Selection for resistance to the sweet potato weevil, Cylas formicarius Fabr.
1992
Amalin, D.M. | Chujoy, E. | Gerpacio, Ma.T.L. (International Potato Center, P.O. Box 933, Manila (Philippines))
A scheme to screen sweet potato germplasm for resistance to the weevil Cylas formicarius consisted of four steps. Step 1 or initial elimination is a field screening of test clones, in observation plots with no replications. Step 2 or second elimination trial involves a no-choice test, of clones selected in Step 1, either under laboratory or greenhouse conditions, arranged in an experimental design with replications. Step 3 or the advanced trial is the field screening of clones selected in Step 2. This scheme was found to be fast and a cheaper way to screen a large number of clones. Moreover, in Step 3 a relatively large number of replications can be accommodated such that inconsistency of resistance result among replications or among plots can be checked. To avoid pseudo-resistance a standard evaluation of resistance is very necessary, specifically in a multilocational trial. The resistance rating procedure must be flexible to check the effect of the varying levels of the insect pest populations. This could be done by using a correction factor in the rating scale, such as the standard deviation
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