ABSTRACT Seed traits associated with tolerance to flooding are poorly understood in tropical palms, despite their potential importance for establishment in wetlands. This study aimed to evaluate whether composite seed lots collected from flooded and dry sites differ in functional anatomical traits, water uptake dynamics, germination, mean germination time, and normal seedling formation under submerged conditions. The composite lots were compared for seed anatomy, histochemistry, chemical composition, imbibition, greenhouse emergence, mean germination time, and post-germinative performance. Seeds from the flooded-site lot had a thicker inner epidermis, greater total seed-coat thickness, and a larger relative lipid area in the endosperm than seeds from the dry-site lot. Water uptake followed a triphasic pattern in both lots; however, the flooded-site lot showed slower initial imbibition and a longer mean germination time under water. In sawdust + sand, germination was similar between lots, whereas under water the flooded-site lot reached 86.50 % of germination and the dry-site lot 45.01 %. The contrast was even more pronounced for normal seedling formation: the flooded-site lot maintained 100 % of normal seedlings in both substrates, whereas the dry-site lot reached only 6.85 % under water.
In cropping systems, the persistence of weed seed banks is a major challenge for sustainable weed management. This study aimed to evaluate the efficiency of pre-sowing and post-emergence herbicide management, combined with pre-harvest physical control, in reducing the ryegrass and wild radish seed bank over five seasons in a wheat-soybean succession. The experiment was conducted in a randomized complete block design with a split-plot arrangement. The seed bank evaluation periods (November 2021, July 2022, and November 2022) were allocated to the main plots, and four desiccation management strategies were allocated to the subplots: glyphosate (900 g ha-¹); glyphosate + clethodim (900 + 120 g ha-¹); glyphosate + saflufenacil (900 + 35 g ha-¹); glyphosate + clethodim + saflufenacil (900 + 120 + 35 g ha-¹). For the latter treatment, the remaining plants were manually uprooted prior to harvest. The chemical control alone, regardless of herbicide combinations, was ineffective in reducing the ryegrass and wild radish seed bank after five years of cultivation. In contrast, the integration of herbicide applications and manual weed removal was the most effective strategy, resulting in improved weed control and higher wheat grain yield. Increasing weed infestation over time in areas under exclusive chemical desiccation management compromised the wheat grain production, rendering harvest unfeasible.
The Dipteryx alata domestication is still in its early stages, characterized by instability in fruit production, absence of proper management practices, and lack of selected cultivars. This study aimed to define D. alata ideotypes for two cultivation systems, based on the perception and preferences of wild harvesters and farmers, as well as on documented phenotypic variability. A questionnaire was administered to wild harvesters and producers of the Goiás state, Brazil (n = 62 valid respondents), and the data were analyzed using descriptive statistics. The results revealed a strong preference for trees with open canopies (80.7 %), large and rounded fruits (87.1 %), and large nuts (61.3 %). The first ideotype, tailored for pure or intercropped systems, is characterized by a short-to-intermediate stature and a compact canopy architecture. The second, designed for silvopastoral systems, features an intermediate-to-tall stature and open canopy architecture. The proposed ideotypes integrate productive and morpho-agronomic attributes, providing a preliminary conceptual and quantitative framework for plant breeding and contributing to the sustainable use and conservation of natural baru populations in the Brazilian Savanna.
Seed traits associated with tolerance to flooding are poorly understood in tropical palms, despite their potential importance for establishment in wetlands. This study aimed to evaluate whether composite seed lots collected from flooded and dry sites differ in functional anatomical traits, water uptake dynamics, germination, mean germination time, and normal seedling formation under submerged conditions. The composite lots were compared for seed anatomy, histochemistry, chemical composition, imbibition, greenhouse emergence, mean germination time, and post-germinative performance. Seeds from the flooded-site lot had a thicker inner epidermis, greater total seed-coat thickness, and a larger relative lipid area in the endosperm than seeds from the dry-site lot. Water uptake followed a triphasic pattern in both lots; however, the flooded-site lot showed slower initial imbibition and a longer mean germination time under water. In sawdust + sand, germination was similar between lots, whereas under water the flooded-site lot reached 86.50 % of germination and the dry-site lot 45.01 %. The contrast was even more pronounced for normal seedling formation: the flooded-site lot maintained 100 % of normal seedlings in both substrates, whereas the dry-site lot reached only 6.85 % under water.
