In southern Bahia, Brazil, cabrucas are the traditional agroforests in which cacao trees are planted under thinned-out native forests. To analyze the role of cabrucas in tree species conservation, we inventoried the non-cocoa trees in 1.0 ha plots of cabruca in 16 cocoa farms and compared our results with a similar survey undertaken in the early 1960s in the same region to analyze the long term changes. We also interviewed 160 cocoa farmers to investigate their preferences for species and the main practices used in managing shade trees. The cabrucas showed high levels of tree diversity for an agroforestry system (Shannon index ranging from 2.21 to 3.52) and also high variation in structure and composition among the different farms. Forest specialist trees accounted for most species (63.9%) in the survey and were among the species most preferred by the farmers, although we found evidence that some of these trees are gradually being replaced by other species.Our results indicate that cabrucas are poor substitutes for undisturbed forests in terms of tree species richness, but their presence in human-altered landscapes is of utmost Electronic supplementary material The online version of this article (

Flooding is common in lowlands and areas with high rainfall or excessive irrigation. A major effect of flooding is the deprivation of O 2 in the root zone, which affects several biochemical and morphophysiological plant processes. The objective of this study was to elucidate biochemical and physiological characteristics associated with tolerance to O 2 deficiency in two clonal cacao genotypes. The experiment was conducted in a greenhouse with two contrasting clones differing in flood tolerance: TSA-792 (tolerant) and TSH-774 (susceptible). Leaf gas exchange, chlorophyll (Chl) fluorescence, chemical composition and oxidative stress were assessed during 40 d for control and flooded plants. Flooding induced a decrease in net photosynthesis, stomatal conductance and transpiration of both genotypes. In flood conditions, the flood-susceptible clone showed changes in chlorophyll fluorescence, reductions in chlorophyll content and increased activity of peroxidase and polyphenol oxidase. Flooding also caused changes in macro-and micronutrients, total soluble sugars and starch concentrations in different plant organs of both genotypes. Response curves for the relationship between photosynthetically active radiation (PAR) and net photosynthetic rate (P N ) for flooded plants were similar for both genotypes. In flood conditions, the flood-susceptible clone exhibited (1) nonstomatal limitations to photosynthesis since decreased in maximum potential quantum yield of PSII (F v /F m ) values indicated possible damage to the PSII light-harvesting complex; (2) oxidative stress; (3) increased leaf chlorosis; and (4) a reduction in root carbohydrate levels. These stresses resulted in death of several plants after 30 d of flooding.

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The amount of genetic diversity in parental lines of commercial sorghum [Sorghum bicolor (L.) Moench] hybrids is unknown, yet such comprehensive knowledge could improve the effectiveness of future hybrid development programs. Restriction fragment length polymorphisms (RFLPs) and pedigree data were used to investigate the genetic relationships in a group of 58 fertility restorer (R) and 47 sterility maintainer (B) elite sorghum inbred lines. The objectives of this study were to (i) assess the level of genetic variation for RFLPs in these lines, (ii) estimate genetic similarity (GS) based on RFLPs and pedigree information for R‐ and B‐lines, and (iii) examine the agreement between RFLP‐based GS and coancestry coefficient (f) for related (f> 0) pairs of inbreds. R‐lines, derived mainly from Feterita and Zera‐zera, and B‐lines, mostly from kafir germplasm, were analyzed for RFLPs with 104 DNA probes. A total of 326 patterns of RFLP bands was observed, with 276 being common to both R‐ and B‐lines, 32 unique to R‐lines, and 18 unique to B‐lines. On average, 3.6 patterns per clone‐enzyme combination were found for R‐lines and 3.0 for B‐lines. Average GS based on RFLPs was 0.67 for R‐lines and 0.76 for B‐lines, indicating more diversity within the R‐group The average for R‐lines was 0.08 and for B‐lines 0.07. Cluster analysis of GS estimates from the entire set (105) of inbreds revealed separate groups for R‐ and B‐lines in agreement with parental types, pedigree information, and the classification system used by breeders. R‐lines clustered into two main groups, one derived mainly from Feterita and the other from Zera‐zera. B‐lines were grouped into different sub‐clusters. GS and f were positively correlated for R‐lines (r = 0.46) and for B‐lines (r = 0.43), suggesting that RFLP data may help quantify the degree of relatedness in elite sorghum germplasm.

Cacao (Theobroma cacao L.) was grown as an understory tree in agroforestry systems where it received inadequate to adequate levels of photosynthetic photon flux density (PPFD). As atmospheric carbon dioxide steadily increased, it was unclear what impact this would have on cacao growth and development at low PPFD. This research evaluated the effects of ambient and elevated levels carbon dioxide under inadequate to adequate levels of PPFD on growth, physiological and nutrient use efficiency traits of seven genetically contrasting juvenile cacao genotypes. Growth parameters (total and root dry weight, root length, stem height, leaf area, relative growth rate and net assimilation rates increased, and specific leaf area decreased significantly in response to increasing carbon dioxide and PPFD. Increasing carbon dioxide and PPFD levels significantly increased net photosynthesis and water-use efficiency traits but significantly reduced stomatal conductance and transpiration. With few exceptions, increasing carbon dioxide and PPFD reduced macro–micro nutrient concentrations but increased uptake, influx, transport and nutrient use efficiency in all cacao genotypes. Irrespective of levels of carbon dioxide and PPFD, intraspecific differences were observed for growth, physiology and nutrient use efficiency of cacao genotypes.