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DOAJ Open Access 2026
Mediterranean Intercropping Production Systems: Challenges and Opportunities

Ermelinda Silva, Sara Najjari, Oren Shelef et al.

Intercropping is a pivotal strategy for achieving Sustainable Development Goal (SDG) number 2—<i>End hunger, achieve food security and improved nutrition and promote sustainable agriculture</i> (SDG 2)—by enhancing food security agroecosystem resilience and sustainability. By integrating diverse species within the same plot, this sustainable approach takes advantage of the beneficial interactions between them. The simultaneous cultivation of multiple crop species within the same field increases agricultural diversification and contributes to a more resilient production system, breaking the uniformity of modern intensive agriculture. The objective of this review is to evaluate intercropping practices throughout the Mediterranean, specifically in Southern Europe (Portugal, Spain, Italy, and Greece), North Africa (Morocco, Algeria, and Tunisia), and the Middle East (Turkey, Israel, and Jordan). This review intends to show advantages and disadvantages of intercropping and crops used and also highlight how intercropping systems affect crop production and quality, soil quality and microbiome, and proliferation of weeds, pests and diseases. The literature suggests that diversification in agriculture supports biodiversity and ecosystem services by the cultivation of diverse crop species together and, hence, may reduce independence in external outputs such as nutrient supply, pesticides and soil amendment. Despite the potential benefits of intercropping, the major caveats of this practice are the competition between different crops on resources, potential risks of plant protection, technical challenges of integrating the different requirements of each crop used in the system, and culture-related restrictions or regulations.

DOAJ Open Access 2024
Intercultural Competencies: Understanding High- vs. Low-Context Cultures

Pablo Lamino, John Diaz

This first publication in the Intercultural Competencies series provides valuable insights and recommendations on engaging diverse clientele by understanding and applying high-context and low-context cultural communication styles. Written by Pablo Lamino and John Diaz, and published by the UF/IFAS Department of Agricultural Education and Communication, November 2024.

Agriculture (General), Plant culture
DOAJ Open Access 2023
AMMI and GGE biplot analyses of Bambara groundnut [Vigna subterranea (L.) Verdc.] for agronomic performances under three environmental conditions

Vincent Ishola Esan, Grace Oluwasikemi Oke, Timothy Oyebamiji Ogunbode et al.

IntroductionThe two most common styles to analyze genotype-by-environment interaction (GEI) and estimate genotypes are additive main effects and multiplicative interaction (AMMI) and genotype + genotype × environment (GGE) biplot. Therefore, the aim of this study was to find the winning genotype(s) under three locations, as well as to investigate the nature and extent of GEI effects on Bambara groundnut production.MethodsThe experiment was carried out in the fields of three environments with 15 Bambara groundnut accessions using the randomized complete block design (RCBD) with three replications each in Ibadan, Osun, and Odeda. Yield per plant, fresh seed weight, total number of pods per plant, hundred seed weight, length of seeds, and width of seeds were estimatedResultsAccording to the combined analysis of variance over environments, genotypes and GEI both had a significant (p &lt; 0.001) impact on Bambara groundnut (BGN) yield. This result revealed that BGN accessions performed differently in the three locations. A two-dimensional GGE biplot was generated using the first two principal component analyses for the pattern of the interaction components with the genotype and GEI. The first two principal component analyses (PCAs) for yield per plant accounted for 59.9% in PCA1 and 40.1% in PCA2. The genotypes that performed best in each environment based on the “which-won-where” polygon were G8, G3, G2, G11, G6, and G4. They were also the vertex genotypes for each environment. Based on the ranking of genotypes, the ideal genotypes were G2 and G6 for YPP, G1 and G5 for FPW, G15 and G13 for TNPP, G3 and GG7 for HSW, G7 and G12 for LOS, and G10 and G7 for WOS. G8 was recorded as the top most-yielding genotype. G8, G4, G7, and G13 were high yielding and the most stable across the environments; G11, G14, and G9 were unstable, but they yielded above-average performance; G14, G12, G15, and G1 were unstable and yielded poorly, as their performances were below average. Bowen was the most discriminating and representative environment and is classified as the superior environment.DiscussionBased on the performance of accessions in each region, we recommend TVSU 455 (G8) and TVSU 458 (G3) in Bowen, TVSU 455 (G8) and TVSU 939 (G6) and TVSU 454 (G1) in Ibadan, and TVSU 158 (G2) and TVSU 2096 (G10) in Odeda. The variety that performed best in the three environments was TVSU 455 (G8). They could also be used as parental lines in breeding programs.

