Peruvian Journal of Agronomy

Published by Universidad Nacional Agraria la Molina
Online ISSN: 2616-4477
Publications
Probit analysis to characterize the basic line of susceptibility of T. urticae to Spirodiclofen.
The use of inhibitors of lipids synthesis is among the available strategies for the control of Tetranychus urticae (Acari: Tetranychidae) in strawberry plantations. The study aimed to monitor the susceptibility to Spirodiclofen in field populations of T. urticae from strawberry plantations in Lima region, Peru. Adult T. urticae were collected from strawberry plantations in districts of Aucallama, Chancay, Huaral, and Santa Rosa de Quives in Lima region, Peru. A population collected from Acalypha wilkesiana in campus of the Universidad Nacional Agraria La Molina (UNALM), where chemical pesticide has never been applied, was used as a susceptible reference line. This reference line was subjected to toxicological bioassays to estimate the LC50 and LC95. Afterward, bioassays were conducted on the population using the LC50 and LC95 estimated for the susceptible reference line. The obtained data was subjected to one-way analysis of variance and mean comparison was done by Tukey test (α = 0.05). There were no significant differences between the four populations’ LC50 and LC95, with respect to the estimated susceptible reference line. This implies that the four studied populations of T. urticae are susceptible to Spirodiclofen, with no evident resistance problems. Therefore, Spirodiclofen is a useful tool for the control of T. urticae form strawberry plantations in the studied location. The factors that influenced the results are discussed in the present work.
 
Location of the district of Río Negro in the province of Satipo in the department of Junín, Peru.
Key dates in the management of the MD2 pineapple experiment in Satipo. MAT, months after transplant.
La piña (Ananas comosus) es una especie muy cultivada en diferentes países tropicales. Sin embargo, su floración natural es un evento fisiológico que puede dificultar la labor de cosecha, trayendo consigo problemas económicos. En tal sentido, este trabajo tuvo como objetivo determinar el efecto de la Aviglicina sobre la floración de piña cv. ‘MD2’ en la selva central del Perú. Se estudiaron tres dosis (150 mg · L-1, 250 mg · L-1 y 350 mg · L-1) de Aviglicina (AVG) (producto comercial Retain 15 %), con 6 y 11 aplicaciones. En general, los resultados confirman la aparición de floración natural (FN) en condiciones de Satipo. Las altas dosis de AVG (250 mg · L-1 y 350 mg · L-1) inhibieron la aparición de las inflorescencias durante casi todas las evaluaciones, especialmente con once aplicaciones comparadas con el tratamiento sin AVG ni TIF (Tratamiento de inducción floral) (FN). Asimismo, FN presentó tres periodos con tasas relativa de aparición de inflorescencias (TRAI) diferentes, siendo la primera la que tuvo mayor TRAI y mayor duración (42 días). Finalmente, se concluye que la aplicación de AVG tuvo un efecto significativo en el retardo de la aparición de las inflorescencias, motivo por el cual se sugiere su aplicación en el cultivo de piña. Sin embargo, son necesarios más estudios para seguir profundizando el conocimiento sobre el manejo de este regulador de crecimiento.
 
In Peru it is very important to increase food quality and production in the rural areas where a high poverty and malnutrition problems are found. Mutation induction is used to improve well adapted cultivars, by upgrading one or two characteristics, while retaining all its original attributes. Hordeum vulgare mutant lines were developed from the cultivar UNALM 96, following irradiation at 200 and 300 Gray. Mutant lines were selected in the M8 generation with higher agronomic performance and nutritive quality. They were adapted to the highlands with grain yield within the range of ,100 and 8,731 kg/ha, over the value of the parental material (4,246 kg/ha) and showed improved contents of P (131 mg/g dry weight-DW), Zn (66 mg/g DW), Mn (55 mg/g DW), Fe (57 mg/g DW) and Cu (63 µg/g DW).
 
Simplified flowchart of the algorithm, with emphasis on the input data required for the numeric simulation. The clause [3] refers to each iteration for the three known diapauses, and [12] is the number of monthly iterations and data used for calculations; the arrays modeling diapause are bi-dimensional because three ratios of diapause are present for different periods throughout the year.
In Integrated Pest Management practices, knowledge from multiple disciplines is incorporated to facilitate the understanding of a problem and the development a practical, feasible, and ecologically sustainable solution. A froghopper (Aeneolamia spp.) plague can trigger major economic losses in sugarcane plantations in countries such as El Salvador and others in Latin America. Losses are often due to a lack of understanding of the life cycle of a pest and the underestimation of its annual reproductive potential. An algorithm was developed to model the most relevant aspects of froghopper reproduction and its interactions with the environment, to facilitate the prediction of potential increases in adult populations and its propagation in fields. Data on several biological variables were collected as numerical measures and used to perform calculations based on a mathematical model designed particularly to simulate the reproduction of the pest, its economic threshold, and potential losses due to major natural events, with the aim of developing a tool that could support decision-making. The predictions of the tool were consistent with the findings of other studies in the field. The software and its installation instructions can be downloaded for free from https://drive.google.com/file/d/1oUWTTbi lWMhoFuTH4wCKtuzjFwDd89/view
 
La producción de Arándanos en Perú ha tenido un rápido crecimiento en los últimos cinco años, pasando de no tener una superficie de más de 3050 hectáreas en la actualidad. Como resultado de este aumento, han aparecido muchos problemas patológicos de las plantas, entre ellos Phytophthora sp. provocando plantas con síntomas de marchitez, rojizo de hojas inferiores, muerte regresiva, pudrición de raíces y copa de diferentes zonas de producción del Perú. Sin embargo, no se reporta identificación en Perú. Por ello, este estudio se realizó en la Clínica de Fitopatología de la Universidad Nacional Agraria La Molina con el objetivo de identificar las especies de Phytophthora.causando pudrición de la corona y la raíz aislada del arándano en Perú. Se identificaron cuatro aislamientos del campo de arándanos por características morfológicas, moleculares y patogénicas. Todos los aislamientos formaron colonias de tipo corral con hinchazón de hifas en agar PDA y V-8 y produjeron esporangios obpiriformes o elipsoidales y clamidosporas de globo. El espaciador transcrito interno (ITS) del rDNA se amplificó y secuenció con el cebador ITS1 / ITS4 para confirmar la identificación.Todas las secuencias de nucleótidos ITS de los aislados obtenidos se enviaron al GenBank de NCBI (número de acceso MH777152 para aislar AR-1, MH777151 para aislar AR-2, MH777150 para aislar AR-4 y MH777149 para aislar AR-3). Cada una de las secuencias mostró 100% de homología con secuencias de referencia de P. cinnamomien GenBank. Las pruebas de patogenicidad mostraron síntomas de enrojecimiento y coloración amarillenta y pudrición de la raíz y la corona en Blueberry cv. Biloxi después de 30 días de inoculación. Finalmente, concluyó que P. cinnamomi es la especie que causa la pudrición de la corona y la raíz en Blueberry en Perú. Hasta donde sabemos, este es el primer informe de P. cinnamomi en arándanos en Perú.
 
Strawberry (Fragaria ananassa) plants showing symptoms of leaf spot were found in the producing areas of Manchay Bajo, Pachacamac District, Lima, Peru. The responsible pathogen was isolated and observed under a microscope to examine its morphological characteristics and the size of its structures, resulting in its identification as the fungus Corynespora cassiicola. Healthy strawberry plants that had been inoculated with C. cassiicola in a greenhouse developed lesions after 3 days and exhibited symptoms consisting of dark brown spots that had light brown centers and were surrounded by yellow halos, which coalesced and subsequently caused necrosis of the whole leaf. In vitro tests demonstrated that the fungus Trichoderma harzianum strain T-22 showed antagonistic activity against C. cassiicola, causing 41.8% mycelial growth inhibition, and the fungicides fosetyl-aluminum (Aliette®) and thiabendazole (Mertect®a) inhibited mycelial growth by 100.00% and 96.32%, respectively. However, in vivo, 0.75 g/L of the fungicide azoxystrobim (Stronsil®) gave the best control of C. cassiicola and the lowest area under the disease progress curve (AUDPC), followed by 1.5 mL/L of thiabendazole (Mertect) under greenhouse conditions. The isolate was found to be pathogenic, and its morphological identification was confirmed.
 
