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O objetivo deste estudo foi comparar diferentes ferramentas de tomada de decisão no controle da ferrugem asiática da soja. Para isso, foram realizados experimentos nas safras de 2022/23 e 2023/24 usando as seguintes estratégias de tomada de decisão: i) aplicações preventivas de fungicidas, ii) caça esporos, iii) sistema de vulnerabilidade climática (Plataforma Agroconnect) e iv) aplicações curativas de fungicidas após constatação de sintomas. Os resultados sugerem a importância das aplicações de fungicidas, especialmente de forma preventiva, como medida ainda eficaz e confiável para proteger as plantas de soja contra a ferrugem-asiática-da-soja, garantindo assim uma maior estabilidade na produção e rentabilidade dos produtores.

We investigate and characterize the morphophysiological changes related to germination and the initial growth and development of seedlings of wild and cultivated genotypes of the genus Hevea spp. in finding to add value to new clones. Seeds from six genotypes (H. brasiliensis (Willd. Ex A. Juss) Mull. Arg, H. guianensis Aubl., H. spruceana (Benth.) Mull. Arg., RRIM 600, Fx 3844, and IAN 873) were sterilized, and their imbibition curve, germination parameters, and initial seedling growth were characterized. In parallel, the morphology of the germination and post-germination stages was monitored from seeds germinated in washed sand. Morphological differences in the seeds/embryos, different strategies in the imbibition process, emergence, and initial seedling growth were observed. The species H. guianensis and H. spruceana showed the greatest differences in size, shape, and color of the seeds/embryos and initial seedling growth. The characteristics of the seed coat patterns, the seedling imbibition, growth, and development processes can serve as morphophysiological markers for genotype identification and selection. This is the first morphophysiological study of seeds and seedlings of wild and cultivated genotypes of species of the genus Hevea. We conclude that there is considerable phenotypic variability among species of the Hevea genus regarding seed and seedling morphophysiology, which can be explored in the rubber tree breeding programs. Key words: phenotypic variation, seed imbibition, rubber tree, wild and cultivated genotypes, Introduction Species of the genus Hevea belong to the Euphorbiaceae family and are distributed in the Brazilian Amazon and Bolivia, Colombia, Peru, Venezuela, Ecuador, Suriname, and Guyana. Among the species [...]

Abstract Background Titanium dioxide nanoparticles (TiO2 NPs) have been reported to have contrasting effects on plant physiology, while their effects on sugar, protein, and amino acid metabolism are poorly understood. In this work, we evaluated the effects of TiO2 NPs on physiological and agronomical traits of tomato (Solanum lycopersicum L.) seedlings. Tomato seeds were treated with TiO2 NPs (1000 and 2000 mg L− 1), TiO2 microparticles (µPs, 2000 mg L− 1) as the size control, and ultrapure water as negative control. Results The dry matter of stems (DMs), leaves (DMl) and total dry matter (DMt) decreased as particle concentration increased. This trend was also observed in the maximum quantum yield of light-adapted photosystem II (PSII) (Fv´/Fm´), the effective quantum yield of PSII (ΦPSII), and net photosynthesis (Pn). The concentrations of sugars, total soluble proteins, and total free amino acids were unaffected, but there were differences in the daily dynamics of these compounds among the treatments. Conclusion Our results suggest that treating tomato seeds with TiO2 might affect PSII performance, net photosynthesis and decrease biomass production, associated with a concentration- and size-related effect of TiO2 particles.

