Scielo RSS <![CDATA[Chilean journal of agricultural & animal sciences]]> vol. 38 num. 2 lang. es <![CDATA[SciELO Logo]]> <![CDATA[RESPUESTA DEL MAÍZ (<em>Zea mays</em> L.) A LA APLICACIÓN FOLIAR DE ABONOS ORGÁNICOS LÍQUIDOS]]> RESUMEN El maíz (Zea mays L.) es un insumo básico en la alimentación a nivel mundial que se cultiva empleando principalmente fertilizantes minerales y prácticas que contribuyen a la degradación de los suelos. Los abonos orgánicos son una alternativa que contribuye a limitar la degradación de los suelos y a mejorar la productividad de los cultivos. El objetivo de la investigación fue determinar la respuesta del maíz a la aplicación de abonos foliares orgánicos líquidos y estimar la rentabilidad económica de cada tratamiento. Se usó un diseño de bloques completamente al azar con cinco tratamientos: pescado hidrolizado (T1), aceite de Neem (T2), estiércol líquido bovino digerido al 60% (T3), fertilización NPK (T4) y testigo (T5). Los resultados indicaron que las plantas de maíz con fertilización NPK alcanzaron el menor número de días a la floración masculina (51,50) y femenina (53,50), y la mayor altura de mazorca (101,25 cm). Las que recibieron fertilización NPK y las que recibieron estiércol líquido de bovino alcanzaron los valores más altos en longitud de mazorca (18,17 y 16,44 cm, respectivamente), cantidad de granos por hilera (32 y 29 unidades, respectivamente) y rendimiento de grano (7,32 y 6,95 t·ha-1, respectivamente). No se presentaron diferencias significativas en el número de hileras en mazorca. La mayor rentabilidad se obtuvo con estiércol líquido bovino (54,01%), seguido de NPK (52,61%). Se concluye que el estiércol líquido de bovino aplicado de manera foliar permite alcanzar rendimientos cercanos y rentabilidad superior a los obtenidos con fertilización convencional NPK.<hr/>ABSTRACT Maize (Zea mays L.) is a worldwide staple food, cultivated using mainly mineral fertilizers and other soil degradation practices. Biofertilizers are an alternative to help limit soil degradation and improve crop productivity. This research aims to determine maize response to foliar applications of liquid organic fertilizers. A completely randomized block design with five treatments was used: hydrolyzed fish (T1), Neem oil (T2), digested liquid bovine manure (T3), NPK fertilization (T4), and the control (T5). The results show that maize plants with conventional fertilization reached the lowest number of days to male (51.50) and female flowering (53.50), and the highest ear height (101.25 cm). Maize plants with NPK fertilization and those receiving liquid bovine manure recorded the highest values in extended ear length (18.17 and 16.44 cm, respectively); number of grains per row (32 and 29 units, respectively); and grain yield (7.32 and 6.95 t·ha-1 respectively). There were no significant differences in the number of rows per ear. The highest cost-effectiveness was obtained with liquid bovine manure (54.01%), followed by NPK (52.61%). In conclusion, foliar applications of digested liquid bovine manure result in similar yields and higher cost-effectiveness to those obtained by conventional NPK fertilization. <![CDATA[OVERCOMING SEED DORMANCY OF JUNGLERICE (<em>Echinochloa colona</em>)]]> ABSTRACT Junglerice (Echinochloa colona L. Link) seed dormancy can persist 8 months after harvest and, once overcome, seeds can germinate over a long period of time. Light or high temperatures could overcome seed dormancy, while the effects of seed coat softening and nitrate addition are not well known. This study aimed to determine the germinative response, persistence and treatments to overcome seed dormancy of junglerice. Seed samples were taken from a monoculture crop (soybean, S1) and a 3-yr rotation crop (wheat/soybean-corn-soybean, S2). Every 3 wk for 30 wk, hot-water washed (WW) seeds were evaluated. After 33 wk of storage, the effects of potassium nitrate (KNO3), dehulling (DE), WW, previous water immersion (IM) and exogenous gibberellic acid (GA) were evaluated in three different experiments (pre-germinative tests with KNO3, DE and WW; KNO3 and IM; and GA). The results showed that seed dormancy persisted until 21 wk. From 21 to 30 wk, germination response increased by 25 and 59 % on WW-treated seeds from S1 and S2, respectively. After 33 wk of storage, only KNO3 was significantly higher (p &lt; 0.05), with 88 and 126 % increases in seed germination in S1 and S2, respectively. These results indicate that junglerice seed dormancy is not related to glumes. Hot water improves the germinative response probably due to an acceleration in post-harvest maturation, while KNO3 is a positive regulator to overcome seed dormancy. <![CDATA[AGRONOMIC YIELD AND ESSENTIAL OIL PROPERTIES OF PURPLE CONEFLOWER (<em>Echinacea purpurea</em> L. MOENCH) WITH DIFFERENT NUTRIENT APPLICATIONS]]> ABSTRACT Echinacea purpurea is cultivated around the world due to its unique pharmacological effects. The aerial parts of the plant, especially its flowers, contain a wide variety of beneficial bioactive substances. The objective of this study was to evaluate the effect of different nutrient applications on the growth parameters, essential oil yield, and compounds of Echinacea purpurea L. Moench in Afyonkarahisar/Turkey. The experiment was conducted over a 3-year period (2016-18), including four experimental treatments (F0: control, F1: 75 kg ha-1 N; F2: 150 kg ha-1 N; and F3: 75 kg ha-1 N + foliar fertilizer). As a general result of five cuttings, F2 and F3 had a positive effect on agronomic yield. F2 and F3 recorded the highest plant height (91 and 90 cm, respectively) and yields for fresh bud (578 and 543 kg ha-1), dry bud (118 and 112 kg ha-1), fresh flower (8,595 and 7,449 kg ha-1), dry flower (2,021 and 1,745 kg ha-1), fresh herb (32,645 and 29,291 kg ha-1), dry herb (8,746 and 7,745 kg ha-1) and essential oil (4.55 and 3.57 L ha-1). Sesquiterpene hydrocarbons were the most abundant chemical group compound of E. purpurea essential oil. Germacrene D (20.4-50.6%) was the predominant constituent, recording its maximum level in F1. Other major compounds were β-pinene, β-myrcene, α-humulene, δ-cadinene, spathulenol, and α-cadinol. The application of 150 kg ha-1 N as well as the combined use of 75 kg ha-1 N and foliar application of macro and micro elements resulted in the highest agronomic yield and essential oil production. <![CDATA[CHARACTERIZATION OF RHIZOME AND PSEUDOSTEM WET ROT OF ORGANIC BANANA (<em>Musa</em> sp.) IN PIURA, PERU]]> ABSTRACT Organic banana (Musa sp.) is one of the most important export crops in Peru, especially in the Department of Piura. The cultivation of the crop is mainly affected by biotic factors, resulting in important economic losses. The aim of this research was to characterize the causal agent of banana bacteriosis disease in Piura. Bacterial isolates were extracted from rhizome and pseudostem samples of organic bananas with typical symptoms of soft rot from different banana growing areas of Piura. Sixty colonies were obtained, while 10 isolates were selected for presenting cultural and morphological characteristics similar to those of Pectobacterium (01MB, 04MB, 05MB, 06MB and 10MB) and Dickeya (02MB, 03MB, 08MB, 07MB and 09MB); different biochemical and molecular tests were conducted. The pathogenicity of the isolates was confirmed by in vitro and in vivo inoculation of rhizome pieces and pseudostems from cultivated plants. The 10 isolates were gram negative and with perimeter flagella. The biochemical tests showed that all the isolates were positive on nutrient agar medium, Mac Conkey, catalase, gelatin hydrolysis and growth at 37°C, whereas they were negative on King’s B medium, nitrate reductase and oxidase tests. Isolates 02MB, 03MB, 08MB, 07MB and 09MB also tested positive for erythromycin and indole, while isolates 01MB, 04MB, 05MB, 06MB and 10MB were positive for CVP (Crystal violet pectate). Molecular identification and phylogenetic analysis confirmed that isolates 01MB, 