African mahogany (Khaya grandifoliola) is a forest species of considerable economic interest, whose clonal propagation may benefit from the development of efficient tissue culture protocols. The present study aimed to evaluate callus induction in African mahogany leaves using concentrations of 2,4-dichlorophenoxyacetic acid (2,4-D) and benzylaminopurine (BA). The optimal response occurred at a 2,4-D concentration of 67.86 μM, with predominantly friable characteristics, concentrated mainly in the midrib region, and to a lesser extent along the lateral margins of the explant. The BA concentration of 11.31 μM, in turn, promoted the formation of more compact calli, with white coloration, also predominating in the midrib region, with lower occurrence on the lateral margins of the explant.
Rapid propagation technologies have been used to increase the supply of basic cassava (Manihot esculenta Crantz) planting material, with emphasis on the production of etiolated seedlings, use of mini-cuttings, and reduction in the size of conventional stem cuttings. This study aimed to propose an accelerated multiplication protocol based on uninodal segments (single bud), as well as to evaluate whether the physiological age of the source material affects seedling establishment and development. The experiment was conducted using a completely randomized design, in a 3 & times; 3 factorial arrangement, with the cultivars BRS Prata, BRS Poti Branca, and Eucalipto and three physiological ages (top, middle, and base). The basal and middle segments provided a higher survival, whereas apical segments promoted a greater vegetative performance, with plant height reaching up to 57.41 cm, in addition to greater induction of tuberization in the Eucalipto cultivar. The protocol proved to be technically feasible and allowed the estimation of a production of 343 seedlings per year from a single mother plant, exceeding the multiplication rate attributed to mini-cuttings and the conventional method.
Management decisions regarding the choice of forage species and sowing timing may affect crop and pasture establishment and overall system efficiency. This study aimed to evaluate the agronomic performance, yield, and land-use efficiency of upland rice intercropped with Urochloa brizantha cv. Marandu under sowing strategies in tropical conditions. Field experiments were conducted to assess rice yield, forage biomass production, and the efficiency of the intercropping system compared to monoculture. The treatments included forage sowing times in relation to the establishment of the rice crop. Indicators of sustainable intensification, including the land equivalent ratio (LER), resource-use efficiency, and system resilience, were also evaluated. Rice yields ranged from 2.4 to 3.3 Mg ha(-1) and were not reduced by intercropping, when compared with monocropping. The simultaneous forage sowing produced up to 6.8 Mg ha(-1) of forage dry matter, whereas delayed sowing at 45 days after emergence increased the rice yield and resulted in LER values above 2.0. The integration strategy improved the land-use efficiency and contributed to pasture recovery, supporting intercropping agricultural systems.
The adequate sample size helps in the experimental precision and in the efficient use of resources in research with cotton. This study aimed to determine the sample size and understand the dissimilarities between traits and between cultivars of cotton at the stages of first visible flower bud and full maturity. Nine uniformity trials were carried out with the cultivars IMA2106GL, IMA5801B2RF, IMA5802B2RF, TMG31B3RF, TMG44B2RF, IMA5045WS3, TMG51WS3, TMG91WS3, and 21064WS3. At the stage of first visible flower bud, the main stem height, first productive branch height, main stem diameter, and number of leaves, nodes, and primary branches were evaluated; and, at the full maturity stage, in addition to the first five traits, the number of productive branches. Assuming a mean estimation error of 5 % and a confidence level of 95 %, the number of plants needed to measure the traits is 14 for main stem height, and number of leaves and nodes; 38 for main stem diameter and number of primary branches; and 126 for first productive branch height and number of productive branches.
Leucaena leucocephala is an exotic species widely distributed in tropical regions, whose highly competitive potential compromises natural regeneration and highlights the need for sustainable strategies for the management of invasive species. This study aimed to evaluate the allelopathic effects of aqueous grape pomace extracts obtained through two extraction methods (cold and hot) and applied by seed immersion to L. leucocephala at different concentrations (0, 20, 40, 60, 80, and 100 %), in order to assess their potential for controlling seed germination and early seedling growth. Increasing extract concentrations reduced germination, and increased the proportion of abnormal seedlings and the percentage of non-germinated seeds. Growth variables exhibited a biphasic response, with stimulation at intermediate concentrations (50-60 %) and inhibition at higher concentrations (> 80 %). The hot extraction method showed a greater inhibitory effect, which was associated with higher total phenolic compounds.
