Effects of a S-metolachlor based herbicide on two plant models: Zea mays L. and Lactuca sativa L.

Corn is the second most cultivated crop in Brazil, the number-one country in pesticide consumption. Chemical control of weeds is performed using herbicides such as S-metolachlor with pre- and post-emergence action and thus the toxicity of herbicides constitutes a matter of great concern. The present investigation aimed to examine the effects of an S-metolachlor-based herbicide on Lactuca sativa L. (lettuce) and Zea mays L. (maize) utilizing various bioassays. The test solutions were prepared from commercial products containing the active ingredient. Seeds from the plant models were exposed in petri dishes and maintained under biochemical oxygen demand (BOD) at 24°C. Distilled water was negative and aluminium positive control. Macroscopic analyses (germination and growth) were conducted for both plant species, and microscopic analysis (cell cycle and chromosomal alterations) were performed for L. sativa root tip cells. Detrimental interference of S-metolachlor-based herbicide was noted with lettuce for all parameters tested reducing plant germination by over 50% and the germination speed by over 45% and showing a significant decrease in mitotic index, from 16.25% to 9,28% even on the lowest concentration tested. In maize, there was no significant interference in plant germination; however, speed of germination was significantly hampered, reaching a 51.22% reduction for the highest concentration tested. Data demonstrated that the herbicide was toxic as evidenced by its phyto- and cytotoxicity in L. sativa L. and Z. mays L.

Unveiling the Biocontrol Potential of Rhizoplane Bacillus Species against Sugarcane Fusarium Wilt through Biochemical and Molecular Analysis.

BACKGROUND: Biocontrol is regarded as a viable alternate technique for managing sugarcane wilt disease caused by Fusarium sacchari. Many fungal antagonists against F. sacchari, have been reported, but the potential of bacterial antagonists was explored to a limited extent, so the present study evaluated the antagonistic potential of rhizoplane Bacillus species and their mode of action. RESULTS: A total of twenty Bacillus isolates from the rhizoplane of commercially grown sugarcane varieties were isolated. The potential isolate SRB2 had shown inhibition of 52.30, 33.33, & 44.44% and SRB20 of 35.00, 33.15, & 36.85% in direct, indirect, and remote confrontation respectively against F. sacchari. The effective strains were identified as Bacillus inaquosorum strain SRB2 and B. vallismortis strain SRB20, by PCR amplification of 16S-23S intergenic region. The biochemical studies on various direct and indirect biocontrol mechanisms revealed the production of IAA, Protease, Cellulase, Siderophores, and P solubilization. The molecular analysis revealed the presence of antimicrobial peptides biosynthetic genes like fenD (Fengycin), bmyB (Bacyllomicin) ituC (Iturin) and spaS (Subtilin) which provided a competitive edge to these isolates compared to other Bacillus strains. Under greenhouse experiments, the sett bacterization with SRB2, significantly (P < 0.001) reduced the seedling mortality by > 70% followed by SRB20 in F. sacchari inoculated pots. CONCLUSION: The study revealed that the isolates B. inaquosorum SRB2 and B. vallismortis SRB20 can be used as potential bioagents against sugarcane Fusarium wilt.

Plant seedlings of peas, tomatoes, and cucumbers exude compounds that are needed for growth and chemoattraction of Rhizobium leguminosarum bv. viciae 3841 and Azospirillum brasilense Sp7.

This study characterizes seedling exudates of peas, tomatoes, and cucumbers at the level of chemical composition and functionality. A plant experiment confirmed that Rhizobium leguminosarum bv. viciae 3841 enhanced growth of pea shoots, while Azospirillum brasilense Sp7 supported growth of pea, tomato, and cucumber roots. Chemical analysis of exudates after 1 day of seedling incubation in water yielded differences between the exudates of the three plants. Most remarkably, cucumber seedling exudate did not contain detectable sugars. All exudates contained amino acids, nucleobases/nucleosides, and organic acids, among other compounds. Cucumber seedling exudate contained reduced glutathione. Migration on semi solid agar plates containing individual exudate compounds as putative chemoattractants revealed that R. leguminosarum bv. viciae was more selective than A. brasilense, which migrated towards any of the compounds tested. Migration on semi solid agar plates containing 1:1 dilutions of seedling exudate was observed for each of the combinations of bacteria and exudates tested. Likewise, R. leguminosarum bv. viciae and A. brasilense grew on each of the three seedling exudates, though at varying growth rates. We conclude that the seedling exudates of peas, tomatoes, and cucumbers contain everything that is needed for their symbiotic bacteria to migrate and grow on.

Response to carvacrol monoterpene in the emergence of Allium cepa L. seeds exposed to salt stress.

Abiotic stresses including sodium chloride (NaCl) are known to negatively affect plant physiology and seed germination by inducing a delay in establishing seedling emergence. The monoterpene carvacrol is the major component of several aromatic plants and seems to interfere with germination and seedling growth. In this study, we investigated whether treatment with carvacrol attenuates the effects of NaCl on the germination and development of Allium cepa, where biochemical parameters were also analyzed. The results showed that the Emergency Speed Index (ESI) was near to 2.0 in the control group. The groups NaCl, carvacrol alone, and in co-treatment with NaCl exhibited an ESI below 0.8, being significantly smaller when compared to the control. NaCl + carvacrol significantly inhibited seed emergence in relation to the NaCl group. Only the content of malondialdehyde was significantly altered by NaCl.

