1,720,966 research outputs found
Growth and morpho-physiological attributes of drought-tolerance in quinoa (Chenopodium quinoa Willd.) under biochar-amended soil
Full text linkChenopodium quinoa Willd. is a highly nutritious pseudocereal with the potential to address global food insecurity challenges due to current climate change scenarios. However, the water deficit significantly impacted quinoa’s growth despite its inherent tolerance to drought. This research explores quinoa’s morpho-physiological responses to water stress and investigates soil amendments, particularly biochar, as a potential agronomic strategy to mitigate the adverse effects of water scarcity. The current literature highlights that biochar, a carbon-rich material derived from pyrolyzed organic matter, can enhance soil physio-chemical properties, improve plant water status, and promote growth under water limitations. Similar to the reproductive phase, the vegetative growing cycle of quinoa is notably susceptible to the detrimental effects of drought. Agronomic strategies must be implemented to mitigate the negative effects of water stress during the vegetative growing cycle. Applying organic amendments, particularly biochar, becomes increasingly important in this context. A series of experiments were conducted to investigate the impact of organic amendments on the vegetative development of quinoa under water stress. These experiments were initiated by analyzing responses of two biochar types (derived from woodchips and vineyard pruning) and vermicompost (from cattle manure) on the Danish variety Titicaca, which is particularly susceptible to water stress during its early growth stages and widely cultivated around the globe particularly in Europe. The amendments were applied alone and in combination at a 2% (w/w) rate. The results revealed that among the organic amendments tested, woodchip biochar, alone and mixed with vermicompost, significantly improved quinoa’s growth, specifically biomass, by 22% compared to stressed control and water use efficiency. In contrast, vineyard pruning biochar negatively affected plant growth. Successively, the same variety, Titicaca, was further analysed under different woodchip biochar rates (best performing organic amendment) (0%, 2%, and 4%) and two watering regimes (100% and 50% evapotranspiration restitution). The 2% biochar rate enhanced vegetative growth, biomass by 23%, and panicle development by 66% compared to 4%, which negatively affected these parameters, highlighting the importance of choosing the right dose based on soil type. Subsequently, considering the 2% woody biochar rate, five quinoa varieties of different origins were compared and subjected to a water stress period starting from the 12
leaf stage. The results showed that biochar application consistently improved plant growth, particularly plant biomass, leaf nutrients, and enhanced C:N ratio, improving nitrogen bioavailability and translocation. Additionally, biochar addition in the soil positively affected root morphology, including elongation by 23% and development particularly fresh and dry biomass by 122% and 127%, respectively, and physiological attributes, i.e., chlorophyll content, plant water status and gas exchange than non-amended soil, although varietal differences were observed. The Pakistani variety UAFQ7 exhibited superior drought tolerance, while the Danish Titicaca was more sensitive to water stress. Moreover, the Italian variety Quipu significantly increased its yield-contributing traits and even doubled under biochar-amended soil than non-treated ones. Under water stress conditions, varieties positively influenced their stomatal morphology, stomatal regulation, and transpiration rates under biochar-amended soils by enhancing stomatal aperture dimensions and stomatal density, particularly for UAFQ7 by doubling the stomatal density than non-treated soil. Collectively, this research underscores the potential of biochar as a sustainable soil amendment to mitigate drought stress in quinoa by enhancing root development, physiological attributes, and overall plant performance. The findings highlight the need to select appropriate biochar types and rates and quinoa varieties to optimize growth under water-limited conditions, offering a promising agronomic strategy for improving quinoa cultivation in drought-prone regions
Woody Biochar Rate and Water Shortage Impact on Early Growth Stages of Chenopodium quinoa Willd.