DOAJ Open Access 2023
Salt-responsive bermudagrass microRNAs and insights into light reaction photosynthetic performance

Shugao Fan, Erick Amombo, Sheila Avoga et al.

IntroductionBermudagrass (Cynodon dactylon L.) is a warm-season grass with high drought and salt tolerance. However, its cultivation as a silage crop is limited by its lower forage value when compared to other C4 crops. Because of its high genetic variability in abiotic stress tolerance, bermudagrass-mediated genetic breeding offers significant promise for introducing alternative fodder crops in saline and drought-affected regions, and improved photosynthetic capacity is one way for increasing forage yield.MethodsHere, we used RNA sequencing to profile miRNAs in two bermudagrass genotypes with contrasting salt tolerance growing under saline conditions.ResultsPutatively, 536 miRNA variants were salt-inducible, with the majority being downregulated in salt-tolerant vs sensitive varieties. Also, seven miRNAs putatively targeted 6 genes which were significantly annotated to light reaction photosynthesis. Among the microRNAs, highly abundant miRNA171f in the salt tolerant regime targeted Pentatricopeptide repeat-containing protein and dehydrogenase family 3 member F1 both annotated to electron transport and Light harvesting protein complex 1 genes annotated to light photosynthetic reaction in salt tolerant regime vs salt sensitive counterparts. To facilitate genetic breeding for photosynthetic capacity, we overexpressed miR171f in Medicago tracantula which resulted in a substantial increase in the chlorophyll transient curve, electron transport rate, quantum yield of photosystem II non photochemical quenching, NADPH and biomass accumulation under saline conditions while its targets were downregulated. At ambient light level the electron transport was negatively correlated with all parameters while the NADPH was positively associated higher dry matter in mutants. DiscussionThese results demonstrate that miR171f improves photosynthetic performance and dry matter accumulation via transcriptional repression of genes in the electron transport pathway under saline conditions and thus a target for breeding.

DOAJ Open Access 2023
α-Mangostin Content of Mangosteen Leaves (Garcinia mangostana L.) Based on Different Growing Conditions

Ira Rahmiyani, Anna Yuliana, Dea Helyani Rukmana et al.

Environmental factors, such as soil height, plant age, soil conditions, maintenance, and plant seeds influence the content of secondary metabolites in an organism. The growing conditions can also affect the content of active compounds in plants. Xanthone is an active compound in Garcinia mangostana Linn. One of its derivatives is α-mangostin, which has antioxidant, anticancer, antituberculosis and antihistamine effects. This study aimed to determine the effects of growing conditions on the levels of α-mangosteen in mangosteen leaf extract using Thin Layer Chromatography-Densitometry. Standard solution of α-mangosteen and ethyl acetate extract of mangosteen leaves (A and B samples) were analyzed with Camag TLC Scanner 3 using silica gel 60 F254 stationary phase and chloroform-ethyl acetate mobile phase (9:1). The results showed that the Rf values for standard solution of α-mangostin, sample A, and sample B were 0.65, 0.62, and 0.62, respectively. Meanwhile, the levels obtained from samples A and B were 2.10% ± 0.0755 and 2.07% ± 0.0321, respectively. Different growing conditions did not affect the level of α-mangostin ethyl acetate extract of mangosteen leaves.

Agriculture (General), Plant culture
DOAJ Open Access 2023
Priority conservation area of Larix gmelinii under climate change: application of an ensemble modeling

Minglong Gao, Guanghua Zhao, Guanghua Zhao et al.