04MB, 05MB and 10MB corresponded to Pectobacterium carotovorum subsp. carotovorum; isolates 03MB and 08MB corresponded to Dickeya chrysanthemi; and 02MB and 07MB corresponded to Dickeya paradisiaca and Klebsiella variicola, respectively. It was concluded that rhizome and pseudostem wet rot of banana grown organically in Piura is caused by the bacterial complex formed by P. carotovorum subsp. carotovorum, D. chrysanthemi, D. paradisiaca and K. variicola. This is valuable information for the implementation of appropriate disease management practices in the area. <![CDATA[EVALUATION OF THE TOXICITY OF THE Cry2Aa AND CRy2Ab RECOMBINANT PROTEINS AGAINST <em>Tecia solanivora</em> (Lepidoptera: Gelechiidae)]]> ABSTRACT Potatoes can be attacked by several pests such as Tecia solanivora. The cry genes of Bacillus thuringiensis have been used to generate transgenic plants. The objective of this study was to determine the toxicity of the Cry2Aa and Cry2Ab recombinant proteins against larvae of T. solanivora. By PCR, the cry2Aa and cry2Ab genes were amplified using DNA from B. thuringiensis subsp. kurstaki HD-1. Each amplified product was ligated into the pET151/D-TOPO® vector, and subsequently transformed and expressed in Escherichia coli strains BL21. The recombinant clones were confirmed by PCR, restriction enzyme cutting and sequencing analysis. Recombinant proteins were detected by 8% SDS PAGE gels and immunodetection strips. For bioassays, three replicates of Parda Pastusa potato cultivar were nebulized with E. coli BL21-Cry2Aa or E. coli BL1-Cry2Ab recombinant strains and then infected with T. solanivora larvae, reaching levels of efficacy of 71.3 and 36.8 %, respectively. Biostat® 2007 was used to determine lethal concentrations, obtaining LC50 values of 167.7 and 554.6 μg/ml for BL21 Cry2Aa and Cry2Ab, respectively. The results allow concluding that the Cry2Aa protein can be a promising alternative for the biological control of Tecia solanivora . <![CDATA[EFFECT OF SYNTHETIC PESTICIDES ON CONIDIAL GERMINATION AND ENDOPHYTIC ACTIVITY OF <em>Beauveria bassiana</em> AND <em>Metarhizium anisopliae</em> IN COMMON BEAN PLANTS]]> ABSTRACT Common bean (Phaseolus vulgaris L.) is an important legume crop worldwide. Endophytic fungi have proven effective as biocontrol agents in several crops, but they can be affected by pesticides. The aim of this study was to evaluate the effect of synthetic pesticides on the conidial germination and endophytic activity of Beauveria bassiana and Metarhizium anisopliae in P. vulgaris. Three fungicides (Mancozeb, Tebuconazole and Zinc Ethylene-bis), three insecticides (Abamectin, Diazinon and Spirotetramat) and one herbicide (Glufosinate) were evaluated. Each pesticide was applied at the application rate recommended by the manufacturer and also using one-half of the application rate on the commercial strains B. bassiana Bb-18 and M. anisopliae Ma-30. Tebuconazole, Mancozeb and Glufosinate totally inhibited conidial germination. Spirotetramat and Diazinon resulted in a less pronounced negative effect on B. bassiana and M. anisopliae germination. However, Spirotetramat has the lowest impact on the entomopathogenic fungi, allowing for 86 and 74% germination of B. bassiana and M. anisopliae, respectively. Tebuconazole and Mancozeb affected the endophytic activity of the entomopathogenic fungi studied. At one-half of the recommended concentration, Spirotetramat and Zinc Ethylene-bis allowed for the total colonization of B. bassiana in roots of common bean, whereas M. anisopliae reached a colonization of 75%. These results indicate that Spirotetramat, Zinc Ethylene-bis and Diazinon can be used in combination with B. bassiana Ba-18 and M. anisopliae Ma-30. However, Tebuconazole, Mancozeb and Glufosinate should not be combined with these entomopathogenic fungi in Integrated Pest Management programs. <![CDATA[Ceratobasidium sp. AG-A, ROOT PATHOGEN OF Calibrachoa hybrida]]> ABSTRACT Calibrachoa (Calibrachoa hybrida, Solanaceae) is an