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

Introduction. Pepper is one of the Piperaceae family, native to the Malabar Coast, located in Kerala in Southern India. In Costa Rica, main pepper plantations are located from Upala to Talamanca including the entire coastal and lower strip of Sarapiquí. According to feasibility studies, Costa Rica has the potential to produce pepper with high quality parameters; however, vascular diseases are one of the main crop limitations. Objective. To isolatate, and molecularly and morphologically identify species of Fusarium associated with the cultivation of pepper (Piper nigrum L.) in 2 of the main productive areas of the country. Materials and methods. Thirty samples from diseased plants were collected from different farms located in Sarapiqui and Guatuso, symptoms observed in the  adical system and/or the stem base were described in detail for each plant. The twenty one isolates of Fusarium spp. obtained were identified with the partial sequence of the molecular marker Elongation Factor 1α (EF-1α) gene and for the morphogical identification using the PDA and Carnation Leaf Agar (CLA) culture media were used. Results and conclusions. The presence of Fusarium oxysporum was confirmed in the samples from Sarapiquí, and the presence of Fusarium solani was confirmed in the samples from both areas. The presence of the species Fusarium concentricum and Fusarium proliferatum associated with vascular wilt is reported for the first time.  Keywords: Fusarium spp; Piper nigrum; black pepper; soil diseases; symptomatology; molecular markers.

Introduction. In Costa Rica, cultivation practices in conventional wild coriander in open field soil, make resource use inefficient and reduce quality, safety and yields; therefore, an alternative is the protected hydroponic crop. Objective. The objective of this study was to evaluate the effect of protection and nutrition on water parameters: water use efficiency (WUE), crop evapotranspiration (ETc), drainage, crop coefficients (Kc) and the fresh yield of hydroponic wild coriander. Materials and methods. The study was conducted in 2016, at the Fabio Baudrit Moreno Agricultural Experimental Station, Alajuela, Costa Rica. It included 2 stages of a crop, stage I, in dry season protected with sarán and stage II in rainy season protected with plastic. In both stages there were 4 treatments that combined 2 environmental conditions, one with protection (CP) and the other unprotected (SP), with 2 levels of nutrition: high (NA) and low nutrient concentration (NB). A randomized 5 blocks design with bifactorial arrangement of 2 x 2 was used. Results. The yield was similar in CP and SP, however, a lower ETc in CP increased the WUE. The ETc was similar in both levels of nutrition, however, due to higher yield, the WUE in NA was superior. In stage I, drainage was only affected by nutrition, being lower with NB; In stage II, drainage decreased significantly with plastic roof (CP). The Kc were not affected by both factors, obtaining maximum values of 1.15 and 1.4 in stages I and II, respectively. Conclusion. The hydroponic cultivation system represents an excellent alternative to the conventional production system in soil and open field, since it increased the WUE, product of an appreciable reduction of the ETc under protection and a substantial increase in yields with high nutrition level.  Keywords: Irrigation management; evapotranspiration; drainage volume; water use efficiency; crop productivity.

Introduction. The present investigation is the first effort identified in Costa Rica, which compares production costs between organic and conventional vegetables. The project made visible sale prices, unit costs and profit margins of selected products and compared them between both production schemes. Objective. To clarify the causes that can be assigned to the difference in sale prices and production costs between six organic grown vegetables and their conventional counterpart. Materials and methods. A survey was formulated to consult 2 groups of producers, one consisting of 10 organic vegetable producers and the other of ten dedicated to conventional vegetable production. 19 closed questions were asked about  investment and production costs, income, cost- benefit ratio. Selected vegetables were cilantro (Coriandrum sativum), lettuce (Lactuca sativa), potato (Solanum tuberosum), carrot (Daucus carota), celery (Apium graveolens) and broccoli (Brassica oleracea). Recorded data was grouped by production costs and sale prices at farmers markets. Results. Sale prices of organic products per unit sold was higher than that of conventional practices in all cases. It was possible to determine that the percentage difference in prices for carrots was 28.57%, 40% for celery 40%, 25% for cilantro, 53.33% for potatoes, 33.33% for lettuce and 66.67% for broccoli. In addition, conventional products presented higher total cost of production with respect to organic products, this was 41.70% higher for carrots, 65.18% for celery, 29.03% for cilantro, 34.78% for potatoes, 16.65% for lettuce and 44.91% for broccoli. Conclusions. The activities with conventional practices exposed higher costs, due to the demand and purchase of external inputs and the use of machinery, while organic production proposes low dependence on the purchase of external inputs, since those required are mainly generated on the own farm as producers adopt practices that promote the health of the agroecosystem, biodiversity and biological cycles. Keywords: Organic agriculture; conventional agriculture; production costs; selling price.