This study evaluated the effect of salicylic acid (SA) application on yield, fruit quality, and post-harvest storage in Prunus avium subjected to deficit irrigation (DI). A field experiment with six-year-old P. avium cv. Lapins was performed under two water treatments: irrigation at 100% of crop evapotranspiration (ETc) [full irrigation (FI)] and irrigation at 60% ETc from the second fruit phase to harvest time (DI). A single 0.5 mM SA was applied to both water treatments at fruit color change. At harvest time, fruits were collected to determine yield, fruit quality, and quality during post-harvest storage (0, 10, 20, and 30 days). The DI reduced fruit yield (11%), fruit weight (8%), and caliber (6%) and increased firmness (7%) and total soluble solids (TSS) (5%) in P. avium compared with FI plants at harvest time. Our study showed that SA application recovered fruit yield (9%), fruit weight (5%), and caliber (4%), improving TSS in DI plants at day 0. Interestingly, SA application significantly reduced P. avium fruit cracking (78% in FI and 82% in DI). Fruit weight was reduced in all treatments, mainly decreasing by 14% in FI and 13% in DI plants at day 30 of post-harvest storage. Fruit weight did not change during post-harvest storage with SA, except on day 30, where a slight reduction was observed. TSS showed no significant differences during post-harvest storage for all treatments. Therefore, SA could be an interesting tool to mitigate the impact of DI on the yield and fruit quality of P. avium and to reduce fruit cracking and prolong fruit quality during post-harvest storage.

In this study, the physiological performance and fruit quality responses of the highbush blueberry (Vaccinium corymbosum) cultivar Legacy to high temperatures (HTs) were evaluated in a field experiment. Three-year-old V. corymbosum plants were exposed to two temperature treatments between fruit load set and harvest during the 2022/2023 season: (i) ambient temperature (AT) and (ii) high temperature (HT) (5 °C ± 1 °C above ambient temperature). A chamber covered with transparent polyethylene (100 µm thick) was used to apply the HT treatment. In our study, the diurnal temperature was maintained with a difference of 5.03 °C ± 0.12 °C between the AT and HT treatments. Our findings indicated that HT significantly decreased CO2 assimilation (Pn) by 45% and stomatal conductance (gs) by 35.2% compared to the AT treatment. By contrast, the intercellular CO2 concentration (Ci) showed higher levels (about 6%) in HT plants than in AT plants. Fruit quality analyses revealed that the fruit weight and equatorial diameter decreased by 39% and 13%, respectively, in the HT treatment compared to the AT treatment. By contrast, the firmness and total soluble solids (TSS) were higher in the HT treatment than in the AT treatment. Meanwhile, the titratable acidity showed no changes between temperature treatments. In our study, Pn reduction could be associated with stomatal and non-stomatal limitations under HT treatment. Although these findings improve our understanding of the impact of HTs on fruit growth and quality in V. corymbosum, further biochemical and molecular studies are need.

Boron (B) is a micronutrient crucial for the growth, development, productivity, and quality of crops. However, in areas characterized by acid soil (pHwater < 5.0) and high rainfall, soil B concentration tends to decrease, leading to insufficient supply to crops. This study was aimed at determining the optimal rate of B fertilization to enhance Vaccinium corymbosum L. performance in acid conditions. One-year-old cultivars with contrasting Al resistance (Al-sensitive Star and Al-resistant Cargo) were used. Plants were conditioned in plastic pots containing 18 L of half-ionic-strength Hoagland solution (pH 4.5) for 2 weeks. Thereafter, the following B treatments were applied foliarly: control, without B application (distilled water), 200, 400, and 800 mg L−1 of B as Solubor® for up to 72 h. Photosynthetic performance, root and shoot B levels, antioxidants, and oxidative stress were evaluated. Root and shoot B concentrations increased with the increasing B application, being higher in leaves than in roots of both cultivars. Net photosynthesis decreased at 800 mg L−1 B supply and effective quantum yield of PSII at 72 h in all B treatments. Lipid peroxidation increased in both cultivars at 800 mg L−1 B treatment. Antioxidant activity increased in all B treatments in both cultivars; while, at 400 and 800 mg L−1 B, total phenols increased in leaves of cultivar Star and decreased in cultivar Cargo. In conclusion, optimal B foliar application for highbush blueberry appears to be around 400 mg L−1 B. The appropriate B foliar application could help mitigate potential stress-induced problems in highbush blueberry cultivation. However, the optimal foliar B application should be confirmed in field experiments to help the farmers manage B nutrition.