annual flowering ornamental plant, which is widely used in landscape design. In October 2019, 5% of the plants grown in a greenhouse in Buenos Aires, Argentina, showed a sudden wilt characterized by chlorosis, loss of turgor, and root rot. The objective of this study was to identify the causal agent of the disease. Five morphologically identical isolates developed from the roots of wilting plants. One of the isolates was selected and identified using morphological and molecular markers, while its pathogenicity was confirmed by Koch’s postulates. The obtained results allow concluding that Ceratobasidium sp. AG-A (anamorph Rhizoctonia sp.) is the causal agent of the disease. To the best of the authors’ knowledge, this is the first report of Ceratobasidium sp. as pathogen of calibrachoa in the world. <![CDATA[COSTOS ENERGÉTICOS Y ECONÓMICOS DE UN CONJUNTO AGRÍCOLA, TRACTOR - TRASPLANTADORA, EN LABOR DE TRASPLANTE DE TABACO (<em>Nicotiana tabacum</em> L.)]]> RESUMEN La Hacienda Tabacalera Tabaganesha 2 se sitúa en el cantón Valencia provincia de Los Ríos, Ecuador. En el año 2017, la administración a cargo introdujo maquinaria agrícola para aumentar la productividad de trabajo y disminuir costos por uso de jornaleros en la siembra de tabaco. El objetivo de esta investigación fue determinar costos energéticos y económicos totales horarios, y por unidad de área trabajada, del conjunto agrícola tractor Deutz Fahr Agrofarm 420-T y trasplantadora Checchi Magli Unitrium II, en trasplante de tabaco. Los indicadores energéticos y económicos, y posteriores costos energéticos y económicos del conjunto mecanizado fueron estimados usando metodologías para determinación de costos energéticos y la Norma Cubana NC 34-38: 2003. El costo energético total horario, EST, fue 304,89 MJ h-1, mientras que la energía secuestrada en combustibles, ESc, con disposición del 31,8% fue el principal indicador, con un costo por unidad de área trabajada, EST (ha), de 1.172,65 MJ ha-1. Por otra parte, el costo directo de operación, Gd, alcanzó 243,03 USD h-1, mientras que el costo por producto utilizado, Gp, fue el indicador característico (83,6%), estableciéndose un costo por unidad de área trabajada, Gex, de 934,73 USD ha-1.<hr/>ABSTRACT The Tabaganesha 2 tobacco farm is located in the canton of Valencia, province of Los Ríos, Ecuador. In 2017, the administration in charge introduced agricultural machinery to increase labor productivity and reduce costs for the use of day laborers in tobacco planting. The objective of this research was to determine total energy and economic costs per hour, and worked area for, the agricultural set Deutz Fahr Agrofarm 420-T tractor and Checchi Magli Unitrium II transplanter, in tobacco transplanting. Energy and economic indicators as well as subsequent costs of the mechanized set were determined by using methodologies for energy cost estimation and the Cuban Standard NC 34-38: 2003. The total hourly energy cost, EST, was 304.89 MJ h-1, while the energy sequestered by fuel, ESc, was the main indicator, with a share of 31.8%, registering a cost per worked area, EST (ha), of 1,172.65 MJ ha-1. In addition, the direct operating cost, Gd, reached 243.03 USD h-1, while the cost per product used, Gp, was the characteristic indicator (83,6%), establishing a cost per worked area, Gex, of 934.73 USD ha-1. <![CDATA[PERSISTENCIA DEL EFECTO DEL SUBSOLADO EN UN SUELO BAJO ROTACIÓN DE CULTIVOS-PASTOREO EN EL SECANO DE LA REGIÓN DE LA ARAUCANÍA, CHILE]]> RESUMEN La compactación es un problema que se presenta de manera recurrente en los suelos del secano interior de la Región de La Araucanía, afectando considerablemente los rendimientos. El objetivo de este estudio fue determinar la persistencia en el tiempo del efecto del subsolado, como herramienta utilizada para descompactar, en un suelo bajo rotación de cultivos-pastoreo. Se estableció un ensayo de seguimiento por 5 temporadas consecutivas (t), midiendo la compactación dentro del perfil de 0-45 cm de profundidad, considerando