ABSTRACT Red chili pepper Capsicum annuum L. var. annuum plants are one of the fruity vegetable types that are often cultivated in riparian tropical wetlands but are constrained by water stress such as waterlogging during rainy season and drought in dry season. The aim of this research was to evaluate the growth and morpho-physiological responses of red chili pepper cultivars subjected to waterlogging and drought stress conditions. The experiment was carried out in a strip-plot design with two factors. The first factor was three water stress treatments, namely control (field capacity), waterlogging, and drought. The second factor was six cultivars of Indonesian red chili pepper. The findings indicated that both waterlogging and drought stress had a detrimental impact on the reduction of the growth parameters of red chili pepper such as root, shoot and total dry weight. Chili pepper defended its root weights in response to drought stress (0.653 g plant-1) whereas it preserved shoot weight in response to waterlogging (0.913 g plant-1). In the morphological characters, chili pepper exhibited an increase in specific leaf area expansion in response to both waterlogging (150.82 cm2) and drought (188.82 cm2) compared to control (140.91 cm2), but decreased specific leaf weight during stresses and recovered after 7 d in waterlogging. Leaf chlorophyll content (SPAD) and leaf relative water content (LRWC), as physiological characteristics, also experienced a decline during exposure to both waterlogging and drought during 8 d; yet, SPAD and LRWC able to recover completely at 7 d after waterlogging and drought treatment were terminated.

Abstract Introduction. Nitrogen (N) is an essential element for the photosynthesis process, and therefore, a determining factor in yield. The use of optical sensors to determine transmittance indices (SPAD, CCI), reflectance (NDVI) and fluorescence (Fv.Fm -1) related to the state of foliar N, allows adequate management based on non-destructive "in situ" monitoring. Objective. To evaluate the effect of different fertigation management strategies on nitrogen and chlorophyll concentration in the leaf; and the relationship between i- N and Cl concentration in leaf, ii- N and Cl concentration in leaf with yield and iii- N and Cl concentration in leaf with SPAD, CCI, NDVI and Fv.Fm -1 indices. Materials and methods. Six treatments were evaluated in an unrestricted randomized design with a 2 x 3 factorial arrangement, which combined 2 irrigation strategies (E1: low volume and more frequent and E2: high volume and less frequent) and 3 levels of nutrition: low (NB), medium (NM) and high (NA). The direct measurements of N and Cl in the leaf were determined with the Kjeldahl method and by ethanol extraction, respectively. Results. Nutrition level affected N content, where the NM and NA treatments were similar, although higher than NB. The regression model showed little ability to estimate N and yield from the Cl content in the leaf. Estimation of Cl in the leaf from the CCI (R2: 0.71) and SPAD (R2: 0.75) indices were only promising in NB. To estimate foliar N, the regression with Fv.Fm -1 showed R2 values of 0.89 in NB and 0.69 in NM; while for NDVI the R2 values were 0.61 in NB and 0.47 in NM. Conclusion. SPAD, CCI, NDVI and Fv.Fm -1 indices showed potential to estimate chlorophyll and N concentration in the leaf with low and medium nutrient inputs, and with limitations in treatments with high nutrient inputs.

Resumen Introducción. El nitrógeno (N) es un elemento esencial para el proceso de fotosíntesis, y por tanto, determinante en el rendimiento. El uso de sensores ópticos para determinar índices de transmitancia (SPAD, CCI), reflectancia (NDVI) y fluorescencia (Fv.Fm -1) relacionados con el estado del N foliar, permite un adecuado manejo a partir del monitoreo “in situ” no destructivo. Objetivo. Evaluar el efecto de diferentes estrategias de manejo del fertiriego sobre las concentraciones de nitrógeno y clorofila en hoja; y la relación entre i- concentración de N y de clorofila (Cl) en hoja, ii- concentración de N y de Cl en hoja con el rendimiento y iii- concentración de N y de Cl en hoja con índices SPAD, CCI, NDVI y Fv.Fm -1. Materiales y métodos. Se evaluaron 6 tratamientos en un diseño irrestricto al azar con arreglo factorial 2 x 3, que combinaron 2 estrategias de riego (E1: bajo volumen y de mayor frecuencia y E2: alto volumen y menor frecuencia) y 3 niveles de nutrición: bajo (NB), medio (NM) y alto (NA). Las medidas directas de N y Cl en hoja se determinaron con el método Kjeldahl y por extracción con etanol, respectivamente. Resultados. El nivel de nutrición afectó el contenido de N, donde los tratamientos NM y NA fueron similares, aunque superiores a NB. El modelo de regresión mostró poca capacidad para estimar N y rendimiento a partir del contenido de Cl en hoja. La estimación de Cl en hoja a partir de los índices CCI (R2: 0,71) y SPAD (R2: 0,75) resultaron prometedores solamente en NB. Para estimar N foliar, la regresión con Fv.Fm -1 mostró valores de R2 de 0,89 en NB y 0,69 en NM; mientras que para NDVI los valores R2 fueron 0,61 en NB y 0,47 en NM. Conclusión. Los índices SPAD, CCI, NDVI y Fv.Fm -1 presentaron potencial para estimar la concentración de clorofila y de N en hoja con aportes bajo y medio de nutrientes, y con limitaciones en los tratamientos con altos aportes de nutrición.