The objective of the present research was to identify the causal agent of soft rot disease in the stems of pitahaya plants (Hylocereus undatus (Haw.) Britton & Rose), also known as dragon fruit, in two production areas of Peru. Typical symptoms observed include rotting and soft consistency in stems, as well as yellowish colourations, which usually begin at the tips and outer edges of the stems and extend until they are completely decomposed. Symptomatic samples of pitahaya stalks were collected from two commercial fields, the first from the district of Independencia, Pisco, Ica, and the second from the district of Naranjos, Rioja, San Martin. The collected samples were transferred to the phytopathology laboratory of the National Agrarian University – La Molina where 19 bacterial colonies isolated from symptomatic stem tissue were processed. Nine bacterial colonies were selected from the initial 19 for further analysis. The nine selected colonies were gram negative, positive for the catalase enzyme, negative for the enzyme oxidase, and positive for pectinase production, which causes soft rot in potato tubers. These results indicated that these isolates correspond to the Enterobacteriaceae family. According to molecular tests and analysis of the 16s region of ribosomal DNA, all bacteria corresponded to a single taxonomic genus, Enterobacter. This bacterium presented a 99.85% homology with Enterobacter cloacae (accession number MH788982.1). The sequences from the nine selected isolates were entered into GenBank under accession number MN784371. In the pathogenicity test, 100% infection was obtained in the pitahaya stems and plants inoculated with E. cloacae, and the symptomatology that developed was the same as that observed in the two fields from where the samples were collected. Given these results, it can be concluded that E. cloacae is a causative agent of soft rot disease of the stems of H. undatus in the districts of Independencia and Naranjos, and this is also the first report of this bacterium as a pathogen of pitahaya in Peru.
 
Province and District of Cajatambo. Source: Google Map Data (2017).
Long-term plots for the monitoring of induced post-agricultural succession.
Evolution of average monthly precipitation (mm) from January 2015 to December 2017. Source: Cajatambo CWS, SENAMHI.
Comparison of accumulated monthly precipitation (mm) from 2015 to 2017. Source: Cajatambo CWS, SENAMHI.
Main plant families and their richness recorded in the plots of early post-agricultural succession in Cajatambo, Lima (2015 to 2017).
In this paper, the floristic composition is studied in plots of early post-agricultural succession induced in four agroecosystems (Ocopata, Rancas, Tupicocha and Ucupi) in the district of Cajatambo, Lima. The plots are located between 2,992 masl and 4,220 masl in three plant formations (agriculture, scrubland and grassland), and the description of the floristic composition was made before and after inducing the succession between 2015 and 2017. The number of determined plants is 78, all of which belong to 30 botanical families, of which the Asteraceae (16 species), Fabaceae (11 species) and Poaceae (8 species) families stand out. Indeed, the only common species among the four agroecosystems is Medicago polymorpha; moreover, five species appear in three of the four agroecosystems: Brassica rapa subsp. campestris and Verbena litoralis (Ocopata, Tupicocha and Rancas), Oenothera rosea and Trifolium repens (Ocopata, Rancas and Ucupi) and Bidens andicola (Tupicocha, Rancas and Ucupi).
 
Scale and sub-indicators for meeting basic needs.
Scale and sub-indicators of economic risk.
El objetivo de esta investigación fue determinar las consecuencias de la adopción en términos de sustentabilidad social, ambiental, económica y general de sistemas de producción agroecológicos de la parroquia de Toacaso. Para determinar los indicadores se utilizó la metodología propuesta por Sarandón (2002), considerando las dimensiones económica, social, cultural y ambiental y se adaptó la metodología propuesta por Ortiz y Pradel (2009) en la evaluación de impactos en programas de Manejo Integrado de Plagas, se realizó encuestas con preguntas alusivas a las consecuencias sociales, económicas y ambientales, dirigida a 44 agricultores agroecológicos y 44 a productores convencionales en la parroquia Toacaso. Adicionalmente, se identificó como tratamiento “control” a una muestra de 44 productores convencionales tomados en la parroquia Mulaló, lo que permitió realizar una comparación con y sin adopción de prácticas agroecológicas. De las 44 unidades productivas que implementaron el sistema de producción agroecológica el 27,27% alcanzaron sustentabilidad general, el índice promedio de sustentabilidad general fue de 2,16, 86,36% alcanzo sustentabilidad ambiental, el 47,72% sustentabilidad económica, y el 47,73% tienen sustentabilidad social.
 
Location map of the farms in the district of Yurimaguas (Loreto) that participated in the Sustainable Landscapes for the Amazon project, according to geo-referencing (elaboration: Bach. André Mauricio Valderrama Espinoza).
Leaf spots on palm heart. The small, blackish spots correspond to Colletotrichum siamense and the straw-colored spots to Neopestalotiopsis foedans.
Banana leaf spots caused by Mycosphaerella fijiensis; the causative agent of black leaf streak disease.
Results of molecular ID of the isolates (from the plant samples with symptoms of leaf spots and regressive death) compared with the NCBI.
Un sistema agroforestal (SAF) se caracteriza por tener una diversidad de componentes como especies forestales maderables y no maderables, así como cultivos, pastos o un sistema de producción ganadera. Esta diversidad de componentes en el sistema reduce la intensidad de las enfermedades, por ejemplo, las foliares. Los objetivos fueron detectar los microorganismos fúngicos asociados a las manchas foliares de las especies vegetales que forman parte de los sistemas de producción agroforestal de los agricultores de Yurimaguas (Loreto) que participaron en el SLA y determinar el nivel de incidencia de las manchas foliares en los sistemas de producción agroforestal. En estas fincas se implementaron diferentes sistemas de cultivo de la tierra, como la palma (Bactris gasipaes) para producir palmitos y cacao (Theobroma cacao), incluyendo el plátano (Mussa sp.). También, sistemas silvopastoriles con especies maderables de crecimiento rápido y lento y ganado con pastos para el pastoreo y la reforestación en áreas de bosques secundarios en estado de degradación. Se realizó la prospección, recolección y determinación de la incidencia de las enfermedades en cada finca, y posteriormente se identificaron con métodos moleculares utilizando los cebadores ITS 1 e ITS 4. Los síntomas que se observaron, predominantemente, fueron manchas foliares en cacao (patrón), palma y plátano. No se observaron síntomas de marchitamiento, decaimiento o podredumbre. La incidencia se evaluó en dos periodos de recolección (2018 y 2019). Los hongos aislados de las manchas foliares fueron Pestalotiopsis sydowiana y Colletotrichum siamense como agentes causantes de las manchas foliares en palma y cacao, y Mycosphaerella fijiensis en plátano. Al determinar la incidencia desde abril de 2018 hasta octubre de 2019, se observó una disminución de este parámetro para las fincas con palma, especialmente en aquellas donde la implementación consistió en mejorar el sistema de producción a través de la fertilización con base en los requerimientos del cultivo. Se concluyó que la mayor intensidad de enfermedades foliares se presentó en los sistemas agrícolas con monocultivo de palma con un 100 % al inicio de la evaluación, y para los sistemas agroforestales en el prototipo silvopastoril, solo se detectó en un rango de 0 % a 25 %.
 
