Silicon mitigates the negative impacts of salt stress in soybean plants.

BACKGROUND: Soybean is widely cultivated around the world, including regions with salinity conditions. Salt stress impairs plant physiology and growth, but recent evidence suggests that silicon (Si) is able to mitigate this stressful condition. Therefore, the purpose of this study was to evaluate how different strategies of Si application impact on salt stress tolerance of an intermediate Si accumulator species (soybean). Therefore, we applied four treatments: Si-untreated plants (Si 0); foliar spraying at 20 mmol L-1 (Si F); nutritive solution addition at 2.0 mol L-1 (Si R), and combined foliar spraying at 20 mmol L-1 plus nutritive solution at 2.0 mmol L-1 (Si F + R). We investigated how Si application modified growth, leaf gas exchange, photosynthetic pigments, chlorophyll fluorescence, relative water content (RWC), nutrient accumulation, and ion homeostasis of soybean plants submitted to different levels of salt stress (50 and 100 mmol L-1 NaCl). RESULTS: Salinity induced an expressive reduction in ion accumulation, plant water status, and growth of soybean, while Si application promoted contrary effects and increased potassium (K+ ) accumulation, water status, photosynthetic pigment content, chlorophyll fluorescence parameters, and gas exchange attributes. Additionally, Si application enhanced Si accumulation associated with decreased Na+ uptake and improved morpho-physiological growth. CONCLUSION: The use of exogenous Si can be an efficient strategy to attenuate the harmful effects of salt stress in soybean plants. The best application strategy was observed with combined foliar spraying with Si included in the nutritive solution (Si F + R). © 2023 Society of Chemical Industry.

Aplicación conjunta del consorcio microorganismos benéficos y FitoMas-E® incrementan los indicadores agronómicos del frijol / Joint application of beneficial microorganisms consortium and FitoMas-E® increases the agricultural indicators of beans

RESUMEN El uso de microorganismos benéficos en conjunto con bioestimulantes vegetales puede ser una alternativa eficiente para mejorar la productividad del fríjol. El objetivo de este estudio fue determinar el efecto de la aplicación individual y combinada entre los bioestimulantes ME-50® y FitoMas-E® en el incremento agroproductivo del fríjol en época de siembra tardía. La investigación, se desarrolló en la Cooperativa de Créditos y Servicios "Mártires de Taguasco", Sancti Spíritus, Cuba. Se realizó un experimento en condiciones de campo con el cultivar ʻVelazco largoʼ. Los tratamientos, se distribuyeron en bloques al azar, en esquema factorial 2×2, con cinco réplicas, dos niveles ausencia y presencia del consorcio ME-50® y su combinación con la no aplicación y aplicación de FitoMas-E. Los efectos de los bioestimulantes se observaron en los parámetros de i) crecimiento: hojas por planta, área foliar y la masa seca y ii) productivos: número de vainas por planta, granos por vaina, masa de 100 granos y el rendimiento. Los resultados revelaron que la aplicación conjunta de ambos bioestimulantes fue más eficiente en el aumento del crecimiento y la productividad, que la aplicación individual y la no aplicación de bioestimulantes, al incrementar el rendimiento en 10 y 71 %, respectivamente. Los hallazgos de este estudio sugieren que la combinación entre el ME-50® y el FitoMas-E® constituye una alternativa eficiente, económica y viable, para aumentar la productividad del fríjol en época de siembra tardía.

ABSTRACT The use beneficial of microorganisms jointly with vegetal biostimulants can be an efficient alternative to improve the productivity of beans. The purpose of this research was to determine the effect of individual and joined application of the biostimulants ME-50® and FitoMas-E® in the agroproductive increase of the bean in the late sowing season. The research was conducted at the collective farmer "Martires de Taguasco", Sancti Spiritus, Cuba. An experiment was carried out under field conditions with the cultivar ʻVelazco Largoʼ. The treatments were distributed in random blocks, in a 2×2 factorial scheme, with five replications, two levels absence and presence of the ME-50® consortium and its combination with no application and application of FitoMas-E®. The biostimulants effects were observed in i) growth parameters: leaves per plant, leaf area and dry mass; ii) production parameters: number of pods per plant, grains per pod, the mass of 100 grains and yield. The results revealed that the joint application of both biostimulants was more efficient in increasing growth and productivity than the individual application and the non-application of biostimulants, due to the yield increase of 10 and 71 %, respectively. The findings of this study suggest that the join application between ME-50® and FitoMas-E® constitutes an efficient, economical and viable alternative to increase bean productivity in the late sowing season.