ABSTRACT The semi-permanent coastal upwelling system within the Humboldt Current System (HCS) off northern Chile provides nutrient-rich, oxygen-poor water to the euphotic zone that contributes to high levels of primary production and restricts the vertical distribution of most zooplankton species according to their tolerance to hypoxia within this highly heterogeneous environment. The day/night vertical distributions of two calanoid copepods, Eucalanus inermis and Nannocalanus minor, were studied concerning the presence of oxygen-poor water associated with the Oxygen minimum zone (OMZ) at a coastal and an offshore station off northern Chile (∼20°S), by stratified sampling from the surface to a depth of 600 m. At the coastal station, most of the population of both species remained above the OMZ, whereas at the offshore station, most populations remained at the edge of the OMZ. Both species exhibited reverse diel vertical migration between day and night and were positively correlated with dissolved oxygen and chlorophyll-a, suggesting that both species may prefer oxygenated waters and avoid the OMZ. However, E. inermis and N. minor exhibited distinct behavior, with E. inermis displaying significant variations among stations and strata and N. minor showing differences only among strata, particularly in the upper strata where it was more aggregated. The results helped us understand the behavior and distribution of zooplankton related to OMZ and how they may change as ocean temperature increases worldwide.

Abstract Background: Agricultural management modifies the microclimate in the cultivated area, improving the physiology and productivity of plants. Questions: How does the microclimate, physiology and productivity of maize vary in a monoculture (M) and a milpa (polyculture, MFC) in shallow and deep soils of Yucatan? Study species: Zea mays L. Study site and date: Yucatán, Mexico; 2022 Methods: Air and soil temperature, water vapor pressure deficit, dew formation and volumetric soil water content (CVA); CO2 assimilation (A), transpiration (E), stomatal conductance (gs), water use efficiency, chlorophyll content (CC), quantum efficiency, electron transport rate and non-photochemical dissipation in maize plants were measured at 40 and 75 days after planting, in milpas and monocultures in Peto (shallow soil with high stoniness) and Mama (deeper soils with low stoniness), Yucatán. Results: The soil temperature was up to 5 °C higher in Peto and 2 °C in Mama in M compared to MFC, where soil water was also up to 22 % higher than in M. Maize plants in Mama showed higher A and E than those of Peto; the plants in MFC in Peto had higher A, E and gs than those of M; the opposite was observed in Mama. The CRA and CC were higher in MFC plants in Peto. Conclusions: The microclimatic modification associated with the polyculture, and its effect on maize was related to the soil: the Milpa was more productive on stony soils and monoculture in deep soils. The CVA was higher in MFC.

Resumen Antecedentes: El manejo agrícola modifica el microclima en el área de cultivo, afectando la fisiología y productividad de las plantas. Preguntas: ¿Cómo varía el microclima, fisiología y productividad del maíz en un monocultivo (M) y una milpa (policultivo, MFC) en suelos profundo y superficial de Yucatán? Especie de estudio: Zea mays L. Sitio de estudio: Yucatán, México; 2022 Métodos: Se midió temperatura del aire y suelo, déficit de presión de vapor, formación de rocío y contenido volumétrico de agua en suelo (CVA); asimilación de CO2 (A), transpiración (E), conductancia estomática (gs), eficiencia en el uso del agua, contenido de clorofila (CC), eficiencia cuántica, tasa de transporte de electrones y disipación no fotoquímica en plantas de maíz a 40 y 75 días después de la siembra, en milpas y monocultivos en Peto (suelo superficial, alta pedregosidad) y Mama (suelo más profundo, baja pedregosidad), Yucatán. Resultados: La temperatura del suelo fue hasta 5 °C mayor en Peto y 2 °C en Mama en M respecto a MFC, que registró hasta 22 % mayor CVA que M. El maíz en Mama presentó mayor A y E que en Peto; las plantas en MFC en Peto tuvieron mayor A, E y gs que las de M; en Mama fue lo contrario. El CRA y CC fue mayor en plantas de MFC en Peto. Conclusiones: La modificación microclimática y su efecto sobre el maíz dependió del suelo: MFC fue más productiva en suelos superficiales, mientras M en suelos profundos. El CVA fue mayor en MFC.

