Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

Pyriproxyfen, a juvenile hormone analog (JHA), is considered as reduced-risk alternative to synthetic pesticides for crop protection. It has been frequently used in agriculture and public health to manage insect pests.  However, recent studies have reported that pyriproxyfen may have adverse physiological effects on non-target organisms. This study investigated the effects of sublethal doses of the endocrine disrupting insecticide pyriproxyfen on Drosophila melanogaster Meigen (Diptera: Drosophilidae) as a non-target and biological model. Results showed that pyriproxyfen had a noticeable effect on developmental stages of the individuals of the exposed generation. Pyriproxyfen treatment significantly shortens adult longevity of both sexes, female and male. Finally, these results suggest that reproduction capacity in D. melanogaster is impacted by reducing the number of progeny after the parent’s generation treatment with pyriproxyfen. These research findings indicate that sublethal exposure to pyriproxyfen induces adverse physiological effects and affects offspring growth rates in non-target insects of Drosophila.

Cover stubble in the zero tillage system benefits weed control. However, the influence of different cover crops on their composition and diversity in cowpea cultivation is little known. This study investigates the phytosociology, diversity and equity indices, control, similarity and beta diversity of weeds in cowpea cultivation managed on different cover crops. The experiment was carried out in a completely randomized block design, in a split plot scheme, with four repetitions. The plots were made up of straw from cover plants: spontaneous vegetation (T1), brachiaria (T2), millet (T3), sunn hemp (T4), jack beans (T5), brachiaria+crotalaria (T6), brachiaria+pig beans (T7), millet+crotalaria (T8), millet+pig beans (T9) and black mucuna (T10). The subplots were made up of treatments with and without weeding. The species Tridax procumbens, Digitaria horizontalis and Digitaria insularis were the most important species in the phytosociological study. The treatments changed the number of individuals and the diversity and equitability indices. In weeding management, T6 and T8 coverage showed greater diversity, while T9 showed greater evenness. Without weeding, T2 and T6 had fewer individuals and greater diversity, however, T8 and T9 showed greater evenness. Cover crops showed differences in weed suppression efficiency in weed-treated areas. However, brachiaria cultivation stood out as one of the most efficient for controlling these weeds. The similarity and beta diversity of weeds varied between treatments.

One of the benefits of shade-grown coffee crops is litter deposition, which can improve nutrient cycling and increase organic matter in the soil. The objective of this study was to evaluate the contribution of tree species in the production and deposition of litter, as well as in the potential of nutrient cycling in a coffee crop. Litter samplings were carried out in the tree planting rows (TPR) and between tree planting rows (TPI). Four deposition points were sampled in the TPR and TPI, spaced apart at 1.5, 3.0, 4.5, and 6.0 m from the trunk of the trees (Anadenanthera falcata, Peltophorum dubium and Cassia grandis). Nine samplings were carried out between October 2016 and September 2017. Higher deposition occurred in May, August, and September, and it was higher in the TPR. The species that most contributed to the deposition were the coffee plants and C. grandis. The coffee crop showed the highest accumulation of nutrients owing to the higher deposition of litter and higher levels of N, K and Mg, while C. grandis was the forest species that concentrated most Ca and S. The influence of forest species on nutrient cycling is minimal, primarily due to the reduced contribution of litter compared to coffee trees.

Lettuce is the most consumed leafy crop worldwide and the high levels of nitrates in its leaves can be carcinogenic. The objective of this study was to evaluate the effect of different nitrate/ammonium ratios in the nutrient solution and two light intensities (200 and 400 μmol·m⁻²·s⁻¹) on the growth and nutrient concentration of lettuce plants under hydroponic conditions. Controlled environment chambers (light and temperature) and a floating root system were used with the application of Steiner's nutrient solution modified for each of the treatments. Treatments consisted of combinations of three nitrate/ammonium ratios (100/0, 75/25, and 50/50) and two LED light intensities. The variables evaluated were root volume, fresh and dry weight of the leaves, dry weight of the root, total dry weight and the mineral composition of the leaves. The experimental design was completely randomized with a 3 × 2 factorial arrangement with six repetitions. For the statistical analysis of the data, an analysis of variance and a comparison of means test were performed (Tukey, p≤0.05). The results showed that increasing the proportion of ammonium reduced the volume and dry weight of the root without affecting the fresh weight of the leaf. Increasing the light intensity increased the root volume and the fresh and dry weight of the leaves, while ammonium reduced the levels of potassium, calcium and nitrates in the leaves, especially when an intensity of 400 μmol·m⁻²·s⁻¹ was applied. These results suggest that optimizing nitrate/ammonium ratios and light conditions improves biomass production and nutritional quality of hydroponic lettuce.