lecturas del Índice de Cono ≥2000 kPa como indicador de suelo compactado. El diagnóstico se realizó el año 2015 (t0), mientras que los ensayos de seguimiento se iniciaron el 2016 (t1) con una siembra de avena, incluyendo dos tratamientos: “Con subsolado” y “Sin subsolado”. Los resultados obtenidos indican que la utilización del subsolado incrementó el rendimiento un 14,9% comparado con el testigo (sin subsolado). Posteriormente, el sitio experimental fue utilizado para pastoreo extensivo todo el año sin regulación de carga animal entre las temporadas 2017-2020 (t2-t5). Durante ese periodo, se realizó el seguimiento de la persistencia del efecto del subsolado en el espacio ocupado por las parcelas experimentales, evaluando la compactación del perfil de 0-45 cm y contrastando los valores obtenidos el 2015 (t0). En la última temporada evaluada (t5), el perfil de 0-10 cm presentó lecturas superiores al límite considerado como compactado, lo cual fue atribuido al uso ganadero del sitio. Se concluye que las lecturas del grado de compactación (kPa) retornan a la condición original (t0) a partir de la segunda temporada luego del subsolado (t2), con lo cual se termina el efecto residual del subsolado.<hr/>ABSTRACT Compaction is a recurring problem in soils of the dryland zone of the Araucanía Region, affecting yields considerably. The objective of this study was to determine the persistence over time of the effect of subsoiling, as a tool to reduce soil compaction, on a soil under crop rotation-grazing. A field experiment was established for 5 consecutive seasons (t). Soil compaction was measured at a depth of 0-45 cm, using the Cone Index as an indicator and considering ≥2000 kPa as compacted soil. The diagnosis was conducted in 2015 (t0), while the experimental trials started in 2016 (t1) when oats were sown on a site with two different treatments: ‘Subsoiling’ and ‘No subsoiling’. The obtained results showed that subsoiling increased yield by 14.9% compared to the no subsoiling treatment. Subsequently, the experimental site was used for grazing without animal load control from 2017 to 2020 (t1-t5). During this period, the persistence of the effect of subsoiling on the experimental site was evaluated by measuring soil compaction of a depth of 0-45 cm and contrasting the values to those obtained in 2015 (t0). In the last season (t5), the 0-10 cm profile showed surface compaction, which was attributed to grazing. It can be concluded that compaction levels (kPa) return to the original levels (t0) from the second season after subsoiling (t2), which ends the residual effect derived from the use of this tool. <![CDATA[ANTIBIOTIC-RESISTANCE PROFILE OF <em>Staphylococcus aureus</em> STRAINS IN THE PORK SUPPLY CHAIN]]> ABSTRACT Staphylococcus aureus can develop antimicrobial resistance (AMR), which is one of the global health care concerns. It can colonize skin and nares of animals and humans, with the risk of entering the food supply chain. The aim of this study was to determine the antibiotic-resistance profile of Staphylococcus aureus strains through the pork supply chain. The epsilon test (Etest) and the disk diffusion method were used to determine the antibiotic susceptibility of fifty-five S. aureus strains isolated from pigs (n=28, nasal and skin), carcasses (n=12, surface of carcasses), and meat (n=15, pork chop and leg). An 83.6% of the isolates exhibited AMR, with a higher prevalence in pigs and a high rate of penicillin resistance. Ten antibiotics of seven classes were used to assess the susceptibility of S. aureus isolates. Multidrug-resistance (MDR) was detected in 38.2% of the isolates, being PEN-ERY-CIP-TET the most common resistance profile. Strains exhibiting oxacillin- and cefoxitin-resistance were mecA-negative, while one strain was identified as vancomycin-intermediate S. aureus (VISA). The results confirm that measures to control and mitigate AMR need to be implemented, particularly during the different animal production stages.