Introduction. Phytopathogenic fungi cause losses in tomato production and for this reason it is important and necessary to find alternatives aimed at managing antagonistic agents that are efficient and compatible with the environment. Objective. To determine the effectiveness of native and exotic strains of Trichoderma spp. against Fusarium spp. at laboratory level. Materials and methods. Commercial products of Trichoderma spp. with native (THM-03 and THM-04) and imported strains (THU-01 from the United States and THC- 02 from Colombia) were used. Pathogen was isolated from diseased tomato plants, for which morphological and molecular analyses were used for identification. Dual culture technique was used to evaluate radial growth of the antagonist (RGA) and the pathogen, mycoparasitism and percentage of radial growth inhibition (PRGI). Results. T. asperellum, T. asperelloides and T. guizhouense were identified; the pathogen was identified as F. oxysporum. Mean RGA values of 25.6, 39.3, 41.2 and 32.1 mm were obtained for THU-01, THC-02, THM-03 and THM-04, respectively; and 42.75 mm for the control. Regarding mycoparasitism, THC-02, THM-03 and THM-04 presented complete invasion of the F. oxysporum colony, with sporulation and THU-01 only managed to invade a quarter of the pathogen ́s surface. PRGI was determined, in which significant differences were found between Trichoderma strains where the most effective strains were THM-03 and THC-02 with 67 and 63% inhibition, respectively. Conclusion. This in vitro study showed differences in the antagonistic capacity of different Trichoderma species against the pathogen F. oxysporum. Strains of T. asperellum (THC-02), T. asperelloides (THM-03) and the native strain T. guizhouense (THM-04) showed to be more aggressive in combat of the pathogen, regardless of its origin, thus the study could be expanded with the use of more isolates. Keywords: Percentage of radial growth inhibition (PRGI); antagonist; native strains; biological control; mycoparasitism.

Introduction. The pea is a profitable crop in Nariño-department which represents approximately 43% of pea production in Colombia and involves around 8000 farmers dedicated to its production in green pod. The farmers use varieties with high production costs, thus an improvement in profitability of this crop is neccesary. The University of Nariño’s Andean Crops research group, obtained 21 advanced pea lines with afila (af) gene. These lines present appropriate phenotypic characteristics to efficiency optimize of actual tutoring system. Objective. To determine the direct and indirect effects that are present in genetic correlations between the yield and its components, to contribute to the selection by yield of genotypes peas with afila (af) gene. Materials and methods. The 21 lines were evaluated in a splits plot design, where the main plot was the densities and the subplot were the genotypes. The results were subjected to analysis of variance and the genetic correlations between yield components were determined. To establish the direct and indirect effects of the components over yield, Path coefficient was made. Results. 73% of the genetic correlations between yield components were significant. The weight one hundred green grains (PCGV) and number of pods per plant (NVP) corresponded to the variables with the greatest direct effect. Conclusion. Genetic correlations analysis indicates that is possible to select genotypes with higher weight pod from the length of their pods. The direct effects NVP and PCGV were the most important, confirming their usefulness in selection by yield. Keywords: Lines; system of tutoring; varieties; yield components; path coefficient.