Annual rainfall distribution from 2007 to 2016 in Santo Tomas, Yurimaguas.
Monthly rainfall distribution during 2016 in Santo Tomas, Yurimaguas.
Eight month year old dry biomass in the three farms in Santo Tomas, Yurimaguas (W, R and C are Washington, Roberto and Clais farmers, respectively).
Biomass production of Centrosema covers for each of the agroforestry systems established in Santo Tomas Yurimaguas.
Esta investigación a largo plazo se está llevando a cabo en tierras degradadas de baja fertilidad en los trópicos húmedos de la Amazonía peruana. El objetivo es recuperar tierras degradadas para una agricultura sostenible que se vio afectada por la agricultura migratoria y los pastos sobrepastoreados. Los ensayos de recuperación en tres fincas son cultivos de cobertura fertilizados con la leguminosa Centrosema (Centrosema macrocarpum), y el establecimiento del prototipo de sistemas agroforestales se basa en a) árboles leñosos con Swietenia macrophylla, Guazuma crinita (GC), Calycophylum spruceanum (CS ) y Simarouba amara (SA), b) árboles frutales leñosos con Cedrelinga cateniformis, GC, SA, Inga edulis y Bactris gasipaes, y ac) sistema silvopastoril con Centrosema y árboles leñosos con GC, SA y CS.Los suelos degradados compactados se cubrieron con pasto degradado (Brachiaria brizantha) y malezas, y el suelo era muy ácido (80% de saturación de Al) con 4 ppm de P y baja materia orgánica del suelo y capacidad de intercambio catiónico. El suelo fue desyerbado y fertilizado con un fertilizante combinado a base de roca fosfatada (40 kg / ha), luego se plantó Centrosema seguido de la plantación de árboles con aplicación de fertilización localizada. En tres meses tuvimos una cobertura del 100% y se controló la maleza. La biomasa promedio de Centrosema en 8 meses fue de 8.12 T / ha, y mientras los diferentes árboles crecían con 55 a 89 por ciento de supervivencia por estrés hídrico, Centrosema recuperó la compactación del suelo hasta 20 cm de profundidad.La biomasa se puede utilizar como forraje para animales pequeños y para enriquecer el suelo. La acumulación media de nitrógeno total en la biomasa fue de 232 kg / ha. El suelo fue desyerbado y fertilizado con un fertilizante combinado a base de roca fosfatada (40 kg / ha), luego se plantó Centrosema seguido de la plantación de árboles con aplicación de fertilización localizada. En tres meses tuvimos una cobertura del 100% y se controló la maleza. La biomasa promedio de Centrosema en 8 meses fue de 8.12 T / ha, y mientras los diferentes árboles crecían con 55 a 89 por ciento de supervivencia por estrés hídrico, Centrosema recuperó la compactación del suelo hasta 20 cm de profundidad. La biomasa se puede utilizar como forraje para animales pequeños y para enriquecer el suelo. La acumulación media de nitrógeno total en la biomasa fue de 232 kg / ha. El suelo fue desyerbado y fertilizado con un fertilizante combinado a base de roca fosfatada (40 kg / ha), luego se plantó Centrosema seguido de la plantación de árboles con aplicación de fertilización localizada. En tres meses tuvimos una cobertura del 100% y se controló la maleza. La biomasa promedio de Centrosema en 8 meses fue de 8.12 T / ha, y mientras los diferentes árboles crecían con 55 a 89 por ciento de supervivencia por estrés hídrico, Centrosema recuperó la compactación del suelo hasta 20 cm de profundidad. La biomasa se puede utilizar como forraje para animales pequeños y para enriquecer el suelo. La acumulación media de nitrógeno total en la biomasa fue de 232 kg / ha. En tres meses tuvimos una cobertura del 100% y se controló la maleza. La biomasa promedio de Centrosema en 8 meses fue de 8.12 T / ha, y mientras los diferentes árboles crecían con 55 a 89 por ciento de supervivencia por estrés hídrico, Centrosema recuperó la compactación del suelo hasta 20 cm de profundidad. La biomasa se puede utilizar como forraje para animales pequeños y para enriquecer el suelo. La acumulación media de nitrógeno total en la biomasa fue de 232 kg / ha. En tres meses tuvimos una cobertura del 100% y se controló la maleza. La biomasa promedio de Centrosema en 8 meses fue de 8.12 T / ha, y mientras los diferentes árboles crecían con 55 a 89 por ciento de supervivencia por estrés hídrico, Centrosema recuperó la compactación del suelo hasta 20 cm de profundidad. La biomasa se puede utilizar como forraje para animales pequeños y para enriquecer el suelo. La acumulación media de nitrógeno total en la biomasa fue de 232 kg / ha.
 
To evaluate the behaviour of cassava clones (Manihot esculenta Crantz), the physiological quality of the propagation material was assessed, and an agronomic characterisation was conducted; this was essential for the generation of information on the clones’ productive potential. The trial was conducted in the experimental field of the Roots and Tubers programme (PIPS-RT) of the National Agrarian University–La Molina. Following a completely randomised block design with four replications, clones from the PIPS-RT were evaluated. Variables were assessed to determine the clones’ physiological quality in terms of the number of viable stakes, normal seedlings, abnormal seedlings and percentage of stake survival. The agronomic characteristics evaluated were plant height, stem diameter and yield. The Morocha clone had the highest percentage of viable stakes and normal seedlings, i.e. 80.95% and 73.81%, respectively. The highest yield was also produced by the Morocha clones (13 t/ha) followed by the Donoso 2 (7.20 t/ha) and Blanca Cajamarca (6.80 t/ha) varieties.
 
de Siguas, Arequipa Province, Peru. The concentrations used were 2, 4, and 6 kg ha−1 with 4 applications by means of impregnation to the transplant and via drench every 15 days. The statistical design was through a DBCA with factorial arrangement randomly distributed in four blocks. The tests used were the orthogonal contrast test and Duncan’s multiple comparison test (α = 0.05). The findings showed that the treatment concentrations of 4 kg ha−1 and 6 kg ha−1 resulted in a lower incidence of Fusarium oxysporum, at 6.71% and 9.36%, an ABCPE of 637.78 and 950.14 units, and an exportable yield of 66.34 t ha−1 and 65.42 t ha−1, respectively, displaying significant differences from the control. The first application was statistically significant to the treatments with the highest number of applications, showing a greater exportable yield of 67.54 t ha−1. The best interactions between concentrations and applications were 6 kg ha−1 with 1 application, 4 kg ha−1 with 2 applications, and 4 kg ha−1 with 1 application, with exportable yields of 70.66, 69.61, and 69.11 t ha−1, respectively.
 
Garlic (Allium sativum L.) is an important crop for domestic consumption in Peru. However, there is insufficient information available on crop management, particularly on fertiliser application to local cultivars. In order to evaluate the response of three garlic cultivars to three fertilisation methods, an experiment was conducted at the Donoso Experimental Station in Huaral district, a province of Lima. Three garlic cultivars were used as experimental materials: ‘Cincomesino’, ‘Arequipeño 14’ and ‘Margosino’. Three methods of fertilisation were applied as treatments: broadcast application before furrowing (M1), fertilisation in a superficial groove or false furrow (M2), and fertilisation in the lateral furrows, or band application (M3). The experiments were installed in three parcels for each cultivar, with a randomised complete block design for each parcel and four replications. In general, localised fertilisation methods showed the best performance for the broadcast method. Regarding total yield, fertilisation at the sides of the furrow (M3) for ‘Cincomesino’ reached 13.08 t/ha. The highest yield for the ‘Arequipeño 14’ cultivar (12.25 t/ha) was achieved using fertilisation with a surface groove or false furrow (M2). For the ‘Margosino’ cultivar, fertilisation on the sides of the furrow was ideal, and the yield was 10.95 t/ha.
 
This experiment was carried out at the province of Arequipa, to determine broccoli residual effects on the sclerotia population of Sclerotium cepivorum on the soil and determine the best fungicides and biocontrol agents on the biggest red onion production. In two field areas infected with Sclerotium cepivorum, soil samples were carried out to determine the number of sclerotia at the beginning and the end of the trial. One area received broccoli residues before treatment installation. The experiment had a laboratory and a field phase. The block design was used completely randomized (DBCA), using seven fungicide treatments (T1) control, Iprodione (T2), Thiabendazole (T3), Boscalid (T4), Carbendazim (T5), T harzianum (T6), Bacillus subtilis (T7). Both areas received the same treatments. The density of sclerotia in the soil was not significant between these areas. However, the addition of broccoli had lower percentages of incidence and severity and higher yields in all treatments. At the area that received broccoli, the Boscalid (T4) and the Iprodine (T2) fungicide were highlighted with 43.33 T/ha and 28.33 T/ha, respectively; the area without broccoli, the T4 with 38.33 T/ha and T2 with 25.56 T/ha. T5 (Carbendazim) had the lowest yield: 15.00 T/ha without broccoli and 19.58 T/ha with broccoli.
 
Onion crop begins with seedling preparation and finishes with transplanting. In some Peruvian onion-productive areas, it is assumed that seedling thickness is important to have a better yield. Four different seedling thickness of red onion (Allium cepa L.) were evaluated between February and June 2017 in Santa Rita de Siguas, Arequipa, Peru. The seedling thicknesses evaluated were very thin (2.00 mm – 3.49 mm), thin (3.50 mm – 4.99 mm), standard (5.00 mm – 6.49 mm) and thick (6.50 mm – 7.99 mm). The plant density was 340 000 plants ha−1. The experimental design was a randomized complete block with four treatments and five replications. The variables evaluated were plant height (cm), leaf number, stemlike diameter (mm), bulb diameter (mm), total yield (t ha−1), and marketable yield categories (t ha−1). The leaf number, plant height, and stemlike diameter among treatments were significantly different, with higher values in the “standard” and “thick” treatments up to 60 days after transplanting. The harvest was earlier in the “standard” and “thick” treatments. The “very thin” and “thin” treatments needed more days to harvest than the others. The “thin” treatment showed the highest total yield. There were no significant differences between marketable yield categories in all treatments. It was concluded that seedling thickness upon transplanting influences the yield under the conditions in this study.
 