Histogenesis and reserve dynamics during the maintenance of dormancy and germination in seeds of the basal palm Mauritiella armata.

The germination and post-seminal development of Arecaceae are notably complex due to the microscopic dimensions of the embryonic axis, the occurrence of dormancy, and the diversity of reserve compounds. In-depth information on this subject is still limited, especially in terms of the basal sub-family Calamoideae. Mauritiella armata is widely distributed in the Amazon region and is considered a key species in flooded ecosystems (veredas) in the Cerrado biome. We sought to describe histogenesis and reserve compound dynamics during the germination of M. armata, as well as the changes in incubated seeds over time. Seeds with their operculum removed (the structure that limits embryonic growth) were evaluated during germination using standard methods of histology, histochemistry, and electron microscopy. Evaluations were also performed on intact seeds incubated for 180 days. The embryos show characteristics associated with recalcitrant seeds of Arecaceae: a high water content (>80%), differentiated vessel elements, and reduced lipid reserves. Both the embryo and endosperm store abundant reserves of proteins, neutral carbohydrates, and pectins. The completion of germination involves cell divisions and expansions in specific regions of the embryo, in addition to the mobilization of embryonic and endospermic reserves through symplastic and apoplastic flows. Intact seeds show dormancy (not germinating for 180 days), but exhibit continuous development associated with cell growth, differentiation, and reserve mobilization. The anatomical and histochemical characters of M. armata seeds indicate an association between recalcitrance and dormancy related to the species' adaptation to flooded environments.

Effects of gibberellic acid concentration and fruit maturation stage on seed germination and vigor of pitahaya seedlings / Doses de ácido giberélico e estágio de maturação de frutos na germinação de sementes e vigor de plântulas de pitaya

With increased interest in cultivation, the study of white-fleshed pitahaya (Selenicereus undatus (Haw.) D.R. Hunt, Cactaceae family) seedling production is of fundamental importance in the search for novel techniques to increase cultivation and guarantee homogeneous and productive orchards. The present study investigated the influence of various gibberellic acid (GA3) concentrations and fruit maturation stages on seed germination and vigor of white-fleshed pitahaya seedlings, considering the physiological quality of seedlings produced to support genetic breeding and conservation programs of the species. White-fleshed pitahaya seeds at two maturation stages (physiologically ripe and maintained at 10 °C in Biochemical Oxygen Demand incubators for three months) were treated with varying GA3 concentrations of 0, 50, 100, and 500 mg/L. We observed the influence of fruit storage on seedling germination, emergence, and growth as a function of GA3 concentration. According to the results, seeds extracted from ripe white-fleshed pitahaya fruits grown under the conditions tested here required GA3 application to increase seedling emergence and vigor, with optimal doses in the 150-300-mg/L range. In the case of pitahaya fruits intended for storage for future seed removal and maintained under the same sowing conditions, the application of higher doses of GA3 was necessary when compared to the previous condition, with a minimum dose of 500 mg/L GA3. The present study shows that the maturation stage of white-fleshed pitahaya fruits intended for seed removal influences the quality of seedlings; therefore, the use of seeds extracted from ripe pitahaya fruits without fermentation is more appropriate for the purpose.

Com o crescente interesse no seu cultivo, estudos na produção de pitaya ((Selenicereus undatus (Haw.) D.R. Hunt, família Cactaceae) é de fundamental importância quando se busca novas técnicas para o incremento do cultivo e garantia de um pomar homogêneo e produtivo. Objetivou-se avaliar a influência do uso de diferentes concentrações de ácido giberélico e do estágio de maturação de frutos na germinação de sementes e vigor de plântulas de pitaya vermelha da polpa branca, tendo em vista a qualidade fisiológica de mudas produzidas a fim de subsidiar trabalhos de melhoramento genético e conservação da espécie. Foram utilizadas sementes de frutos de pitaya vermelha da polpa branca em dois estágios de maturação (fisiologicamente maduros e conservados à 10°C em BOD por 3 meses), tratadas com diferentes concentrações de ácido giberélico: 0, 50, 100 e 500 mg/L. Foi possível observar que houve influência do armazenamento de frutos na germinação, emergência e crescimento das plântulas em função das concentrações de ácido giberélico. Assim, verifica-se que, no caso de sementes extraídas de frutos maduros de pitaya vermelha da polpa branca, quando semeadas nas condições do presente estudo, é necessário a utilização de GA3 para incrementar a emergência e o vigor das plântulas, com doses ótimas variando entre 150 e 300 mg/L. No caso da necessidade em armazenar os frutos de pitaya para a posterior retirada de sementes, também nas mesmas condições de semeadura do presente estudo, observa-se que, em síntese, é necessária a utilização de GA3, porém em doses maiores do que o observado no primeiro, sendo de, no mínimo, 500 mg/L. O presente estudo mostra que há influência do estágio de maturação dos frutos de pitaya vermelha de polpa branca para retirada de sementes sobre a qualidade das mudas, concluindo que o uso de sementes extraídas de frutos maduros, sem fermentação, é mais adequado para esta finalidade.

Identification and Characterization of VDAC Family in Maize.

