Ciencia Agropecuaria

OPTIMAL NITROGEN DOSE FOR THE IDIAP FL-ALANJEÑA-22 RICE VARIETY

Luis A. Barahona-Amores, Rubén D. Samaniego-Sánchez, Rubén E. Rodríguez-Navarro — Fri, 25 Jul 2025 00:00:00 +0000

To optimize the efficiency of nitrogen (N) use, its management must be focused on an adequate synchronization of its balance in the soil with the demand of the plant. This study aimed to determine the optimal nitrogen dose for the IDIAP FL Alanjeña-22 rice variety, for efficient management of nitrogen fertilization. The trial was carried out in Tonosí, Los Santos, Panama, during the months of August to December of the 2021 and 2022 agricultural cycles. Six doses ranging from 0 to 250 kg N/ha with constant P and K were evaluated, using a randomized complete block design with three replications. Plant height, lodging, days to flowering and maturation, reaction to diseases, NDVI, chlorophyll, foliar %N, plant cover, and grain yield were evaluated. Variance analysis and mean separation with DMS, correlation analysis and nonlinear regression analysis were performed with the Quadratic (MC), Quadratic Plateau (CP) and Linear Plateau (LP) models. Statistical differences were found in the variables with respect to the N doses, except for the days to flowering and ripening. The doses of 100, 150, 200 and 250 kg N/ha showed greater plant height, lodging, blast, neck blast, grain spotting, NDVI, chlorophyll, %N and % cover, while there was no difference in yields from 100 kg N/ha. The optimal dose found differs with the regression model used, with values of 101, 136 and 182 kg N/ha with LP, CP and MC, respectively. The CP model had a better accuracy in calculating the optimal N dose, with data closer to zero in the difference between the observed values minus the expected values and an R² of 0.97, compared to the other models, thus indicating that the optimal economic dose of N for the IDIAP FL Alanjeña-22 variety is 126 kg N/ha.

MORPHOAGRONOMIC CHARACTERIZATION OF CREOLE RICE: MULTIVARIATE STATISTICS IN TOABRÉ, COCLÉ, PANAMA

Fri, 25 Jul 2025 00:00:00 +0000

In Panama, the traditional planting system of landrace rice in the 2018-2019 production cycle involved 23 530 producers, with 25 550 ha planted with an average harvest of 2.28 t^.ha^-1. The aim was to agronomically characterize 36 accessions of landraces rice from Toabré (Penonomé) and to verify their genetic variability through multivariate statistics. It was carried out in the San Miguel Valley, (Coordinates: 08°47’49.6” N; 080°18’31.3” W), Cocle province, Panama. The genetic material consisted of 36 accessions collected among farmers from 15 communities of Toabré. The experimental unit was 2 x 3 m (6 m²), with a separation between rows of 0.40 m and 0.30 m between plants. Quantitative (12) and qualitative (20) characteristics were evaluated. Similarity relationships were determined by cluster analysis, based on Euclidean distance; and UPGMA clustering. Dendrogram were generated with UPGMA clustering and Gower's distance. The combined analysis of the quantitative and qualitative variables was made to obtain a dendrogram. The morpho-agronomic characteristics of the collected landrace rice accessions showed the existing genetic diversity. The multivariate analyzes applied separately to the qualitative and quantitative variables and the combination of both, allowed the rice accessions to be grouped into groups of similarity. Similarity analyzes of the quantitative and qualitative characteristics and the combination of both showed dendrogram with five clusters, suggesting that some accessions that present different names according to the collecting community appear to be similar. The genetic diversity of the landrace rice of the Toabré district was confirmed with the morphoagronomic characterization by means of multivariate statistics.

