Lipid peroxidation and chlorophyll fluorescence of photosystem ii performance during drought and heat stress is associated with the antioxidant capacities of C3 sunflower and C4 maize varieties

Agricultural production is predicted to be adversely affected by an increase in drought and heatwaves. Drought and heat damage cellular membranes, such as the thylakoid membranes where photosystem II occurs (PSII). We investigated the chlorophyll fluorescence (ChlF) of PSII, photosynthetic pigments, membrane damage, and the activity of protective antioxidants in drought-tolerant and -sensitive varieties of C3 sunflower and C4 maize grown at 20/25 and 30/35 °C. Drought-tolerant varieties retained PSII electron transport at lower levels of water availability at both temperatures. Drought and heat stress, in combination and isolation, had a more pronounced effect on the ChlF of the C3 species. For phenotyping, the maximum fluorescence was the most effective ChlF measure in characterizing varietal variation in the response of both species to drought and heat. The drought-tolerant sunflower and maize showed lower lipid peroxidation under drought and heat stress. The greater retention of PSII function in the drought-tolerant sunflower and maize at higher temperatures was associated with an increase in the activities of antioxidants (glutathione reductase, superoxide dismutase, catalase, peroxidase, and ascorbate peroxidase), whereas antioxidant activity declined in the drought-sensitive varieties. Antioxidant activity should play a key role in the development of drought- and heat-tolerant crops for future food security

Homosexuality in the afrocentric conception of Molefi Kete Asante: between liberation and oppression

Com este artigo, pretende-se discutir a conceção relativa à homossexualidade apresentada por uma das correntes filosóficas mais destacadas da contemporaneidade: o Afrocentrismo. Esta corrente, inspirada na lição de Check Anta Diop, tem sido desenvolvida pelo afro-americano Asante, que a concebe como paradigma alternativo ao eurocêntrico, visando libertar as mentes dos africanos (do continente e da diáspora) das influências ocidentais, enraizadas na experiência colonial e da escravatura. Entretanto, um dos limites que, na visão dos autores, este paradigma encontra, reside na negação da dignidade da homossexualidade e dos homossexuais, com base numa suposta tradição africana. O artigo procura, portanto, demonstrar as profundas ambiguidades do Afrocentrismo sobre este assunto, colocando a questão da homossexualidade como central para que o elementar direito de opção sexual seja livre e possa ser aceite na cultura africana.info:eu-repo/semantics/publishedVersio

Crown condition assessment at the CONECOFOR Permanent Monitoring Plots.

A detailed crown condition assessment is currently being carried out at the CONECOFOR (CONtrollo ECOsistemi FORestali, Control of Forest Ecosystems) plots. The assessment began in 1996, and during the first two years (1996 and 1997) an assessment form based on previous regional experience was used; in 1998 the new official EU form was adopted. The resulting loss of comparability means that only a few indices can be used in the temporal series 1996-1999. Much effort was devoted to Quality Assurance (QA) procedures. The QA program is structured as follows: (i) specific field manuals have been adopted and are continuously updated; (ii) a national training and intercalibration course (NT&IC) is undertaken yearly before beginning the assessment campaign;( iii) field checks are carried out yearly on a large number of plots. The results of the QA program have shown that for several indices the quality objectives were not reached, but the quality of the data is improving with time. To express the change in crown conditions in each area, a complex index (CCI = Crown Condition Index) was adopted. This index is the result of the sum of the relativized values of all the common indices used during the four years. The following parameters were used: transparency, ramification type, leaf colour alteration extension, leaf damage extension, alteration of leaf distension extension. The range within which the CCI fluctuates was evaluated taking into account all the observations carried out at a given plot throughout the years. The number of cases over a given threshold (outliers) was calculated for each year. The threshold for outliers was calculated as the median value plus 2 times the range of the interquartile value. All individual cases exceeding this value are considered outliers. The results are presented for all the areas in which the data set is complete for the four years. The yearly fluctuations are discussed and related to possible causes

Cultural policies in Mozambique between national identity and local instances (1975-2009)

Este artigo tem como objectivo analisar a implementação das políticas culturais em Moçambique de 1975 a 2009. Apesar de muitos esforços, os resultados conseguidos foram modestos. A implementação das políticas culturais em Moçambique pode ser subdividida em três gerações ou fases, nomeadamente a consolidação da identidade e preservação do património, a regulação econômica do setor cultural e a produção e difusão do setor cultural. A abordagem metodológica adotada foi de tipo qualitativo, centrada na análise documental e legislativa do material disponível, segundo uma perspectiva histórica. O que resultou da investigação foi que no período socialista a política cultural expressava uma visão enraizada numa ideologia clara (o socialismo), que porém não considerou adequadamente as instâncias culturais a nível local, ao passo que, com a “Segunda República”, o Estado se tornou cada vez menos interventivo e mais regulador, deixando largo espaço às forças do mercado, e por vezes utilizando algumas manifestações culturais e tradicionais como meio de controlo político das massas.info:eu-repo/semantics/publishedVersio