The voltage-dependent anion channel (VDAC) is the most abundant protein in the outer mitochondrial membrane (OMM) of all eukaryotes, having an important role in the communication between mitochondria and cytosol. The plant VDAC family consists of a wide variety of members that may participate in cell responses to several environmental stresses. However, there is no experimental information about the members comprising the maize VDAC (ZmVDAC) family. In this study, the ZmVDAC family was identified, and described, and its gene transcription profile was explored during the first six days of germination and under different biotic stress stimuli. Nine members were proposed as bona fide VDAC genes with a high potential to code functional VDAC proteins. Each member of the ZmVDAC family was characterized in silico, and nomenclature was proposed according to phylogenetic relationships. Transcript levels in coleoptiles showed a different pattern of expression for each ZmVDAC gene, suggesting specific roles for each one during seedling development. This expression profile changed under Fusarium verticillioides infection and salicylic acid, methyl jasmonate, and gibberellic acid treatments, suggesting no redundancy for the nine ZmVDAC genes and, thus, probably specific and diverse functions according to plant needs and environmental conditions. Nevertheless, ZmVDAC4b was significantly upregulated upon biotic stress signals, suggesting this gene's potential role during the biotic stress response.

Long-term seedling and small sapling census data from the Barro Colorado Island 50 ha Forest Dynamics Plot, Panama.

Tropical forests are well known for their high woody plant diversity. Processes occurring at early life stages are thought to play a critical role in maintaining this high diversity and shaping the composition of tropical tree communities. To evaluate hypothesized mechanisms promoting tropical tree species coexistence and influencing composition, we initiated a census of woody seedlings and small saplings in the permanent 50 ha Forest Dynamics Plot (FDP) on Barro Colorado Island (BCI), Panama. Situated in old-growth, lowland tropical moist forest, the BCI FDP was originally established in 1980 to monitor trees and shrubs ≥1 cm diameter at 1.3 m above ground (dbh) at ca. 5-year intervals. However, critical data on the dynamics occurring at earlier life stages were initially lacking. Therefore, in 2001 we established a 1-m2 seedling plot in the center of every 5 × 5 m section of the BCI FDP. All freestanding woody individuals ≥20 cm tall and <1 cm dbh (hereafter referred to as seedlings) were tagged, mapped, measured, and identified to species in 19,313 1-m2 seedling plots. Because seedling dynamics are rapid, we censused these seedling plots every 1-2 years. Here, we present data from the 14 censuses of these seedling plots conducted between the initial census in 2001 to the most recent census, in 2018. This data set includes nearly 1 M observations of ~185,000 individuals of >400 tree, shrub, and liana species. These data will permit spatially-explicit analyses of seedling distributions, recruitment, growth, and survival for hundreds of woody plant species. In addition, the data presented here can be linked to openly-available, long-term data on the dynamics of trees and shrubs ≥1 cm dbh in the BCI FDP, as well as existing data sets from the site on climate, canopy structure, phylogenetic relatedness, functional traits, soil nutrients, and topography. This data set can be freely used for non-commercial purposes; we request that users of these data cite this data paper in all publications resulting from the use of this data set.

Crescimento de mudas de Cordia trichotoma submetidas a diferentes fontes e doses de fertilizantes / Seedling growth of Cordia trichotoma subjected to different sources and doses of fertilizers

Cordia trichotoma é uma espécie de grande interesse econômico, contudo as informações de suas necessidades nutricionais ainda são incipientes. Dessa forma, objetivou-se avaliar a eficiência e doses adequadas de fontes de fertilizantes para produção de mudas de Cordia trichotoma. O experimento foi conduzido em delineamento inteiramente casualizado, em fatorial 3x5, com três fontes defertilizantes, sendo dois adubos de liberação lenta e uma fonte prontamente solúvel (MAP, combinado com KCl), nas doses de 0, 50, 100, 150 e 200%, em relação a dose recomendada. Aos 270 dias, realizou-se a mensuração das variáveis altura, diâmetro de coleto, massa seca e Índice de Qualidade de Dickson. Para cada variável, foi realizado o cálculo da dose máxima de eficiência técnica (DMET). O uso de MAP e KCl proporcionou crescimento superior das mudas em relação às fontes de ALL, para todas as variáveis avaliadas. As médias de DMET encontradas para o ALL1, ALL2 e MAP e KCl foram de 195%, 190% e 120%, respectivamente. Assim, recomenda-se o uso de MAP e KCl, na dose de 120%, ou seja, 0,08 g L-1de KCl e 0,12 g L-1de MAP para fertilização de mudas de Cordia trichotoma.(AU)

Cordia trichotoma is a species of great economic interest, however information on itsnutritional requirement is still incipiente. Thus, the objective was to evaluate the efficiency and adequate doses ofdifferent sources of fertilizers, for the production of Cordia trichotomaseedlings. The experiment was conducted in a completely randomized design (DIC), in a 3 x 5 factorial, with three different sources of fertilizers, two slow-release fertilizers (ALL1 and ALL2) and the use of readily soluble sources (MAP and KCl). The second factor represents the tested doses 0, 50, 100, 150 and 200%, in relation to a dose considered standard. The doses of the slow-release fertilizer were based on the standard dose of0.44 g seedlings-1, while the readily soluble fertilizer doses were of a fixed dose of 0.08 g seedlings-1 of KCl, and increasing doses ofMAP, based on the standard dose of 0.1 g changes -1. At 270 days after sowing, the variables height, collecting diameter, dry mass and Dickson's Quality Index were measured. For each variable, the maximum technical efficiency dose (DMET) was calculated. The use of MAP and KCl provided superior growth of seedlings in relation to ALL sources, for all variables evaluated. The DMET found for ALL1, ALL2 and MAP and KCl were 200%, 200% and 120%, respectively. Thus, it is recommended to use MAP and KCl, at a doseof 120%, that is, 0.08 g L-1of KCl and 0.12 g L-1 of MAP for fertilization of Cordia trichotomaseedlings.(AU)

Cytogenotoxic, insecticidal, and phytotoxic activity from biomass extracts of the freshwater algae Nitella furcata.