Are the interaction effects of warming and drought on nutritional status and biomass production in a tropical forage legume greater than their individual effects?

MAIN CONCLUSION: Drought alone and drought plus warming will change the nutrient requirements and biomass distributions of Stylosanthes capitata, while warming will be advantageous only under well-watered condition for the next decades. Climate change effects on natural and managed ecosystems are difficult to predict due to its multi-factor nature. However, most studies that investigate the impacts of climate change factors on plants, such as warming or drought, were conducted under one single stress and controlled environments. In this study, we evaluated the effects of elevated temperature (+ 2 °C) (T) under different conditions of soil water availability (W) to understand the interactive effects of both factors on leaf, stem, and inflorescence macro and micronutrients concentration and biomass allocation of a tropical forage species, Stylosanthes capitata Vogel under field conditions. Temperature control was performed by a temperature free-air controlled enhancement (T-FACE) system. We observed that warming changed nutrient concentrations and plant growth depending on soil moisture levels, but the responses were specific for each plant organ. In general, we found that warming under well-watered conditions greatly improved nutrient concentration and biomass production, whilst the opposite effect was observed under non-irrigated and non-warmed conditions. However, under warmed and non-irrigated conditions, leaf biomass and leaf nutrient concentration were greatly reduced when compared to non-warmed and irrigated plants. Our findings suggest that warming (2 °C above ambient temperature) and drought, as well as both combined stresses, will change the nutrient requirements and biomass distributions between plant aerial organs of S. capitata in tropical ecosystems, which may impact animal feeding in the future.

Changes in soil water availability and air-temperature impact biomass allocation and C:N:P stoichiometry in different organs of Stylosanthes capitata Vogel.

Temperature and soil water availability play important roles in the biogeochemical cycles of essential elements for plant growth, such as carbon (C), nitrogen (N), and phosphorus (P). In this study, we investigated how drought and warming impact C:N:P stoichiometric ratios of different plant organs (leaves, inflorescences, and stems), and biomass allocation and production of a field-grown pasture of Stylosanthes capitata, a tropical forage legume. We evaluated the effects of elevated temperature (+2 °C above ambient temperature) under two conditions of soil water availability, irrigated, and non-irrigated. In general, we observed that different functional plant organs showed distinct responses to drought and warming demonstrating how important is to evaluate different functional plant organs to unravel crop nutrient dynamics. In addition, interactive effects between warming and drought were observed in many situations, highlighting the importance of multifactorial studies. Our data showed that warming produced plants with more inflorescences, decreasing leaf:inflorescence ratio. However, only warming under well-watered conditions improved biomass production (in 38%). Warmed and irrigated plants showed higher stoichiometric homeostasis compared to other treatments. In an opposite direction, drought decreased P concentration and increased N:P ratios in different organs, reducing the stoichiometric homeostasis under both conditions of temperature. We have concluded that warm and well-watered conditions without restrictions in soil nutrient availability can enhance plant production, presumably due to a higher level of stoichiometric homeostasis.

Silicon application induces changes C:N:P stoichiometry and enhances stoichiometric homeostasis of sorghum and sunflower plants under salt stress.