ABSTRACT Chrysopogon zizanioides (L.) Roberty, or vetiver grass, is a deep-rooted perennial grass. An examination of allelopathy using a metabolomic approach offers valuable insights into vetiver extract’s mechanism of action and phytotoxicity. This study utilised an untargeted metabolomics approach through the use of choisum (Brassica rapa L. subsp. chinensis (L.) Hanelt var. parachinensis (L.H. Bailey) Hanelt) as target plant because it is easier to cultivate and susceptible to the extract. Vetiver root methanolic extracts at various concentrations (0, 0.1, 1, 10, 50, and 100 mg mL-1) were sprayed at 100 mL m-2 on choisum seedlings at the 2 to 3 leaves stage. After 21 d, the Soil Plant Analysis Development (SPAD) and chlorophyll content of exposed choisum were measured, and their metabolites were subjected to gas chromatography-mass spectrometer (GC-MS)-based metabolomics analysis. The result demonstrated that the 100 mg mL-1 methanolic extract significantly decreased SPAD reading by 57.29% and reduced chlorophyll content by 66.38% (chl a) and 73.49% (chl b) of choisum compared to the control. Furthermore, considerably reduced stomatal length of exposed choisum, up to 34.31%, was observed when exposed to maximum concentration (100 mg mL-1). In total, nine metabolites with variable importance in projection (VIP) > 1 and P < 0.05 were found and identified as amino acids and carbohydrates. The highest concentration of extract enriched pathways of propanoate, Se-compound, cysteine, and methionine metabolism in choisum, suggesting the extract induced plant stress. The findings confirm the allelopathic potential of vetiver root and provide insight into the response of choisum to the allelopathic activity of vetiver grass root methanolic extract.

ABSTRACT Boron toxicity is a severe abiotic stress affecting plant growth and productivity in semi-arid regions of the world including Anatolian plateau. In this study, we investigated antioxidative responses of cotton (Gossypium hirsutum L.) as well as four different B transporter and aquaporin gene activities, which are early B stress responders, by using miR408 overexpression strategy. miR408 is a conserved microRNA in plant kingdom involved in almost all physiological responses of the plants as well as responses under abiotic and biotic stresses. Our results showed that, miR408 overexpression improved overall antioxidative status of cotton plants under B stress, in terms of reduced ion leakage and malondialdehyde levels and increased proline, chlorophyll and relative water contents. We also detected strong B transporter BOR1, BOR2 and water channel PIP1;1 and PIP2;1 gene expression in cotton leaf tissues under almost all treatments. miR408 overexpressing plants exhibited differential gene expression patterns when compared to control plants, always increasing with stress duration, revealing direct or indirect regulation of the genes by miR408 under B toxicity. Our results showed that, miR408 overexpression can be used as a strategy to improve B toxicity tolerance of cotton plants to increase agricultural production or for phytoremediation purposes on B rich soils.

Resumo A verificação de mudanças morfológicas e fisiológicas sob diferentes condições luminosas em espécies frutíferas nativas em estágio juvenil é importante, uma vez que indicam o ambiente adequado para a formação de mudas com alto vigor. Objetivou-se verificar o crescimento e as alterações morfofisiológicas sob gradiente de sombreamento em mudas de feijoa (Acca sellowiana (O. Berg) Burret) para obter mudas de boa qualidade, adequadas para fomentar os plantios da espécie em pomares. As mudas foram cultivadas por vinte e um meses sob quatro tratamentos de sombreamento (0%, 30%, 50% e 80%). Foram avaliados parâmetros de crescimento, pigmentos fotossintéticos, trocas gasosas, fluorescência da clorofila e anatomia foliar. Mudas a pleno sol e 30% de sombra apresentaram maior crescimento em altura, diâmetro e acúmulo de massa seca, devido à maior taxa de fotossíntese. Como principais mecanismos de aclimatação sob 80% de sombra, as mudas desenvolveram maior área foliar, redução da espessura do limbo foliar e aumento do rendimento quântico do fotossistema II. Mesmo assim, a assimilação líquida de CO2 e a taxa de transporte de elétrons foram menores e, consequentemente, houve restrição ao crescimento e acúmulo de massa seca das mudas no maior nível de sombreamento. Portanto, para a obtenção de mudas de feijoa de maior qualidade, recomendamos que seja realizada a pleno sol ou até 30% de sombra, para maximizar o vigor das mudas em viveiros e, posteriormente, este ambiente de luz também pode ser utilizado em pomares para favorecer o crescimento e a produção de frutos.