The expansion of canola into tropical regions requires an understanding of the relationships among yield, water-use efficiency, and oil content under irrigated conditions. This study aimed to evaluate the effects of sowing date, water replacement level, and genotype on the performance of irrigated canola. The experiment was conducted using a randomized complete block design, involving three sowing dates (April25, May 11 and 25), three water replacement levels (100, 70, and 40 % of the crop evapotranspiration-ETc), and three hybrids. The aboveground biomass, seed yield, harvest index, water productivity, and oil content were evaluated. Sowing date was the main factor determining crop performance. The mean maximum temperatures during the last 45 days of the crop cycle increased from 24.0 to 26.6 degrees C between the earliest and latest sowing dates. Sowing on April 25 resulted in a greater biomass (15.6 Mg ha-1), seed yield (2.89 Mg ha-1), and oil content (30.2 %), whereas sowing on May 25 reduced the seed yield by nearly 60 %. The full ETc replacement maximized the seed yield, whereas the severe water deficit (40 % ETc) reduced the biomass and oil content. The seed water productivity ranged from 5.23 to 6.75 kg m-3, with the highest value observed at the intermediate sowing date. Diamond showed a greater yield, water productivity, and harvest index. The early sowing associated with the adequate water replacement maximized the yield and oil content.
Citrus farming in Brazil faces phytosanitary problems, especially postbloom fruit drop, caused by the Colletotrichum abscissum fungus. This study investigated the action of mandarin essential oils on the in vitro development of C. abscissum. Essential oils of IAC 2019Maria mandarin, Murcott IAC 221 tangor, and Late IAC 585 willowleaf mandarin were analyzed, extracted from immature and ripe fruits at different dosages (0, 2, 4, 8, 16, and 32 & micro;L mL-1), as well as the main chemical components found on them, and the in vitro inhibition of mycelial growth, sporulation, and spore germination of the fungus. Limonene was the main compound found for all mandarin varieties at both ripening stages. The essential oil from immature fruits of Late IAC 585 showed a greater mycelial growth inhibition (66.89 %), whereas that from ripe IAC 2019Maria mandarin fruits stood out with greater inhibition (67.24 %). Both essential oils from immature fruits controlled sporulation; but, for ripe fruits, only the dosages influenced the conidia reduction. The dosages of 16 and 32 mu L mL-1 of the essential oils extracted from immature and ripe fruits of the three mandarin varieties inhibited spore germination, indicating a potential alternative strategy for disease management.
Drought stress reduces soybean [Glycine max (L.)] yield stability in tropical environments, particularly from flowering to pod formation. This study aimed to identify adaptive traits and underlying mechanisms of tropical soybean lines under water-limited conditions, as well as to assess the selection potential under non-stress environments. Twenty-five high-yield soybean genotypes carrying the long juvenile (lj) and pod dehiscence1 (pdh1) genes were selected and evaluated under normal (f 80 % of the field capacity-FC) and water-deficit (f 50 % FC) conditions. Two potentially tolerant (which demonstrated a higher capacity to maintain physiological performance and metabolic stability under water deficit) and two susceptible genotypes were identified for further indepth evaluation. Proline and malondialdehyde (MDA) were negatively and significantly correlated with grain yield under normal and water-deficit conditions. Both characters showed high broad-sense heritability across the environments, indicating strong genetic control and stable phenotypic expression. The simultaneous increase of proline and MDA is associated with reduced grain yield, indicating a stress-induced metabolic tradeoff in which carbon and energy are redirected from reproductive development toward cellular protection mechanisms in the soybean genotypes.
There are knowledge gaps in the management of sorghum-forage intercropping during the off-season under Brazilian Savanna conditions due to the lack of selective herbicides. This study aimed to determine the optimal doses of the imazethapyr+ imazapic ready-mix herbicide to manage Megathyrsus maximus cv. BRS Tamani intercropped with sorghum [Sorghum bicolor (L.) Moench], as well as to assess the effects of crop residue on the weed suppression and performance of the succeeding soybean crop. The experiment was carried out in a randomized block design, with four replications. The treatments included sorghum monoculture and intercropped with M. maximus, subjected to five doses of the Zelone (R) commercial herbicide (0, 18.75 + 6.25, 37.50 + 12.50, 56.25 + 18.75, and 75.00 + 25.00 g a.i. ha(-1) of imazethapyr + imazapic). There was initial phytotoxicity in BRS Tamani, reaching 80 % at 14 days after the application, followed by a gradual recovery. The 1.05 and 1.4 L c.p. ha(-1 )doses provided an effective forage suppression. The sorghum yield was affected by the coexistence with BRS Tamani; however, the application of the 1.05 and 1.4 L c.p. ha(-1) doses resulted in a yield similar to that of the sorghum monoculture. The residue from the intercropping system delayed the weed infestation, eliminating the need for pre-emergence herbicide application in the soybean without affecting the crop establishment or yield. It is necessary to suppress BRS Tamani when intercropped with sorghum using 1.05 and 1.4 L c.p. ha(-1) herbicide doses. Mulch delayed the weed infestation without negatively affecting the soybean development or yield.