Beneficial effects of silicon (Si) on growth have been observed in some plant species, reportedly due to stoichiometric changes of C, N, and P. However, little is known about the effects on the stoichiometric relationships between C, N, and P when silicon is supplied via different modes in sorghum and sunflower plants under salt stress conditions. Therefore, the current study was performed to investigate the impact of differing modes of Si supply on shoot biomass production and C:N:P stoichiometry in sorghum and sunflower plants under salt stress. Two experiments were performed in a glass greenhouse using the strong Si-accumulator plant sorghum, as well as the intermediate type Si-accumulator sunflower, both of which were grown in pots filled with washed sand. Plant species were cultivated for 30 days in the absence or presence of salt stress (0 or 100 mM) and supplemented with one of four Si treatments: control plants (without Si), 28.6 mmol Si L-1 via foliar application, 2.0 mmol Si L-1 via nutrient solution, and combined application of foliar and nutrient solution, each group with five replications. The results revealed that supplied Si modified the C, N, and P concentrations, thereby enhancing the C:N:P stoichiometry and shoot dry matter of sorghum and sunflower plants under salt stress. Both application of Si via nutrient solution, as well as combined application via foliar and nutrient solution, increased the C:N ratio in both plant species under salt stress, but in sorghum plants decreased the C:P and N:P ratios and increased the shoot biomass production by 39%, while in sunflower plants increased the C:P and N:P ratios and increased the shoot biomass production by 24%. Our findings suggest that salt stress alleviation by Si impacts C:N:P stoichiometric relationships in a variable manner depending on the ability of the species to accumulate Si, as well as the route of Si administration.

Toxicidad amoniacal afecta la absorción de cationes y el crecimiento de plantas de papaya inclusive con adición de silicio / Ammonia toxicity affects cations uptake and growth in papaya plants inclusive with silicon addition

ABSTRACT High ammonia (NH4 +) concentration can exert stress on many plants, which causes nutritional disorders and reduction on plant growth. However, depending on the intensity of the stress, it may be attenuated by silicon. In this work, the response of impact of cations and silicon accumulations and plant growth in cultivated papaya plants was investigated under different toxic ammonia concentrations regardless of the presence of silicon (Si). The experiment was conducted at the Universidade Estadual Paulista (UNESP) with papaya seedlings, variety 'Grupo Formosa' (Calimosa híbrida 01), grown in a glass greenhouse, in 1.7 dm3 pots filled with pine and coconut fiber-based substrate. The experimental design was a randomized block design, in a 5 x 2 factorial arrangement. There were five ammonium concentrations: 10, 20, 40, 80, and 100 mmol L-1 that were delivered via nutrient solution, in the absence and presence of Si (2 mmol L-1), with five replicates. After 31 days of growth, the cations and silicon accumulations in the shoot, plant height, stem diameter, root, and shoot dry matter were evaluated. Results revealed that increased ammonia concentration showed toxicity in papaya plants and stronger reductions in Ca, Mg, K and Si accumulations, plant heights, stem diameters, and root and shoot dry matter production, even when silicon was present and with greater effects on the shoot dry matter (87 %) than that of the roots (13 %).

RESUMEN Las altas concentraciones de amonio (NH4+) pueden ejercer estrés en las plantas cultivadas, lo que causa trastornos nutricionales y reducción del crecimiento. Sin embargo, dependiendo de la intensidad del estrés, este puede atenuarse mediante el silicio (Si). En este trabajo, se investigó la respuesta de la acumulación de cationes y silicio y el crecimiento de plantas de papaya cultivadas en diferentes concentraciones tóxicas de amonio independientemente de la presencia de silicio. El experimento se realizó en la Universidade Estadual Paulista (UNESP), con plántulas de papaya, variedad Grupo Formosa (Calimosa híbrida 01), cultivadas en invernadero, en macetas de 1,7 dm3, rellenas con sustrato a base de fibra de pino y coco. El diseño experimental fue en bloques al azar, en esquema factorial 5x2, con cinco concentraciones de amonio 10, 20, 40, 80 y 100 mmol L-1, en la ausencia y presencia de Si (2 mmol L-1), con cinco repeticiones. A los 31 días posteriores del inicio de los tratamientos, se evaluó la acumulación de calcio, magnesio, nitrógeno, potasio y silicio, altura de la planta, diámetro del tallo y la materia seca de la raíz y los brotes. Los resultados revelaron que el aumento de la concentración de amonio mostró toxicidad en plantas de papaya y una reducción en la acumulación de calcio, magnesio, potasio y silicio, la altura de la planta, diámetro del tallo y la producción de materia seca de raíces y brotes, aunque el silicio esté presente, con mayor afectación en la materia seca de los brotes (87 %) que en las raíces (13 %).