Larix gmelinii (Rupr.) Kuzen is a major tree species with high economic and ecological value in the Greater Khingan Mountains coniferous forest of Northeast China. Reconstructing the priority Conservation Area of Larix gmelinii under Climate could provide a scientific basis for its germplasm conservation and management. The present study used ensemble and Marxan model simulations to predict species distribution areas and delineate priority conservation areas for Larix gmelinii in relation to productivity characteristics, understory plant diversity characteristics, and climate change impacts. The study revealed that the Greater Khingan Mountains and the Xiaoxing'an Mountains, with an area of approximately 300 974.2 km2, were the most suitable for L. gmelinii. The stand productivity of L. gmelinii in the most suitable area was significantly higher than that in the less suitable and marginally suitable areas, but understory plant diversity was not dominant. The increase in temperature under future climate change scenarios will reduce the potential distribution and area under L. gmelinii; the species will migrate to higher latitudes of the Greater Khingan Mountains, while the degree of niche migration will gradually increase. Under the 2090s-SSP585 climate scenario, the most suitable area for L. gmelinii will completely disappear, and the climate model niche will be completely separated. Therefore, the protected area of L. gmelinii was demarcated with a target of the productivity characteristics, understory plant diversity characteristics and climate change sensitive area, and the current key protected area was 8.38 × 104 km2. Overall, the study’s findings will lay a foundation for the protection and rational development and utilization of cold temperate coniferous forests dominated by L. gmelinii in the northern forested region of the Greater Khingan Mountains.

DOAJ Open Access 2022
First Isolation and Characterization of <i>Serratia liquefaciens</i> Associated with Rot Disease of <i>Malus domestica</i> (Apple) Fruit and Its Inhibition by <i>Origanum vulgare</i> (Oregano) Oil

Ashraf Khalifa

Microbial food spoilage has been a major source of concern because it widens the global food production-to-consumption gap. Thus, in the current study, we aimed to isolate, characterize and identify bacteria associated with spoiled apple fruit in Al-Ahsa city, Saudi Arabia. MDK33, a bacterial strain isolated from rotten apple fruit, was characterized at the phenotypic and genotypic levels. Furthermore, the antibacterial effect of oregano essential oil (OEO) against MDK33 was investigated. MDK33 formed circular colonies with entire margins, and the cells were Gram-negative rods with no endospores. Biochemical characterizations of MDK33, as revealed by the Biolog Gen III MicroPlate test system, indicated that the strain utilized 66 (~70%) of the 94 diverse metabolites and did not utilize 29 (~30%). MDK33 grew well on a variety of substrates, including pectin, gelatin, Tween 40 and dextrin, at pH 5 and 6; tolerated salts up to 4% NaCl; and was resistant to multiple antibiotics. Furthermore, based on the sequences of the 16S rRNA gene, MDK33 was identified as <i>Serratia liquefaciens</i> at a 99.73% identity level. Koch’s postulates were affirmed, confirming that <i>S. liquefaciens</i> MDK33 is the causative agent of apple rot disease in Al-Ahsa, Saudi Arabia. The minimum inhibitory concentration (MIC) of 0.23 mg/mL for oregano oil against <i>S. liquefaciens</i> MDK33 demonstrated remarkable antibacterial and antibiofilm activities. This is the first isolation of pathogenic <i>S. liquefaciens</i> as the causative agent of rot disease of apple fruit and its inhibition by oregano oil. Furthermore, the findings pave the way for oregano oil to be evaluated as a natural preservative to reduce post-harvest losses while maintaining high quality for sustainable food security in future studies.

DOAJ Open Access 2021
Comparison of C:N:P Stoichiometry in the Plant–Litter–Soil System Between Poplar and Elm Plantations in the Horqin Sandy Land, China

Kai Wang, Risheng Zhang, Lining Song et al.