Due to its nutritional relevance and edaphoclimatic adaptability, several studies have been carried out on chickpea (Cicer arietinum L.); however, further information about growing periods is still needed, especially regarding the quality of seeds in regions outside the Cerrado (Brazilian Savanna). This study aimed to analyze the physiological and sanitary quality of chickpea seeds (BRS Cristalino cultivar) obtained from different sowing dates in the central region of the Rio Grande do Sul state, Brazil. Seeds from nine sowing dates, between July and October, were evaluated. Germination, first count, seedling length and mass, and electrical conductivity tests were also performed, as well as pathogen incidences. The sowing dates influenced the incidence of Rhizopus spp. and the evaluated physiological parameters, except for root dry mass and length. The seeds showed a high incidence of Fusarium spp. and Aspergillus flavus, but it was the presence of Rhizopus spp. that negatively affected their vigor and viability. Unfavorable climate conditions at the end of flowering and close to harvests, especially between September and October, limited the seed performance. Minimum air temperatures below 10 degrees C did not prevent germination and plant development. The production of chickpea seeds in the central region of Rio Grande do Sul is feasible with sowing at the end of July, since the lots showed germination rates equal to or greater than 80 %, meeting the requirements of seed marketing standards.
Pitaya cultivation has been boosted around the world, but soil acidity can limit its development. This study aimed to evaluate the fertility of an Ultisol subjected to liming, as well as the growth and nutrition parameters of yellow pitaya (Selenicereus megalanthus) plants in the first year of cultivation. The experimental design was randomized blocks, with five treatments (0.00, 0.48, 0.96, 1.44, and 1.92 t ha-1 of limestone) and four replicates. Growth parameters such as total length, and number, diameter, and thickness of the cladodes, as well as the nutrient contents in the plants, were evaluated. The soil pH, calcium and magnesium concentrations, and base saturation increased with the limestone doses, whereas the potential acidity and exchangeable aluminum decreased. There was no difference among the treatments for the plant growth parameters and nitrogen, phosphorus, potassium, sulfur, copper, manganese, zinc, and boron contents. The calcium and magnesium contents in the plants increased, whereas the iron content decreased with the doses of the corrective. Liming improved the soil fertility, but did not alter the growth parameters of yellow pitaya in the first year of cultivation. The calcium and magnesium contents were higher and the iron content was lower with 1.92 t ha-1 of limestone.
The dependence on external inputs, combined with their limited availability and regulatory restrictions in organic systems, represents a major challenge to the sustainability of vegetable production. This study aimed to determine the effects of the use of mulch formed from gliricidia straw and elephant grass on the agronomic performance and on the transfer of N from mulch to vegetables grown in the succession lettuce-Indian spinach, in an organic system. The design was randomized blocks, with four replications. The treatments were: mulch with 100 % of gliricidia, 75 % of gliricidia + 25 % of elephant grass, 50 % of gliricidia + 50 % of elephant grass, 25 % of gliricidia + 75 % of elephant grass, 100 % of elephant grass, and no mulch. Agronomic traits and transfer of N from straw to vegetables were evaluated. The biomass yield in the vegetables was higher in the treatments with 75 % or more of gliricidia. The transfer of N from straws with higher proportions of gliricidia to lettuce varied between 45 and 50 %. For the Indian spinach, mulching with gliricidia promoted nitrogen transfer ranging from 26 to 38 %. Mulching with gliricidia also resulted in higher rates of nitrogen transfer to the vegetables. There was no difference in the efficiency of N recovery from straw for the vegetables between the mulches made of gliricidia or elephant grass.