Different methods of silicon application attenuate salt stress in sorghum and sunflower by modifying the antioxidative defense mechanism.

Soil salinization is the most common abiotic stress limiting agricultural productivity worldwide. Recent research has suggested that the application of silicon (Si) has beneficial effects against salt stress in sorghum (Sorghum bicolor L. Moench) and sunflower (Helianthus annuus L.) by regulating the antioxidant system, mineral nutrients, and other important mechanisms. However, whether these effects can be achieved through foliar application of Si, or whether Si application affects Si-accumulating (e.g., sorghum), and intermediate-Si-accumulating (e.g., sunflower) plant species differently, remains unclear. This study investigated different methods of Si application in attenuating the detrimental effects of salt stress, based on the biological responses of two distinct species of Si accumulators, under greenhouse conditions. Two pot experiments were designed as a factorial (2 × 4), randomized complete blocks design (RCBD) with control and salt-stress groups (0 and 100 mmol.L-1 NaCl), and four Si-treatment groups: control (no Si), foliar application (28.6 mmol.L-1), root application (2 mmol.L-1), and combined foliar and root applications. Our results showed that the harmful effects of salt stress were attenuated by Si treatments in both plant species, which decreased Na+ uptake and lipid peroxidation, and increased Si and K+ uptake, relative leaf water content, antioxidant enzyme activities, leaf area, and shoot dry matter. These results were more prominent when Si was applied via nutrient solution in the sorghum plants, and the combined foliar and root applications of Si in sunflower plants. In addition, foliar application of Si alone is an efficient alternative in attenuating the effects of salinity in both plant species when Si is not available in the growth medium. These results suggest that the Si application method plays an important role in Na+ detoxification by modifying the antioxidative defense mechanism, which could actively mediate some important physiological and biochemical processes and helps to increase the shoot dry matter production in sorghum and sunflower plants under salt stress.

Physiological role of silicon in radish seedlings under ammonium toxicity.

BACKGROUND: High concentrations of ammonium as the sole nitrogen source may result in physiological and nutritional disorders that can lead to reduced plant growth and toxicity. In this study, we hypothesized that ammonium toxicity in radish seedlings (Raphanus sativus L.) might be mitigated by the incorporation of silicon (Si) into applied nutrient solution. To examine this possibility, we conducted a hydroponic experiment to evaluate the effects of five concentrations of ammonium (1, 7.5, 15, 22.5, and 30 mmol L-1 ) on the photosynthesis, green color index, stomatal conductance, transpiration, instantaneous water-use efficiency, and biomass production of radish in the absence and presence (2 mmol L-1 ) of Si. The experimental design was a randomized block design based on a 2 × 5 factorial scheme with four replicates. RESULTS: The highest concentration of applied ammonium (30 mmol L-1 ) was found to reduce the photosynthesis, transpiration and total dry biomass of radish seedlings, independent of the presence of Si in the nutrient solution. However, at lower ammonium concentrations, the application of Si counteracted these detrimental effects, and facilitated the production of seedlings with increased photosynthesis, greater instantaneous water-use efficiency, and higher total dry biomass compared with the untreated plants (without Si). Transpiration and stomatal conductance were affected to lesser extents by the presence of Si. CONCLUSION: These findings indicate that the addition of Si to nutrient solutions could provide an effective means of alleviating the unfavorable effects induced by ammonium toxicity at concentrations of less than 30 mmol L-1 . © 2020 Society of Chemical Industry.