Abstract Understanding morphological and physiological changes under different light conditions in native fruit species in juveniles’ stage is important, as it indicate the appropriate environment to achieve vigorous saplings. We aimed to verify growth and morphophysiological changes under shade gradient in feijoa (Acca sellowiana (O. Berg) Burret) to achieve good quality saplings adequate to improve cultivation in orchards. The saplings were grown for twenty-one-month under four shading treatments (0%, 30%, 50%, and 80%). Growth, photosynthetic pigments, gas exchanges, chlorophyll fluorescence, and leaf anatomy parameters were evaluated. Saplings under full sun and 30% shade had higher height and diameter growth and dry mass accumulation due to higher photosynthesis rate. As main acclimatization mechanisms in feijoa saplings under 80% shade were developed larger leaf area, reduced leaf blade thickness, and enhanced quantum yield of photosystem II. Even so, the net CO2 assimilation and the electron transport rate was lower and, consequently, there was a restriction on the growth and dry mass in saplings under deep shade. Therefore, to obtain higher quality feijoa saplings, we recommend that it be carried out in full sun or up to 30% shade, to maximize the sapling vigor in nurseries and, later, this light environment can also be used in orchards for favor growth and fruit production.

Resumo A pitaia vermelha (Hylocereus costaricensis) é uma promissora espécie, com elevado potencial de cultivo devido às qualidades organolépticas e funcionais de seus frutos. Entretanto, a salinidade da água de irrigação pode afetar o rendimento produtivo da cultura. Diante disso, materiais ricos em substâncias orgânicas podem minimizar os danos provocados pelo excesso de sais no solo e/ou na água. Assim, o objetivo deste trabalho foi avaliar a influência de fontes de matéria orgânica como atenuante do estresse salino na produção e respostas bioquímicas de mudas de pitaia vermelha. O delineamento inteiramente casualizado em esquema fatorial 4 × 5, com cinco fontes de matéria orgânica (húmus, esterco ovino, biofertilizante, composto orgânico e areia + solo) e quatro salinidade (0.6, 2.6, 4.6 e 6.6 dS m-1), com quatro repetições e duas plantas por vaso foi utilizado. O comprimento da parte aérea, comprimento da raiz, diâmetro do cladódio, número de cladódios, número de brotos, volume da raiz, massa seca da parte aérea, massa seca da raiz e massa seca total, razão da massa seca da raiz e da parte aérea, clorofila a, b e total, aminoácidos e os açúcares solúveis foram avaliados aos 120 dias após o início da aplicação dos tratamentos. A pitaia vermelha é moderadamente tolerante a salinidade. O composto orgânico e estrume ovino atenuam os efeitos nocivos da salinidade nas mudas de pitaia vermelha. Sob condições de estresse salino, as plantas aumentam os níveis de aminoácidos e açúcares totais.

Abstract Red pitaya (Hylocereus costaricensis) is a promising species, with high cultivation potential due to the organoleptic and functional qualities of its fruits. However, irrigation water salinity can affect the crop yield. Therefore, materials rich in organic substances can minimize the damage caused by excess salts in soil and/or water. Thus, the objective of this study was to evaluate the influence of organic matter sources as attenuators of salt stress on the production and biochemical responses of red pitaya seedlings. A completely randomized design in 4 × 5 factorial scheme, with five sources of organic matter (humus, sheep manure, biofertilizer, organic compost and sand + soil) and four salinities (0.6, 2.6, 4.6 and 6.6 dS m-1) with four replicates and two plants per plot was used. The shoot length, root length, cladode diameter, number of cladodes, number of sprotus, root volume, shoot dry mass, root dry mass and total dry mass, root and shoot dry mass ratio, chlorophyll a, b and total, amino acids and soluble sugars were evaluated at 120 days after the treatments began to be applied. Red pitaya is moderately tolerant to salinity (ECw from 4.0 to 6.0 dS m-1). Organic compost and sheep manure attenuate the harmful effects of salinity on red pitaya seedlings. Under salt stress conditions, red pitaya plants increase their levels of proline, amino acids and total sugars.