Agroecology, the application of ecological concepts to agricultural production, has been developing over the last years with consequent promotion for discovery of bioactive compounds to control pests and abolish crop diseases. In this context, algae from Nitella genus are characterized by high potential for bioeconomic applications due to (1) available biomass for harvesting or cultivation and (2) production of allelochemicals, which present a potential to protect field crops from insect infestation. Therefore, this study aimed to determine primary and secondary metabolites derived from aqueous and hydroethanolic extracts of Nitella furcata and to evaluate phytotoxic, cytogenotoxic, insecticidal, and pro-oxidative activities of these extracts. Determination of metabolites showed the presence predominantly of carbohydrates, proteins, phenols, and flavonoids in hydroethanolic extract. Both extracts of N. furcata interfered in the germination of seeds and development of seedlings of Lactuca sativa, with hydroethanolic extract exhibiting greater inhibition. Both extracts also interfered with meristematic cells of Allium cepa as evidenced by chromosomal alterations and higher pro-oxidative activity. Aqueous extract at 5 and 0 mg/ml produced 100% insect mortality. Further, hydroethanolic extract at 0 mg/ml was lethal immediately upon exposure. Therefore, results demonstrate that N. furcata is potential algae species to be considered for development of environmental and ecotoxicological studies as a source of compounds with potential use in agroecological strategies.

Protein Profiling of Psittacanthus calyculatus during Mesquite Infection.

Psittacanthus calyculatus is a hemiparasite mistletoe that represents an ecological problem due to the impacts caused to various tree species of ecological and commercial interest. Although the life cycle for the Psittacanthus genus is well established in the literature, the development stages and molecular mechanism implicated in P. calyculatus host infection are poorly understood. In this study, we used a manageable infestation of P. laevigata with P. calyculatus to clearly trace the infection, which allowed us to describe five phenological infective stages of mistletoe on host tree branches: mature seed (T1), holdfast formation (T2), haustorium activation (T3), haustorium penetration (T4), and haustorium connection (T5) with the host tree. Proteomic analyses revealed proteins with a different accumulation and cellular processes in infective stages. Activities of the cell wall-degrading enzymes cellulase and ß-1,4-glucosidase were primarily active in haustorium development (T3), while xylanase, endo-glucanase, and peptidase were highly active in the haustorium penetration (T4) and xylem connection (T5). Patterns of auxins and cytokinin showed spatial concentrations in infective stages and moreover were involved in haustorium development. These results are the first evidence of proteins, cell wall-degrading enzymes, and phytohormones that are involved in early infection for the Psittacanthus genus, and thus represent a general infection mechanism for other mistletoe species. These results could help to understand the molecular dialogue in the establishment of P. calyculatus parasitism.

Phytotoxicity of Quillaja lancifolia Leaf Saponins and Their Bioherbicide Potential.

Weeds are major threats to the integrity of agricultural and natural environments due to their invasive and competing potential. Bioherbicides are substances based on natural compounds that are biodegradable and often have low residual effects. Plant species able to produce and release phytotoxic compounds may represent effective bioherbicide sources. Leaves of Quillaja lancifolia D.Don (formerly Q. brasiliensis (A.St.-Hil. & Tul.) Mart.) produce water-soluble specialized metabolites of the saponin class that could be evaluated for phytotoxic activity and potential as natural herbicides. This study was conducted to examine the impacts of Q. lancifolia total saponins aqueous extract (AE) at 4 and 10% (w/v) and of two combined reverse-phase chromatography purified saponin fractions (QB) at 1 and 2% (w/v) on morpho-physiological parameters of Lactuca sativa (lettuce) and Echinochloa crus-galli (barnyardgrass) in pre- and post-emergence bioassays. QB was only tested in pre-emergence assays. In pre-emergence bioassays, the germination rate and germination kinetics were determined. Post-emergence evaluations included effects on seedling morphology, root and shoot length, dry mass, and chlorophyll content. Osmotic potential and pH analyses ruled out roles for these factors in the observed responses. AE had a high inhibitory impact on the germination of both lettuce and barnyardgrass. QB at 1% and 2% (w/v) significantly decreased the growth of lettuce seedlings germinated in its presence by more than 10-fold. Phytotoxic effects on the post-emergence growth of lettuce, especially at the highest concentration tested of AE (10% w/v), was also observed. The presence of quillaic acid-based triterpene saponins in AE and QB was confirmed using different analytical methods. Therefore, both saponin-enriched fraction and aqueous extracts of Q. lancifolia inhibited tested plant growth and development. The water solubility of saponins and the availability of a sustainable source of these molecules from the leaves of cultivated young Q. lancifolia plants make them attractive candidates for use as bioherbicides.

