Ricardo Manuel Bardales-Lozano

Camu camu is an Amazonian fruit shrub from the Myrtaceae family, naturally growing in floodplains of the Amazon basin. Its significance lies in its fruit production, characterized by high vitamin C content and bioactive components. This study aimed to identify promising accessions within the camu camu germplasm collection in the Peruvian Amazon by evaluating multiple morphological traits and high phenotypic stability across different cropping seasons. A panel of 215 individuals from 43 accessions was evaluated over three growing seasons (2021/2022, 2022/2023, and 2023/2024) to identify stable accessions. Twenty-six quantitative descriptors were analyzed, including traits related to leaves, flowers, fruits, seeds, and fruit yield per plant. The Weighted Average of Absolute Scores Biplot (WAASB), based on the Best Linear Unbiased Predictions (BLUPs) of the genotype-environment interaction, was employed to assess the stability of accessions across three growing seasons. Factor analysis was also used to identify relationships among multiple variables. The genotype x environment interaction (GEI) effects were significant for all descriptors, except for ºBrix, while environmental effects were significant for most descriptors. A cumulative variance of 74% was explained by eight principal components. The BLUP analysis and WAASB index effectively identified stable camu camu accessions with high agromorphological values, emphasizing their contribution to the genetic variability of the collection. Furthermore, the MET evaluation facilitated the selection of accessions with multiple traits adapted to diverse environments. Results highlight the efficiency of BLUP and WAASB in assessing genotypic stability, resource optimization, and sustainability in breeding programs for this species.

The emergence of asparagus seeds is slow and may compromise stand uniformity, being influenced by the physiological quality of the seeds and the composition of the substrate. This study aimed at evaluating the vigor and physiological performance of commercial and locally produced seed lots of Asparagus officinalis, grown in different substrates under greenhouse conditions at the Agricultural Sciences Center, Boa Vista, Roraima, Brazil. In Experiment I, emergence, mean emergence time (MET), and emergence speed index (ESI) of commercial and local seeds were evaluated in a completely randomized design with ten replications. In Experiment II, seedlings obtained from commercial seeds were transplanted into five substrate formulations containing different proportions of Oxisol (Brazilian classification: Yellow Latosol), earthworm humus, and carbonized rice husk. Commercial seeds showed higher final emergence (89.3%) and higher ESI compared to local seeds (68.8%), indicating greater physiological vigor, while MET did not differ between seed sources. The different substrate formulations did not influence root length, number of branches, number of fleshy roots, or number of stems. The initial growth of asparagus seedlings was affected by substrates with balanced proportions between mineral and organic fractions. It is concluded that seed origin directly influences emergence, and that the substrates S40H40CC20, S30H30CC40 and S20H20CC60 favor the initial growth of seedlings.

Seedling production of native tree species faces significant challenges, including difficulty in collecting seeds. Jacaranda copaia is a pioneer species with wide distribution in Amazonia, with an important ecological and economic role. This study evaluated the survival rate of J. copaia by the seedling rescue method and the use of different doses of the controlled-release fertilizer Osmocote (15-09-12) on seedling quality. Seedlings from different matrices were rescued from natural regeneration and evaluated for survival 30 days after rescue. To evaluate seedling growth and quality, four doses of Osmocote (0; 1.5; 3.0; 4.5 g plant−1) were tested. The overall survival rate was 84%. The dose of 3.0 g plant−1 of Osmocote was the most efficient, promoting significant increases in the growth of J. copaia seedlings. At 180 days, there was a 113.3% increase in height and 129.9% in stem collar diameter compared to the control. There was also a significant increase in shoot (2.28 ± 0.47 g), root (0.86 ± 0.17 g), and total dry mass (3.14 ± 0.54 g), with balanced relationships between shoot dry mass/root dry mass ratio (3.69 ± 0.64) and higher Dickson quality index (0.54 ± 0.12). The regression models adjusted for all variables showed high coefficients of determination (R2), ranging from 98% to 99%, indicating a strong association between the applied doses and the analyzed parameters. The results show that the use of controlled-release fertilizer is an effective technique to improve the performance of native seedlings, being especially recommended for ecological restoration and reforestation projects.