The consumption of insects is a widespread practice among indigenous or native peoples of the Amazon. To assess the knowledge of the diversity of resources for entomophagy from the perspective of these peoples, testimonies or references about knowledge and feeding traditions of 100 people were collected in 37 localities in seven provinces of the department of San Martín in the basin of the Huallaga River. One cumulative species curve and the probability function of new species were estimated, then the probability of not finding a new species (99.5 %) to n100 was determined. The specimens that were captured in the field (54 %) were compared with representative specimens and databases, and the information provided by the participants was analysed to approximate the preliminary taxonomic locations of the remaining part of the sample. We found 46 resources for entomophagy and reported for first time in the Peruvian Amazon, the feeding with Chrysophora chrysochlora, Podalia sp., Lusura chera, and Cymothoidae, among others. Entomophagy is a deeply rooted practice in the native and riverine populations of the Huallaga basin, where Rhynchophorus palmarum, Rhinostomus barbirostris, Atta cephalotes sspp. and Brassolis sophorae were the most consumed for 78 % – 97 % of people. The least consumed species have the common characteristic of being scarce and they were part of the diet of the oldest segment in previous decades. At least 10 resources ceased to be consumed by the members of the sample. In addition to nutritional potential, the diversity of edible arthropod fauna represents complementary values for community health and cultural identity; however, most of these resources (87 %) are threatened and could disappear in brief time, as is the knowledge related to their use.
 
In the rhizosphere, as the zone of biological activity, diversity of microorganisms can be found like bacteria of the genus Pseudomonas. They are characterized for controlling pathogens like Phytophthora cinnamomi, also to be promoters of growth. For this reason, in the present study, bacteria of the genus Pseudomonas were isolated from the avocado rhizosphere of the provinces of Casma, Huaral, and Lima. A total of six strains (R2, R5, R7, R10, S10 and S6) were selected for evaluating their biocontrol capacity against P. cinnamomi under in vitro and greenhouse conditions. In the in vitro test, strains S6 and S10 controlled 30.3 and 44 %, respectively. Under greenhouse conditions, Pseudomonas strains were inoculated on 4-month-old avocado cv. “Zutano” plants. Five months later, we evaluated the following variables: severity in roots, height increase, fresh root and leaf weight, and percentage of root and leaf dry matter. In greenhouse, the best strains in the control of P. cinnamomi were S6, R2, R7 and R10, controlling 55.2, 39.5, 33.7 and 31.0 %, respectively. In the increase of height, the strains S6, R2, R7 and R10 reached 11.4, 9.3, 7.6 and 5.1 cm, respectively. The percentage of dry matter of roots, strains S10, R10 and R7 obtained 29.6, 27.5 and 27.9 %, respectively. In this study, it was observed that although the application of Pseudomonas controls P. cinnamomi, it also induces the root and apical growth of avocado.
 
The honeys from stingless bees (Hymenoptera: Apidae: Meliponini) are recognized for their medicinal properties. They are commonly used by many indigenous groups around the world. However, in Peru stingless beekeeping is practiced in an artisanal way and the honeys remain products whose qualities are still little studied. The objective of this work was to analyze physicochemical characteristics and microbiological quality of honeys produced by Scaptotrigona polysticta Moure, Melipona illota Cockerell and Tetragonisca angustula Latreille in apiaries of department of San Martin, Peru. In June and November 2019, 30 honey samples were collected from 24 colonies housed in two apiaries in the towns of Tarapoto and Chasuta. Significant differences (p 10 CFU / mL) according Peruvian sanitary norm № 071-Minsa/Digesa-V.01, in 30 and 50% of the samples of S. polysticta and T. angustula, respectively. These results contribute to the knowledge of the stingless bee honeys of Peru providing important references for the quality standard setting process and the advancement of stingless beekeeping.
 
Adult Europs sp. (Order Coleoptera, Family Monotomidae).
This survey aimed to determine the pollinating insects of the flowers of the cherimoya crop (Annona cherimola Mill.) located at the Program of Research and Social Projection in Fruit Trees (PIPS-FRUTALES) at the Universidad Nacional Agraria La Molina. Fifteen trees were selected randomly, and evaluations were performed from 31 October to 15 November 2018. Three replicates were performed, each replicate was formed by a set of five trees and were evaluated in three different weeks. Each tree was evaluated in four quadrants, according to the location of the flowers (external or internal) and the floral phases of the crop (female or male). The collection of the insects from the cherimoya flowers was performed using an aspirator, then the insect morphotypes were determined and classified according to order, family, genus and/or species through the use of taxonomic dichotomous keys and the support of specialists. The collected insects belonged to the orders Coleoptera, Hymenoptera, and Hemiptera, with Coleoptera having the highest diversity (17 morphospecies) and quantity (242 specimens). The genus Europs (Monotomidae) proved to be the most abundant group of Coleoptera during the assessment period, followed by morphospecies of the families Nitidulidae, Anthicidae, Staphylinidae, Scarabaeidae, Anobiidae, and Buprestidae. The pollinating insects present in the cherimoya crop were satisfactorily classified into genera and species.
 
The effects of gamma radiation on the germination, survival, and morphological damage in characteristics of the M1 generation of coffee (Coffea arabica L. var. typica) plants was evaluated using seeds collected from Santa Teresa and Chaupimayo, Peru. Under net house, the percentage of germination was 68%, 35%, 10%, and 0% for the Santa Teresa seeds and 75%, 49%, 17% and 0% for the Chaupimayo seeds with irradiation treatments of 0, 50, 100 and 150 Gy, respectively, whereas under laboratory conditions, germination levels were between 70% and 94% across all treatments. The survival rate also decreased with increasing radiation levels, with values of 45%, 32%, 28%, and 10% in the laboratory and 29%, 9%, 6%, and 0% in the net house for the Santa Teresa seeds and 58%, 45%, 38%, and 8% in the laboratory and 42%, 15%, 7%, and 0% in the net house for the Chaupimayo seeds with irradiation treatments of 0, 50, 100, and 150 Gy, respectively. Morphological changes were observed in the plants that survived irradiation at a dose of 100 Gy in terms of the leaf shape, leaf apex shape, young leaf color, plant height, stem diameter, number of leaves per plant, leaf length, leaf width, and distance from the cotyledon to the first node.
 
In order to know the effect of three levels of potassium on five eco-physiological parameters in sunflower, open-pollinated achenes Victory cultivar, were sown at a density of 11.08 plants m-2 with a fertilization of 100N-50P kg ha-1 N=nitrogen, P= phosphorous, K= potassium. Traits evaluated were: agronomic yield, leaf area index, light attenuation coefficient and intercepted radiation. The treatments consisted of three potassium levels: 0, 50 and 100 kg ha-1 (K2O) and four repetitions (3x4) resulting in 12 experimental units, which were evaluated under a randomized complete block design. The results indicate that the application of 50 and 100 kg ha-1 of potassium increase the agronomic yield, leaf area index, intercepted radiation as well as the light attenuation coefficient. From this investigation it can be concluded, that potassium is a very important nutrient for sunflower when it is sown in dry climates such as the Tehuacan valley, Puebla.
 
The study was conducted in the districts of Huacrachuco and San Pedro de Cholon, province of Marañon and Huanuco region. The aim of the study was to describe the in-situ conservation and ethno-botanical indicators of the phenotypic variability of Arracacha (Arracacia xanthorrhiza Bancroft), Yacon (Smallanthus sonchifolius H. Robinson) and wild relatives. Work was done in the farmers’ plots where they preserved from one to three morphotypes of A. xanthorrhiza and S. sonchifolius, and farmer communities where preserved wild plant relatives. A total of thirteen farmers from three farmer communities in the Huarachuco district, and nine from two farmer communities in the district of San Pedro de Cholon were selected. Six in-situ conservation and three ethno-botanical indicators were described. By using morphological descriptors 23 samples of grown arracacha and 34 of grown yacon, three samples each of wild arracacha and yacon were characterized. Based on this characterization, results were as follow: three different morphotypes of grown arracacha for 21 descriptors, four different morphotypes of grown yacon for 18 descriptors, two ecotypes of wild arracacha (the low field ecotype located in a range of altitude of 2500 to 2750 meters above sea level and the height field ecotype located above 3530 m.a.s.l.) and two ecotypes of wild yacon (yellow and red ecotypes).
 