Afforestation is among the most effective means of preventing and controlling desertification. Silver poplar (Populus alba) is commonly planted tree species for afforestation of the Horqin Sandy Land of China. However, this species has exhibited some drawbacks such as top shoot dieback, premature senescence and mortality, and soil and ecosystems degradation. In contrast, Siberian elm (Ulmus pumila) rarely experiences these problems in the same regions. Ecological stoichiometry plays a vital role in exploring ecological processes and nutrient cycle relationships in plant–litter–soil systems. To explore the differences in the carbon (C), nitrogen (N), and phosphorus (P) balance, the stoichiometry characteristics and stoichiometric homeostasis in elm and poplar plantations in the Horqin Sandy Land, we measured C, N, and P concentrations in leaves, branches, roots, litter, and soils and analyzed N and P resorption efficiencies in the two plantations. The results showed that soil C and N concentrations, C:P, and N:P were greater in the elm plantation than in the poplar plantation. The leaf and root C:P and N:P during summer and litter N and P concentrations were greater, whereas N and P resorption efficiencies were lower, in the elm plantation than in the poplar plantation. Generally, elm exhibited greater N:P homeostasis than poplar. N and N:P homeostasis were greater in roots than in leaves and branches in the elm plantation, but they varied with soil N concentration and N:P in the poplar plantation. These findings indicate that poplar exhibited more developed internal nutrient conservation and allocation strategies but poor nutrient accumulation in soil, which may contribute to degradation of poplar plantation. In contrast, elm tended to return more nutrients to the soil, showing an improved nutrient cycle in the plant–litter–soil system and increased soil C and N accumulation in the elm plantation. Therefore, compared with poplar, elm may be a more suitable afforestation tree species for the Horqin Sandy Land, in terms of promoting the accumulation of soil nutrients and enhancing nutrient cycling in the plant–litter–soil system.

DOAJ Open Access 2021
Arbuscular Mycorrhizal Fungi and Nutrition Determine the Outcome of Competition Between Lolium multiflorum and Trifolium subterraneum

Stephan Unger, Franziska M. Habermann, Katarina Schenke et al.

Arbuscular mycorrhizal fungi (AMF) may affect competitive plant interactions, which are considered a prevalent force in shaping plant communities. Aiming at understanding the role of AMF in the competition between two pasture species and its dependence on soil nutritional status, a pot experiment with mycorrhizal and non-mycorrhizal Lolium multiflorum and Trifolium subterraneum was conducted, with manipulation of species composition (five levels), and nitrogen (N)- and phosphorus (P)- fertilization (three levels). In the non-mycorrhizal state, interspecific competition did not play a major role. However, in the presence of AMF, Lolium was the strongest competitor, with this species being facilitated by Trifolium. While N-fertilization did not change the competitive balance, P-fertilization gave Lolium, a competitive advantage over Trifolium. The effect of AMF on the competitive outcome may be driven by differential C-P trade benefits, with Lolium modulating carbon investment in the mycorrhizal network and the arbuscule/vesicle ratio at the cost of Trifolium.

DOAJ Open Access 2021
Groundwater Depths Affect Phosphorus and Potassium Resorption but Not Their Utilization in a Desert Phreatophyte in Its Hyper-Arid Environment

Bo Zhang, Bo Zhang, Bo Zhang et al.

Nutrients are vital for plant subsistence and growth in nutrient-poor and arid ecosystems. The deep roots of phreatophytic plants are necessary to access groundwater, which is the major source of nutrients for phreatophytes in an arid desert ecosystem. However, the mechanisms through which changes in groundwater depth affect nutrient cycles of phreatophytic plants are still poorly understood. This study was performed to reveal the adaptive strategies involving the nutrient use efficiency (NUE) and nutrient resorption efficiency (NRE) of desert phreatophytes as affected by different groundwater depths. This work investigated the nitrogen (N), phosphorus (P), and potassium (K) concentrations in leaf, stem, and assimilating branch, as well as the NUE and NRE of the phreatophytic Alhagi sparsifolia. The plant was grown at groundwater depths of 2.5, 4.5, and 11.0 m during 2015 and 2016 in a desert-oasis transition ecotone at the southern rim of the Taklimakan Desert in northwestern China. Results show that the leaf, stem, and assimilating branch P concentrations of A. sparsifolia at 4.5 m groundwater depth were significantly lower than those at 2.5 and 11.0 m groundwater depths. The K concentrations in different tissues of A. sparsifolia at 4.5 m groundwater depth were significantly higher than those at 2.5 and 11.0 m groundwater depths. Conversely, the NRE of P in A. sparsifolia was the highest among the three groundwater depths, while that of K in A. sparsifolia was the lowest among the three groundwater depths in 2015 and 2016. The N concentration and NUE of N, P, and K in A. sparsifolia, however, were not influenced by groundwater depth. Further analyses using structural equation models showed that groundwater depth had significant effects on the P and K resorption of A. sparsifolia by changing soil P and senescent leaf K concentrations. Overall, our results suggest groundwater depths affect P and K concentrations and resorption but not their utilization in a desert phreatophyte in its hyper-arid environment. This study provides a new insight into the phreatophytic plant nutrient cycle strategy under a changing external environment in a hyper-arid ecosystem.