High-throughput phenotyping has emerged as a strategic tool in maize breeding, enabling the rapid and accurate assessment of agronomic traits. This study aimed to select vegetation indices derived from RGB imagery for the identification of high-yielding maize genotypes under contrasting nitrogen fertilization conditions at the plot level. A total of 35 maize genotypes were evaluated in a randomized complete block design with a split-plot arrangement and three replications, subjected to two nitrogen levels (20 and 140 kg ha-1). Four unmanned aerial vehicle flights were conducted at two altitudes (60 and 80 m), and genetic and spatial analyses were performed using mixed models (REML/ BLUP). The flight conducted at 61 days after planting (V7/V8 stage) at 60 m of altitude exhibited the highest repeatability and accuracy. The blue green pigment index (BGI) demonstrated high sensitivity in discriminating nitrogen levels and in the indirect selection of high-yielding genotypes. The genotypes G42, G4, G34, G31, G20, G16, and G1 were identified as superior for grain yield. Vegetation indices based on the blue spectral band, such as BGI, are effective for the early selection of genotypes under nitrogen stress conditions prior to flowering.
Polyamines play an important role in regulating plant growth, as well as in physiological and metabolic processes related to crop performance. This study aimed to evaluate the effects of polyamine use on early growth, yield, and quality traits of Borago officinalis L. A factorial layout was performed using a randomized complete block design, considering two factors: seed priming and foliar spraying. Seed priming included one control (dry seeds) and priming with distilled water, putrescine, spermine, and spermidine. Foliar spraying included one control (no spraying) and spraying at the four-leaf stage, at 50 % of the flower bud formation and 50 % of flowering. Seed priming with spermidine and spermine, combined with foliar spraying at 50 % of the flower bud stage, increased chlorophyll contents. The highest carotenoid contents were observed in plants grown from spermidine-primed seeds and sprayed with putrescine at 50 % of the flower bud stage. The highest mucilage percentages and yield performance were obtained for the spermidine and spermine priming, followed by putrescine spraying at 50 % of the flower bud and flowering stages. The saponin content was high in plants from spermidine-primed seeds sprayed at 50 % of the flower bud stage. The use of polyamines increased the essential oil content and yield, in addition to change the relative proportions of palmitic, oleic, and gamma-linolenic fatty acids, in comparison to the control.
High-throughput phenotyping using unmanned aerial vehicles (UAVs) and spectral vegetation indices has been proposed to overcome the cost and logistical constraints of manual measurements in multi-environment breeding trials. However, the reliability of models trained on spectral data to predict structural traits across genotypes and environments remains unclear. This study aimed to develop an approach for predicting soybean plant height (PH) and first pod insertion height (FPIH) using UAV-based vegetation indices acquired at the flowering stage, as well as to compare extreme gradient boosting (XGBoost), multilayer perceptron (MLP), random forest (RF), and multiple linear regression (MLR) models under realistic cross-validation scenarios. Trials were conducted across multiple seasons using UAV multispectral imagery, with PH and FPIH manually measured. The models were evaluated under five phenotyping scenarios: baseline calibration using all data; prediction in a completely unmeasured future season; estimation of missing genotypes within a partially sampled season; calibration using a small fraction of data from a new season; and prediction under absence of field records for specific genotypes across environments. When all data were used for calibration, non-linear models showed a high apparent accuracy. However, prediction in unseen seasons failed for all models, reflecting strong genotype & times; environment interactions. Under reduced phenotyping within the same environment network, the models maintained a robust accuracy for PH, whereas FPIH predictions declined to moderate levels. UAVbased models are reliable for interpolation, but limited for extrapolation without local calibration, enabling reductions of up to 80 % in manual measurements for PH and 20-30 % for FPIH.
Naturally colored cotton stands out socioeconomically in northeastern Brazil; however, the low water availability and high evapotranspiration rates limit its growth and yield. This study aimed to evaluate the effects of irrigation levels and salicylic acid concentrations on the growth and yield of naturally colored cotton cultivars. The experiment was conducted in a randomized block design, with 64 experimental units, in a 2 & times; 4 & times; 2 factorial scheme, with four replications and one plant per plot, with plants grown in pots adapted to drainage lysimeters. The treatments included two irrigation levels (100 and 50 % of the water requirement), four salicylic acid concentrations (0, 1.5, 3.0, and 4.5 mM), and two cultivars (BRS Rubi and BRS Safira). The reduced irrigation level (50 %) negatively affected the growth, accumulation, and yield of the naturally colored cotton cultivars, with the productive variables being the most impacted. The average application of 2.9 mM of salicylic acid promoted greater growth and yield, in addition to mitigating the effects of water deficit on the number of bolls. BRS Safira stood out in growth, biomass, and productive components, outperforming BRS Rubi under different water conditions.
