Influence of freezable/non-freezable water and sucrose on the viability of <Emphasis Type="Italic">Theobroma cacao</Emphasis> somatic embryos following desiccation and freezing

Encapsulated cocoa (Theobroma cacao L.) somatic embryos subjected to 0.08–1.25 M sucrose treatments were analyzed for embryo soluble sugar content, non-freezable water content, moisture level after desiccation and viability after desiccation and freezing. Results indicated that the higher the sucrose concentration in the treatment medium, the greater was the extent of sucrose accumulation in the embryos. Sucrose treatment greatly assisted embryo post-desiccation recovery since only 40% of the control embryos survived desiccation, whereas a survival rate of 60–95% was recorded for embryos exposed to 0.5–1.25 M sucrose. The non-freezable water content of the embryos was estimated at between 0.26 and 0.61 g H₂O g⁻¹dw depending on the sucrose treatment, and no obvious relationship could be found between the endogenous sucrose level and the amount of non-freezable water in the embryos. Cocoa somatic embryos could withstand the loss of a fraction of their non-freezable water without losing viability following desiccation. Nevertheless, the complete removal of potentially freezable water was not sufficient for most embryos to survive freezing.     

Microsatellite markers in a complex of Horismenus sp. (Hymenoptera: Eulophidae), parasitoids of bruchid beetles

Parasitoids of the genus Horismenus (Hymenoptera: Eulophidae) are the main natural enemies of bruchid beetles that feed on several species of Phaseolus beans. Samples of Horismenus depressus, H. missouriensis and H. butcheri were collected from seeds of three Phaseolus species throughout Mexico to examine the impact of plant variability on the genetic structure of parasitoid populations. For this purpose, six microsatellite loci were isolated and characterized. These loci are of great interest in understanding the taxonomy of the genus Horismenus, the most important Eulophid genus in the Neotropics.     

Ecological,economic and social perspectives on cocoa production worldwide

Cocoa is a crop grown largely by smallholder farmers in the lowland tropics, including parts of Latin America, West Africa, and Indonesia. Research suggests that it has the potential to provide biodiversity benefits when grown under certain shade conditions, especially when compared with alternative land uses. The primary literature on cocoa production reveals a range of objectives for improvement of cocoa production on small farms. These objectives are sometimes in direct opposition to each other, for example, increasing productivity through shade removal and chemical inputs, and the desire to increase biodiversity benefits. These opposing goals demonstrate some real trade-offs faced by cocoa producers. We summarize the current literature, drawing attention to some of these trade-offs and highlighting important ecological, economic, and social considerations. In considering strategies for ameliorating these negative tradeoffs, we make two primary policy recommendations. First, we suggest that outreach focusing on farm diversification may be the most effective way of optimizing ecological, economic, and social outcomes. Farm diversification may provide an effective means of achieving improved farmer security and dissuade farmers from abandoning or planting cocoa according to price fluctuations, thus reducing the use of new forest areas in cocoa production. Secondly, we suggest greater focus on determining effective economic incentives for maintaining shade in cocoa production. For example, price premiums associated high quality shade-grown cocoa may increase economic benefits while simultaneously providing incentives to farmers to maintain shade in production. Lastly, we identify some important areas of research for further informing policy in this arena.     

Isoenzyme Variation in Asian Beans

Electrophoretic variation of isoenzyme characters encoded by 20 gene loci has been studied in 9 species of Asian beans, comprising subgenus Ceratotropis of the genus Vigna. Four species of hypogeal germination type, V. angularis, V. umbellata, V. dalzelliana and V. minima, are shown to form a distinct monophyletic group in the subgenus, sharing common electromorphs of two major isoenzymes of aspartate aminotransferase. V. glabrescens is confirmed to be an allotetraploid derivate of two diploids closely related to V. radiata and V. umbellata, but divergent from their contemporary accessions analyzed. V. trilobata is the most variable species of the subgenus in isoenzyme characters. It reveals intraspecific differentiation at several isoenzyme loci correlated with the seed morphology and geographical localization.