Resumo Para mitigar os efeitos deletérios do estresse salino, tem se utilizado substâncias capazes de atuar como atenuantes e/ou indutoras de tolerância ao estresse, viabilizando o uso de águas salinas e contribuindo para desenvolvimento da agricultura irrigada. Neste contexto, objetivou-se com presente estudo, avaliar o efeito da pulverização foliar com peróxido de hidrogênio como atenuante do estresse salino sobre a morfofisiologia da gravioleira. O estudo foi conduzido sob condições de casa de vegetação, em Campina Grande - PB, utilizando-se o delineamento de blocos casualizados, no arranjo fatorial 4 × 4, cujos tratamentos resultaram da combinação de quatro níveis de condutividade elétrica da água de irrigação - CEa (0,8 – controle; 1,6; 2,4 e 3,2 dS m-1) e quatro concentrações de peróxido de hidrogênio - H2O2 (0; 10; 20 e 30 µM), com três repetições. A aplicação foliar de peróxido de hidrogênio na concentração de 10 µM aumentou o crescimento, a síntese de clorofila e o teor relativo de água nas folhas e consequentemente reduziu o déficit de saturação hídrica foliar da gravioleira irrigada com CEa de até 1,6 dS m-1. A concentração de peroxido de hidrogênio de 30 µM intensificou o estresse salino sobre o extravasamento de eletrólitos no limbo foliar e os pigmentos fotossintéticos da gravioleira, aos 270 dias após o transplantio.

Abstract To mitigate the deleterious effects of salt stress, substances capable of acting as mitigators and/or inducers of tolerance to stress have been used, enabling the use of saline waters and contributing to the development of irrigated agriculture. In this context, the aim of the present study was to evaluate the effect of foliar spraying with hydrogen peroxide as an attenuator of salt stress effects on soursop morphophysiology. The experiment was conducted under greenhouse conditions in Campina Grande - PB, Brazil, using a randomized block design, in a 4 × 4 factorial arrangement, whose treatments resulted from the combination of four levels of electrical conductivity of irrigation water - ECw (0.8 – control, 1.6, 2.4, and 3.2 dS m-1) and four concentrations of hydrogen peroxide - H2O2 (0, 10, 20, and 30 μM), with three replicates. Foliar application of hydrogen peroxide at a concentration of 10 µM increased growth, chlorophyll synthesis, and relative water content in the leaves and consequently reduced the foliar water saturation deficit of soursop irrigated with ECw up to 1.6 dS m-1. The concentration of hydrogen peroxide of 30 µM intensified the salt stress on the electrolyte leakage in the leaf blade and the photosynthetic pigments of soursop, 270 days after transplanting.

Abstract Chives are one of the most popular spice plants in world cuisine. It is usually produced by small producers, often in an organic farming system. However, research with chives in this production system is lacking. The purpose of this study was to evaluate the production of chives with the use of organic fertilizers before planting and in top dressing. Seven treatments were evaluated, resulting from the factorial 2x3+1, with two organic fertilizers (castor bean cake and hoof and horn powder) x 3 application modes (100% before planting; 100% in top dressing; 50% before planting and 50% in top dressing) + 1 control (without these organic fertilizers). The experimental design was in randomized blocks, with five replications and plots of 1 m2. The relative index of chlorophyll (“Spad” index), height, number of leaves, fresh and dry weight of the plants were evaluated. All treatments of the factorial were better than the control, showing that these organic fertilizers improve production in chives. It is recommended to use the hoof and horn powder in installments (50% before planting and 50% in top dressing) or 100% in top dressing, the latter option being more interesting for reducing the need for labor, with just one application moment.

