No abstract

Frosty pod rot (FPR) (Moniliophthora roreri), along with black pod rot (Phytophthora species) and witches’ broom disease (Moniliophthora perniciosa) constitute the main phytosanitary problems limiting cacao (Theobroma cacao) production causing severe yield losses. One of the main sought after methods of pod rot management is the selection of tolerant cacao genotypes. Typically, the selection is carried out through the quantification of the percentage of diseased pods (PDP). However, PDP does not consider the relative productivity, or production potential (PT) of the genotype. Production potential can vary among cacao genotypes. Consequently, genotypes with similar PT can have similar or vastly different disease tolerance levels as measured by PDP. The disease and production index (DPI) was developed to integrate a genotype's tolerance to M. roreri and other diseases as measured by PDP, with its PT. Here, we evaluated the number of healthy pods, number of diseased pods, and weight of fresh seed for 29 clones grown in replicated five‐tree plots over 4 years. The data obtained was used to calculate PDP and DPI for each clone for three different disease combinations: frosty pod rot alone, pod rots other than frosty pod rot, and the combination of all pod rots. Multivariate analysis verified that DPI discriminated between clones based on productivity and disease tolerance. Surprisingly, there was a close ranking of clones between resistance to FPR and resistance to all other pod rots. The DPI can be used in breeding programmes focused on the selection of high yielding disease‐tolerant cacao genotypes.

The information about nutritional aspects of trees in the tropical dry forest is scarce. This investigation aims to establish a normal range of foliar nutrient concentration to four forestry species as related to their growth rates and biological nitrogen fixation capacity in the seasonally dry ecosystem at Guanacaste, Costa Rica. Foliar samples for four species, Dalbergia retusa (cocobolo), Enterolobium cyclocarpum (guanacaste), Hymenaea courbaril (guapinol or jatobá) and Schizolobium parahyba (gallinazo or pachaco), all belonging to the Fabaceae family, were analyzed for N, P, Ca, Mg, K, S, Fe, Mn, Cu, Zn, B and Na. Nutrient concentration varied with species according to their ability to fix nitrogen and their rate of growth. The overall concentration of macronutrients was higher in nitrogen-fixing species compared with non-fixing species, and within each one of those groups, the species with higher growth rate presented more macronutrients than species with low growth rate. According to the concentration of foliar nutrients accumulated in the foliage, we recommend that H. courbaril and D. retusa could be grown in the region soils with medium fertility and E. cyclocarpum and S. parahyba in the more fertile soils. Values ranges of foliar concentrations considered as satisfactory presented in this work are new for D. retusa and H. courbaril and improve the scarce information available for E. cyclocarpum and S. parahyba.

Urban expansion and contemporary climate variations are caused by different proximate and underlying multidimensional factors. A spatiotemporal analysis of the urban socio-ecosystem generates key information for planning a sustainable urban model. We analyzed the spatiotemporal pattern of urban expansion and maximum temperature variations in a hierarchy of four categories of cities in the South American tropics in a sequence of seven-time intervals between 1985 and 2018. We defined the boundaries of 31 cities using spatiotemporal information on climatic, topographic, forest, demographic, and economic dimensions. This information was used to run several linear and nonlinear models that would explain the pattern of urban expansion and maximum temperature variations. We found that the historical pattern of expansion varied over time by city category; however, by the end of the first two decades of the 21st century, expansion was significantly higher for all categories. All dimensions contributed to explaining the expansion. An increasing altitude, the steepness of the slope, and a lower roughness index were the proximate causes of increasing the probability of city expansion; on the contrary, vegetation cover had the least importance, suggesting degradation of peripheral ecosystems. Underlying causes, an increase in the gross domestic product (GDP), and demographic variations were of high importance in explaining the probability of expansion in the region. We suggest that the systematic transition from peri-urban soil to impervious cover in the South American tropics is key to both local and global land surface energy balance.