Un ensayo en macetas fue realizado en el campus de la Universidad Nacional Agraria La Molina, para evaluar el efecto de la ceniza de cascarilla de arroz, escoria básica de horno cuchara y silicato de potasio, en las propiedades químicas del suelo y en la biomasa del arroz (Oryza sativa L.) cv. ‘Fedearroz 60’, usando material de suelo procedente de un campo arrocero en Aucayacu, Huánuco, Perú. Las dosis fueron calculadas en base a la concentración de silicio biodisponible (SiA) de cada enmienda para lograr 100, 200 y 400 ppm (p / p) de SiA en suelo antes de la siembra, además de testigos sin aplicación de silicio. Se empleó un diseño completo al azar con arreglo factorial de 3 × 4 en el que se evaluó la absorción de Si en tejidos, disponibilidad de SiA al final de la campaña, volumen radicular, habilidad de macollamiento, panículas por planta y espiguillas por panícula promedio. Se registraron las variaciones semanales de salinidad y pH en el material de suelo empleado como sustrato, así como las variaciones diarias de temperatura e intensidad luminosa. Se encontró que el silicato de potasio a 200 ppm incrementó sostenidamente el SiA en suelos y el Si en tejido; sin embargo, no hubo influencia en los componentes del rendimiento. La escoria básica también incrementó el SiA en suelos, pero presentó reacciones tóxicas severas en las dosis de 200 ppm y 400 ppm. La ceniza de cascarilla de arroz no influyó significativamente en los parámetros de silicio, ni en los componentes de rendimiento. Se concluyó que para las condiciones de suelo y clima en la que se desarrolló el experimento, el incremento en la concentración de silicio en suelo y tejidos, no influyó en los componentes del rendimiento del arroz. Pese a ello, la escoria presenta una extraordinaria capacidad encalante y la ceniza una gran cantidad de P, K y micronutrientes.
 
Sweetpotato (Ipomoea batata L.) is an economically important crop grown in Peru. The present study aimed to determine the soil arthropods associated with sweetpotato and its relative abundance in sweetpotato production fields in La Molina, Lima, Peru. Evaluations were conducted at Universidad Nacional Agraria La Molina, from February to August 2017. Samples were collected using pitfall traps and examined at the Klaus Raven Büller Entomology Museum. Soil morphospecies were extracted and separated from collected samples and then counted, recorded and identified. They were also admitted to the Entomology Museum collection. Eighty morphospecies in the classes Collembola, Insecta, Malacostraca, Arachnida and Chilopoda of phylum Arthropoda were recorded. Within the Collembola class, Entomobryidae was the most abundant family; within Insecta, Gryllus spp. (Gryllidae); within Malacostraca, Porcellio laevis (Porcellionidae); within Arachnida, Theridion volubile (Theridiidae) of the order Aranea; and within Chilopoda, the order Lithobiomorpha. By understanding the diversity of arthropods, it may inform future measures and improve control of pests by taking into consideration the soil arthropods among which important beneficial natural enemies could be found.
 
The aim of the study was to evaluate the in vitro propagation ability of 10 clonal lines of thorny globe artichoke (Cynara scolymus L.). The study methodology comprised five stages of evaluation. The stages evaluated were initiation, multiplication, rooting, acclimatization, and transplant to the field. The study began with the initiation of dissected shoot tips of 10 clonal lines in test tubes containing the Murashige and Skoog (MS) medium. Best results were obtained when explants were cultured on an induction medium containing MS + naphthalene acetic acid (NAA) 1.0 mg l−1 + benzyl aminopurine (BA) 1.0 mg l−1, highlighting clonal lines L-250, L-132, and L-62. Because of high rates of vitrification and phenolization in the initial stage, clonal lines L-24, L-127, and L-142 were discarded from the study. Therefore, only seven clonal lines were included for evaluation in the multiplication stage. Once the microplants were obtained under laboratory condition in the culture medium, they were immediately transferred to a proliferation medium containing MS + BA 1.0 mg l−1. Only in three clonal lines (L-132, L-200, and L-250), a high multiplication rate (3.5 shoots/explant) was achieved with axillary bud formation. Of the seven clonal lines evaluated, clonal line L-250 achieved the highest rates in the variables shoot height (3.38 cm), number of leaves (13.4), and number of shoots/explant (4.4). In the rooting stage, clonal line L-250 obtained a significant improvement by transferring plantlets to direct acclimatization after 20 days of in vitro root induction in a medium containing MS + NAA 1.0 mg l−1. Similarly, in the acclimatization stage, the clonal line L-250 showed a significant result. Then, in the transplantation stage, the plants were transplanted to the field with 100% rooting; 30 days after the transplantation, the clonal line L-250 obtained 100% survival in the field than the control treatments (offspring from two locations were used – Mito and Alayo). As the rooting period is reduced by approximately 20 days by inducing direct root formation under greenhouse conditions, the micropropagation technique is optimized with the protocol used in this study.
 
The scheme of the tractor-sprayer assembly used in the experiment. Notice the horizontal spray boom, the droplegs, and the nozzles distribution.
Analysis of variance of copper deposit by a mixed model for repeated measurements.
Asparagus (Asparagus officinalis L.) is a difficult crop to treat with spraying pesticides because its architecture makes it difficult for droplets to penetrate inside of the canopy, where its pests are located. This study aims to examine the influence of operational parameters, such as nozzle inclination and application rates on the inner side of the canopy. We installed nozzles in the spray boom and its droplegs in three different inclinations: 0° with the plant, 30° in the direction of movement of the tractor-sprayer assembly (+30°), and 30° in the opposite direction (−30°). We applied the mixture in application rates of 600, 900, and 1,200 L ha−1. More so, the regulation used by the farmer of 0° and 800 L ha−1 was applied as a control. Copper (Cu) was used as a tracer for the mixture in a dose of 13.5 g ha−1. Also, non-plasticized polyvinyl chloride grooved tubes (PVC) were installed inside the asparagus canopy and polyethylene sheets were placed on the pipes at different heights from the ground. Later, we analyzed the sheets with atomic absorption spectrophotometry. Results showed that the nozzle inclination and sampling height had notable effects on the copper deposit. Conversely, different application rates showed no varied effects significantly. The greatest copper deposition in the asparagus canopy was achieved with a nozzle inclination of +30° with any application rate. Finally, we recommend regulating the sprayers with a nozzle inclination of +30° and an application rate of 600 L ha−1 as the most effective adjustment for the distribution of pesticides and represent the lowest cost of operation since there is no influence of the application rate.
 
Asparagus plantation in the Chavimochic Irrigation Project.
The present study was conducted in the fields of the Chavimochic irrigation, located in La Libertad Region-Peru. Prodiplosis longifila Gagné (Diptera Cecidomyiidae) is considered the key pest of asparagus and other vegetables cultivation. This study aimed to characterize the presence of this insect pest in asparagus crop under drip irrigation conditions, in order to find the best alternatives for its control. The cultivar most planted in the Chavimochic Irrigation is cultivar UC 157 and that the meteorological conditions of the area are optimal for the production of asparagus; but also for the establishment and reproduction of the insect. The morphology of asparagus is favorable for reproduction of the insect, from larva to adult, since it frequently bracts and flowers at larval stage and establishs itself at the adult stage; at the base of the plant. All experiments conducted, had at least three repetitions and the results are given on average. The insect can have many hosts and an average biological cycle of 11 days, with the highest populations in the months of May and November. Throughout the day; the adult populations are very active from 10 pm to 4 am. The drip irrigation system provides better conditions for the establishment of the insect and its reproduction in the fields, as well as the design of double row sowing so water management becomes an important factor for managing its populations. From the 100% puparium that fell to the ground, only 37.95% emerged as adults. The percentage of damaged stems per linear meter can be 70.46 and healthy stems 29.54. The number of larvae per shoot can be from 68 to 489 while number of larvae per male flower can be from 2 to 7 individuals. There is a relationship between flowering and the number or pre-pupae fallen to the ground, but as the crop develops, the adult´s number decrease, but nevertheless is still aggressive and permanent.
 
The asparagus, a dioecious plant, usually includes plants of both sexes, though also hermaphrodite ones. The male inflorescences are frequented by adult Prodiplosis longifila, who lay such large amounts of eggs on them that its populations can reach millions of individuals over a lapse of 20 to 30 days, which is the plant regular flowering period. The field investigation took place in two locations: (i) the Irrigation Research Unit of the Universidad Nacional Agraria La Molina (UNALM) and (ii) properties of the Agricultural Society of Virú (SAVSA). The number of fallen flowers and larvae per bud after applying multiple treatments on asparagus plots of the two locations was counted to determine the best concentration and application time of various fertilizers to induce the highest percentage of flower fall to manage P. longifila populations. In the UNALM the fertilizer B Dose 2 generated the highest percentage of fallen flowers, 82.1 % ± 14.85 %, and the fertilizer C Dose 1 caused 74.94 % ± 13.78 %. In SAVSA the fertilizer B Dose 3 made a percentage of fallen flowers of 50.6 % ± 21.56 % and fertilizer B Dose 2, 49.85 % ± 16.28 %. The average number of P. longifila 2nd-stage larvae, evaluated on fifteen flowers and in three moments was 3.9 larvae. Foliar fertilizers applications affected both male and female flowers almost equally in all treatments, percentage-wise. Foliar fertilizers promote asparagus flowers falling, consequently contribute to a significative reduction of P. longifila populations, due to a larvae exposition to rapid desiccation under the sun.
 