Abstract Tomato plants infested by Fusarium oxysporum (Fol) show limitations in yield and fruit quality. The application of silicic acid could be used as an alternative to mitigate damage caused by this pathogen. In this work, the effect of silicic acid on "Rio Grande" variety tomato plants inoculated with Fol was studied. Silicic acid was applied via foliar weekly on tomato plant (ten applications). Treatments consisted of silicic acid + Fol, silicic acid, Fol and an absolute control. The incidence and severity of Fol wilt, content of antioxidant compounds (lycopene, β carotene, chlorophylls, vitamin C, reduced glutathione, phenols, flavonoids, total antioxidants and proteins), enzymatic activity (APX, CAT, GPX and SOD), PAL, salicylic and jasmonic acid, and the expression of genes involved in the synthesis of PR1, JA, GAME1, PAL5-3, ET and ABA, were determined. ASi+Fol-treated plants, compared to Fol-inoculated plants, disease incidence Fol wilt was reduced by 32% and severity by 22%, also presented an increase in chlorophyll a, b and total (49.1, 59.4 and 46.7%, respectively), as well as flavonoids (24.6%), the plants overexpressed the genes that participate in the synthesis of PR1, JA, GAME1, PAL5-3, ET and ABA at 31 dat (days after transplant), induced a reduction in reduced glutathione, antioxidant capacity by DPPH, CAT, jasmonic acid and the expression of all the genes evaluated in this work at 73 dat. The plants treated with ASi, in comparison with Fol, presented an increase in proteins, lycopene, vitamin C (30.3, 65.0, 52.7%, respectively), chlorophylls and the expression of PAL5-3 (31 dat), GAME1 and ET (73 dat). In the case Fol, a higher concentration of vitamin C, phenols, DPPH, PAL, CAT, GPX, salicylic and jasmonic acid was observed, and increase in the expression of JA, GAME1, PAL5-3, and ABA (73 dat), but it also induced a reduction in the concentration of flavonoids, chlorophylls and the expression of the six genes determined in this work at 31 dat. On the other hand, T0 plants, compared to Fol, showed an increase in proteins, lycopene, flavonoids (33.1, 62.0, 27.8%, respectively), as well as, chlorophyll, and the expression of all the genes analyzed in 31 dat, except for ET. The foliar application of silicic acid decreased the negative effects caused by Fol through the increase of antioxidant compounds and changes in the expression of genes related to the defense system in tomato plants.

Resumen Las plantas de tomate infestadas por Fusarium oxysporum (Fol) muestran limitaciones en rendimiento y calidad de frutos. La aplicación de ácido silícico podría ser una alternativa para mitigar los daños causados por este patógeno. En este trabajo se estudió el efecto del ácido silícico en plantas de tomate variedad “Rio Grande” inoculadas con Fol. Se aplicó ácido silícico vía foliar semanalmente en plantas de tomate (diez aplicaciones). Los tratamientos consistieron en ácido silícico + Fol, ácido silícico, Fol y un control absoluto. Se determinó la incidencia y severidad de la marchitez de Fol, el contenido de compuestos antioxidantes (licopeno, β caroteno, clorofilas, vitamina C, glutatión reducido, fenoles, flavonoides, antioxidantes totales y proteínas), actividad enzimática (APX, CAT, GPX y SOD), PAL, ácido salicílico y jasmónico, y la expresión de genes que participan en la síntesis de PR1, JA, GAME1, PAL5-3, ET y ABA. En las plantas tratadas con ASi+Fol, en comparación con las plantas inoculadas con Fol, se redujo la incidencia de la enfermedad en un 32% y la severidad en un 22%. También presentaron un incremento de clorofila a, b y total (49.1, 59.4 y 46.7%, respectivamente), así como de flavonoides (24.6%), las plantas sobreexpresaron los genes que participan en la síntesis de PR1, JA, GAME1, PAL5-3, ET y ABA, a los 31 ddt, indujeron una reducción de glutatión reducido, capacidad antioxidante por DPPH, CAT, ácido jasmónico y la expresión de todos los genes evaluados en este trabajo a los 73 ddt. Las plantas tratadas con ASi, en comparación con Fol, presentaron un incremento de proteínas, licopeno, vitamina C (30.3, 65.0, 52.7%, respectivamente), clorofilas y la expresión de PAL5-3 (31 ddt), GAME1 y ET (73 ddt). En el caso de Fol, se apreció mayor concentración de vitamina C, fenoles, DPPH, PAL, CAT, GPX, ácido salicílico y jasmónico, y ligeramente un incremento de la expresión de JA, GAME1, PAL5-3 y ABA (73 ddt), pero también indujo una reducción en la concentración de flavonoides, clorofilas y la expresión de los seis genes determinados en este trabajo a 31 ddt. Por su parte las plantas T0, comparado con Fol, se observó aumento de proteínas, licopeno, flavonoides (33.1, 62.0, 27.8%, respectivamente), así como clorofilas, y la expresión de todos los genes analizados a los 31 ddt, a excepción de ET. La aplicación foliar de ácido silícico disminuyó los efectos negativos causados por Fol a través del aumento de compuestos antioxidantes y cambios en la expresión de los genes relacionados con el sistema de defensa en plantas de tomate.