STRUCTURAL STABILITY OF THE SOIL WHEN USING DIFFERENT ORGANIC COMPONENTS EVALUATED IN THE VEGETATION HOUSE

Fri, 25 Jul 2025 00:00:00 +0000

The physical, chemical behavior and soil organic matter (SOM) were evaluated with different sources of organic fertilizers and how they influence the structural stability of the soil used for cocoa cultivation. The study was carried out in a greenhouse covered with saran mesh in the years 2021 and 2022. Five treatments and four repetitions were evaluated in a completely randomized design. T1: Witness; T2: Composted chicken manure; T3: Field residues; T4: Ashes; T5: Compost. 20 pots were used with 15 kg of dry, undisturbed soil and a dose of 15 Mg.ha^-1 of each amendment. Physicochemical parameters and SOM were evaluated at depths of 0 to 5 cm and 5 to 10 cm. Soil pH increased its levels in all treatments compared to the control, with ash obtaining better results with levels of 6.5 and 6.2 at both depths. SOM and Nitrogen maintained a slight increase in their applied treatments, with compost being better with a content of 6.7% and 0.30% respectively. Phosphorus in the soil presented better bioavailability with the application of ashes, with a concentration above 29 mg.kg^-1. For the weighted average diameter (WMD), the crop residue and the composted chicken manure reached the highest values with 0.60 mm. It is concluded that composted chicken manure, compost and crop residue, were able to adhere mostly to soil particles or structural aggregates, while providing improved nutritional bioavailability that could be utilized by plants.

PRESENCE OF MYCOTOXINS IN MALTING BARLEY (Hordeum distichum L.) AND ITS RELATIONSHIP WITH CONTAMINATING FUNGI

Fri, 25 Jul 2025 00:00:00 +0000

The study focuses on the identification and quantification of mycotoxins in malting barley used as feed for cattle raised at the facilities of Agro Biológicos de Panamá, a company located in Hato de San Juan de Dios, in the district of Aguadulce, Coclé province. Culture tests were conducted with four types of malting barley samples: dry seed, pre-disinfected seed, leachate, and forage. Microscopic cultures of forage grass were also performed. The fungi were categorized as storage fungi. Genera and species that produce mycotoxins, such as aflatoxins and ochratoxins, were identified, with the genera Aspergillus sp. and Penicillium sp. being the most prominent in both samples analyzed. The genus Trichoderma sp. was also identified. Furthermore, an evaluation of aflatoxin levels was conducted before and after implementing additional prevention, control, and growth factor management measures, including temperature, humidity, and oxygen levels, demonstrating that the treatment was effective, as the levels detected did not exceed the limits permitted in Panama. These studies suggest that constant monitoring of these measures ensures progress in the right direction, maintaining minimal or nonexistent levels of mycotoxins.

ZOOTECHNICAL INDICES AND PRODUCTIVITY INDICATORS FOR DUAL-PURPOSE SYSTEMS

Fri, 25 Jul 2025 00:00:00 +0000

The objective was to determine the zootechnical indices and productivity indicators and their impact on the productivity of the production system. The work was carried out in Colón, East Panama and Darién and the information was obtained from a survey applied to 20 farms. The zootechnical indices evaluated were: birth rate (BR), calf mortality rate (CM), calving interval (CI), open days (OD), age at first service (AFS), age at first calving (AFC), lactation duration (LD), birth weight (BW), weaning weight (WW) and cow-milking: inventory ratio (MC/I). The productivity indicators considered were: production/cow/day (PCD), lactation productivity (LP), milk production/year (MP/year), milk production/ha (MP/ha), kg of meat/year (MP/year) and kg of meat/ha (MP/ha). The analysis was carried out using a basic statistical design and multivariate analysis (MA) was used for productivity indicators. The indices were as follows: BR: 25.9% (±16.1), CM: 3.90% (±11.6), BW: 40.12 (±6.83 kg); WW 124.42 (±16.19 kg), CI: 424.67 (±205.57 days), OD: 151.0 (±88.9), AFS: 19.66 months, AFC: 28.6 months, LD: 223.75 (±25.59 days), MC/I: 27% (±14%). The MA allowed the formation of 5 groups, of them, number 5 presented the best productive indicators with a PCD of 6.46 L (±1.42), LP 1,479.06 L (±332.17), MP/year 48,666.67 (±8,429.31), MP/ha 718.65 L (±579.47). It is also one of the groups with the highest MP/year (5,307.12 ±4,833.71) and MP/ha with 145.45 kg (±57.53). The results allow us to conclude the need to improve zootechnical indices and indicators to achieve the sustainability of these systems.

