Peruvian Journal of Agronomy

Journal Information
EISSN : 2616-4477
Published by: Universidad Nacional Agraria la Molina (10.21704)
Total articles ≅ 61
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Diego Almeyda Carbajal, Andrés Virgilio Casas Díaz, Mirna Zuzunaga Bedón
Peruvian Journal of Agronomy, Volume 5, pp 71-77; https://doi.org/10.21704/pja.v5i3.1845

Abstract:
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.
Paul Gastañadui, Rocío Moreno, Patricia Elena Quiroz-Delgado, Walter Eduardo Apaza-Tapia
Peruvian Journal of Agronomy, Volume 5, pp 78-86; https://doi.org/10.21704/pja.v5i3.1846

Abstract:
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.
A. Cerna, D. Vecco-Giove, M. Doria, H. Panduro, J. Rojas, P. García, , B. Sangama, J. Macedo, M. Ubeda, et al.
Peruvian Journal of Agronomy, Volume 5, pp 44-59; https://doi.org/10.21704/pja.v5i2.1773

Abstract:
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.
Alejandro Kepler Llanos Melo, Walter Eduardo Apaza-Tapia
Peruvian Journal of Agronomy, Volume 5, pp 60-70; https://doi.org/10.21704/pja.v5i2.1771

Abstract:
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.
Denis Paolo Cáceres Candia, Alejandro Risco Mendoza, Patricia Elena Quiroz-Delgado, Walter Eduardo Apaza-Tapia
Peruvian Journal of Agronomy, Volume 5, pp 18-24; https://doi.org/10.21704/pja.v5i1.1670

Abstract:
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.
Denis Paolo Cáceres Candia, Alejandro Risco Mendoza, Patricia Elena Quiroz-Delgado, Walter Eduardo Apaza-Tapia
Peruvian Journal of Agronomy, Volume 5; https://doi.org/10.21704/pja.v5i1.1360

Suzan Abd El- Latif Kamel Ibrahim, Mohamed Ali Abdelsatar, Mohamed Abd El-Raheem Ahmed, Magdy M. Niazy
Peruvian Journal of Agronomy, Volume 5, pp 1-17; https://doi.org/10.21704/pja.v5i1.1656

Abstract:
Six divergent genotypes of sesame (Sesamum indicum L.) were crossed using a half diallel excluding reciprocal crosses, to estimate heterosis, combining ability and nature of gene action for studied traits under two irrigation regimes. The two irrigation regimes were normal irrigation conditions with amount of applied water 5952.38 m3/ha and water stress conditions with amount of applied water 2976.19 m3/ha at Etay-El-Baroud Agricultural Research Station, Behaira governorate, Agricultural Research Center, Egypt during 2019 summer season. A randomized complete block design with three replications was used for each irrigation regimes. The variation of genotypes and their components from parents, crosses and parents versus crosses were highly significant for all studied traits under both irrigation regimes and their interactions with irrigation. Variation attributable to general and specific combining ability was highly significant for seed yield and yield components under both irrigation regimes. The parents L92 and L110 were the best combiners for seed weight per plant and most of its components under both irrigation regimes. The best F1 cross combination was L92 × L110 in specific combining ability and heterotic effects over mid- and better-parents under both irrigation regimes for seed weight per plant and most of its attributes. The preponderance of additive gene action in the inheritance of most studied traits was observed, that further confirmed by its significance and the value of average degree of dominance exceeding the unity. Narrow-sense heritability varied from 0.19 for number of branches per plant to 0.47 for 1000 seed weight under normal irrigation, whereas, under water stress conditions, it ranged from 0.14 for number of branches per plant to 0.42 for fruiting zone length. Parents L95 and L93 under normal irrigation and L93 and L110 under water stress conditions carried mostly genes with dominant effects for seed weight per plant, in contrary, L92 and L110 under normal irrigation and L92 and L12 under water stress conditions carried mostly recessive alleles for seed weight per plant. Hence, the results will be used to develop a sesame breeding scheme at Etay-El-Baroud Agricultural Research Station.
Sandro Sardón Nina, Raúl D. Zapata Hernández, Luis A. Arias López
Peruvian Journal of Agronomy, Volume 5, pp 35-43; https://doi.org/10.21704/pja.v5i1.1680

