Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Se presenta un recuento de las principales obras que han constituido la base del conocimiento sobre los condrictios en Chile, a partir del siglo XVIII hasta el siglo XX. También se resumen aspectos importantes de lo avanzado hasta el presente siglo y se entregan opiniones relacionadas con posibles desarrollos futuros.

The razor surgeonfish, Prionurus laticlavius, listed on the IUCN Red List of Threatened Species under the Least Concern category, plays an important ecological role as energy regulator in reef communities, but it is sought by the aquarium and aquaculture industry, and also is consumed by people. This study estimated the length-weight relationship (LWR) and relative condition factor (Krel) in P. laticlavius. The equation for length-weight relationship was TW= 0.02 TL3.01 for the Overall category, and the relative condition factor was 1.28. A total of 379 fish (3-45.6 cm total length) were collected in the southwestern coast of the Gulf of California using harpoon (for large fishes) and hand net (for small fishes), of which 181 were females (20.2-45.6 cm), 137 males (20.6-43.4 cm), and 61 juveniles (3-19.5 cm). Allometric coefficient b of LWR for the Overall category suggested isometric growth (b = 3.01), positive allometric growth for juveniles (b = 3.14), and negative allometric growth for adults (2.75). Results of Krel showed higher values for females during the warm season. The population showed a good nutritional condition, mainly in the warm season. This work is the first to estimate LWR and Krel for P. laticlavius, which will inform stock assessment and the management of this species in the Gulf of California.

The dusky finless skate Gurgesiella furvescens appears sporadically as part of the bycatch in the trawl fishery targeting demersal crustaceans on the continental shelf and upper slope of the north-central area of Chile (26ºS-33ºS). Demersal crustaceans could be forage for deep-water predators such as G. furvescens, and sizes and shapes of prey eaten could be restricted by mouth size. The diet composition of G. furvescens was determined based on specimens collected from the bycatch of trawls targeting demersal crustaceans in 2013. Analysis of the stomach contents revealed that the diet was mainly nylon shrimp Heterocarpus reedi (32.8% by weight), deep-water shrimp Haliporoides diomedeae (7.2% by weight), and indeterminate crustaceans (9.0% by weight). The diet composition was similar between sexes, body length, or depth strata. Prey size was a linear function of Gurgesiella furvescens mouth width, and prey mass positively related with G. furvescens individual mass. Although squat-lobsters Pleuroncodes monodon and Cervimunida johni were abundant in the study area, the presence of nylon shrimp and deep-water shrimp in the diet of G. furvescens may be due to the preference or selection of this type of prey in deep waters.

The genus Psammobatis is endemic to South America, and three of its species are sympatric along the Chilean coast. Their morphological similarity as well as the lack of type material of P. scobina, has made its taxonomic identification especially complex. The aim of this work is to allow for objective identification and comparisons of P. scobina, providing a new morphological characterization, incorporating both morphometric and meristic features for both sexes, and designating a Neotype. Morphometric and meristic data are presented separately for the Neotype, and for males and females to determine variability between sexes. Although there is overlap between some morphometric features of males and females, there are also some morphometric measures that differed between sexes among specimens of similar sizes, such as disc width, length of posterior pelvic lobe, preoral length, distance between fifth gill slits and distance from cloaca to second dorsal fin. Additionally, Principal Component Analysis and cluster analyses allowed to identify sexual dimorphism in specimens, with the most influential variables related to tail length. There are several unresolved issues regarding the taxonomy of this problematic genus, especially those regarding P. scobina and P. normani, which are sympatric in the southeastern Pacific. In addition to the analysis of skeletal structures and egg cases, an integrative comparative morphometric analysis, based on a recent standardized methodology with the inclusion of both morphological and molecular data, is still needed. The designation of a Neotype for objective comparative purposes, will allow such future study.

Pseudobatos prahli is considered a low-medium fishing importance species in Ecuador, caught as target species and bycatch in both artisanal and industrial fisheries. Despite its importance, some basic aspects of its biology remain unknown, turning its study a priority. The aim of the present research was to describe for the first time the reproductive biology of P. prahli based on the analysis of individuals landed in the port of Santa Rosa, Province of Santa Elena, Ecuador. A total of 96 females and 165 males were sampled from January 2013 to January 2014. Females presented larger sizes (51-86 cm total length, TL) than males (51-78 cm TL), but no significant differences were found between the mean sizes of both sexes. The sexual proportion of landed individuals (0.6F:1M) suggested that free-living individuals segregate by sex, however, sex proportion of embryos was similar to the proportion 1F:1M. The number of mature individuals (64%) in the landings was larger than the immature ones (36%). Mean size at maturity (L50) of females (65.9 cm TL) was also slightly larger than that for males (61.8 cm TL). Size at birth was estimated at 22.5 cm TL. Ovarian fecundity ranged from 1 to10 and uterine fecundity from 1 to 6, and a positive but low linear relationship was found between both fecundity estimates and maternal size. Based on the comparison of some reproductive parameters, such as mean size at maturity, gestation period and fecundity, it can be concluded that P. prahli is one of the species with lowest biological productivity among the species of the same genus.