Microorganismos eficientes y vermicompost lixiviado aumentan la producción de pepino / Efficient microorganism and lixiviate vermicompost applications increase the cucumber production

RESUMEN Los principales problemas de la producción de pepino, residen mayormente en la escasez de fertilizantes minerales, afectaciones climatológicas y limitado uso de los biofertilizantes, por lo cual, es importante buscar alternativas eficientes que aumenten la productividad, la racionalidad y la sustentabilidad. El objetivo de esta investigación fue evaluar la utilización individualizada y asociada de los biofertilizantes microorganismos eficientes y vermicompost lixiviado en el incremento agroproductivo del pepino. El trabajo fue desarrollado en la unidad productiva "El Estadio", Sancti Spíritus, Cuba, entre enero a abril de 2015 y fue utilizado el cultivar Su Yi Sung de pepino. Los tratamientos aplicados fueron un control, inoculación al suelo y aplicaciones foliares de Microorganismos eficientes y vermicompost lixiviado, a 100 y 200mL L-1 y la inoculación al suelo, con Microorganismos eficientes, a 100mL L-1 y aplicaciones foliares con vermicompost lixiviado, a 100mL L-1. Las variables evaluadas fueron el número de hojas, de flores femeninas y de frutos por planta, longitud de frutos (cm), masa de los frutos (g) y el rendimiento (kg m-2). Los resultados mostraron que la aplicación individual y combinada de los biofertilizantes tuvieron un efecto bioestimulante en la producción de pepino y la aplicación de microorganismos eficientes a 100mL L-1 y la combinación con vermicompost lixiviado a 100mL L-1 constituyen una alternativa en la productividad del cultivo, especialmente, porque aumentaron el número de hojas, flores femeninas, frutos, masa y longitud de los frutos e incrementaron el rendimiento en 42% con relación al tratamiento control.

ABSTRACT The main problems of cucumber production reside fundamentally by the mineral fertilizer's shortage, climatic affectation and limited use of biofertilizers, which is important to looking for efficient alternatives that increase productivity, rationality and sustainability. The objective of this research was to evaluate the effect of individualized and associated use of biofertilizers efficient microorganisms and lixiviate vermicompost on the agro-productive increase of cucumber. The work was developed in the productive unit "El Estadio", Sancti Spíritus, Cuba, between January to April 2015 and Su Yi Sung cultivar of cucumber was used. The treatments used were a control (no application), soil inoculation and foliar applications with efficient microorganisms and lixiviate vermicompost at 100 and 200mL L-1, and soil inoculation with efficient microorganisms at 100mL L-1 and foliar applications with lixiviate vermicompost at 100mL L-1. The following variables were observed: number of leaves, female flowers and fruits per plant, length of fruits (cm), mass of fruits (g) and yield (kg m-2). The results showed that the individual and combined application of biofertilizers had a biostimulants effect on cucumber production. The efficient microorganism's application at 100mL L-1 and the combination with lixiviate vermicompost to 100mL L-1 constituting a sustainable alternative in the cucumber productivity, especially because they increased the number of leaves, female flowers, fruits, mass and length of fruits and increasing the yield by 42 % compared to control treatment.

Silicon attenuates sodium toxicity by improving nutritional efficiency in sorghum and sunflower plants.

Salt stress is known to negatively affect the fundamental processes in plants, reducing their growth and yield. The role of Silicon (Si) to protect the sorghum and sunflower plants against salinity stress was assessed. The objective of this study was to evaluate the effects of different forms of Si application on the uptake and use efficiency of macronutrients and micronutrients in sorghum and sunflower plants under salinity stress under greenhouse conditions. Two experiments were conducted using sorghum and sunflower under greenhouse conditions. Four Si levels were applied to plants: no Si application; foliar application of 28.6 mmol.L-1; root application of 2.0 mmol.L-1; and combined Si application with both via nutrient solution and foliar spraying. Each Si treatment was applied in the absence and presence of NaCl (100 mM). Thirty days after treatments, sodium (Na+) and Si accumulation, nutrient uptake and use efficiency, and the roots and total plant dry weight were measured. Salinity stress induced nutritional imbalance and decreased dry weight production in both plant species. Our results showed that Si application alleviated the salinity stress by decreased Na+ uptake and increased nutritional efficiency, thereby favoring the total plant dry weight in sorghum by 27% and sunflower by 41%. This occurred when Si was applied either via root or in combination via root and foliar application, respectively. Collectively, our findings indicate that Si application can attenuate the deleterious effects of salt stress and increase yield in sorghum and sunflower plants in a sustainable manner.