Effect of biochar amendment on morphology, productivity and water relations of sunflower plants under non-irrigation conditions

páginas.-- 6 figuras.-- 2 tablas.-- 56 referencias.-- Supplementary data to this article can be found online at http://dx.doi.org/10.1016/j.catena.2016.07.037.Three biochars (B1: pine wood, B2: paper-sludge, B3: sewage-sludge) produced under controlled pyrolysis conditions and one produced in kilns (B4: grapevine wood) were used as organic ameliorants in a Calcic Cambisol, which represents a typical agricultural soil of the Mediterranean region. This field study was performed with plants of sunflower (Helianthus annuus L.) at the experimental station “La Hampa”, located in the Guadalquivir river valley (SW Spain). The soil was amended with doses equivalent to 1.5 and 15 t ha− 1 of the four biochars in two independent plantations. In addition, un-amended plots were prepared in both experiments for comparison purposes. The major goal of this study was the assessment of the effect of biochar amendment on the physiology and development of sunflower plants at field conditions. During most of the growing period plants of un-amended and amended plots showed no stress symptoms either by their appearance or by stress-sensitive biochemical parameters such as the stability of the photosystem II (QY). Biochar addition had no effect on seed germination. Addition of 1.5 t ha− 1 biochar did not significantly change the pH of the soil, its electrical conductivity (EC) or its water holding capacity (WHC). Concomitantly the plant development and plant biomass production remained unaltered. Amendments with 15 t ha− 1 slightly increased the WHC of the soil but showed no lasting impact on the soil pH. It stimulated plant growth and led to a greater leaf area, larger plant stems and wider inflorescences of the sunflower plants than those cultivated on the un-amended soil. At the end of the experiment, biochar amendment of soil caused no significant increase of the total biomass production excepting B4, the biochar with the lowest capacity of water retention, which exhibited the highest vegetative growth and seed production. The lack of rain during the last weeks caused a water shortage in the culture that produced greater QY loss in non-amended plants. Interestingly, better growth of amended plants during the drought period correlated with higher reduction of stomatal conductance, indicating that the greater water use efficiency is at the origin of the better crop performance of biochar-amended plants. This finding points to the agronomic relevance of biochar amendment of Mediterranean rain fed crops.The Marie Skłodowska-Curie actions of the European Union's FP7 People Programme (REA grant agreement no PCIG12-GA-2012-333784-Biocharisma project) and the Spanish Ministry of Economy and Competitiveness (MINECO) (project PCGL2012-37041) are thanked for the financial support of the present study. The Spanish Ministry of Education, Culture and Sport is acknowledged for funding the FPU fellowship (FPU 13/05831) of Marina Paneque, and the contract of Juan De Dios Franco-Navarro (AGL2009-08339/AGR). The European Biochar Network (Biochar as option for sustainable resource management-COST action TD1107) and Bodegas Torres (Spain) are acknowledged for providing the biochar samples. M. Velasco is gratefully acknowledged for her technical assistance at field.Peer reviewe

Chloride regulates leaf cell size and water relations in tobacco plants

19 páginas.-- 9 figuras.-- 5 tablas.-- 77 referencias.-- Supplementary Data: Supplementary_figures_S1_S7___Tables_S1_S7.pdfChloride (Cl–) is a micronutrient that accumulates to macronutrient levels since it is normally available in nature and actively taken up by higher plants. Besides a role as an unspecific cell osmoticum, no clear biological roles have been explicitly associated with Cl– when accumulated to macronutrient concentrations. To address this question, the glycophyte tobacco (Nicotiana tabacum L. var. Habana) has been treated with a basal nutrient solution supplemented with one of three salt combinations containing the same cationic balance: Cl–-based (CL), nitrate-based (N), and sulphate+phosphate-based (SP) treatments. Under non-saline conditions (up to 5mM Cl–) and no water limitation, Cl– specifically stimulated higher leaf cell size and led to a moderate increase of plant fresh and dry biomass mainly due to higher shoot expansion. When applied in the 1–5mM range, Cl– played specific roles in regulating leaf osmotic potential and turgor, allowing plants to improve leaf water balance parameters. In addition, Cl– also altered water relations at the whole-plant level through reduction of plant transpiration. This was a consequence of a lower stomatal conductance, which resulted in lower water loss and greater photosynthetic and integrated water-use efficiency. In contrast to Cl–, these effects were not observed for essential anionic macronutrients such as nitrate, sulphate, and phosphate. We propose that the abundant uptake and accumulation of Cl– responds to adaptive functions improving water homeostasis in higher plants.This work was supported by the Spanish Ministry of Science and Innovation-FEDER grant AGL2009-08339/AGR. The help, expertise, and technical assistance of C. Rivero, A. Vázquez, S. Luque, B.J. Sañudo, F.J. Durán, Y. Pinto, and J. Espartero are gratefully acknowledged. We would like to extend our gratitude to the valuable reviews and contributions by the anonymous referees and the editor, Timothy Colmer, which helped us to improve the manuscript substantially.Peer reviewe