Cattails in Peruvian sector of Titicaca Lake, is still used as human food, so it is necessary to know its nutritional qualities and potential, therefore, it is proposed to characterize its nutritional composition and ethnobotanical value. Proximal analyses of basal stems, rhizomes and rhizomatic shoots ("chullu", "siphi" and "saka" respectively, by their local names of the edible parts) were carried in six replicates each and three for mineral analysis (Fe, P, K, Ca and I) under UV/VIS spectrophotometry and volumetric analisys; in addition, 45 people from communities surrounding Titicaca were interviewed, to know basic aspects of its ethnobotanical importance. Chullu and saka presented similar humidity levels (93,17 % and 92,87 %) and significantly lower in siphi (75,89 %); all of them had high ash contents (6,04 to 9,85%), chullu and saka were rich in fiber (22,59 % and 20,87 %) and siphi was high in carbohydrates (65,91 %), all three had moderate protein levels (6,97 to 10,44%). Siphi prevailed in calcium and iron contents (12,38 and 1,57 mg·(100 g)-1 respectively), high iodine concentrations were noted in the three organs, reaching 271,33 mg.(100g)-1 in siphi, higher than any conventional food. Almost 100 % of residents stated that they knew cattail as food for humans, with the highest report of use for chullu (65,08 %) and the lowest for siphi (12,70 %). Due to its nutritional qualities and ethnobotanical value, S. californicus represents an important alternative as a non-conventional food resource.

Cherimoya (Annona cherimola Mill.) is a plant that is cultivated mainly in the inter-Andean valleys of the Lima region, Peru, which present suitable conditions for its production. However, these conditions also favor the development of pathogens that cause the decline and death of cherimoya plants. The objective of the study was to molecularly identify the causal agent of cherimoya root rot. Cherimoya roots with mild and severe symptoms of root rot were collected from the valleys: Huanangui, San Antonio de Cumbe and Huaral, Lima. Seven Phytophthora isolates were obtained on PDA and V8 media with coralloid, petiolate mycelium, coenocytic hyphae with hyphal swellings, obpyriform sporangia, ovoid without papillae and globose chlamydospores. The cytochrome oxidase subunit II (Cox2) and elongation factor alpha 1 (EF1-α) regions were amplified using primers FM75, FM78, EF1AF and EF1AR. The sequences obtained showed a similarity of 99,22 to 99,87 % for Cox2 and 99,04 to 100 % with EF1-α for Phytophthora cinnamomi. The phylogenetic tree showed a topology consistent with the Phytophthora accessions. It is concluded that P. cinnamomi is the cause of root rot, this being the first report on the presence of this pathogen in custard apple plants in Peru.

The strawberry (Fragaria x ananassa) is a plant species of great economic and agri-food importance, which is grown in agro-industrial regions of Mexico such as Bajío. The main input for agricultural production is seedlings, whose first stage of multiplication begins with the formation of clones by in vitro culture from selected mother plants. However, several characteristics of the regenerated plants may present variations that reduce their agronomic and commercial value. This variability is due to multiple factors, although the effect of auxin and cytokinin combinations, as well as their concentrations, stands out. The aim of the present study was to regenerate strawberry plants in vitro by direct organogenesis at different concentrations of auxins and cytokinins. Explants were obtained from apical meristems on the stolons of mother plants of the Camino Real variety. A total of 21 treatments of auxins (indole-3-butyric acid –IBA and 2,4-dichlorophenoxyacetic acid –2,4-D) and citocinins (benzylaminopurine –BAP and kinetin) were used for organogenesis evaluation. The highest number of vitro plants regenerated with the combination of IBA and BAP at 0,4 mg·L-1, with an average regeneration rate of 68,3 %. In this treatment, the vitro plants showed better development and high antioxidant response. The highest average proline concentration of 1,7 µg mL-1, in the control treatment without auxins or cytokinins.

