vicia (common vetch) were inoculated with a population of Meloidogyne chitwoodi from Utah or with one of three M. hapla populations from California, Utah, and Wyoming. Alfalfa (M. scutellata) and red clover (T. pratense) were the most susceptible of all the legume species. Plant survival rates were 86, 39, 46, and 39% for M. scutellata and 55, 40, 28, and 10% for T. pratense, respectively, when inoculated with M. chitwoodi, and with M. hapla from California, Utah, and Wyoming. All plants of all other legume species survived all nematode populations, except for 4% of the white clover (T. repens) plants inoculated with the California M. hapla population. Plant growth of most legumes was reduced by one or more nematode populations. All legumes were better hosts for the M. hapla populations than for M. chitwoodi at a greenhouse temperature of 24 ñ 3 C. Root-knot galling differed among nematode populations and species. Root galling indices (1 = none, 6 = very severely galled) ranged from 1.00 on Lathyrus inoculated with the California population of M. hapla, to 5.38 for milkvetch inoculated with the Wyoming population of M. hapla. The nematode reproductive factor (Rf = final nematode population /initial nematode population) ranged from 0.0 for all nematode populations on Lathyrus to 34.8 for the Wyoming population of M. hapla on Medicago sativa. More plant species were resistant to M. chitwoodi than to the M. hapla populations. No plants of white clover were resistant to any nematode populations. Lathyrus was resistant to all populations.