Boron (B) is an essential microelement for plants, and its deficiency can lead to impaired development and function. Around 50% of arable land in the world is acidic, and low pH in the soil solution decreases availability of several essential mineral elements, including B, magnesium (Mg), calcium (Ca), and potassium (K). Plants take up soil B in the form of boric acid (H3BO3) in acidic soil or tetrahydroxy borate [B(OH)4]- at neutral or alkaline pH. Boron can participate directly or indirectly in plant metabolism, including in the synthesis of the cell wall and plasma membrane, in carbohydrate and protein metabolism, and in the formation of ribonucleic acid (RNA). In addition, B interacts with other nutrients such as Ca, nitrogen (N), phosphorus (P), K, and zinc (Zn). In this review, we discuss the mechanisms of B uptake, translocation, and accumulation and its interactions with other elements, and how it contributes to the adaptation of plants to different environmental conditions. We also discuss potential B-mediated networks at the physiological and molecular levels involved in plant growth and development.

Macrospora leaf spot (MLS), caused by the fungus Stenocarpella macrospora, is one of the most important diseases affecting maize in Brazil. However, there are no MLS-resistant cultivars commercially available. Therefore, this study aimed to investigate the lesion expansion rate of MLS in four maize genotypes, leaf wetness duration (0-, 6-, 12-, 18-, 24-, 30-, 36-, 42-, and 54-hour post-inoculation), disease development severity in three maize genotypes, and resistance/tolerance levels to MLS in 141 maize genotypes commercially grown in Brazil. The estimates were performed using logistic models adjusted to the parameters analyzed, except for resistance/tolerance levels, which were analyzed using proposed severity and resistance scales. The experiment was carried out at the Laboratory of Plant Phytopathology of the Epagri/Cepaf, Santa Catarina State, Brazil, from 2016 to 2020. Disease resistance was significantly different among genotypes and fungal isolates. However, none of the genotypes showed resistance or high tolerance levels to MLS. Leaf wetness duration influenced maximum disease severity, and lesion expansion rate differed significantly among the genotypes tested. All information generated in this study is essential for breeding programs of maize for MLS resistance

A competitividade do agronegócio brasileiro depende da utilização de práticas sustentáveis de cultivo, que respeitem o meio ambiente e estejam de acordo com as exigências dos consumidores. Uma prática essencial em qualquer sistema de produção é o manejo de plantas daninhas. Assim, o objetivo deste trabalho foi realizar o levantamento fitossociológico de plantas espontâneas, o seu aporte de matéria seca e o rendimento de grãos em áreas de milho e soja, conduzidos nos sistemas sustentável e convencional. O estudo foi instalado em uma área de 17,11ha, dividida em quatro talhões (T): T 1 - sustentável com 5,25ha; T 2 - convencional com 4,85ha; T 3 - convencional com 3,88ha; T 4 - sustentável com 3,13ha, em sistema de rotação milho x soja. Os talhões sustentáveis foram localizados ao lado dos talhões convencionais com soja e milho para estabelecer o comparativo. Em cada talhão foram georreferenciados 10 pontos para a coleta de amostras de plantas espontâneas e para determinar o rendimento das culturas durante quatro anos. As espécies de plantas espontâneas e de coberturas foram identificadas e colocadas em estufa para secagem a 60°C até obterem a massa constante para a determinação da massa seca. A riqueza de espécies variou conforme sistema e safra. O incremento de resíduos vegetais no sistema sustentável reduziu a presença de nabiça, buva e erva-estrela. Em 2018, o rendimento da soja sustentável superou o convencional e em 2020 o milho convencional superou o sustentável. Nos demais anos os rendimentos se mostraram semelhantes.