Full text linkThe application of biochar to agricultural soils has been proven to have many advantages, including the improvement of soil water holding capacity and plant growth, particularly under limiting conditions of water supply. The response of quinoa (Chenopodium quinoa Willd.) to water shortage occurring during the vegetative growth stages is not well known. Therefore, the present study aimed to evaluate the combined effects of three wood chip biochar rates (0%, 2% and 4%) and two water regimes (100 and 50% evapotranspiration losses restitution) on the vegetative development and water status of quinoa (cultivar Titicaca). The results showed that the treatment with 2% wood chip biochar improved plant height, leaf and branch number and stem diameter during the vegetative growing cycle compared to the 0% (control) and 4% biochar treatments, which were not different from each other. At the end of the experiment, when the plants were at the flowering initiation stage, increases of 23% in leaf area, 22% in fresh biomass, 27% in main panicle length and 36% in sub-panicle number were observed. The application of woody biochar at a 4% rate, although improving the plant water status with increases of 10% in RWC and 18% in Ψ, did not enhance the vegetative development of the quinoa. The water shortage negatively affected both the growth performance and plant water status. The best growth response of quinoa was observed only when the plants were treated with a 2% biochar rate and were fully irrigated
Woody Biochar Differently Influences Plant Water Status and Growth of Five Quinoa (Chenopodium Quinoa Willd.) Varieties Under Water Stress
Full text linkOnly few studies have evaluated the responses of quinoa varieties to biochar amendment under water-limited conditions
during the early growth stages. We examined the interaction between soil treated with and without biochar and water
stress applied during the vegetative development on water relation and growth of quinoa varieties. Five varieties (Titicaca,
Quipu, Regalona, UAFQ7, and Q126) were grown in soil without and with 2% (w/w) woodchip biochar and subjected
to two successive water stress cycles, by withholding water until soil reached the permanent wilting point, started from
12-leaf stage. The morpho-physiological attributes, leaf nutrients and total bacterial count were assessed during the experiment.
Biochar significantly improved plant growth, water use efficiency (WUE), and yield-related traits across all varieties
under water-stressed conditions. Biochar under water-limited conditions enhanced plant water status, indicated by lower
pre-dawn water potential and increased relative water content compared to non-treated soil. The UAFQ7 showed superior
growth with biochar, producing more leaves and larger leaf areas (1517 vs. 1378 cm2/plant). Titicaca was more sensitive
to drought, with a considerable reduction in leaf area (1268 vs. 1386 cm2/plant), fresh and dry biomass (6.4 vs. 7.4 g)
compared to well-watered conditions. Quipu produced longer panicles, further enhanced by biochar (17 vs. 12 cm). A
significant increase of 17% in WUE was observed in biochar-treated plants compared to non-amended ones. Woodchip
biochar seems to mitigate the adverse effects of water stress in quinoa, but the responses vary among varieties
Mitigation of Drought Stress for Quinoa (<i>Chenopodium quinoa</i> Willd.) Varieties Using Woodchip Biochar-Amended Soil
Full text linkDrought stress deteriorates agro-ecosystems and poses a significant threat to crop productivity and food security. Soil amended with biochar has been suggested to mitigate water stress, but there is limited knowledge about how biochar affects the physiology and vegetative growth of quinoa plants under soil water deficits. We grew three quinoa (Chenopodium quinoa Willd.) varieties, Titicaca (V1), Quipu (V2), and UAFQ7 (V3) in sandy loam soil without (B0) and with 2% woodchip biochar (B2) under drought conditions. The drought resulted in significant growth differences between the varieties. V3 performed vegetatively better, producing 46% more leaves, 28% more branches, and 25% more leaf area than the other two varieties. Conversely, V2 displayed significantly higher yield-contributing traits, with 16% increment in panicle length and 50% more subpanicles compared to the other varieties. Woodchip biochar application significantly enhanced the root development (i.e., root biomass, length, surface, and projected area) and plant growth (i.e., plant height, leaf area, and absolute growth rate). Biochar significantly enhanced root growth, especially fresh and dry weights, by 122% and 127%, respectively. However, biochar application may lead to a trade-off between vegetative growth and panicle development under drought stress as shown for V3 grown in soil with woodchip biochar. However, V3B2 produced longer roots and more biomass. Collectively, we suggest exploring the effects of woodchip biochar addition to the soil on the varietal physiological responses such as stomatal regulations and mechanisms behind the increased quinoa yield under water stress conditions
Enhancing Vegetative Growth of Quinoa and Soil Properties under Water Shortage through Targeted Organic Amendments
Full text linkThe scarcity of water resources is considered a major threat and challenge for agriculture.