ABSTRACT In this study, chemical changes during the development of acerola, cultivar Okinawa, were evaluated. The biochemical alterations during the development of the acerola cultivar Okinawa were evaluated, to determine the peroxidase activity (POD) and its thermal stability. Peroxidase (POD) has been considered the main enzyme responsible for the quality deterioration of fruits. Additionally, characteristics evaluated in this study can be important postharvest quality criteria for fruit processing, screening and breeding. Changes in physiological development were evaluated by the determination of moisture content, ascorbic acid, ashes, total and reducing sugars, pectin, chlorophyll a and b, amounts of anthocyanins, flavonols and total carotenoids. These biochemical determinations may serve as a basis for further improvement of techniques for predicting and modeling the optimal harvesting time. The values of chlorophylls, anthocyanins, flavonols, and carotenoids were higher in the peel rather than in the pulp (p < 0.05). Acerola presents high levels of ascorbic acid. The development of acerola (from opening of flowers to maturation of fruits) was of 25 days. The increase of the values for total and reducing sugars, anthocyanins, carotenoids, the solubilization of pectic acid and degradation of chlorophyll suggested that physiological maturation and harvest day occurred on days 19 and 23 after anthesis, respectively. The specific activity of POD was higher in the green stage. Maximum POD activity was observed at pH 6.5 and 45 ºC. Total inactivation was not achieved, suggesting the presence of isoenzymes with high thermal resistance. A loss of 50% of activity occurred after 4 minutes of treatment at 80 °C.

ABSTRACT Second-generation glyphosate-tolerant maize (Roundup Ready 2, RR2) is characterised by the expression of the cp4epsps gene. Despite some studies suggesting possible undesirable effects from the application of glyphosate in RR2 maize, other reports have demonstrated glyphosate selectivity for RR2 plants, with minor damage symptoms, if any, and with no negative effects on the chlorophyll indices. The aim of this study was to evaluate the effect of different types of glyphosate management, formulations and rates of application on chlorophyll indices and the agronomic performance of an RR2 maize genotype expressing the cp4epsps gene. Five experiments were conducted in a full factorial design (2 x 5 x 5) to evaluate two types of management, two formulations and five rates of glyphosate. Damage symptoms, chlorophyll indices and variables related to agronomic performance (plant height, stem diameter, yield and 100-grain weight) were evaluated. Similar crop responses were found for each of the glyphosate formulations (potassium salt and isopropylamine salt) and types of management (single application and sequential application) under test, indicating that the use of glyphosate-based commercial products affords flexibility in terms of formulation and frequency of application. Glyphosate formulated as potassium salt or isopropylamine salt and applied to RR2 maize either in a single application (full rate) or in two sequential applications (each at half rate) has a similar effect and may therefore be used without distinction. However, it is important to consider the rate of application since high rates of glyphosate (especially greater than 1,440 g ae ha-1) may affect the development and production of RR2 maize.

ABSTRACT: Pineapple is a tropical fruit with high demand by the fruit market in Brazil. Fruits of the cultivar ´Turiaçu` stans out in local consumer markets due to its excellent quality. The objective of this work was to evaluate ecophysiological responses of ´Turiaçu` pineapple plants at the vegetative and reproductive stages to soil fertilization and crop location, and their effects in fruit yield. The study was conducted in the cities of São Luís and Turiaçu, MA, Brazil. Plants under mineral and organic fertilization in two locations, São Luís and Turiaçu, and in two seasons, dry and rainy season, were evaluated during dry and rainy seasons. Chlorophyll index, photochemical efficiency, gas exchange, and fruit yield were evaluated. The pineapple plants presented decrease in the photosynthetic activity, at both developmental stages and in both seasons, when grown in São Luís. The CO2 photosynthetic assimilation decreased. The PSI and PSII activity, according with photosynthetic index, was more sensitive at the reproductive than at the vegetative stage. The organic fertilization was not appropriate for the ´Turiaçu` pineapple crops, regardless of the crop location. The fruit yields were 54.4% and 57.9% lower in São Luís, under mineral and organic fertilization, respectively. Thus, the ecophysiology of ´Turiaçu` pineapple was more affected by water availability than by soil fertility in the municipality of Turiaçu.

