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- Author or Editor: Eladio Arnaud-Santana x
The heritability of leaf, pod, and seed reactions; stem color and abaxial leaf pubescence; and the association of these traits were studied in advanced dry bean recombinant inbred lines derived from the Phaseolus vulgaris crosses `PC-SO' × XAN-159, `PC-50' × BAC-6, and `Venezuela 44' × BAC-6. The reaction to Xcp was quantitatively inherited in all three plant organs. Qualitative inheritance was found for stem color and leaf pubescence. Low to intermediate heritability values were obtained for the leaf and seed reactions to Xcp. Heritability estimates were consistently low for the pod reaction to Xcp. Low nonsignificant Pearson correlations were detected between leaf and pod reactions, leaf and seed reactions, and pod and seed reactions, except for the latter two correlations, which were low and significant in lines from the cross `PC-50' × XAN-154. Genetic correlations between leaf and pod reactions and leaf and seed reactions were low and significant in lines from all crosses, except for Venezuela 44 × BAC-6 in the latter case. Genetic correlations between pod and seed reactions were low and nonsignificant, except in the cross `PC-50' × XAN-159, for which a low significant correlation was observed. No significant association was found between Xcp leaf reaction and stem color or leaf pubescence. A breeding strategy for improving resistance to Xcp in P. vulgaris is discussed.
Bean golden mosaic (BGM), rust (RU), web blight (WB), and common blight (CB) are major constraints affecting bean yields in the Dominican Republic (DR). The objectives of the USAID DR supported project were to educate graduate students, improve research facilities and equipment, institutionalize the project, and develop a comprehensive bean disease management program. The project trained 25 researchers. A national center for bean improvement (CIAS) was established. Facilities for plant pathology, germplasm storage, and screenhouses were built and equipment and vehicles were acquired. The high-yielding rust-resistant red mottled bean variety `PC-50' was introduced and grown on about 60% of the hectarage. However, BGM became a serious problem with the increase of the white fly population (vector of BGMV) due to increased vegetable production. Under severe BGM, yields were low in plantings made after 15 Dec. The combination of the use of `PC-50', along with a fallow period with delayed planting until early November, reduced the populations of white fly, BGM, RU, and CB and led to a dramatic yield increase of beans and to self sufficiency in beans in the DR. PC-50 became damaged by a new RU race and a resistant line PC-21-SMA (UPR) was released. New bean lines with resistance to BGM, WB, RU, and CBB are being tested for release.