In Vitro Polyploidization of Brassolaeliocattleya Hybrid Orchid.

The Cattleya (Orchidaceae-Laeliinae subtribe) intergeneric hybrids, such as Brassolaeliocattleya (Blc.), have great ornamental value, due to their compact-size, with large and high color diversity of flowers. Artificial induction of polyploidy brings agronomic, ornamental and genetic benefits to plants. Polyploidization efficiency depends on factors, such as the type of antimitotic, polyploidization method, concentrations, exposure times and type of explant. This study aimed to develop a protocol to polyploidize Blc. orchids, by testing two types of explants (seeds and protocorms), concentrations and exposure times to colchicine. The effects of colchicine on the in vitro development of explants were also investigated. The responses of explants to colchicine depended on the concentrations, exposure time and the interaction of these factors. Flow cytometric analysis evidenced high endopolyploidy and allowed the separation of polyploidized (4C, 8C and 16C peaks) from non-polyploidized (only 2C and 4C peaks) plants. The highest percentage of polyploid plants was regenerated from protocorms (16.4%) treated with colchicine instead of seeds (3.2%). Protocorms treated with colchicine at 500-750 µM for 18 h resulted in the best percentage of polyploidization. Additionally, in vitro natural polyploidization using protocorms was reported (11.5%). Cytological analyses allowed an estimation of the number of chromosomes of the parents (≡70), polyploidized (≡140) and non-polyploidized progeny (≡70).

In vitro germination and reserve mobilization of Vriesea friburgensis Mez / Germinação in vitro e mobilização de reservas de Vriesea friburgensis Mez

Studies on the germination and establishment of plants are key pieces to understanding the reproductive success of plants. This work aimed to describe in vitro germination and reserve mobilization in the bromeliad Vriesea friburgensis through morphological, histochemical, and biochemical analysis. The conditions used in this study for the in vitro germination are adequate. From the third day of in vitro inoculation, a uniform germination of 98% was obtained, exhibiting a high physiological quality of the seeds and a high potential to produce seedlings (94%). There is early reserve mobilization, which began in the imbibition phase. The accumulated reserves in the endosperm cytoplasm are degraded by hydrolytic enzymes provided by the aleurone layer. It is possible that compounds in the cell walls of the endosperm contribute to a lesser extent in mobilization. Additionally, it was observed that starch accumulation in the cotyledon increases when the seedling has formed. Results from this study provide insights for future studies on ecology, seed technology, and conservation in this species. This study contributes to the limited knowledge of the dynamics of reserves during germination and seedling establishment in Bromeliaceae. To the best of our knowledge, this is the first study with this approach in the genus Vriesea.

Estudos sobre germinação e estabelecimento de plantas são peças-chave para entender o sucesso reprodutivo das plantas. Este trabalho teve como objetivo descrever a germinação in vitro e a mobilização de reservas na bromélia Vriesea friburgensis por meio de análises morfológicas, histoquímicas e bioquímicas. As condições utilizadas neste estudo para a germinação in vitro são adequadas. A partir do terceiro dia de inoculação in vitro, obteve-se germinação uniforme de 98%, apresentando alta qualidade fisiológica das sementes e alto potencial de produção de plântulas (94%). Há uma mobilização precoce de reservas, iniciada na fase de embebição. As reservas acumuladas no citoplasma do endosperma são degradadas por enzimas hidrolíticas fornecidas pela camada de aleurona. É possível que compostos nas paredes celulares do endosperma contribuam em menor grau na mobilização. Além disso, observou-se que o acúmulo de amido no cotilédone aumenta com a formação da plântula. Os resultados deste estudo fornecem informações para estudos futuros sobre ecologia, tecnologia de sementes e conservação desta espécie. Este estudo contribui para o conhecimento limitado da dinâmica das reservas durante a germinação e estabelecimento de plântulas em Bromeliaceae. Até onde sabemos, este é o primeiro estudo com esta abordagem no gênero Vriesea.

Production of dinizia excelsaducke (fabaceae) seedlings subjected to increasing doses of controlled release fertilizer / Produção de mudas de dinizia excelsaducke (fabaceae) submetidas a doses crescentes de fertilizante de liberação controlada

Dinizia excelsais one of the largest trees in the Amazon rainforest, with significant economic potential for the recovery of degraded areas. It is a key species for biodiversity and increased forestbiomass. However, studies related to seedling production of this species are still scarce. In this study, we evaluated the production and quality of D. excelsaseedlings in response to the application of controlled-release fertilizer doses. The experimental design was completely randomized, applying different doses of Osmocote®(T1=0; T2=4.1; T3=8.2; and T4=12.3 g.dm-³) with four replicates, using vermiculite and coconut fiber (1:1 v/v) as the substrate. We assessed the number of leaves and leaflets, shoot and root length, stem diameter, seedling height, shoot-to-stem diameter ratio, leaf area, dry mass of shoot, root, and total biomass. The data were subjected to analysis of variance and regression analysis. The seedlings responded positively to the use of Osmocote®, and starting from the 4.1 g.dm-³dose, biomass accumulation showed better results, making it a recommended practice that allows cost savings in seedling production of this species.(AU)