RESUMO: O abacaxi é uma fruta tropical com alta demanda pelo mercado de frutas no Brasil. Os frutos da cultivar ´Turiaçu`se destacam nos mercados consumidores locais pela excelente qualidade. O objetivo deste trabalho foi avaliar as respostas ecofisiológicas de plantas de abacaxizeiro ´Turiaçu`nos estádios vegetativo e reprodutivo à adubação do solo e ao local de cultivo, e seus efeitos na produção de frutos. O estudo foi realizado nas cidades de São Luís e Turiaçu, MA, Brasil. Plantas sob adubação mineral e orgânica foram avaliadas durante as estações seca e chuvosa. Foram avaliados teores de clorofila, eficiência fotoquímica, trocas gasosas e produção de frutos. As plantas de abacaxi apresentaram diminuição da atividade fotossintética, em ambas as fases de desenvolvimento e em ambas as estações, quando cultivadas em São Luís. A assimilação fotossintética de CO2 diminuiu. A atividade de PSI e PSII foi mais sensível na fase reprodutiva do que na fase vegetativa. A adubação orgânica não foi adequada para as lavouras de abacaxi ´Turiaçu`, independente do local de cultivo. As produtividades de frutos foram 54,4% e 57,9% menores em São Luís, sob adubação mineral e orgânica, respectivamente. Assim, a ecofisiologia do abacaxi de ´Turiaçu`foi mais afetada pela disponibilidade hídrica do que pela fertilidade do solo no município de Turiaçu.

Summary: The salinity of soils and water for irrigation is a limitation that influences the productivity of crops that has increased worldwide and affects the morphology and physiology of plants since it causes osmotic stress and ionic toxicity and impairs the absorption of water and nutrients. The effect of salt stress on some morphological and physiological traits in Coccoloba uvifera (L.) L. (sea grape) seedlings from different origins was evaluated and the traits whose behavior under salt stress could be used as an effective criterion of tolerance to salinity were determined. A completely randomized design experiment with ten repetitions was performed. The factors under study were salinity (0, 5, 15, and 25 dS m-1), which was maintained for a period of sixteen weeks, and the second factor was the origin of the plant material. The salinity level and the seedlings’ origin significantly influenced the morphological and physiological variables controlled. However, it is necessary to carry out in situ experiments to obtain more information related to the mechanisms used by sea grape to tolerate salinity conditions, because in the consulted sources no research focused on evaluating the effect of salinity and the origin on the morphology and physiology of C. uvifera seedlings in Cuba has been found. The results of the research provide preliminary information to understand the negative effect of salt stress on this type of plant. The behavior of some controlled traits under salt stress can be used as an effective criterion of tolerance to salinity.

Resumen: La salinidad de los suelos y del agua para riego es una limitante que influye en la productividad de los cultivos que se ha incrementado a nivel mundial y afecta la morfología y fisiología de las plantas, ya que provoca estrés osmótico y toxicidad iónica, lo que perjudica la absorción de agua y nutrientes. Se evaluó el efecto del estrés salino en características morfológicas y fisiológicas de plántulas de Coccoloba uvifera (L.) L. (uva de mar) de diferente origen, y se determinaron las características cuyo comportamiento ante el estrés salino podrían utilizarse como indicador de tolerancia a la salinidad. El experimento se estableció en un diseño completamente aleatorizado con diez repeticiones. Los factores en estudio fueron la salinidad (0, 5, 15 y 25 dS m-1), la cual se mantuvo durante un período de doce semanas, y el segundo factor fue el origen del material vegetal. El nivel de salinidad y el origen de las plántulas influyeron significativamente en las variables morfológicas y fisiológicas controladas. Sin embargo, es necesario realizar experimentos in situ para obtener mayor información relacionada con los mecanismos utilizados por la uva de mar para tolerar las condiciones de salinidad, pues en las fuentes consultadas no se han encontrado investigaciones enfocadas en evaluar el efecto de la salinidad y el origen en la morfología y fisiología de plántulas de C. uvifera en Cuba. Los resultados de la investigación aportan información preliminar para comprender el efecto negativo del estrés salino en este tipo de plantas. El comportamiento de algunas características controladas bajo estrés salino puede ser utilizado como criterio efectivo de tolerancia a la salinidad.