Smallanthus sonchifolius (yacon) is a functional food native to the South American Andes. Its tuberous root and leaves are the main parts consumed; however, few studies have been carried out on its phenotypic variability. This study aimed to characterize 214 yacon accessions from the Germplasm Bank of the Instituto Nacional de Innovación Agraria (INIA), Peru. Twelve qualitative and seven quantitative variables were used. Accession Y-74 showed the largest leaf dimensions, while Y-28 showed the highest productivity per plant. Multiple correspondence analysis and principal component analysis revealed that the variables propagule color, leaf shape, root pulp color, leaf length and width, root weight per plant, and yield contributed significantly to the discrimination and identification of promising accessions. The geographical grouping of the accessions showed differences between accessions from the north and south of Peru. The qualitative phylogenetic tree showed 12 morphological groups discriminated mainly by leaf morphology and root characteristics, while the dendrogram analysis identified four clusters, with Cluster II standing out with an average yield of 73.5t/ha of tuberous roots. These results are important, as they allowed the identification of promising accessions and useful traits that can contribute to improving productivity and promoting the expansion of yacon cultivation at national and international levels.

El tomate cherry está aumentando su demanda en el mercado de Brasil, especialmente por presentar características deseables para el consumo. Los estudios que buscan optimizar el cultivo del tomate cherry de forma agroecológica aún son escasos y poco concluyentes. El objetivo de este trabajo fue evaluar el efecto de biofertilizantes en el desarrollo vegetal y en la producción de tomate cherry en el estado de Roraima, Brasil. El experimento se llevó a cabo en un invernadero en el Centro de Ciencias Agrarias de la Universidad Federal de Roraima, Boa Vista. En el experimento se utilizó un diseño en bloques completos al azar, con arreglo factorial 2 x 4, con cuatro repeticiones. Se evaluaron dos tipos de fertilización orgánica utilizando el biofertilizante común (BC: 50 % de estiércol de ganado vacuno + 50 % de agua) y el biofertilizante enriquecido (BE: 15 % de estiércol de ganado vacuno + 15% de estiércol de aves + 10 % de cáscara de arroz carbonizada + 10 % de polvo de grava basáltica + 50 % de agua), con las siguientes dosis (0; 800; 1600 y 2400 mL planta-1). El análisis de los resultados reveló efectos significativos en ambos factores y su interacción, promoviendo respuestas crecientes en la masa seca de la parte aérea, masa seca de las raíces, número de frutos producidos y diámetro ecuatorial de los frutos. Sin embargo, las plantas tratadas con el biofertilizante enriquecido presentaron mayores valores en comparación con las plantas tratadas con el biofertilizante común. El mayor rendimiento fue promovido por las dosis crecientes de los biofertilizantes, independientemente del tratamiento. El uso de biofertilizantes en dosis crecientes promueve el desarrollo vegetativo y productivo del cultivo de tomate cherry.

Changes in soil attributes following changes in management strategies in rice cultivation can alter soil quality, either positively or negatively. The aim of this study was to evaluate soil quality indicators, based on physical, chemical and microbiological soil attributes in Amazonian savanna under rice cultivation with different ages. The research was conducted in five areas under continuous rice cultivation during 1, 3, 8, 13, and 25 years, compared with local reference native vegetation. Soil samples were collected at 0-10 cm depth and evaluated for physical attributes such as texture and bulk density, chemical properties such as soil organic carbon, total nitrogen, exchangeable cations, available P, pH, CEC and C/N ratio; and microbiological attributes like microbial biomass carbon, soil microbial respiration, metabolic ratio and microbial coefficient. Acid phosphatase and urease activity were evaluated. With longer periods of time of rice cultivation, soil quality was enhanced with increasing soil fertility, increased soil organic carbon content and enzyme activity. The paddy soil indicators were sensitive to changes in rice cultivation and its duration. Acid phosphatase activity and available phosphorus increased with longer time of rice cultivation, indicating a possible conversion of inorganic into organic phosphorus forms, corroborated by increasing phosphatase activity. Microbiological (SMB-C, SBR, qMIC and qCO2) and biochemical (urease and acid phosphatase) indicators, as well as soil organic carbon and total nitrogen were highly sensitive to land use changes. Chemical and microbiological indicators are suitable for estimating paddy soil quality in lowland of Amazonian savanna.