Introduction. Conventional laboratory methods to analyze soil nutrients are usually time-consuming and costly. On the other hand, the visible and infrared spectroscopy offers a rapid technique to characterize soils. The spectral signatures encode information about the inherent composition of the soil, which comprises mineral composition, nutrient content, organic compounds and water. Objective. The main objective of this study was to build spectral libraries for the tropical soils of Costa Rica and to determine the optimal hyperspectral wave bands in the visible and near infrared and shortwave infrared to characterize soil properties in laboratory. Materials and methods. The hyperspectral measurements were carried out with an ASD FieldSpec 4 spectroradiometer to generate spectral reflectance signatures of more than 1300 soil samples from Costa Rica preprocessed at EARTH University’s soil laboratory. The nutrient content of each soil sample was determined by inductively coupled plasma. In addition, pH, exchangeable acidity, base saturation, acid saturation, effective cation exchange capacity, soil carbon, organic matter and soil texture were evaluated. Algorithms in MATLAB were developed to compile a hyperspectral data base and used a partial least squares regression (PLSR) methods to generate predictive models for these soil properties from hyperspectral signatures. Results. This spectroscopic approach combined with machine learning models allowed the identification of specific optimal wavebands in the spectral areas in which each nutrient can be predicted. An accurate estimation of the concentration of different components (Ca, Mg, Fe, C, N and CECe) was achieved with an R2 greater than 0,8 and a mean square error (RMSE) lower than 10%. Conclusion. These spectroscopic technics combined with the PLS regression, can provide a very useful tool for precision agriculture in tropical soils of Costa Rica. Keywords: Spectroradiometry; hyperspectral signatures; machine Learning; PLSR modeling; precision agriculture.

Introduction. The absence of economic information constitutes a barrier to the promotion of silvopastoral systems. The forest component represents a marginal contribution to the livestock economy, which maintains a high carbon footprint and occupies 43% of the territory. A new silvopastoral model of greater economic, social and environmental impact is required. Objective. To generate information on the costs of tree cultivation, in a silvopastoral design that manages to integrate the livestock business with that of wood. Materials and methods. The complete cost structure of the forest component is reported, based on melina and teak clones. The information from ordinary  compact plantations was adapted to a strip tree cultivation system within a cattle farm, utilized in the northern region of Costa Rica. The information was differentiated in two scenarios, the high and low investment model, according to the technological package used. Results. The trees were planted within two fenced-strips of six meters wide per hectare at the boundaries of the grazing paddocks. Within the strips, trees were planted in an irregular distribution, at a distance of 2,5 m between rows and 4.0 m between trees, which allowed planting of 150 trees.ha-1 in a cycle of 8 years for melina and 16 years for teak. Conclusions. Total cost of growing melina in 2 strips.ha-1, in the high investment model was ₡751 759 (US $1307) and ₡966 818 (US $1681) for teak. In the low investment model, the total cost for melina was ₡545 739 (US $949) and ₡714 548 (US $1242) for teak. Labor represented 41% of the total costs in melina and 44% in teak. This silvopastoral design requires planting of 4.17 ha with melina and 5.5 ha with teak in order to obtain the same amount of wood as in a conventional plantation. Keywords: Forest economy; livestock; forestry plantations; agroforestry systems.

Introduction. Grazing intensity and nitrogen fertilization in integrated crop-livestock system (ICLS) are factors that influence pasture productivity and, consequently, impact on livestock production. Objective. The objective was to evaluate the effect of grazing intensity and nitrogen fertilization on grazing height of ryegrass (Lolium multiflorum Lam. cv. ‘Winter Star’), in an integrated crop-livestock system (ICLS). Materials and methods. A completely randomized block design was used with a 2 x 2 x 5 factorial arrangement, with 3 replications. The first factor was grazing intensity with 2 levels: high height (HH = 25 cm) and low height (LH = 10 cm). The second factor was nitrogen fertilization with two levels: N (nitrogen) applied to the grass (NP) during the winter and N applied in the grain crop (NG) during the summer, both in doses of 200 kg.ha-1 of N. The third factor was the evaluation period (5 periods). Italian ryegrass was considered. Results. In the HHNP treatment, greater homogeneity of the grass and a higher percentage of heights (between 10 and 25 cm) were observed; however, a lower homogeneity with the treatments LHNG and LHNP in which a greater area was detected with heights lower than the lower critical limit (10 cm). Conclusion. It is concluded that a lower grazing intensity and higher nitrogen fertilization (HHNP) offers a greater height of ryegrass and an adequate weight gain in animals in an ICLS. Keywords: Pasture; integrated systems; nitrogen; continuous grazing.

