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Submitted to: Journal of Nematology
Publication Type: Abstract Only Publication Acceptance Date: 6/8/2012 Publication Date: 12/15/2012 Citation: Davis, R.F., Anderson, W.F. 2012. Identification of widely varying levels of resistance to meloidogyne incognita in sweet sorghum. Journal of Nematology. 44:475. Interpretive Summary: Technical Abstract: Sweet sorghum (Sorghum bicolor) is a potential bioenergy crop that could be incorporated into annual cropping systems in the southern US, where it would likely be rotated with cotton. The desirability of including sweet sorghum in a cotton cropping system will be influenced by sweet sorghum’s host status for Meloidogyne incognita, which is the primary pathogen of cotton in the US, but almost no information is available on the host status of sweet sorghum for M. incognita. However, grain sorghum, which is also S. bicolor, is reported as both a poor host and as a good host to M. incognita, and some reports state that sorghum is a host without reporting the amount of reproduction. We hypothesized that a broad range of resistance and susceptibility could be found in a genetically diverse collection of sweet sorghum entries. A series of greenhouse tests were conducted to evaluate the reproduction of M. incognita on 82 sorghum entries obtained from several different sorghum collections. Entries were arranged by height into four groups, and 19 to 22 entries were evaluated in each of four tests. Corn (Zea mays) was used as a susceptible standard in each test. Tests were conducted in a randomized complete block design with three replications. In each replication, three plants of a single entry were planted into a 15-cm-diam. pot. Two to three weeks after planting, 8000 eggs of M. incognita were added to each pot. Nematode eggs were extracted 8 weeks after inoculation, and the number of plants/pot, total root weight/pot, and total eggs/pot were recorded, and eggs/plant and eggs/gram root were calculated. Mean root weights of the sorghum varied from 18 to 282% of the weight of corn roots. Nematode reproduction on sorghum ranged from 0 to 379% of the eggs per plant found on corn, and from 0 to 216% of the eggs/g root found on corn. Eggs/plant recovered from 30 (37%) of the 82 sorghum entries tested, and eggs/g root recovered from 29 (35%) of the entries, were less than 10% of the levels recovered from corn. This preliminary screen confirms that there is a very wide range of resistance to M. incognita among sweet sorghum genotypes. |