Abstract:
Humic substances (HS) are the main component of soil organic matter (SOM), a product of the pedogenetic process. In this study, the morphometric factors and climatic variable that condition the degree of humification, the organic carbon content of humic acids (HA) fulvic acids (FA) of 42 soil samples are related through the functional equation of factors of state of the soil proposed by Jenny. The degree of humification was determined by the Nagoya method proposed by Kumada. The quantification of organic carbon was determined using the method by Walkley and Black. The morphometric parameters of the relief were obtained from the Digital Elevation Model (DEM) and the climate parameter of the MODIS sensor. The results show that the relief factor conditions the degree of humification and the climate factor conditions the organic carbon content of humic acids (HA) and fulvic acids (FA).
Sandro Sardón Nina, Raúl D. Zapata Hernández, Luis A. Arias López
Peruvian Journal of Agronomy, Volume 5, pp 25-34; https://doi.org/10.21704/pja.v5i1.1676

Abstract:
This study compared the organic carbon (OC) content in fractions of humic acids (HA) and fulvic acids (FA) in five soil orders (Aridisol, Entisol, Histosol, Inceptisol and Mollisol) and know their association with the degree of humification. Extraction and fractionation, as well as the degree of humification was carried out by the Nagoya method proposed by Kumada. OC quantification was determined by the Walkley and Black method. The results are: the average OC content of HAs of the order Aridisol differs from that of Histosols, Inceptisols, and Mollisols. The order Entisol presented differences with the Histosols and Mollisols, the soils of the order Inceptisol presented differences with the Aridisols and Histosols and those of the order Histosol differed from the Aridisols, Entisols and Inceptisols. Similarly, those of the Mollisol order differed with the Aridisols, Entisols and Inceptisols. In the fraction of FA the average OC content of the order Aridisol deferred from that found in Histosols, Inceptisols and Mollisols. The Entisol order differed from the Mollisols; likewise, the Inceptisol order differed from the Aridisols and Mollisols and the Histosol order differed from the Aridisols. Finally, the order Mollisol was also different from the Aridisols, Entisols, and Inceptisols. Soil types do not show wetting patterns, because they are not based on pedogenetic processes and these have a wide range of characteristics in surface horizons.
Peruvian Journal of Agronomy, Volume 4, pp 82-87; https://doi.org/10.21704/pja.v4i3.1649

Abstract:
Climate change is an obvious threat to agriculture, food security and conservation of plant genetic resources. Potato is a globally important food. In Peru, there is high variability and diversity of wild and cultivated species, such that they are considered as one of the region’s most vulnerable to the impact of climate change. With these considerations, we report the results of an investigation in which a preliminary screening of the reaction to drought of 67 native potato morphotypes was conducted to verify for differences in morphological indicators of growth, development, and production of tubers in response to continuous irrigation (CI) and restricted irrigation (RI) treatments. In the course of this study, 21 irrigations were applied to plants by CI (every 1-2 days) and, in the same period, 7 irrigations were applied to plants by RI (every 5-6 days). Comparison of characteristics average in all the morphotypes with plants under CI and RI, indicated that RI did not show differences in height of plants, length of internodes, or leaf and terminal leaflet indexes, and that RI reduced the stem thickness and dry weight of foliage. In this study, we highlight the morphotypes whose plant characteristics present higher averages with respect to their clonal counterparts that were treated with CI. The positive relationship between the number and weight of tubers harvested, as well as the significant reduction of both components of low RI yield is confirmed. In addition, we also highlight the response of some morphotypes that present higher tuber yield under RI. The native morphotypes that were identified as tolerant (according their responses in the characteristics of their plants and yield of tubers under RI) are as follows: BGR 19 (“Rayhuana”); BGR 99 (“Yuracc ñahui hualash”); BGR 170 (“Yana utcush”); and BGR 238 (“Muru huayro”).
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