Guazuma crinita is an important fast-growing timber tree species widely used in agroforestry systems in the Peruvian Amazon. The objectives of our research were (i) to assess genetic diversity of G. crinita using inter-simple sequence repeat (ISSR) markers and (ii) estimate correlation between genetic and geographic distances among provenances. The sample included 44 genotypes from 11 provenances in the Aguaytia and neighboring Pachitea watersheds in the Peruvian Amazon. Ten ISSR primers amplified a total of 65 bands of which 61 were polymorphic (93.8 %). The range of DNA amplification varied from 260 to 2,200 bp. Among the provenances, Macuya exhibited the highest percentage of polymorphic bands (PPB) with 67.7 %, 0.21 Nei's gene diversity (He) and 0.33 Shannon index (I). Overall genetic differentiation (G st) was 0.03, indicating 97 % of genetic diversity within provenances. Gene flow (Nm) was 12.9 alleles per generation. Cluster analysis was not related to geographic origin, suggesting a common gene pool. However a weak positive correlation (r = 0.27, P < 0.05) was found between genetic and geographic distance. This is the first study of genetic diversity and structure of G. crinita. We recommend in situ conservation strategies for populations with high levels of genetic diversity.

An understanding of wood physical properties and the interrelationships that govern them is required for efficient utilization of timber tree species. Guazuma crinita is a fast-growing timber tree of agroforestry systems in the Peruvian Amazon. The aim of this study was to assess variation in wood physical properties within the G. crinita stem. Wood samples were obtained from the base, middle and top of the stem of 12 randomly selected eight-year-old trees from six provenances in order to determine wood moisture content, density, specific gravity, radial, tangential and volumetric shrinkage and the coefficient of anisotropy. Pearson correlations between physical properties were also determined. The highest basic density was 459 kg/m3 from Tournavista provenance. Mean basic density and specific gravity were 430 kg/m3 and 0.45 respectively. There was statistically significant variation (p ≤ 0.05), due to stem level within the trees. The moderate values of density and anisotropy coefficient (1.56) suggest that G. crinita is a stable wood; these are important advantages in terms of costs of the processes of transport and transformation. Given the variation found in the limited tree samples of this study, we recommend further analysis with larger samples from different provenances and planting zones.Variación de las propiedades físicas en troncos de Guazuma crinita, una especie maderable en el Amazonas Peruano El entendimiento de las propiedades físicas de la madera y de las interrelaciones que las gobiernan es necesario para el uso eficiente de las especies maderables. Guazuma crinita es una especie arbórea de rápido crecimiento en sistemas agroforestales del Amazonas peruano. El objetivo de este estudio fue determinar la variación de las propiedades físicas de la madera en el fuste de árboles G. crinita. Las muestras de madera fueron obtenidas de la base, parte media y parte superior del tronco de 12 árboles de ocho años de edad aleatoriamente seleccionados, de seis lugares de procedencia. Con ellas se determinó: contenido de humedad, densidad, densidad relativa, contracciones radial, tangencial y volumétrica y coeficiente de anisotropía; se determinaron también las correlaciones de Pearson entre las propiedades físicas. La densidad básica mayor fue 459 kg/m3, de la procedencia de Tournavista. Las densidades básica y relativa promedio fueron 430 kg/m3 y 0.45, respectivamente. Se encontró variación estadísticamente significativa (p ≤ 0.05) entre alturas en el fuste. La madera moderadamente densa y el coeficiente de anisotropía (1.56) sugieren que G. Crinita es una madera estable, lo que representa importantes ventajas en términos de costos por transporte y proceso de transformación. Debido a la variación encontrada en las limitadas muestras de árboles de este estudio, se recomienda la realización de más análisis con mayores muestras y de diferentes sitios y plantaciones.

The department of Piura is the main mango producer in Peru accounting for 66.7% of the national crop. The objective of the study was to characterize the fruits of forty varieties of mango preserved since 1969 in northwestern Peru. The fruits were harvested at the El Chira Agrarian Experimental Station, Department of Piura from December 2019 to January 2020. Thirteen quantitative fruit variables were evaluated: width, thickness, length, weight, seed width, seed thickness, seed length, percentage of seed, percentage of fresh skin, percentage of pulp, texture, °Brix, and pulp / seed ratios. The varieties with the highest percentage of pulp were Tommy Atkins, Haden x carabao 1, Irwin, and Jaffra, the latter was also the variety with the highest pulp / seed ratio (17.0). The varieties with the highest ° Brix were Blacman (21.3 ° Brix) and Julie (22.0 ° Brix). Knowledge of the fruit characteristics is essential for proper selection and use by the industry, especially those with a higher pulp weight to obtaining higher yields in processing.