The use of biostimulants has been an agricultural strategy to improve crop yield and quality. These products can be a sustainable alternative that aligns with ecological agricultural practices, promoting increased productivity and minimising environmental impact. The study consisted of evaluating the effect of biostimulants on rice crop development and yield. A randomised complete block design was used with a factorial arrangement of three biostimulants by three doses plus a control treatment. The variables evaluated were plant height, number of tillers per plant, number of days to flowering, number of grains per ear, weight of 1000 grains and yield. The results show that the biostimulants stimulated the growth and yield of the rice crop. The variables plant height and number of tillers were benefited with the treatments T3 (Isabión, 1000 mL·ha-1) followed by T9 (Proboost, 1000 mL·ha-1); the same treatments promoted an increase in the number of grains per spike and weight of 1000 grains. Treatment T3 showed the highest yield with a value of 4472.19 kg·ha-1. The application of the biostimulant Isabión at a dose of 1000 mL·ha-1 showed the best results in the variables evaluated.

Common bean is seriously affected by weeds interference, which can vary according to the weed's emergence time and the crop's planting season. This study aimed to evaluate the effects of relative times of Raphanus raphanistrum emergence on white beans in winter and summer season. An experiment was carried out for each season in 1.2 m x 1.2 m beds using a randomized block design, with Raphanus raphanistrum emergence times of 0, 10, 20, 30, 40, and 50 days after bean emergence (DABE) and a control without the weed, in four replications. Height, number of leaflets, chlorophyll content, leaf area and dry matter of stems, leaflets, and fruit were determined in the crop. Also, weight of grains and pods per plant, weight of 100 grains and yield at harvest. Furthermore, dry matter of Raphanus raphanistrum's stems, leaflets, and fruit was determined. The data was subjected to analysis of variance using the F test, and means were compared using Tukey test at 5 % probability level. The lowest values for bean grain weight (152.72 g plant-1) and pod weight (223.67 g plant-1) in winter season were recorded when Raphanus raphanistrum emerged at 10 DABE. The summer season showed the lowest bean grain and pod weight values (81.45 and 121.5 g plant-1, respectively) when Raphanus raphanistrum emerged simultaneously with the crop. Raphanus raphanistrum emergence time altered its interference with beans. Moreover, planting season influenced crop and weed development, thus varying the effects of weed's relative time of emergence on the crop.

Pineapple (Ananas comosus) crop generates a high volume of harvest residues, resulting in significant environmental impact, primarily due to the large quantity of biomass left after fruit harvesting. This study aimed to evaluate fiber production and quality using two defibration methods, manual and mechanical, on leaves from three strata of MD2 pineapple plants subjected to different pre-conditioning techniques: soaking in water for 8 and 15 days, and NaOH solution for 1 hour. Results of this study demonstrated that 70 % of the leaves were suitable for defibration. The highest fiber yields were obtained from leaves in the middle and upper strata of the plants, with values of 8.98 and 12.4 g, respectively. The extraction time was shorter in the mechanical method, being 22 times more efficient than the manual method. The mechanical method favored fiber production when no prior conditioning of the leaves was performed, extracting an average of 50.5 g per plant. The manual method performed better when leaves were subjected to soaking in water or NaOH, extracting between 14.5 and 16.3 g per plant. Additionally, changes in the mechanical properties of the fiber were found to depend on the stratum of the plants and leaf pre-conditioning techniques. Our results contribute to explore the potential uses of fiber extracted by strata and highlight the possibilities of implementing pre-conditioning techniques.