The Chavimochic irrigation project is one of the leading projects in Peru. In this project, irrigation water is derived from the Santa river to irrigate the valleys of Chao, Viru, and Moche, including desert zones between valleys. In this study, we aimed to characterise the Hass avocado and asparagus farms in desert areas of the Chavimochic irrigation project. Social, economic and environmental information was collected through structured surveys of 12 asparagus and 17 avocado farms. Four groups of asparagus farms and three groups of avocado farms were identified based on principal component and cluster analyses. Profitability of the avocado crop was higher than that of the asparagus crop, and irrigation caused more significant variability in the crop yield of avocado than that of asparagus. From the social perspective, the income of farm personnel was related to the level of education, and female personnel showed more participation in the Chavimochic irrigation project than in other agroecosystems of Peru.
 
In Peru, gasoline containing lead as a main component was used in vehicles up until 2006, when the Government banned its sale. However, since this was preceded by a century of constant use, there is a high chance that most urban soils are polluted with this heavy metal. Hyperaccumulator plants that take up heavy metals from the soil and store them in their tissues without showing any symptoms of toxicity may be the solution to this problem, as the use of these plants for phytoremediation does not require large amounts of money, can be carried out in situ, and is environmentally friendly, making it one of the best options for urban areas. However, unfortunately, there are only a few known species of hyperaccumulator plants that can be grown in urban environments. Therefore, we conducted a bioassay at the Soil Fertility Laboratory of the Agronomy Faculty at the National Agrarian University La Molina, Peru, over a period of 4 months to determine the hyperaccumulation capacity of Salvia splendens ‘Red Vista’ and to examine whether the mycorrhizal fungus Glomus intraradices can enhance the extraction of lead from the soil. After harvest, the plants were divided into three parts (roots, leaves, and inflorescences) to determine the concentrations of lead in the various tissues. We found that S. splendens ‘Red Vista’ did not accumulate high amounts of lead in its tissues even when it was associated with G. intraradices and consequently should not be considered for use in phytoextraction.
 
Evaluation of sociocultural sustainability (ISC), ecological (IE), economic (IK) and General Sustainability Index (ISG) of lemon producing farms, in Santa Elena, Ecuador.
Se aplicaron encuestas a una muestra de 83 productores de limón de esta provincia, con preguntas estructuradas sobre dimensiones económicas, ecológicas y socioculturales. La sustentabilidad se determinó con técnicas de análisis multicriterio para calcular el Indicador Económico (IK), Indicador Ecológico (IE) e Indicador Sociocultural (ISC), para estimar el Indicador General de Sustentabilidad (IS Gen) de cada finca. El 25,3% de las explotaciones tenían un IK> 2; 60,24% un IE> 2 y 55,4% un ISC> 2. El 74,7% de las fincas tenían un IS Gen
 
Stem diameter (cm), root dry weight (g), and root length (cm) of avocado seedlings inoculated with Phytophthora cinnamomi and treated with different Trichoderma isolates for 60 days
Trichoderma strains used for the control of P. cinnamomi in avocado under greenhouse conditions. Chavimochic -Trujillo.
Percentage of healthy roots in avocado seedlings inoculated with Phytophthora cinnamomi treated with different Trichoderma strains
Avocado root rot caused by Phytophthora cinnamomi is one of the main problems affecting avocado (Persea americana) cultivation in Peru, especially at the Chavimochic Irrigation Project. The objective of this study was to evaluate the effect of different Trichoderma strains on the control of Phytophthora cinnamomi in Zutano rootstock under greenhouse conditions. Five isolates of Trichoderma were tested: Trichoderma sp. (Chav01); Trichoderma harzianum (Chavo2); Trichoderma harzianum (UNALM01); Trichoderma viride (UNALM02); and a commercial strain of Trichoderma sp. Evaluations were performed at 30, 45, and 60 days. All isolates colonized the rhizosphere of the avocado. No relation was found between the formation of more Trichoderma colonies and Phytophthora improved control. All strains controlled the root rot, but Chav01 and Chav02 showed the greatest diameter of stem, dry matter in the root, and percentage of healthy root in comparison with UNALM01, UNALM02, and the commercial strain. Thus, the native isolates of Trichoderma from the Chavimochic area can be added to the list of potential new Trichoderma species to control Phytophthora cinnamomi.
 
List of Lasiodiplodia theobromae isolates from 'Hass' avocado fruit
Stem-end rot (SER) of avocado is caused by several fungal species, and it is presented worldwide. This plant disease currently affects several avocado producer regions in Peru, causing fruit rot, impacting the industry negatively. Research about SER distribution in the canopy of avocado trees is limited. Thus, the present study aimed to compare which areas in the canopy are prone to have more SER in ‘Hass’ avocado harvested fruit in two different coastal areas in Peru. The experiment was conducted in the northern (Barranca) and southern (Cañete) of Lima. ‘Hass’Avocado fruits from both producer areas were collected to identify the causal agent; Lasiodiplodia theobromae was isolated from infected fruits. Identification was conducted based on morphological features and a partial DNA sequence of the translation elongation factor 1-α gene (tef1-α). The results showed that fruits inside the tree canopy were prone to have a higher disease incidence than the fruits located in the external site (P<0.001). Besides, internal-site fruits displayed a higher percentage of infected fruit for each grade disease (P<0.001) than external-site fruits, except for grade 0 (fruits without symptoms) and grade 1. Finally, the results suggested that the altitude where the fruit is positioned on the canopy could influence the incidence of SER, where fruits located in the high part revealed less incidence than the low section. The results are valuable for enhancing management strategies and avoiding postharvest loss of avocado fruits in our region.
 
Lily (genus Lilium) is one of the most important flowers for bulb and cut flower production in the world. Lilium rubellum Baker is a native species of Japan that exhibits early flowering, is pink coloured, and possesses a pleasant fragrance, which makes it an important genetic resource for breeding lilies. In this work, the genetic diversity of L. rubellum was studied among three natural populations located in Fukushima Prefecture, Japan, which have been designated as the Mt. Azuma, Nango and Atsushio-kano populations. A total of 31 accessions collected in 1997 were analysed using Random Amplified Polymorphic DNA (RAPD) markers. Eighteen decamer primers produced 98% polymorphic RAPD bands; furthermore, 11 of the 18 primers produced 10 or more polymorphic bands with a mean per primer Polymorphic Information Content of 0.382. Among the three populations, the mean Shannon index, Nei´s gene diversity and percentage of polymorphic loci were 0.2749, 0.4099 and 76.7%, respectively. These data revealed that there is a high genetic diversity within all the populations. Analysis of the three genetic diversity indices within populations showed that the Nango population had the highest genetic diversity, whereas the Atsushio-kano population had the lowest. An unweighted pair group method with arithmetic mean dendrogram based on Jaccard´s similarity coefficient was constructed, and the three populations of L. rubellum collected in the Fukushima prefecture were clearly differentiated at 0.61 similarity index. The Nango and Mt. Azuma populations were genetically closer than the Atsushio-kano population. The analysis of molecular variance showed a 29.53% variance among the populations. This study revealed that there is high genetic diversity within populations and moderate genetic diversity among the three natural populations of L. rubellum Baker in the Fukushima Prefecture of Japan.
 
Potato is an important food and cash crop in Perú. Its production is limited due to seed quality, and other biotic and abiotic factors. Here we explore a new alternative for potato pre-basic seed production named temporary immersion bioreactor (TIB). Potato microtubers production using TIB comprises two phases: multiplication and microtuberization. During the multiplication phase, we used 50 segments of four nodes from a semi-solid medium with an immersion and frequency time of five minutes and three hours, respectively. In addition, a photoperiod of 16 hours of light and eight hours of darkness during 28 days were employed. For the microtuberization phase and under darkness conditions during 60 days, we used 80 g/l of sucrose and 30 ml/explant as a volume for the medium. Then, it was possible to obtain five, six, and 2.5 microtubers per explant of potato varieties “Canchan INIA”, “Capiro”, and “Papa 3”, respectively.
 