Peach palm tree products, including palm hearts, are in high demand worldwide, often consumed either in natura or with minimal processing, and possess significant economic value in various markets. Minimally processed peach palm (Bactris gasipaes Kunth) are suitable to yellowing during storage thereby compromising its market value. In order to understand the surface yellowing in different sections of palm heart (median and basal regions), packaged or un-packaged with PVC were evaluated for anatomical and metabolic changes during 0, 4, 8, and 12 days of cold storage. The tissues showed surface yellowing at the end of cold storage. The outer cell layers exhibited differentiating parenchymal and dermal tissues, and superficial cells collapsed in the yellowing tissues. The metabolite analysis indicated reduction in the contents of some tricarboxylic acid cycle intermediates, sugars, and antioxidants in minimally processed palm heart during cold storage. The reduction in these compounds boosted the biosynthesis of amino acids in the peach palm. The highest metabolic changes and yellowing were observed after 8 days of storage, with higher intensity at 12 days, suggesting loss of quality, nutritional value, and shelf-life. Changes in the metabolites were mostly affected by storage time, and packaging with PVC provides better conditions for maintaining post-harvest quality. This pioneering study on the metabolism and anatomy of minimally processed peach palm heart fills some gaps about the yellowing, quality, and shelf life of this product.

ABSTRACT The incidence of the olive caterpillar Palpita forficifera is among the main phytosanitary problems in olive groves in Brazil, and the use of resistant cultivars can be a useful tool to be incorporated into an integrated management strategy of this pest. The objective of this study was to evaluate the consumption and oviposition of P. forficifera on three olive cultivars in laboratory bioassays, in order to identify a potential antixenosis-type resistance. The cultivars evaluated were Arbequina, Arbosana and Koroneiki. Oviposition free choice tests were carried on young trees of the cultivars, with 7 days old adults. For consumption, detached leaves from the different cultivars were used in no choice and free choice tests with 5th instar larvae. The oviposition of P. forficifera was similar in all three cultivars. As for consumption, in no choice test, Arbequina had a higher dry mass consumed, yet, in free choice tests, no significant difference was observed in the fresh and dry mass consumed on the three cultivars. These results suggest that none of the cultivars expressed antixenosis-type resistance.

Diatoms outcompete other phytoplankton for nitrate, yet little is known about the mechanisms underpinning this ability. Genomes and genome-enabled studies have shown that diatoms possess unique features of nitrogen metabolism however, the implications for nutrient utilization and growth are poorly understood. Using a combination of transcriptomics, proteomics, metabolomics, fluxomics, and flux balance analysis to examine short-term shifts in nitrogen utilization in the model pennate diatom in Phaeodactylum tricornutum, we obtained a systems-level understanding of assimilation and intracellular distribution of nitrogen. Chloroplasts and mitochondria are energetically integrated at the critical intersection of carbon and nitrogen metabolism in diatoms. Pathways involved in this integration are organelle-localized GS-GOGAT cycles, aspartate and alanine systems for amino moiety exchange, and a split-organelle arginine biosynthesis pathway that clarifies the role of the diatom urea cycle. This unique configuration allows diatoms to efficiently adjust to changing nitrogen status, conferring an ecological advantage over other phytoplankton taxa.

Abstract Heterosis for agronomic traits is a widespread phenomenon that underpins hybrid crop breeding. However, heterosis at the level of cellular metabolites has not yet been fully explored. Some metabolites are highly sought after, like capsaicinoids found in peppers of the Capsicum genus, which confer the characteristic pungent (‘hot’) flavour of the fruits. We analysed the metabolic profile of the fruit placenta and pericarp of inter- and intra-specific hybrids of two species of Capsicum peppers, C. chinense (cv. Habanero and cv. Biquinho) and C. annuum var. annuum (cv. Jalapeño and cv. Cascadura Ikeda) in complete diallel crosses with reciprocals. The parents and hybrids were grown in a glasshouse and the profile of primary metabolites (sugars, amino acids and organic acids) and capsaicinoids was generated via gas chromatography–time of flight-mass spectrometry (GC–TOF-MS) and ultra-performance liquid chromatography coupled to a mass spectrometer (UPLC-MS), respectively. We found considerable heterotic effects specifically for capsaicinoids accumulation in the fruit placenta of the hybrids, including those derived from non-pungent parents. Furthermore, a large fraction of fruit primary metabolism was influenced by the specific cross combination, with marked parent-of-origin effects, i.e. whether a specific genotype was used as the pistillate or pollen parent. The differences in metabolite levels between the hybrids and their parents provide a snapshot of heterosis for primary and secondary metabolites and may contribute to explain the manifestation of whole-plant heterotic phenotypes.