Length-weight relationships (LWR) were estimated for four species of batoids, Zapteryx xyster, Rostroraja equatorialis, Pseudobatos leucorhynchus and Gymnura crebripunctata, collected in Ecuadorian waters. Values of the allometric growth parameter (b) oscillated from 2.41 to 3.15. Pseudobatos leucorhynchus and G. crebripunctata exhibited isometric type growth, while Z. xyster and R. equatorialis showed negative and positive allometric growth, respectively. New records of minimum sizes were obtained for free-swimming R. equatorialis (7.8 cm TL) and G. crebripunctata (20.0 cm DW). Data obtained constitute a baseline for future management and conservation studies.

Solid matrix priming (matriconditioning) permits slow seed hydration, and germination and emergence period reduction. In general, seeds need to be soaked to start their germination process. The objective of this study was to evaluate the effect of the matriconditioning under the imbibition curve and the physiological performance of two lots of chia seeds with different qualities. The study was performed with chia seeds harvested by small-scale farmers. To estimate the imbibition curve, seeds from both lots were started in the imbibition process on a stainless-steel screen placed in plastic boxes, containing 55.5 grams of sterilized vermiculite and moisturized with distilled water at 100% of their retention capability. The imbibition curve weights were made 0, 2, 4, 8, 16, and 32 hours after the process had started. Simultaneously, in each evaluation period, seeds were submitted to the following tests: germination, first count of germination, plantlet shoot, root and total lengths, emergence velocity index and average time, and accumulated emergence. A completely randomized experimental design was used. It was possible to conclude that the beginning of phase II of germination in matriconditioned seeds varies in function of the chia seeds' lot quality. The matriconditioning contributes to the physiological performance, increasing and accelerating plantlets' emergence.

Among the weeds that interfere with the growth and development of sweet sorghum, beggar ticks stands out, because it has a high competitive capacity for the available resources. This study aims to compare the competitive ability of sweet sorghum (Sorghum bicolor (L.) Moench) against hairy beggarticks (Bidens pilosa L.), as a function of cultivar and plant proportion. Experiments were conducted in a greenhouse in a completely randomized design with four replications and six treatments. Treatments were arranged in replacement series in the proportions of 100:0, 75:25, 50:50, 25:75, and 0:100% (sorghum:weed) equivalent to 20:0, 15:5, 10:10, 5:15 and 0:20 plants per pot with 8 dm3 capacity of sweet sorghum (cultivars ‘BRS 506’, ‘BRS 509’ or ‘BRS 511’) against hairy beggarticks. Fifty days after emergence, plant leaf area (LA), aboveground dry mass (DM), photosynthesis (A), and transpiration rates (E) were measured. Competitive ability was analyzed by using the graphical analysis method and building diagrams based on total and relative productivity. Competitiveness, clustering coefficient, and aggressiveness were also determined. Sorghum cultivars, in general, showed losses independently of the proportion of hairy beggarticks. Statistical analysis showed small differences in competitive ability among sorghum cultivars; ‘BRS 509’ was also demonstrated to be slightly more competitive than ‘BRS 506’ and ‘BRS 511’ against hairy beggarticks. This, however, is unlikely to provide a competitive advantage for ‘BRS 509’ in production fields, and hairy beggarticks should be efficiently controlled early in the crop cycle to avoid productivity losses, independently of the sorghum cultivar.

The interrow spacing commonly used in cassava cultivation in Brazil, especially in the Agreste region of Alagoas, ranges from 100 to 120cm. However, the reduction in row spacing can provide agronomic and environmental benefits in cassava cropping systems. Thus, this work aimed to evaluate the performance of two cassava varieties cultivated with reduced interrow spacing. Two experiments were conducted in the field, one in 2015/16 and another in 2017/18. A Split Plot design with four replications was used in both experiments. Four interrow spacing were evaluated in the main plot: 60, 80, 100 and 120cm, with plants spaced 60cm apart within rows, giving populations of 27,778, 20,833, 16,667 and 13,889 plants per hectare, respectively. In the subplots, two cassava varieties were evaluated: Caravela and Pretinha. An increase in interrow spacing promoted a linear reduction in the stem green mass of cassava. Plant height, leaf green mass, main stem diameter, root yield, tuberous root length, tuberous root diameter, flour percentage, flour yield, and starch content were not influenced by changes in interrow spacing. The Pretinha variety was superior to Caravela in the following evaluated traits: stem green mass, the diameter of tuberous roots, root yield, plant height, and flour yield. The results indicate the possibility of altering the interrow spacing in cassava to assist in the cultural management, without impacting crop yield.  

Wheat is one of the most economically important cereals for the Department of Boyacá; however, the cultivated area sees low yields, phytosanitary problems, and a lack of genetic materials with desirable agronomic characteristics. The present study aimed to morphoagronomically characterize 49 accessions from the FENALCE germplasm bank using morphological and yield descriptors and multivariate and cluster analyses. The variables auricle color, edge shape, precocity, growth habit, grain size and serosity showed little genetic variability, while the number of tillers per plant, number of spikelets per spike and glume color showed high genetic variability. The principal component analysis, based on the correlation matrix, showed that the first four principal components (PC) explained 71% of the total variation observed in the characterized accessions. The cluster analysis formed three groups according to the evaluated morphological characteristics, with group three containing the accessions with the best agronomic characteristics. None of the evaluated accessions had rust damage. Around 15 wheat accessions had good agronomic performance under the conditions of this study, which should be used in future genetic improvement programs aimed at identifying elite materials in the Department of Boyacá.