Acta Horticulturae

While the molecular response of model plants to salt stress in the short-medium term (hours-days) has been broadly studied, the knowledge about the nature of genes involved in maintaining homeostatic conditions in the long term (months-years) in woody perennial trees has not been addressed yet. We have analyzed physiological parameters and the transcriptome profiles of photosynthetically active leaves from citrus trees acclimatized to moderate salinity (NaCl 30 mM) after 2 years treatment. Through functional genomics, global gene expression in response to NaCl treatment in mature (8 months-old) and young (2 months-old) leaves has been analyzed and compared. Although young leaves (YL) accumulated low levels of chloride (0.51%+/- 0.06), they exhibited a much stronger response to salinity in term of the number of differentially expressed genes (1,211 genes) compared with mature leaves (ML), which accumulated higher chloride levels (1.05%+/- 0.01), and exhibited a much lower number of differentially-responsive genes (100 genes). In this work, a number of responses have been observed that differ from those described in previous studies of citrus plants non-acclimatized to salt stress (Brumos et al., 2009), whose principal manifestation was the lack of repression of primary metabolism in leaves at the molecular and physiological levels. Results describing enriched functional categories of differentially expressed genes are presented and discussed highlighting how the long-term acclimation to NaCl stress involves drastically different molecular strategies depending on the developmental stage of plant leaves

Chloride Nutrition Regulates development, Water Balance and Drought Resistance in Plants

6 páginas.-- 5 figuras.-- 9 referencias.-- Poster presentado en el XII Luso-Spanish Symposium on Plant Water Relations – Water to Feed the World. 30th of September – 3rd of October (Evora) PortugalCl- is a strange micronutrient since actual Cl- concentration in plants is about two orders of magnitude higher than the content required as essential micronutrient. This accumulation requires a high cost of energy, and since Cl- is a major osmotically active solute in the vacuole, we propose that Cl- plays a role in the regulation of water balance in plants. We show here that, when accumulated to macronutrient levels, Cl- specifically regulates leaf cell elongation and water balance parameters, improving water relations at both the leaf tissue and the whole plant levels, increasing drought resistance in higher plants.This work was supported by the Spanish Ministry of Science and Innovation-FEDER grant AGL2009-08339/AGR.Peer Reviewe

Coping With Water Shortage: An Update on the Role of K+, Cl-, and Water Membrane Transport Mechanisms on Drought Resistance

Drought is now recognized as the abiotic stress that causes most problems in agriculture, mainly due to the strong water demand from intensive culture and the effects of climate change, especially in arid/semi-arid areas. When plants suffer from water deficit (WD), a plethora of negative physiological alterations such as cell turgor loss, reduction of CO2 net assimilation rate, oxidative stress damage, and nutritional imbalances, among others, can lead to a decrease in the yield production and loss of commercial quality. Nutritional imbalances in plants grown under drought stress occur by decreasing water uptake and leaf transpiration, combined by alteration of nutrient uptake and long-distance transport processes. Plants try to counteract these effects by activating drought resistance mechanisms. Correct accumulation of salts and water constitutes an important portion of these mechanisms, in particular of those related to the cell osmotic adjustment and function of stomata. In recent years, molecular insights into the regulation of K+, Cl-, and water transport under drought have been gained. Therefore, this article brings an update on this topic. Moreover, agronomical practices that ameliorate drought symptoms of crops by improving nutrient homeostasis will also be presented