The flowers blight caused by Botrytis cinerea Pers. is among the most important citrus diseases, especially in cultivars whose flowering coincides with the humid seasons of the year. As a result of the pathogenic features of this fungus and the complex nature of its control, it is necessary to establish a correct plan for the usage of highly efficient fungicides. The study aimed to evaluate the effect of four chemical fungicides, such as Captan (0.25%), Propineb (0.25%), Fludioxonil + Cyprodinil (0.05%), and Iprodione (0.15%); as well as the effect of a biological fungicide, such as Melaleuca alternifolia extract (0.1%), on Botrytis cinerea Pers. Two phases were established: the first, under laboratory conditions of Department of Plant Pathology of National Agrarian University-La Molina (UNALM), evaluated the effect on mycelial inhibition at 1, 3, and 7 days after inoculation with poisoned potato dextrose agar medium. The second, under field conditions (Sayan - Huaura), evaluated the effect on incidence of the disease in flowers. In the field condition, two applications, incidence, and humid chambers were evaluated. The yield was estimated by counting the fruits. The results showed that, under laboratory conditions, Captan, Fludioxonil + Cyprodinil, and Iprodione exhibited high efficacy in the control of B. cinerea. However, under field conditions, Fludioxonil + Cyprodinil and Iprodione exhibited a significant control of B. cinerea. A similar trend was obtained for the yield estimates.
 
Leaf photosynthesis-photosynthetically active radiation (PAR) response curves. A is the net carbon assimilation rate during days after planting (DAP) in the different treatments of nitrogen fertilization: (•) 0, (∆) 100, (◊) 200 and (□) 300 kg N ha -1 .
Pattern of total dry biomass accumulation in tubers (A) and total dry biomass (B) during days after planting (DAP) in the different treatments of nitrogen fertilization: 0, 100, 200 and 300 kg N ha -1 . The curves correspond to the adjustments Gompertz functions.
Pattern of dry weight accumulation of different organs during days after planting (DAP) for in the different treatments of nitrogen fertilization: 0, 100, 200 and 300 kg N ha -1 . The different letters indicate that there are significant differences between treatments per sampling period (p <0.05).
Nitrogen fertilization has positive effects on growth and production of potato crop. The objective of this study was to assess the differences of the photosynthetic response and biomass partitioning patterns during the main phenophases of the potato cultivar Capiro under different nitrogen nutrition fertilization treatments in the tropical Andes of Mérida, Venezuela. Plots of 40 m2 (2,625 plants m-2) were established under a random block design with three replications by nitrogen fertilization treatment: 0, 100, 200, and 300 kg. N ha-1. Photosynthesis and biomass were measured in the different organs in the main phenological stages of the crop. The results indicate that photosynthesis tends to increase slightly with the nitrogen supply; although the differences were not always significant and, decreases during crop growth. Tubers yield it was markedly influenced by the nitrogen fertilization. The total biomass production, as well as biomass allocation in different organs showed differences between treatments, maintaining the following order: 300-N> 200-N> 100-N> 0 N. When analyzing the biomass accumulation curves, it is estimated that the application of 250 kg N ha-1 as mineral fertilizer is enough to reach optimal production yields.
 
Daphnia magna is proposed as a bioindicator to establish the minimum concentration capable of controlling pests before performing toxicity tests. This study uses the proposed pest control extracts of two Peruvian species, Clibadium peruvianum Poepp. (seeds) and Petiveria alliacea L. (leaves). The toxicological effects of the plant extracts were evaluated with D. magna, using five neonates over a period of 24–48 h. A lack of mobility or the absence of heart rhythm for 15 s under a stereomicroscope was considered to indicate mortality. Organic extracts were discarded due to their higher toxicity when compared with the aqueous extracts of C. peruvianum and P. alliacea, which had LC50 = 460.74 mg/L and LC50 = 711.18 mg L−1 at a concentration of 10 mg L−1, respectively. Using this Daphnia-safe concentration, toxicity tests were performed on the third instar larvae of Musca domestica (housefly). Higher activity was observed with an aqueous extract of seeds of C. peruvianum and a leaf aqueous extract of P. alliacea, showing 58.33% and 56.7% mortality against M. domestica, respectively. Both extracts induced abnormal changes in the development of the housefly, causing deformation, burns, and dehydration of tissues in the larvae. It is evident that using D. magna as a preliminary toxicological test allows the determination of concentrations that are safer to use while maintaining the activity of the extracts as a botanical biopesticide, thus posing the lowest risk to the environment, ecosystems, their species, and human health.
 
The potato (Solanum tuberosum L.) is important as both a food and a source of economic activity in Peru. However, potato production is limited by seed quality and other biotic and abiotic factors. We explore a new alternative method for producing prebasic seeds of Peruvian potato varieties known as temporary immersion bioreactors (BIT). The process of producing potato microtubers using BIT consists of two phases: proliferation and microtuberization. During the proliferation phase, we seeded six nodal segments of three nodes in a liquid culture medium with 30 g of sucrose under a photoperiod of 16 light hours and eight dark hours. This phase also included an irrigation cycle of five minutes every three hours for 30 days. During the microtuberization phase, the conditions were changed to a medium with 80 g of sucrose in darkness, and the same irrigation cycle was used for 60 days. Under these conditions we obtained 20, 18.4, 13.4, 13.4, and 4.6 microtubers of the varieties Peruanita, Canchan, Capiro, Unica, and Yungay, respectively.
 
A review of current and specific literature was carried out in order to elaborate a proposal for the management of Chloridea virescens in the cultivation of blueberry (Vaccinium corymbosum L.), developing strategies in each component of Integrated Pest Management (IPM), including Cultural Control, Ethological Control, Biological Control, and Chemical Control (PBUA and PQUA). Likewise, steps in the genetic improvement for quantitative resistance of the blueberry to this pest (Lepidoptera: Noctuidae) using wild relatives of this crop as a source of resistance genes are proposed.
 
Esta investigación se llevó a cabo en el Centro de Investigaciones IVITA de la Universidad Nacional Mayor de San Marcos en el departamento de Junín, Perú. El objetivo principal fue determinar el efecto de plantas de arveja ( Pisum sativum ), sembradas al voleo para establecer un cultivo temporal, sobre la abundancia y composición botánica de especies de malezas durante el establecimiento de una mezcla de pastos de gramíneas y leguminosas en el Valle del Mantaro . Se evaluaron los siguientes tratamientos: T1, pasto mixto con deshierbe manual, sin arveja. T2, pasto mixto sin deshierbe y guisante de olor. T3, pasto mixto con guisante de olor y sin deshierbe. Se utilizó un diseño de bloques completamente aleatorizados con tres repeticiones para el análisis estadístico del experimento. Todas las parcelas fueron sembradas con, 10 kg ha-1 de Lolium multiflorumJusticia. 'Tama', 10 kg / ha de Lolium boucheanum K. 'Belinda', 5 kg / ha de Medicago sativa L. 'SW8210' y 3 kg / ha de Trifolium pratense L. 'Quiñequeli'. 50 kg / ha-1 adicionales de Pisum sativum L. 'INIA 103 Remate' se difundieron primero en el tratamiento T3. La composición botánica de las malezas se evaluó en los tratamientos T2 y T3. Las familias de malezas Asteraceae y Poaceae registraron mayor número de especies mientras que la familia Brassicaceae registró la mayor abundancia, durante el establecimiento de pasturas en el Valle del Mantaro. Las especies más importantes según el Índice de Valor de Importancia (IVI) fueron: Brassica rapa subsp. campestris, Avena sativa y Medicago polymorpha .
 
Mean values of fenitrothion residues through time after treating wheat grains with the Sumigranplus® formulation. Values have been logarithmically transformed and the regression has been adjusted.
Mean values of esfenvalerate residues through time after treating wheat grains with the Sumigranplus® formulation. The values have been logarithmically transformed and the regression has been adjusted.
Fenitrothion residues (mg kg −1 ) in wheat grains treated with the insecticide mixture fenitrothion + esfenvalerate.
Fenitrothion residues (mg kg −1 ) in wheat flour and bran.
Chemical insecticides are commonly used to control insect pests in stored wheat. However, the presence of insecticide residues in food may endanger consumers. We studied the degradation and persistence of two insecticides, fenitrothion and esfenvalerate, in wheat grain, bran, and flour. The application system was calibrated to treat grain at theoretical concentrations of 10 and 0.5 mg kg−1 of fenitrothion and esfenvalerate, respectively. Samples treated with the insecticide mixture were collected at 0, 15, 30, 60, 90, 120, 180, 240, and 360 days after treatment. Samples were analyzed quantitatively by gas chromatography with an electron capture detector (ECD, Ni63). The experimental design was completely randomized with three replicates. Esfenvalerate was more persistent than fenitrothion, with the residues of both insecticides concentrated mainly in the bran, and with least amounts in the flour. The concentrations of fenitrothion residues during the 120-day preharvest interval exceeded the maximum residue limit (MRL) of 1 mg kg−1 set by Brazilian legislation. We discuss the factors that influence the degradation/persistence of fenitrothion and esfenvalerate.
 