The invention of a tradition: the role of historical sources in the debate between Afrocentrists and their critics

Este artigo visa analisar o uso das fontes históricas no debate entre a corrente filosófica do Afrocentrismo e as críticas que esta recebeu. O Afrocentrismo, principalmente na versão elaborada por Asante, propõe a revisão radical e a superação do paradigma eurocêntrico. O alicerce desta proposta é a ideia de que o pensamento filosófico e científico surgiu em África, nomeadamente na civilização egípcia, considerada “negra”, de acordo com a lição de Anta Diop. As provas de matriz histórica utilizadas pelos afrocentristas foram largamente contestadas. O artigo pretende evidenciar a forte ligação entre elaboração filosófica, aparato ideológico e “invenção” duma tradição histórica por parte do Afrocentrismo, cujo uso instrumental das fontes entra em choque com as regras básicas da ciência histórica. Daqui, as duras críticas recebidas, devido à sua escassa fiabilidade epistemológica e metodológica.info:eu-repo/semantics/publishedVersio

Inconsistent relationships among protection, benthic assemblage, habitat complexity and fish biomass in Mediterranean temperate rocky reefs

Marine Protected Areas (MPAs) have been proved to effectively protect and restore fish assemblages. There is mixed evidence regarding the effects of MPAs on benthic assemblages, habitat complexity, and how protection might mediate the effects of habitat features (including biotic and abiotic components) on fish assemblages, with very little information concerning temperate areas. Here, our aim is to assess how protection 1) influences benthic assemblages and habitat complexity, and 2) mediates the effects of habitat complexity on fishes. Using non-destructive methods (photosampling for shallow rocky benthic assemblages, and underwater visual census using strip transects for fish assemblages) to characterize benthic and fish assemblages, we sampled 15 Mediterranean locations, each including protected and unprotected sites. In all, we sampled 90 sites, and analyzed 2,760 photos and 800 replicated transects, gathering information on 44 benthic and 72 fish taxa. Abiotic, biotic and synthetic (i.e. combining the previous two) complexity indices have been computed to synthesize habitat features. Overall, whole benthic assemblages did not significantly differ between protected and unprotected conditions, but higher cover of the ecologically important erect algae belonging to the genus Cystoseira sensu lato was recorded within MPAs. Abiotic, biotic and synthetic complexity did not show clear patterns related to protection levels, displaying inconsistent responses between different locations. Our findings highlight that protection has a generally positive effect on fish biomass, this latter variable responding independently of the habitat complexity. Our study, in conclusion, confirms that MPAs can be effective to protect and restore rocky-reef assemblages, highlighting the need for more in-depth exploration of the mechanisms determining the different responses of benthic taxa to protection and how this can influence the associated fish assemblages

On the tracks of Nitrogen deposition effects on temperate forests at their southern European range - an observational study from Italy

We studied forest monitoring data collected at permanent plots in Italy over the period 2000\u20132009 to identify the possible impact of nitrogen (N) deposition on soil chemistry, tree nutrition and growth. Average N throughfall (N-NO3+N-NH4) ranged between 4 and 29 kg ha 1 yr 1, with Critical Loads (CLs) for nutrient N exceeded at several sites. Evidence is consistent in pointing out effects of N deposition on soil and tree nutrition: topsoil exchangeable base cations (BCE) and pH decreased with increasing N deposition, and foliar nutrient N ratios (especially N : P and N : K) increased. Comparison between bulk openfield and throughfall data suggested possible canopy uptake of N, levelling out for bulk deposition >4\u20136 kg ha 1 yr 1. Partial Least Square (PLS) regression revealed that - although stand and meteorological variables explained the largest portion of variance in relative basal area increment (BAIrel 2000\u20132009) - N-related predictors (topsoil BCE, C : N, pH; foliar N-ratios; N deposition) nearly always improved the BAIrel model in terms of variance explained (from 78.2 to 93.5%) and error (from 2.98 to 1.50%). N deposition was the strongest predictor even when stand, management and atmosphere-related variables (meteorology and tropospheric ozone) were accounted for. The maximal annual response of BAIrel was estimated at 0.074\u20130.085% for every additional kgN. This corresponds to an annual maximal relative increase of 0.13\u20130.14% of carbon sequestered in the above-ground woody biomass for every additional kgN, i.e. a median value of 159 kgC per kgN ha 1 yr 1 (range: 50\u2013504 kgC per kgN, depending on the site). Positive growth response occurred also at sites where signals of possible, perhaps recent N saturation were detected. This may suggest a time lag for detrimental N effects, but also that, under continuous high N input, the reported positive growth response may be not sustainable in the long-term