Dinizia excelsaé uma das maiores árvores da floresta amazônica, com grande potencial econômico para recuperação de áreas degradadas. Trata-se de uma espécie-chave para diversidade e aumento da biomassa florestal. Ainda são escassos os estudos relacionados à produção seminal de mudas da espécie. Nós avaliamos a produção e a qualidade de mudas de D. excelsaem resposta à aplicação de doses de adubo de liberação controlada. O delineamento adotado foi inteiramente casualizado, aplicando-se diferentes doses de Osmocote®(T1=0; T2=4.1; T3= 8.2 e T4=12.3 g.dm-³) com quatro repetições, utilizando-se como substrato vermiculita e fibra de coco (1:1 v/v). Foram avaliados número de folhas e folíolos, comprimento da parte aérea e raiz, diâmetro do coleto, altura das mudas, relação comprimento da parte aérea e diâmetro do coleto, área foliar, massa seca da parte aérea, raiz e total. Os dados foram submetidos à análise de variância e regressão. As mudas responderam positivamente ao uso do adubo Osmocote®e a partir da dose 4.1 g.dm-³o acúmulo de biomassa apresentou melhores resultados, podendo ser recomendada, permitindo uma economia nos custos de produção seminal de mudas da espécie.(AU)

Initial development of Euterpe oleracea Martin function containers used in the production of seedlings / Desenvolvimento inicial de Euterpe oleracea Mart em função de recipientes usados na produção de mudas

The açaizeiro (Euterpe oleracea Mart.) is a natural species of the lowland areas of the Amazon region, with the state of Pará as the largest center of natural dispersion of this palm. Much of its production comes from extractivism and has the potential to increase fruit production by projecting the scenario for the advancement of the species' cultivation to the mainland, but it needs to be framed in market standards, therefore, improvement must occur. of seedling production techniques. Thus, this work aimedto evaluate the initial development in açaí plants, produced in containers with different volumes and substrates, during 360 days in the field. The test was carried out in the experimental field of Embrapa Amazônia Oriental, in Belém, PA. Açaizeiro seedlings of the cultivar BRS Pará, produced in two types of substrates (commercial and conventional) were used. For the production of seedlings, the following types of containers were used: plastic bag with dimensions of 18x 24 cm (1900 cm³), which is recommended for the production of açaí seedlings and other fruit trees and tubes with volumes of 280, 175 and 95 cm³. The experiment was installed in a completely randomized block design, using four replications and five plants per plot. Field evaluations took place every 60 days after planting. The variables measured were: plant height, stem diameter and number of leaves. It was observed that the treatments in polyethylene bag had greater development in the analyzed variables,regardless of the substrate used. It was found that there was no significant difference between treatments resulting from seedlings produced in tubes. Therefore, it is concluded that the plants of E. oleracea Mart, cultivar BRS Pará, presented greater initial development when coming from seedlings produced in polyethylene bags in relation to the other containers.(AU)

O açaizeiro (Euterpe oleracea Mart.) é uma espécie natural dasáreas de várzea da região amazônica, sendo o estado do Pará como o maior centro de dispersão natural dessa palmeira. Grande parte de sua produção provém do extrativismo e possui potencial de incremento da produção de frutos ao projetar o cenário para o avanço do cultivo da espécie para a terra firme, mas necessita estar enquadrado nos padrões de mercado, portanto, deve-se ocorrer o aperfeiçoamento das técnicas de produção de mudas. Assim, o trabalho teve como objetivo avaliar o desenvolvimento inicial em plantas de açaizeiro, produzidas em recipientes com diferentes volumes e substratos, durante 360 dias em campo. O ensaio foi realizado no campo experimental da Embrapa Amazônia Oriental, em Belém, PA. Foram utilizadas mudas de açaizeiro da cultivar BRS Pará, produzidas em dois tipos de substratos (comercial e o convencional). Para a produção de mudas foram usados os seguintes tipos de recipientes: saco de plástico com as dimensões de 18 x 24 cm (1900 cm³), a qual é recomendada para a produção de mudas de açaizeiro e outras fruteiras e tubetes com volumes de 280, 175 e 95 cm³. O experimento foi instalado no delineamento experimental em blocos inteiramente casualizados, utilizando-se quatro repetições e cinco plantas por parcela. As avaliações em campo ocorreram a cada 60 dias após o plantio. As variáveis mensuradas foram: altura da planta, diâmetro do coleto e número de folhas. Observou-se que os tratamentos em saco de polietileno houve maior desenvolvimento nas variáveis analisadas, independente do substrato usado. Verificou-se que não houve diferença significativa entre os tratamentos resultantes de mudas produzidas em tubete. Portanto, conclui-se que as plantas de E. oleracea Mart, da cultivar BRS Pará, apresentaram maior desenvolvimento inicial quando oriundas de mudas produzidas em sacos de polietileno em relação aos demais recipientes.(AU)

Light-emitting diodes (LEDs) in development and response to water stress in Eucalyptus benthamii seedlings (Myrtaceae) / Uso de diodosemissores de luz (LEDs) no desenvolvimento e resposta a estresse hídrico em mudas de Eucalyptus benthamii (Myrtaceae)

Plants use light as a source of energy in the process of photosynthesis. Different levels of luminosity cause physiological and morphological changes in the plant, and its success depends on its adaptation to these different levels. Light emitting diodes (LED) have been proposed as a light source in controlled environments. The present research evaluated physiological and morphological aspects in Eucalyptus benthamii (Myrtaceae) seedlings kept under different colors of LED lamps and submitted to water stress. The experiment was carried out in a completely randomized design, in which the treatments were defined as: T1 (control, with white light); T2 (blue light); T3 (red light) and T4 (mixed blue and red light). Red light resulted in the best response to most morphological variables in plant growth. In response to water stress, blue light LEDs resulted in a better seedling response, with slower reduction of photosynthetic rate and other variables. This may indicate the possibility of reducing water deficit damage in seedlings acclimated to blue light prior to field planting.