DOAJ Open Access 2021
Construction of a High-Density Genetic Map for Pitaya Using the Whole Genome Resequencing Approach

Zhijiang Wu, Haiyan Deng, Guidong Liang et al.

Pitaya (<i>Hylocereus undatus</i>) is one of the most economic fleshy fruit tree crops. This study aimed at producing a high-density linkage genetic map of pitaya based on the whole genome resequencing (WGrS) approach. For this purpose, a bi-parental F1 population of 198 individuals was generated and genotyped by WGrS. High-quality polymorphic 6434 single polymorphism nucleotide (SNP) markers were extracted and used to construct a high-density linkage map. A total of 11 linkage groups were resolved as expected in accordance with the chromosome number. The map length was 14,128.7 cM with an average SNP interval of 2.2 cM. Homology with the sequenced reference genome was described, and the physical and genetic maps were compared with collinearity analysis. This linkage map in addition to the available genomic resources will help for quantitative trait mapping, evolutionary studies and marker-assisted selection in the important <i>Hylocereus</i> species.

DOAJ Open Access 2019
Membrane-Specific Targeting of Tail-Anchored Proteins SECE1 and SECE2 Within Chloroplasts.

Stacy A. Anderson, Rajneesh Singhal, Donna E. Fernandez

Membrane proteins that are imported into chloroplasts must be accurately targeted in order to maintain the identity and function of the highly differentiated internal membranes. Relatively little is known about the targeting information or pathways that direct proteins with transmembrane domains to either the inner envelope or thylakoids. In this study, we focused on a structurally simple class of membrane proteins, the tail-anchored proteins, which have stroma-exposed amino-terminal domains and a single transmembrane domain within 30 amino acids of the carboxy-terminus. SECE1 and SECE2 are essential tail-anchored proteins that function as components of the dual SEC translocases in chloroplasts. SECE1 localizes to the thylakoids, while SECE2 localizes to the inner envelope. We have used transient expression in Arabidopsis leaf protoplasts and confocal microscopy in combination with a domain-swapping strategy to identify regions that contain important targeting determinants. We show that membrane-specific targeting depends on features of the transmembrane domains and the short C-terminal tails. We probed the contributions of these regions to targeting processes further through site-directed mutagenesis. We show that thylakoid targeting still occurs when changes are made to the tail of SECE1, but changing residues in the tail of SECE2 abolishes inner envelope targeting. Finally, we discuss possible parallels between sorting of tail-anchored proteins in the stroma and in the cytosol.

DOAJ Open Access 2019
Have you seen a skinny alligator in south Florida? [trifold brochure]

Michiko Squires, Avishka Godahewa, Justin R. Dalaba et al.

This is a trifold brochure based on the fact sheet by the same title, http://edis.ifas.ufl.edu/uw460 The American alligator (Alligator mississippiensis) is an effective indicator for restoration of more natural patterns of water levels and flows through the Everglades. The Florida Everglades is a highly modified system, so monitoring health of alligators can inform how different areas of this large ecosystem are doing. Based on an increase in reports of very skinny alligators, biologists and natural resource managers are seeking help from the public to better understand where and when this problem occurs. This brochure serves as a guide for citizen scientists on how to score alligator body condition and report sightings of very skinny or unhealthy alligators. https://edis.ifas.ufl.edu/uw461 Accessibility Summary: In accordance with Title II regulations this content meets all points of exemption as Archived web content and/or Preexisting conventional electronic documents.