RELATED FACTORS WITH THE INCOME PER HECTARE OF THE COW-CALF SYSTEM, PANAMA

Fri, 25 Jul 2025 00:00:00 +0000

The objective was to evaluate the factors that relate to the gross income per hectare (Iha) in the cow-calf system. It was applied a structured survey to 20 small cattlemen of ASOPEGA (Gualaca, Chiriquí). Selected variables were kilograms of weaned calf per exposed cow to bull (Kgvet), kilograms of sold calf (Kgtrnvnd), stocking rate (UAha), farm size (Areafca), discard rate (Tasadsc), kilograms of weaned calf per pasture hectare (kghapast), herd size (Tamhato), calf crop (Cosecha), and number of cows (Numvaca). Selection of variables were based on a Pearson correlation analysis. Data was analyzed by a path analysis based on structural equations. There were three proposed hypothesized models. Model was selected according to pre-established statistical criteria. The third model was selected. Highest correlations were between Kgtrnvnd vs. Kgvet (r = 0,93***); Tamhato vs. Nmvaca (r = 0,90***), and Tamhato vs. Areafca (r = 0,67***). Direct effects of Kgtrnvnd and UAha on Iha were 0,477 ± 0,140 and 0,532 ± 0,134, respectively. Direct effect of Kgvet on Kgtrnvnd was 0,928 ± 0,024; Numvaca and Areafca on UAha were 0,982 ± 0,184 and -0,988 ± 0,183, respectively. Direct effect of Tamhato on Numvaca was 0,902 ± 0,043. Indirect effect of Tamhato on Iha through Numvaca and UAha was 0,471 ± 0,156. Path analysis resulted in a good methodological tool for research and prediction of cow farm systems to determinate statistically factors that influence on the Iha.

IDENTIFICATION OF KAPPA-CASEIN GENE VARIANTS OF INTEREST IN DAIRY PRODUCTION IN PANAMANIAN BREEDS

Axel Villalobos-Cortés, Ginnette Rodríguez-Espino, Selma Franco-Schafer — Fri, 25 Jul 2025 00:00:00 +0000

This study characterizes kappa-casein (CSN3) gene variants in Guaymí and Guabalá cattle breeds, crucial for the dairy industry due to their impact on milk quality and cheese production. The goal was to identify CSN3 genetic variations and their potential to enhance milk yield in these breeds. DNA from 34 samples was analyzed through 12 polymorphic markers using the Affymetrix Array platform. The study identified five polymorphic variants in both breeds, with notable allele frequency differences, indicating distinct selective pressures in each population. SNPs rs450402006 and rs43703015 showed allele frequencies consistent with prior studies in other breeds, indicating genetic conservation patterns and potential for genetic improvement programs focused on milk production.

A CLOSER ANALYSIS OF THE UNIPARENTAL HAPLOTYPES IN THE GUAYMI AND GUABALA RACES OF PANAMA

Axel Villalobos-Cortés, Hilda Castillo, Selma Franco-Schafer — Fri, 25 Jul 2025 00:00:00 +0000

Mitochondrial DNA (mtDNA) analysis has established itself as a key tool in molecular genetics research, particularly in investigations of population diversity and evolutionary history in animals. Owing to its high polymorphism and the abundance of copies per cell, mtDNA enables efficient data retrieval, even from degraded or ancient samples. In parallel, the study of Y chromosome haplogroups has provided complementary insights into bovine genetic diversity from a paternal perspective. The aim of this study was to characterize mitochondrial and Y chromosome haplotypes in the Guaymí and Guabalá creole cattle breeds of Panama. A fragment of the hypervariable D-loop region of mtDNA and seven Y chromosome markers were analyzed. The findings allowed for the identification of uniparental markers in both breeds. Results indicate that the maternal lineage of these breeds traces back to the Iberian trunk, particularly southern Spain, with possible indirect influence from African lineages. Notably, the Guabalá breed exhibits a paternal genetic signature not previously reported in other cattle breeds.