As plantas utilizam a luz como fonte de energia no processo de fotossíntese. Diferentes níveis de luminosidade causam mudanças fisiológicas e morfológicas na planta, e o seu sucesso depende da sua adaptação a esses diferentes níveis. Diodos de emissão de luz (LED) têm sido propostos como fonte luminosa para ambientes controlados. O objetivo do presente trabalho foi avaliar aspectos fisiológicos e morfológicos em mudas de Eucalyptus benthamii (Myrtaceae) mantidas sob diferentes cores de lâmpadas LED e submetidas ao estresse hídrico. Foram realizados dois experimentos, sendo que um avaliou o efeito de diferentes cores de LEDs no crescimento das mudas e outro analisou o efeito das luzes na aclimatação das mudas e após exposição a deficit hídrico. O experiment foi conduzido em delineamento inteiramente casualizado, em que os tratamentos foram definidos como T1 (controle, com luz branca); T2 (luz azul); T3 (luz vermelha) e T4 (luz azul e vermelha mista). A luz vermelha resultou em melhor resposta para a maioria das variáveis morfológicas no crescimento das plantas. Emresposta ao estresse hídrico, os LEDs de luz azul resultaram em uma melhor resposta das mudas, reduzindo mais lentamente a taxa fotossintética e demais variáveis. Isso pode indicar a possibilidade de reduzir os danos de deficit hídrico nas mudas aclimatadas com luz azul anteriormente ao plantio a campo.

Protocol for in vitro rooting of Pyrus comunnis rootstocks / Protocolo de enraizamento in vitro de porta-enxertos de Pyrus comunnis

Effective protocols for in vitro rooting for woody fruit trees are still a challenge for in vitro seedling production, especially when there is a need to insert new cultivars or rootstocks. These protocols are essential to accelerate studies in plant breeding programs and for seedling distribution. This study evaluated the use of 6-Benzylaminopurine (IBA) in in vitro rooting of Pyruscomunnis rootstocks, clones 'OHxF87' and Pyrodwarf. Explant exposure times (0, 24, 48, 72, and 96 hours) to 20 mg L-1 IBA were tested for in vitro rooting. The exposure to IBA resulted in rooting rates above 80%, surpassing some results reported in the literature. The 24-hour treatment provided 81,81% survival, leading to an average growth of five roots with 19 mm length, for 'OHxF87' rootstock. The same exposure time resulted in the highest survival rate (75%) and the highest mean root number, seven roots per plant with 10 mm length, for 'PDW' rootstock. Root formation did not occur in the absence of synthetic auxin. Therefore, it can be concluded that a 24-hour exposure at 20 mg L-1 IBA was sufficient to promote in vitro rooting in 'OHxF87' and Pyrodwarf rootstocks'.

Protocolos eficazes de enraizamento in vitro de frutíferas lenhosas ainda são um desafio para produção de mudas in vitro, especialmente quando há necessidade de inserção de novas cultivares ou porta-enxerto. Esses protocolos são essenciais para acelerar estudos nos programas de melhoramento genético e também para distribuição posterior das mudas. Nesse sentido, o objetivo deste estudo foi avaliar a utilização da 6-Benzilaminopurina no enraizamento in vitro de porta-enxerto Pirus comunnis, clones 'OHxF87' e Pyrodwarf. Para o enraizamento, foi testado o tempo de exposição dos explantes ao AIB. Para tanto, foram utilizados 20 mg L-1 do fitohormônio nas horas 0, 24, 48, 72 e 96 horas. A exposição ao AIB resultou em taxas de enraizamento acima de 80%, superando alguns resultados encontrados na literatura. Para o porta-enxerto 'OHxF87', o tratamento de 24 horas proporcionou 81,81% de sobrevivência, promovendo em média cinco raízes com comprimento de 19 mm. O mesmo tratamento para o porta-enxerto 'PDW' resultou na maior taxa de sobrevivência (75%), bem como no maior número médio de raízes, sete raízes por planta, com comprimento de 10 mm. Na ausência de auxina sintética, a formação de raízes não ocorreu. Assim sendo, podemos concluir que o tempo de exposição de 24 horas a 20 mg L-1 de IBA foi suficiente para promover o enraizamento de porta-enxertos Pyrus communis de 'OHxF87' e 'PDW'.

Environmental factors on seasonal germination of different weedy rice(Oryza sativa L.) biotypes / Efeitos de fatores ambientais na germinação sazonal de diferentes biótipos de arroz vermelho (Oryza sativa L.)