Agriculture (General), Plant culture
DOAJ Open Access 2019
Ginkgo biloba extract increases neurite outgrowth and activates the Akt/mTOR pathway.

Imane Lejri, Amandine Grimm, Anne Eckert

<h4>Background</h4>Standardized Ginkgo biloba extract (GBE) has demonstrated efficacy in the cognitive functional neuropsychiatric symptoms of patients with Alzheimer's disease (AD). With regard to its underlying molecular mode of action, first evidence was provided that GBE was able to modulate neuronal outgrowth in vitro, but the mechanisms underlying GBE effects on neuroplasticity remain unclear.<h4>Methodology/principal findings</h4>In this study, we investigated the effect of GBE on neurite outgrowth using SH-SY5Y neuroblastoma cells in a 2D and 3D surface culture. The effects of the GBE LI1370 on neuroplasticity and neurite outgrowth were compared to those of nerve growth factor (NGF, 50 ng/ml) which was used as a positive control. We evaluated several parameters of neurite outgrowth such as the neurite number, total neurite length and extend of branching. Our findings showed that GBE (10 and 100 μg/ml) significantly increased neurite outgrowth in the 2D as well as 3D culture model after 3 days of treatment with a comparable effect than that NGF. The use of the 3D cell culture allowed us to better reproduce the in vivo neuronal microenvironment for the evaluation the neurite formation after GBE treatment. In addition, we assessed the effects of GBE on the Akt/mTOR pathway, which is known to promote neuroplasticity induced by nerve growth factors. We showed that GBE treatment induced an increase of phosphorylated IGF1R (Tyr1135/Tyr1136), Akt (Ser473), TSC2 (Ser939), mTOR (Ser2448), PTEN (Ser380) and GSK3β (Ser9).<h4>Conclusion</h4>Together, these findings indicate that GBE promotes neurite growth and activates the PI3K/Akt/mTOR pathway suggesting that this plant extract supports neuronal plasticity.

Medicine, Science
DOAJ Open Access 2016
Comparative transcriptomic analysis of virulence factors in Leptosphaeria maculans during compatible and incompatible interactions with canola

Humira Sonah, Xuehua Zhang, Rupesh Kailasrao Deshmukh et al.

Leptosphaeria maculans is a hemibiotrophic fungus that causes blackleg of canola (Brassica napus), one of the most devastating diseases of this crop. In the present study, transcriptome profiling of L. maculans was performed in an effort to understand and define the pathogenicity genes that govern both the biotrophic and the necrotrophic phase of the fungus, as well as those that separate a compatible from an incompatible interaction. For this purpose, comparative RNA-seq analyses were performed on L. maculans isolate D5 at four different time points following inoculation on susceptible cultivar Topas-wild or resistant near isogenic line Topas-Rlm2. Analysis of 1.6 billion Illumina reads readily identified differentially expressed genes that were over represented by candidate secretory effector proteins, CAZymes, and other pathogenicity genes. Comparisons between the compatible and incompatible interactions led to the identification of 28 effector proteins whose chronology and level of expression suggested a role in the establishment and maintenance of biotrophy with the plant. These included all known Avr genes of isolate D5 along with eight newly characterized effectors. In addition, another 15 effector proteins were found to be exclusively expressed during the necrotrophic phase of the fungus, which supports the concept that L. maculans has a separate and distinct arsenal contributing to each phase. As for CAZymes, they were often highly expressed at 3 dpi but with no difference in expression between the compatible and incompatible interactions, indicating that other factors were necessary to determine the outcome of the interaction. However, their significantly higher expression at 11 dpi in the compatible interaction confirmed that they contributed to the necrotrophic phase of the fungus. A notable exception was LysM genes whose high expression was singularly observed on the susceptible host at 7 dpi. In the case of TFs, their higher expression at 7 and 11 dpi on susceptible Topas support an important role in regulating the genes involved in the different pathogenic phases of L. maculans. In conclusion, comparison of the transcriptome of L. maculans during compatible and incompatible interactions has led to the identification of key pathogenicity genes that regulate not only the fate of the interaction