Esta investigación tuvo como objetivo determinar el ciclo biológico de Plutella xylostella (DBM), criada en brócoli var. Calabrese y coliflor var. Bola de nieve en condiciones de laboratorio con un promedio de 76.1 ° F y 65% RH. El apareamiento de las polillas se realizó en recipientes plásticos de un litro y las posturas se incubaron dentro de vasos de polipropileno de 200 ml, ambos cubiertos con redes. Para proporcionar suministro adecuado a las larvas, las plantas se cultivaron a cubierto para evitar la infestación de plagas. Se utilizaron hojas frescas para alimentar a las larvas hasta la pupación. Los resultados se analizaron con la prueba estadística no paramétrica de Kruskal-Wallis.Se obtuvieron los siguientes parámetros biológicos, criados con hojas de brócoli y coliflor respectivamente: período de incubación 3 días; período larvario 9,76 y 9,69 días; período de pupa 5,1 y 5,3 días; ciclo biológico 19,5 y 19. 9 días y 175 y 187 huevos según la capacidad de oviposición de las hembras apareadas. Estos resultados no muestran diferencias estadísticas significativas del ciclo biológico de la polilla entre las dos plantas hospedantes.
 
Location of the research area.
Extraction and fractionation of soil organic matter (Kumada, 1987).
Classification of types of humic acids in mountain soils.
Las sustancias húmicas (SH) son el componente principal de la materia orgánica del suelo (MOS), producto del proceso pedogenético. En este estudio, se relacionan los factores morfométricos y la variable climática que condicionan el grado de humificación, el contenido de carbono orgánico de los ácidos húmicos (AH) y ácidos fúlvicos (AF) de 42 muestras de suelos mediante la ecuación funcional de factores de estado del suelo propuesto por Jenny. El grado de humificación se determinó por el método Nagoya propuesto por Kumada. La cuantificación del carbono orgánico se determinó mediante el método de Walkley y Black. Los parámetros morfométricos del relieve se obtuvieron a partir del Modelo Digital de Elevación (MDE) y el parámetro climático del sensor MODIS. Los resultados muestran que el factor relieve condiciona al grado de humificación y el factor clima condiciona al contenido de carbono orgánico de los ácidos húmicos (AH) y ácidos fúlvicos (AF).
 
Pre-Soil Physical and Chemical Properties
Soil Properties during Early Season
Soil Properties during Late Season
Este estudio investigó el efecto de dos prácticas de labranza sobre el rendimiento y el crecimiento del maíz, y propiedades seleccionadas del suelo de un Ultisol del estado de Osun en Nigeria. Esto tuvo como objetivo seleccionar una práctica de labranza adecuada para el crecimiento de los cultivos y el mantenimiento del suelo. El estudio se dividió en dos parcelas experimentales durante la temporada de cultivo temprana y tardía en 2014. La primera parcela se desbrozó manualmente para tener labranza cero, mientras que la segunda parcela se aró dos veces y se rastrilló una vez para labranza convencional. Cada parcela tenía tres bloques (23.0 m x 2.5 m) con un callejón de 1.0 m entre bloques y 1.0 m dentro de las parcelas. Tres semillas del cultivo de prueba se colocaron a una distancia de 75 cm x 50 cm por montículo y cada parcela se desyerbó manualmente a intervalos de dos semanas hasta la cosecha. Las propiedades físicas y químicas del suelo seleccionadas y los parámetros de crecimiento de las plantas se recolectaron y determinaron utilizando el método estándar después de cada temporada de cultivo. Al final del experimento, tuvo los valores más altos de altura de planta y suelo en comparación con la labranza convencional. La labranza cero también tuvo valores químicos del suelo más altos en comparación con la labranza convencional. El rendimiento de grano mostró una diferencia significativa entre las prácticas de labranza. La labranza cero tuvo un mayor rendimiento (1.71 t/ha) en comparación con la labranza convencional (0.97 t/ha). El estudio concluyó que la labranza cero era una mejor alternativa para el crecimiento de los cultivos y el mantenimiento del suelo de un Ultisol.
 
Effects of salt stress on leaves loss / plant of each scion/rootstock combination at 90 days. *CLE ('Cleopatra'), MIO ('Mihowase'), PRI ('Primosole'), WMU ('W. Murcott'), CIT ('Swingle Citrumelo').
Cítricos, es uno de los más importantes cultivos de frutales en el mundo y son susceptibles a sales. Los efectos negativos de las sales generalmente reducen producción y calidad de fruta. Para evaluar los efectos de la salinidad en algunos parámetros de crecimiento, un experimento en invernadero fue conducido con los cultivares ‘Mihowase’, ‘Primosole’ y ‘W. Murcott’ en los patrones ‘Cleopatra’ y ‘Swingle citrumelo’ El experimento fue conducido en la Estación Experimental Agraria (EEA) del Instituto Nacional de Innovación Agraria (INIA), Huaral-Donoso a 90 km al norte de Lima. Las plantas fueron irrigadas con una solución salina ClNa y con una conductividad eléctrica de 0.5 o 4.5 dS/m. Las variables evaluadas fueron caídas de hojas, peso fresco y seco de tallos, hojas y raíces y contenido de agua por las plantas. Los resultados mostraron que el patrón ‘Cleopatra’ es más tolerante que ‘Swingle citrumelo’. Las variedades afectaron todas las variables de los dos patrones, siendo más notorio en la cantidad de pelos absorbentes de las raíces. La selección de plantas de mandarinas para producción debería considerar combinación variedad/patrón.
 
Phytoremediation is a potentially less costly approach to treat contaminated soil. Here, the phytoremediation capacity of marigold (Tagetes erecta) in conjunction with EDTA and mycorrhizae was analyzed. Specifically, the ability of the marigold to extract lead from contaminated soils in the Bird Forest Zone of the Huachipa Zoological Park (PZH) was evaluated. Marigold was planted in main areas of interest within the PZH. Plants were treated with different concentrations of mycorrhizae (0 and 0.5 g/kg) and EDTA (0, 0.5 and 1 mg/kg) and later analyzed by atomic absorption spectrophotometry for lead concentrations in the aerial parts and roots of the plants at the end of the experiment. We show that marigold has the ability to extract lead; and under the conditions of the experiment, mycorrhizae did not improve the extraction efficiency. However, EDTA did increase the amount of lead extracted, thus affecting the physiological development of the plant.
 
This study aimed to determine the composition and relative abundance of soil insects associated with lucumo (Pouteria lucuma L.) trees growing in the agricultural fields of the Universidad Nacional Agraria La Molina in Lima, Peru. In total, 12 pitfall traps were installed in a 5-ha lucumo field and samples were collected on a weekly basis for approximately 4 months (March–June). Insects in each sample were separated into morphotypes, and the number of individuals in each morphotype and date of collection were recorded. The collected insects were then identified at the Entomology Museum laboratory in Lima through comparison with museum samples and with the help of identification keys. Individuals in the orders Orthoptera (families Acrididae and Gryllidae), Dermaptera (Anisolabididae), Coleoptera (Carabidae, Staphylinidae, Tenebrionidae, Scarabaeidae and Elateridae), Blattodea (Blatellidae) and Hymenoptera (Formicidae) were identified. Among the Coleoptera, Tetracha chilensis (Laporte, 1834) (Carabidae) was the most abundant species; furthermore, Staphylinidae of the subfamily Oxytelinae and the families Elateridae (Conoderus spp.), Tenebrionidae (Epitragopsis sp.) and Scarabaeidae (Ataenius sp.) were identified. Additional taxa identified were as follow: Gryllus assimilis (Fabricius, 1775) (Gryllidae) in Orthoptera, Euborellia annulipes (Lucas, 1847) (Anisolabididae) in Dermaptera and Linepithema spp. in Hymenoptera.
 
Top-cited authors
Jiban Shrestha
  • Nepal Agricultural Research Council
Dipesh Pokhrel
  • Kathmandu University
Amit Chaudhary
  • University of Brighton
Alberto Julca Otiniano
  • Universidad Nacional Agraria La Molina
Viviana Castro Cepero
  • Universidad Nacional Agraria La Molina