ABSTRACT: Weedy biotypes of Oryza sativa L., (weedy rice) are a serious threat to rice production because of their flexibility in seed germination timing, variable growth forms, and high genetic diversity. Experiments were designed to determine the effects of storage conditions, osmotic stress, pH, salt stress, and burial depth on germination of weedy rice seeds in flooded or non-flooded conditions. Mature weedy rice seeds were gathered from rice fields in the different regions of Turkey. Three biotypes were selected and classified according to awn length; long awn, short awn and awnless. Seasonal germination patterns of weedy rice seeds in the laboratory after retrieval from various depths and timing were affected by burial depth, water regime, and exhumation timing across the treatments for all biotypes. The long and short awn biotypes had higher germination rates than the awnless biotype and did not have a seasonal germination pattern. Seed germination was initiated in the spring, peaked in summer and declined in the fall in flooded and non-flooded treatments for the awnless biotype. The most distinct differences in seedling emergence patterns were observed in awnless and long awn biotypes, and they emerged from 10 cm depth. Our results suggested that flooded conditions reduced the germination of weedy rice biotypes. Flooding rice paddies for a period of time after harvest may improve weedy rice control and decrease the weed population. In addition to deeper cultivation would be more effective in controlling all weedy biotypes since the majority of weed seedling emergence was from shallow depths.

RESUMO: Biótipos de Oryza sativa L., arroz vermelho, são uma séria ameaça à produção de arroz devido à sua flexibilidade no tempo de germinação das sementes, formas de crescimento variáveis e alta diversidade genética. Os experimentos foram projetados para entender os efeitos das condições de armazenamento, estresse osmótico, pH, estresse salino e profundidade de semeadura na germinação de sementes de arroz vermelho em condições de inundação ou não. Sementes maduras de arroz vermelho foram colhidas em campos de arroz em diferentes regiões da Turquia. Três biótipos foram selecionados e classificados de acordo com o comprimento da arista longa, curta e sem arista. Padrões sazonais de germinação de sementes de arroz vermelho no laboratório após a recuperação em várias profundidades e tempos foram afetados pela profundidade de semeadura, regime de água e tempo de permanência no solo entre os tratamentos para todos os biótipos. Os biótipos de arista longa e curta tiveram taxas de germinação mais altas do que o biótipo sem arista e não apresentaram um padrão de germinação sazonal. A germinação das sementes foi iniciada na primavera, atingiu o pico no verão e diminuiu no outono em tratamentos com alagamento e sem alagamento para o biótipo sem armação. As diferenças mais nítidas nos padrões de emergência de plântulas foram observadas em biótipos sem e com arista longa, e emergiram a partir de 10 cm de profundidade. Nossos resultados sugerem que as condições de inundação reduziram a germinação de biótipos de arroz vermelho Parece que inundar os arrozais por um período de tempo após a colheita pode melhorar o controle do arroz vermelho e diminuir a população de arroz vermelho. Além disso, o cultivo mais profundo seria mais eficaz no controle de todos os biótipos de arroz vermelho, uma vez que a maioria da emergência de plântulas de arroz vermelho ocorreu em profundidades rasas.

Commercial characteristics of coffee seedlings produced with different sources of phosphorus and plant growth-promoting bacteria / Características comerciais de mudas de café produzidas com diferentes fontes de fósforo e bactérias promotoras de crescimento de plantas

Considered the economic engine of many countries, the coffee culture represents an important component of the agricultural chain in Brazil. The growing values of commercialization, planting areas, and crop productivity require the acquisition of quality seedlings, which must receive adequate nutritional support through efficient fertilizers. Slow and controlled-release fertilizers, such as organominerals, gain prominence when it comes to increasing efficiency in the use of phosphorus, as well as plant growth-promoting bacteria (PGPB) with phosphate solubilizing characteristics. This study aimed to evaluate the effect of different sources of mineral and organomineral fertilizers, inoculated and non-inoculated with PGPB on the quality parameters of coffee seedlings. In general, the P sources used in the experiment positively interfered with the development of coffee seedlings. This proves that there is a need for nutritional supplementation for the good development of the seedlings. Among the sources used, the organomineral in granulated form showed better performance in coffee seedlings' growth and physiological parameters, proving to be a viable alternative to commonly used fertilizers. The addition of PGPB showed a significant advantage for seedling quality variables.

Considerado o motor econômico de muitos países, a cultura do café representa um importante componente da cadeia agrícola no Brasil. Os crescentes valores de comercialização, das áreas de plantio e da produtividade da cultura requerem aquisição de mudas de qualidade, que devem receber adequado aporte nutricional através do uso eficiente de fertilizantes. Fertilizantes de liberação lenta e controlada, a exemplo dos organominerais, ganham destaque quando se trata de aumento da eficiência no uso do fósforo, assim como as bactérias promotoras de crescimento de plantas (BPCP) com características solubilizadoras de fosfato. Esse estudo teve como objetivo avaliar o efeito de diferentes fontes de fertilizantes mineral e organomineral, inoculados e não inoculados com BPCP, sobre parâmetros de qualidade de mudas de café. De forma geral, as fontes de P utilizadas no experimento interferiram positivamente no desenvolvimento das mudas de café. Isso comprova que existe a necessidade de complementação nutricional para um bom desenvolvimento das mudas. Dentre as fontes utilizadas, o organomineral na forma granulada apresentou melhor desempenho nos parâmetros de crescimento e fisiológicos das mudas de café, mostrando ser uma alternativa viável aos fertilizantes comumente utilizados. A adição de BPCP apresentou vantagem significativa para as variáveis de qualidade das mudas.