Ñuña is a local type of common bean (Phaseolus vulgaris L.) cultivated in the Andean region of Peru. It stands out for its ability to expand and burst when roasted; however, its phenotypic diversity has not yet been fully explored. This study determined the phenotypic variability of Ñuña conserved in the Germplasm Bank of the National Institute of Agrarian Innovation of Peru. The analysis considered qualitative and quantitative traits, using multivariate statistics and comparison of means. Results revealed high phenotypic variability in both qualitative and quantitative traits. In qualitative traits, Multiple Correspondence Analysis found that the dark and light colours of the seed heads contributed most significantly to the variability of the accessions. Phylogenetic hierarchical analysis formed four clusters, representing 37% (I), 4% (II), 7% (III), and 52% (IV) of the accessions, respectively. For quantitative traits, Principal Component Analysis showed no discrimination between regions of origin but indicated a highly positive correlation between leaf length and width, and between pod length and width, as well as seed length, width, thickness and weight. Hierarchical analysis of quantitative characters also formed four clusters, representing 22% (A), 16% (B), 30% (C), and 31% (D) of the accessions, respectively. These clusters, analyzed for means comparison, showed significant differences (p < 0.05) with higher values in cluster B for pod length and width, and seed length, width, thickness and weight. Understanding the variability of the qualitative and quantitative traits of Ñuña is crucial for future genetic improvement studies aimed at achieving cultivars with desirable characteristics.

The micropropagation of camu-camu (Myrciaria dubia) faces significant challenges due to fungal contamination under in vitro conditions. This study investigated the potential of endophytic bacteria isolated from camu-camu as an alternative to chemical treatments for controlling contaminant fungi. The antagonistic activities of Bacillus subtilis, Enterobacter sp., Brevundimonassp., Bacillus sp., and Methylobacterium sp. against the fungi Colletotrichum spp.and Curvularia spp. were evaluated using diffusion and antibiosismethods. In the diffusion method, the pathogen was cultured over the antagonist culture,while in the antibiosis method, fungal growth inhibition was assessed through the production of thermostable metabolites. The experimental design was completely randomized (CRD), with five bacteria, two fungi, five replications, and analysis performed using R software. Results demonstrated that the diffusion method is effective in inhibiting the mycelial growth of Colletotrichum spp. and Curvularia spp., isolated from camu-camu micropropagation. Bacillus sp. exhibited the highest inhibition rates for both fungi, while Brevundimonassp. and Methylobacterium sp. were more effective against Curvularia spp., and Enterobactersp. against Colletotrichum spp. It is concluded that endophytic bacteria are a promising alternative for controlling contaminant fungi in camu-camumicropropagation, highlighting the potential of the diffusion method as an antagonistic action mechanism.

The success of forest plantations depends on the quality of seedlings, which can be ensured through nursery techniques. This study aimed to assess the growth of Cordia trichotoma seedlings in two container volumes combined with four fertilizer compositions. The experimental design was completely randomized in a 2 × 4 factorial arrangement with four replications: two container volumes (170 and 270 cm³) and four fertilizer compositions (Basacote^® [NPK 15-8-12]; Basacote^® + Phusion^® [NPK 9-40-00]; Polyblen^® [NPK 20-5-20]; and Polyblen^® + Phusion^®). Tube volume significantly influenced shoot height, root length, shoot, root, and total dry mass, with 270 cm³ tube presenting higher means (21.26 cm; 19.06 cm; 1.79 g; 3.60 g and 5.39 g, respectively), except for root regeneration potential. The factors tube volume and fertilizer had isolated effects on stem collar diameter and the Dickson Quality Index, with heist means the 270 cm³ tube (5.0 mm and 1.11, respectively) and the Basacote® fertilizer (4.77 mm and 0.99, respectively). Interaction between factors was observed in the shoot height/stem collar diameter ratio, dry mass of shoot/root dry mass ratio, and lignification index. Using 270 cm³ containers and Basacote^® fertilizer resulted in better development of C. trichotoma seedlings.

Essential oils used as bioherbicides are a promising alternative in agriculture. This study aimed to assess the phytotoxic potential of Piper marginatum essential oil through an in vitro study with detached and post-emergence leaves of three commercial species (lettuce, pepper, and tomato) and a weed (Spermacoce verticillata). The experiments were conducted in a randomized design with six treatments that consisted of four concentrations of essential oil (0.001, 0.01, 0.1, and 1% [v/v]) and two control treatments (distilled water, and 1% polysorbate 80 in distilled water). The P. marginatum essential oil had a phytotoxic effect on the leaves of the experimental species. The highest essential oil concentration resulted in greater toxicity effects on tomato, lettuce, and pepper leaves. The 0.1% essential oil concentration completely destroyed the S. verticillata leaves. Seven days after application, the P. marginatum essential oil did not show adverse effects on plant growth in the post-emergence phase. It is recommended to investigate its possible phytotoxic activity in other phases of plant development to understand its mode of action and potential as an alternative to developing bioproducts for weed control.