Guazuma crinita, a fast-growing timber tree species, was chosen for domestication in the Peruvian Amazon because it can be harvested at an early age and it contributes to the livelihood of local farmers. Although it is in an early stage of domestication, we do not know the impact of the domestication process on its genetic resources. Amplified fragment length polymorphic (AFLP) fingerprints were used to estimate the genetic diversity of G. crinita populations in different stages of domestication. Our objectives were (i) to estimate the level of genetic diversity in G. crinita using AFLP markers, (ii) to describe how the genetic diversity is distributed within and among populations and provenances, and (iii) to assess the genetic diversity in naturally regenerated, cultivated and semi-domesticated populations. We generated fingerprints for 58 leaf samples representing eight provenances and the three population types. We used seven selective primer combinations. A total of 171 fragments were amplified with 99.4% polymorphism at the species level. Nei’s genetic diversity and Shannon information index were slightly higher in the naturally regenerated population than in the cultivated and semi-domesticated populations (He = 0.10, 0.09 and 0.09; I = 0.19, 0.15 and 0.16, respectively). The analysis of molecular variation showed higher genetic diversity within rather than among provenances (84% and 4%, respectively). Cluster analysis (unweighted pair group method with arithmetic mean) and principal coordinate analysis did not show correspondence between genetic and geographic distance. There was significant genetic differentiation among population types (F_st = 0.12 at p ˂ 0.001). The sample size was small, so the results are considered as preliminary, pending further research with larger sample sizes. Nevertheless, these results suggest that domestication has a slight but significant effect on the diversity levels of G. crinita and this should be considered when planning a domestication program.

El presente estudio, tuvo como objetivo determinar la influencia de procesos de desinfección, medio de cultivo y fitohormonas en el desarrollo morfogénico In vitro de explantes obtenidas a partir de semilla biológica de la especie Guazuma crinita Mart (Bolaina), el mismo que se realizó en el laboratorio de cultivo de tejidos y meristemas, de la Universidad Nacional de Ucayali. Para ello se desinfectaron las semillas con hipoclorito de sodio al 2%, por un espacio de 0, 5, 10, 15 y 20 minutos (T1, T2, T3, T4, T5). Para promover la germinación se utilizaron medios de cultivo y combinaciones de Fitogel, Fitogel + Sacarosa, Fitogel + Sacarosa + Murashige and Skoog (MS) y Fitogel + Sacarosa + ½ MS (M1, M2, M3, M4); y para la morfogénica se aplicaron cinco tratamientos de concentración de auxinas y citoquininas homogenizadas (AC1, AC2, AC3, AC4, AC5). Del estudio se obtuvo que el T5 (desinfección con hipoclorito de sodio al 2% con exposición de 20 minutos) tuvo un 95% de sobrevivencia; mientras que en la germinación, el medio M1 (Fitogel) presentó el más alto con un 72,55%; finalmente en la morfogénica se determinó que el mejor tratamiento para inducir la formación de callos es el tratamiento AC4 (Kin 12 ppm + AIB 12 ppm), para primordios radiculares el mejor tratamiento AC5 (Kin 4 ppm + AIB 12 ppm) y se logró igual cantidad de brotes con todas las combinaciones de fitohormonas utilizadas. Murashige y Skoog; fitogel; auxinas; citoquininas; callogénesis

The aim of this research was to assess genetic variability of yam Dioscorea trifida genotypes using morphological descriptors for the germplasm collection conserved in the Agricultural Experiment Station in Ucayali, Peru. Thirty-eight morphological traits were evaluated for 30 D. trifida genotypes over ten years; from the data we estimated the Shannon-Weaver diversity index (H’) and the coefficient of variation and performed principal component analysis and cluster analysis. Qualitative traits with high phenotypic diversity index were: petiole anthocyanin (0.86), internal tuber color (0.86), petiole color (0.81) and stem color (0.80). The quantitative traits with the highest coefficient of variation were: tuber weight per plant (33.01) and tuber yield (32.99). Seventy-six percent of the morphological variability is explained by four principal components, the first component is constituted by the characters tuber width, tuber weight per plant, and tuber yield (29%). Five groups of genotypes were also identified with statistically significant differences, where group B stands out for its higher yield in fewer days to harvest. This research reveals wide morphological diversity in genotypes of D. trifida; these results can be used to strengthen the conservation, management, and genetic improvement initiatives of this important species in the Peruvian Amazon.