Introduction. Solid state fermentation is a biotechnology that allows to improve nutritional quality of forages and agricultural by-products in order to be used in ruminant feeding. Objective. To determine the effect of solid state fermentation process on fermentation indicators (temperature and pH) and chemical composition of taiwan grass (Pennisetum purpureum), black forage sorghum (Sorghum almum) and pineapple (Ananas comosus) peel. Materials and methods. A completely randomized design with 3 substrates: taiwan grass, black forage sorghum and pineapple peel with 4 repetitions was used. 1.0 m2 frames, made with concrete blocks; were used, 490 kg of each substrate were mixed with 5% molasses, 1.5% urea, 0.7% ammoniumsulfate, and 0.5% mineral mixture. They were deposited in the frames and the fermentation process was carried out on a disinfected concrete floor provided with shade. Material in the frames was turned every 6 hours for 36 hours while the fermentation process lasted. Results. In relation to temperature, significant statistical differences (p<0.05) were found between substrates for the different fermentation times. At 0 hours, taiwan grass had the highest temperature and at 24 hours of fermentation, pineapple peel reached the peak with a temperature of 42.5°C. Considering pH, significant differences (p<0.05) were found for the different subtrates at different hours of fermentation, and the values ranged from 4.28 to 7.71. Regarding crude protein concentration, significant differences (p<0.05) were found for pineapple peel, which went from 40.48% at 0 h to 43.40% at 24 h and 33.43% at 36 h of fermentation. No significant differences (p>0.05) were found for cell wall components during the fermentation process. Conclusions. Solid state fermentation is a biotechnological process that allowed to detemine its effect on fermentation parameters of 2 forage species and pineapple peel, and also improved crude protein concentration in pineapple peel after 24 h of fermentation. Keywords: pH; temperature; forages; chemical composition; agricultural byproducts.

Introduction. The modern poultry demands the development of feeding strategies that increase the level of sustainability in flocks, which has generated interest in including non-traditional ingredients in poultry diets. Objective. To assess the effect of partial inclusion of cowpea bean (Vigna unguiculata) and banana (Musa spp.) on zootechnical parameters of broilers chicken. Materials and methods. An isoproteic diet (20% CP) and isocaloric (3.7 kcal ED/g) to feed 160 Cobb 500 chicks for 42 days, with partial replacement of 0; 18; 20 and 22% the concentrated food (CF) by a experimental mixture (EM) of V. unguiculata and Musa spp. The birds were randomly distributed in 16 farmyards according to treatments (T): T0: 100% CF; T1: 82% CF + 18% EM; T2: 80% CF + 20% EM and T3: 78% FC + 22% EM and 4 repetitions. For evaluate the productive response the parameters weight gain (TWG), daily weight gain (DWG), feeding conversion factor (FCF), consumption (C), Carcass yield (CY) and mortality (M). Results. The control treatment (T0) recorded the highest TWG (2.461±0.02 g), DWG (58.60±0.03 g), C (4.247±3.20 g) and, FCF (1.73±0.06); however, statistical analysis revealed that T0 and T1 are statistically equal, while T2 and T3 showed significant differences (p<0.05) to each other for the majority of variables and, in front T0 and T1. As for CY, T0 and T1 differed significantly (p<0.05) with respect to T2 and T3. During the experiment, no birds died in any of the treatments evaluated. Conclusion. Replace up to 18% CF with a balanced mixture based on V. unguiculata and Musa spp. in broilers, it has proved to be a nutritional alternative for family poultry farming. Keywords: Poultry farming; alternative diet; partial inclusion, bird nutrition.