Trustworthiness of randomized trials in endocrinology—A systematic survey

Background Trustworthy (i.e. low risk of bias) randomized clinical trials (RCTs) play an important role in evidence-based decision making. We aimed to systematically assess the risk of bias of trials published in high-impact endocrinology journals. Methods We searched the MEDLINE/PubMed database between 2014 and 2016 for phase 2–4 RCTs evaluating endocrine-related therapies. Reviewers working independently and in duplicate used the Cochrane Risk of Bias Tool (CCRBT) to determine the extent to which the methods reported protected the results of each RCT from bias. Results We assessed 292 eligible RCTs, of which 40% (116) were judged to be at low risk, 43% (126) at moderate, and 17% (50) at high risk of bias. Blinding of outcome assessment was the least common domain reported 43% (125), while selective reporting of outcomes was the most common 97% (282). In multivariable analysis, RCTs with a parallel design (OR 2.4; 95% CI; 1.2–4.6) and funded by for-profit sources (OR 2.2; 95% CI; 1.3–3.6) were more likely to be at low risk of bias. Conclusions Trustworthy evidence should ultimately shape care to improve the likelihood of desirable patient outcomes. Six out-of 10 RCTs published in top endocrine journals are at moderate/ high-risk of bias. Improving this should be a priority in endocrine researc

Chloride: a beneficial macronutrient in plants, biological functions and regulation

In the agronomic context, chloride (Cl) has been generally considered a toxic anion rather than a plant nutrient (Colmenero-Flores et al, 2007; Brumós et al, 2009; Brumós et al, 2010). However, we have recently shown that in addition to an essential micronutrient, chloride is a beneficial macronutrient (Franco-Navarro et al, 2016). Under non-saline conditions Clspecifically stimulates higher leaf cell size and leads to a moderate increase of plant fresh and dry biomass mainly due to higher shoot expansion. Clplays specific roles in regulating leaf osmotic potential and turgor, allowing plants to improve leaf water balance parameters. In addition, Clregulates water relations at the whole plant level through reduction of plant transpiration. This is a consequence of a lower stomatal conductance, which results in lower water loss and greater photosynthetic and integrated water-use efficiency (Franco-Navarro et al, 2016). The following open questions about chloride accumulation at macronutrient levels will be addressed: i) does Climprove resistance to water deficit?; ii) why Cl- mediated reduction of stomatal conductance does not result in reduction of net photosynthetic rate?; iii) why nitrate assimilation is not adversely affected?; iv) How is Claccumulation and Cl/NO3 - interaction regulated at the molecular level? We propose that the abundant uptake and accumulation of Clresponds to adaptive functions improving water homeostasis, drought tolerance, and nitrate- and Carbon-use efficiency in plants. In addition, molecular mechanisms regulating the distribution of Clbetween root and shoot according to changing environmental conditions will be proposed. Brumos, J., J.M. Colmenero-Flores, A. Conesa, P. Izquierdo, G. Sanchez, D.J. Iglesias, M.F. Lopez-Climent, A. Gomez-Cadenas, and M. Talon. 2009. Membrane transporters and carbon metabolism implicated in chloride homeostasis differentiate salt stress responses in tolerant and sensitive Citrus rootstocks. Functional & Integrative Genomics 9:293-309. Brumós, J., M. Talón, Bouhlal, R. and J.M. Colmenero-Flores. 2010. Cl- homeostasis in includer and excluder citrus rootstocks: transport mechanisms and identification of candidate genes. Plant, Cell & Environment 33:2012-2027. Colmenero-Flores, J.M., G. Martinez, G. Gamba, N. Vazquez, D.J. Iglesias, J. Brumos, and M. Talon. 2007. Identification and functional characterization of cation-chloride cotransporters in plants. The Plant Journal 50:278-292. Franco-Navarro, J.D., J. Brumós, M.A. Rosales, P. Cubero, M. Talón, and J.M. Colmenero-Flores. 2016. Chloride regulates leaf cell size and water relations in tobacco plants. Journal of Experimental Botany. 67:873-891.Peer Reviewe