Water limitations could strongly affect the growth and development of many crops including quinoa, a
nutrition-rich, climate-resilient crop that is gaining attention globally. Organic amendment application has been reported as a suitable option to mitigate the detrimental impacts of water shortage on soil and plant growth. In this context, two experiments were conducted on Chenopodium quinoa “Titicaca”; in the first experiment, we investigated the effect of different organic amendments, namely woodchips biochar (Bw), vineyard pruning biochar (Bv), and vermicompost (V), applied (alone and mixed) at 2% soil dry weight, on soil properties and the plant biomass of quinoa subjected to a water stress period during vegetative development. Among organic amendments tested, Bw and Bw+V increased plant biomass on average by 15%, while Bv and Bv+V reduced the plant biomass by 62% compared to nonamended
soil (C). A significant reduction in soil pH was observed with Bw (7.61), while BV increased
pH (8.04) compared to C (7.76). The Bw and Bv also reduced soil bulk density (BD) (1.19 g/m3 and 1.13 g/m3, respectively) compared to C (1.28 g/m3). As Bw performed better in the first experiment, the second experiment assessed only Bw at different doses, i.e., 0%, 2%, and 4% under water shortage by restoring only 50% evapotranspiration losses, when soil water content reached the 50% of available water content. Considering the Bw rates, the plants treated with Bw2% showed 34% and 19% more biomass and 36% and 66% more panicles than Bw0% and Bw4%, respectively. The Bw2% decreased the soil pH (7.79 versus 7.85) and electrical conductivity (286 versus 307 μS/cm) compared to Bw0%, which was not different from Bw4%. No differences were observed in BD between Bw0% and Bw2% (on average 1.28 g/m3), while BD decreased in Bw4% (1.06 g/m3). The findings of both experiments
highlighted that the appropriate type and dose of biochar could improve soil properties and help quinoa plants to grow better under water-limited conditions
Evaluation of Vegetative Development of Quinoa under Water Stress by Applying Different Organic Amendments
Full text linkProlonged drought periods, increasingly occurring worldwide due to global climate change, could affect the growth and productivity of both traditional and climate-resilient crops, including quinoa. Specifically, the vegetative growing cycle of this species is highly sensitive to drought conditions. In this context, using organic amendments could help plants cope with drought due to their ability to enhance soil water status. So, the current study aimed to investigate the effect of different organic amendments, i.e., two biochars (from woodchips and vineyard prunings) and a vermicompost (from cattle manure), applied to the soil alone and mixed at 2% rate (w/w), on the vegetative development of quinoa (cv. Titicaca), during which a period of water stress was imposed from the twelve-leaf stage to the bud stage. A set of growth-related parameters were measured both during and at the end of the experiment, along with a set of water-related parameters, at the end of the water-stress period and after soil re-watering. The results showed that woodchip biochar, both alone and mixed with vermicompost, significantly affected plant growth during the water-stress period, also allowing a quicker recovery once drought conditions ended. Indeed, the leaf number and area, SPAD index, leaf and stem fresh weight, and dry matter content in plants treated with woodchip biochar, alone and mixed with vermicompost, were higher than vineyard pruning biochar, alone and mixed with vermicompost and similar to the well-watered control plants. Similar results were observed considering the yield contributing traits detected at the end of the experiment, including the main panicle length, number of sub-panicle, as well as fresh weight and dry matter content of both panicle and sub-panicles. Additionally, the water-related parameters, especially the low turgid weight to dry weight ratio of woodchip biochar treated plants, showed evidence of better growth than vineyard pruning biochar. At the end of the experiment, the WUE of plants treated with woodchip biochar and vermicompost, both alone and mixed, was higher than vineyard pruning biochar alone and mixed with vermicompost. Among the tested organic amendments, woodchip biochar alone and mixed with vermicompost positively affected the vegetative growth response of quinoa under water-stress conditions
Drought Stress in Quinoa: Effects, Responsive Mechanisms, and Management through Biochar Amended Soil: A Review.
Full text linkChenopodium quinoa Willd. (quinoa), a highly nutritious pseudocereal, is a promising crop to address global food insecurity challenges intensified by population growth and climate change. However, drought stress remains a significant constraint for quinoa cultivation. The plant exhibits several morphophysiological adaptations to water stress conditions, including root system modifications, reduced growth rate, leaf abscission, and stomatal closure. While these adaptations enhance drought tolerance, they can also negatively impact plant growth, potentially through alterations in root architecture, physiological changes, e.g., stomatal regulations, and anatomical changes. Different studies have suggested that soil amendment with biochar, a pyrolyzed organic material, can improve quinoa growth and productivity under drought stress conditions. Biochar application to the soil significantly enhances soil physiochemical characteristics and maintains plant water status, thereby promoting plant growth and potentially mitigating the negative consequences of drought on quinoa production. This review focuses on the current understanding of quinoa behavior under drought stress and the potential of soil amendment with biochar as a management strategy. We summarize existing research on applying biochar-amended soil to alleviate quinoa drought stress
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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