DISTRIBUTION OF Corynothrips stenopterus Williams (THYSANOPTERA: THRIPIDAE) IN CASSAVA IN THE CENTRAL PROVINCES OF PANAMA

Fri, 25 Jul 2025 00:00:00 +0000

Thrips (Thysanoptera) include species that cause losses in the production of cassava (Manihot esculenta Crantz, 1766), one of the strategic important crops in Panama. The aim of this research was to determine the morphological characters, damage, and geographical distribution of C. stenopterus in cassava in the Pacific region of the central provinces of Panama. The study was developed during the period from january to december 2023. Sampling was carried out in 20 locations distributed in the central provinces of Panama (Coclé, Herrera, Los Santos, and Veraguas). Within each location, 20 plants were randomly selected, from which the leaves of the middle part of the plants were collected inside a plastic bag with hermetic seal. The samples were transferred to the laboratory to examine the damage on leaves and the number of immature instars and adults of the insect. Adult thrips were mounted on microslides to identify the species by using taxonomic keys. The species C. stenopterus was identified because it has got a dark head and pronotum, but also tergites III–IV and VII–X, with other yellow areas. Adults and immatures cause discoloration symptoms on the underside of the leaf. C. stenopterus is geographically distributed in the Pacific region of the central provinces of Panama and is also associated with the chlorosis of cassava leaves, but for its correct identification, it must be prepared on microslides to observe its characters.

ARTHROPODS PESTS AND BENEFICIALS IN FRUITING TOMATO FIELDS IN LOS SANTOS, PANAMA

Fri, 25 Jul 2025 00:00:00 +0000

Tomato (Solanum lycopersicum L.) is one of the most productive crops in the province of Los Santos, with an estimated 177.7 hectares. The sector decreases its production due to various factors that include crop protection aspects and post-harvest management. The aim of this study was to determine the main arthropods present in fruiting tomato fields in nine locations in the province of Los Santos. Field sampling was carried within the districts of Guararé, Los Santos, and Tonosí in plantations of various tomato varieties and hybrids during the fruiting and harvest period in April 2024. An effort was made to sample each field for 1 hour in total furrow traces of 50 meters long per location. The specimens captured were taken to laboratory conditions for identification. According to the results, seven arthropods were identified, of which the most relevant phytophagous arthropods were the whitefly Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae) and the leaf miner Liriomyza huidobrensis (Blanchard) (Diptera: Agromyzidae). Lacewings Chrysoperla sp. (Neuroptera: Chrysopidae), garden spiders Argiope sp. (Araneae: Araneidae), and the lady beetle Cheilomenes sexmaculata F. (Coleoptera: Coccinellidae) were the most relevant predators found in at least one locality out of the nine visited. The information generated can be used within the components of integrated pest management of tomatoes in the Azuero region.

Spodoptera frugiperda (J. E. SMITH, 1797) (LEPIDOPTERA: NOCTUIDAE), AFFECTING LETTUCE CROPS IN CERRO PUNTA

Rubén D. Collantes-G., Javier E. Pittí-C., Jahzeel Samaniego, Jorge Muñoz — Fri, 25 Jul 2025 00:00:00 +0000

Lettuce (Lactuca sativa L., 1753) is a leafy vegetable widely cultivated in Tierras Altas, Chiriquí; however, it is susceptible to being affected by various pests that feed on the foliage and whose presence compromises its possible commercialization in certain markets. Recently, reports of larvae feeding on the foliage of this vegetable in Cerro Punta were received, which was confirmed in the field that amounted to up to 70% presence, so the aim of the study was to identify the insect species related to these effects. To do this, two systematic samplings were carried out in farmers' plots (30 points per sampling), larvae and adult specimens that were found were also collected, to be analyzed in the laboratory, consulting specialized literature for identification. According to the results, the larva species corresponds to Spodoptera frugiperda (J. E. Smith, 1797) (Lepidoptera: Noctuidae), commonly known as fall armyworm; The adult found is also from S. frugiperda, coinciding with morphological characters described for the species such as the venation of the forewing. This insect is polyphagous and can affect a wide diversity of crops. The moth is widely distributed on the American continent and is the subject of multiple control measures. In addition to identification, biological aspects and recommendations for integrated pest management (IPM) are illustrated, considering cultural control, biological control, ethological control and chemical control.