The gene pools for breeding cassava (Manihot esculenta Crantz) in Africa currently contain only a fraction of the existing genetic variation found in Latin America where the crop originates. Our research aimed to broaden the genetic base in Africa by introducing Latin American (LA) germplasm. The first set of introductions comprised sexual seeds that led to the evaluation of 20,032 seedlings in Nigeria between 1990 and 1994. A second set comprised in vitro cultures, where the dominant CMD2 gene for cassava mosaic disease (CMD) resistance was introgressed into LA germplasm through marker‐assisted selection (MAS). Through MAS 156 genotypes were preselected for the gene and evaluated in Nigeria between 2004 and 2006. Initial results from the first set of introductions indicated that LA germplasm was highly susceptible to CMD, minimizing its usefulness in African cassava‐breeding programs. In the second set of introductions from LA, introgression of the CMD2 gene resulted in high CMD resistance under African field conditions. Now at advanced stages in the African breeding program, 14 genotypes combining CMD resistance and high yield are being evaluated. Marker‐assisted introgression of CMD resistance into LA germplasm has improved the potential value of LA germplasm for Africa and enhanced the prospect of elite LA genotypes being released as improved varieties in Africa.

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El maracuyá (P. edulis f. flavicarpa), la granadilla (P. ligularis) y la gulupa (P. edulis f. edulis) son económicamente las principales especies del género Passiflora L. por su fruto comestible y comercialización en mercados locales e internacionales. El objetivo de este estudio fue identificar el comportamiento fisiológico de la semilla de maracuyá, granadilla y gulupa frente al almacenamiento como una contribución a la conservación ex situ. El diseño experimental utilizado fue completamente al azar con cinco tratamientos y tres repeticiones siguiendo el protocolo de Hong y Ellis (1996). Las semillas de maracuyá y gulupa fueron secadas en cuartos con flujo continuo de aire (20°C±2 y 35% humedad relativa [HR]), donde se les disminuyó el contenido de humedad hasta un rango óptimo de 10-12% en 5 horas y obteniendo una germinación de 100 y 77,1%, respectivamente. En la granadilla, la desecación tardó 20 horas y las semillas germinaron en un 79,5%. Posteriormente, la disminución hasta 6% (20°C±2 y10% HR) tardó 60 horas, para maracuyá y gulupa con una germinación de 81,2 y 98,6%, respectivamente y 105 horas para granadilla con un 91,4% Estudio del comportamiento fisiológico de la semilla de tres especies cultivadas de Passiflora L. (Passifloraceae) como una contribución para la conservación ex situ Study of the physiological behavior of the seeds of three cultivated species of Passiflora L. (Passifloraceae) for contribution to ex situ conservation Frutos de maracuyá, granadilla y gulupa.

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Mechanical scarification with a scalpel is the best treatment to break physical dormancy and reach high germination percentages in many legumes. However, it is highly time-consuming. Given the ecological relation­ship between the presence of physical dormancy and high temperatures in tropical grasslands, dry heat treatment could also promote breaking of physical dormancy in Desmodium and Stylosanthes species. This study assessed seed germination of several accessions of nine species of Desmodium and Stylosanthes. Seeds were treated with dry heat (80°C for 30 minutes) and scarified with a scalpel to determine whether dry heat is a reliable alternative treatment to overcome physical dormancy. Mechanical scarification with a scalpel was effective and resulted in high germination for all species. In S. guianensis, both treatments had an equivalent effect, making dry heat a feasible alternative. Dry heat could also be a reliable alternative in D. heterocarpon, D. velutinum, S. hamata, and S. scabra, but tetrazolium tests may be necessary to confirm viability. For D. barbatum and D. scorpiurus, dry heat could be an alternative but further research is needed to confirm this, while in S. capitata and S. viscosa dry heat is not a reliable alternative.