DOAJ Open Access 2010
Formas de aplicação de nitrogênio em três cultivares de girassol na savana de Roraima Different ways of nitrogen placements in three cultivars of sunflower in the savannah of Roraima

Maria Elena Almeida Ivanoff, Sandra Cátia Pereira Uchôa, José Maria Arcanjo Alves et al.

O nitrogênio é o nutriente que mais limita a produção na cultura do girassol (Helianthus annuus L). A exigência entre cultivares da mesma espécie é distinta, mesmo sob as mesmas condições de cultivo. Objetivando avaliar quatro formas de aplicação do nitrogênio nos componentes de produção de três cultivares de girassol, foi realizado um experimento em delineamento de blocos casualizados em esquema fatorial (3 x 4), com quatro repetições. Os tratamentos consistiram da combinação de três cultivares de girassol: Agrobel 960, Agrobel 962 e Embrapa 122/V2000 e quatro formas de aplicação da dose de 60 kg ha-1 de N: 100% aos 20 dias após a semeadura (DAS) - (0-100-0-0); 30% na semeadura e 70% aos 20 DAS - (30-70-0-0); 30% na semeadura, 30% aos 20 DAS e 40% aos 40 DAS (30-30-40-0); 20% na semeadura, 30% aos 20 DAS, 30% aos 40 DAS e 20% aos 60 DAS (20-30-30-20). As variáveis avaliadas foram: altura de plantas, altura do capítulo, diâmetro da haste, diâmetro do capítulo e a produção de aquênios. A forma de aplicação do N (30-70-0-0) determinou os melhores resultados para as variáveis estudadas, mas a forma (30-30-40-0) proporcionou resultados comparáveis ao tratamento (30-70-0-0); O tratamento onde o N foi aplicado na forma (20-30-30-20) determinou redução no desempenho do girassol em todas as variáveis estudadas. O efeito varietal foi observado apenas para altura da planta e altura do capítulo. A produtividade de aquênios alcançada foi de 1.639 kg ha-1, não havendo superioridade dos híbridos Agrobel 960 e Agrobel 962 em relação à variedade Embrapa 122/V2000.<br>Nitrogen is the nutrient that limits most the production in the culture of sunflower (Helianthus annuus L). The nutritional requirements among cultivars of the same species is distinct, under the same conditions of culture and for the same agricultural year. With the objective of evaluating four different ways of nitrogen application in the production components of different genotypes of sunflower, an experiment was carried out in a randomized block design in a 3 x 4 factorial scheme (genotypes x ways of nitrogen applying) with four replicates . The treatments consisted on the combination of three varieties: Agrobel 960, Agrobel 962 and V - 2000 and four different ways of nitrogen application: 100% at 20 days after sowing (DAS) - (0-100-0-0); 30% at sowing and 70% at 20 DAS - (30-70-0-0); 30% at sowing, 30% at 20 DAS e 40% at 40 DAS (30-30-40-0); 20% at sowing, 30% at 20 DAS, 30% at 40 DAS e 20% at 60 DAS (20-30-30-20). Measured variables were: height of the plant, height of the capitulum, diameter of the stem, diameter of the capitulum and achene yield. The ways of nitrogen application affected all components of yield. The N formulation (30-70-0-0) has determined the best results for the variables studied, but the form (30-30-40-0) provided results comparable to treatment (30-70-0-0); treatments where N was applied as (20-30-30-20) caused decrease in the performance of sunflower for all variables. The varietal effect was observed only for plant height and height of the capitulum. The highest yield of achene achieved was 1.639 kg ha-1, with no superiority for the hybrids Agrobel 960 and 962 in relation to the variety 122/V2000 Embrapa.

Agriculture (General)

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