Plant genetic resources: foundations for a food-secure and climate-resilient future in the Caribbean

Across the Caribbean, climate change will bring about not only challenges but also a wide array of opportunities, which lend greater significance to the region’s wealth of plant genetic resources. Realizing the potential of those resources to help ensure food security and build more-resilient agricultural systems in the face of climate change will require stronger regional cooperation. Its central aims should be to develop timely interventions across national borders that improve the collection, conservation, and sharing of plant genetic resources

Recursos fitogenéticos: bases para un futuro resiliente al clima y libre de hambre en el Caribe

En toda la región Caribe, el cambio climático no solamente planteará desafíos sino también una amplia gama de oportunidades, que ofrecen mayor importancia a la riqueza de recursos fitogenéticos de la región. Materializar el potencial de estos recursos para contribuir a garantizar la seguridad alimentaria y crear sistemas agrícolas más resilientes frente al cambio climático requerirá de una mayor cooperación regional. Los objetivos centrales de esta cooperación deberán ser: desarrollar intervenciones oportunas en las fronteras nacionales que mejoren la colecta, conservación y el intercambio de los recursos fitogenéticos

A study of some morphophysiological factors affecting yield of Pigeonpea grown and their relevance to high intensity production system

A field study was conducted with 38 F6 lines to investigate abscission patterns and their relationship with yield. The rate of abscission increased with the progression of floral nodal position and time after first flowering implying that genotypes with fewer inflorescence nodes and a shorter, synchronous flowering period might have lower abscission rates and be useful for high intensity production. Abscission rate was found to be negatively correlated with yield suggesting that abscission is an important yield limiting factor and genotypic differences in abscission rate were found which could be utilized in breeding a high yielding cultivar. A green house study using rooting boxes demonstrated variations in both canopy and rooting patterns. The results showed that increased number of branches and low branch angle contributed to an erect and compact canopy in ICPH 8 which had also the highest shoot/root ratio. These results suggest that selection of genotypes similar to ICPH 8 might increase productivity at higher planting density. The physiological implications of some of the variation demonstrated are discussed

Sustaining cocoa production through genetic resistance to back pod and leaf blight

The resistance of cocoa to Phytophthora palmivora and its mechanism(s) were investigated in leaves and pods of twelve clones. Anatomical and morphological characteristics including ; cuticle thickness, stomata! frequency and pore length were assessed on leaf and correlated with foliar resistance at penetration stage. Post-penetration resistance was also determined on leaf and pod, and their relationship assessed. Results show a significant difference in leaf susceptibility between surfaces. The adaxial surface appeared less susceptible possibly due to lack of stomata and/or the presence of a thick cuticle. Leaf susceptibility differed significantly at penetration and postpenetration stages suggesting different mechanisms. Correlation analysis shows a strong relationship between the joint effect of cuticle thickness, stomata! frequency, stomata! size and leaf resistance at penetration stage. A close relationship in the rate of spread of lesion in leaf and pod indicates that a reliable assessment of clonal reaction can be based on leaf observation. The results suggest that there are two mechanisms of resistance; one at th,e point of penetration and the other at post-penetration stage. The resistance mechanism(s) at postpenetration stage seems to be common for both leaf and pod, and possibly controlled by biochemical factor(s). This suggest that pod resistance to P.palmivora can be reliably assessed at the seedling stage using leaf resistance to spread as an indicator. Both pathological and genetic implications of these findings are discussed for the improvement of cocoa resistance to P.palmivora infections

INDICATORS OF RESISTANCE IN COCOA (THEOBROMA CACAO) TO BLACK POD DISEASE CAUSED BY PHYTOPHTHORA PALMIVORA

The relationship between morphological characteristics: stomatal frequency, stomatal pore length, surface wax, hardness of pod wall and pod susceptibility to P.palmivora infection was assessed in twelve selected cocoa clones of the Forastero and Trinitario types. Among these clones, significant variation was observed with respect to pod morphological characteristics and their responses to infection. A high positive correlation was obtained between the combined effect of stomatal frequency and pore length, and clonal susceptibility. This suggests that these two morphological characteristics together could be used as a selection criterion for the identification of resistant genotypes

Extensive settlement of the invasive MEAM1 population of Bemisia tabaci (Hemiptera: Aleyrodidae) in the Caribbean and rare detection of indigenous populations

International audienceBemisia tabaci populations belonging to Middle East-Asia Minor one (MEAM1) and Mediterranean (MED) groups (formerly biotype B and Q, respectively) have spread throughout the world. Although the introduction of MEAM1 is documented from several Caribbean islands, it is generally not known whether MED has also been introduced; whether indigenous populations have survived; and if in the affirmative, to which group (s) they belonged. Whiteflies were collected from seven islands on various plant species. The prevalence of MEAM1 and non-MEAM1 individuals was assessed using a microsatellite approach validated with sequences of the mitochondrial cytochrome oxidase I (mtCOI) gene. Of the 262 samples tested, 247 exhibited the MEAM1 pattern, whereas none showed the MED pattern. The mtCOI gene was partially sequenced from a sample of individuals exhibiting MEAM1 (n = 15) and non-MEAM1 patterns (n = 8) and compared with type sequences. The 15 individuals exhibiting the MEAM1 pattern were confirmed to belong to MEAM1. Of the eight individuals representative of the six non-MEAM1 patterns, two belonged to the indigenous New World (NW) group of B. tabaci (NW), one belonged to a distinct species of Bemisia, and five belonged to MEAM1. One individual belonging to NW exhibited 99.9% nucleotide identity with a NW individual from Puerto Rico. The other was identified as the most divergent individual of the North and Central American genetic cluster. We conclude that a highly homogenous MEAM1 population has extensively settled in the Caribbean and that heterogeneous NW populations were still detectable although severely displaced