Different LED light intensity and quality change perennial ryegrass (Lolium perenne L.) physiological and growth responses and water and energy consumption

Light intensity and spectral composition highly affect plant physiology, growth, and development. According to growing conditions, each species and/or cultivar has an optimum light intensity to drive photosynthesis, and different light spectra trigger photosynthetic responses and regulate plant development differently. For the maintenance of natural sports pitches, namely professional football competitions, turf quality is a key condition. Due to the architecture of most football stadiums, the lawns receive low intensities of natural light, so supplementary artificial lighting above the turf is required. The use of light-emitting diodes (LEDs) can have a higher cost–benefit ratio than traditional high-pressure sodium lamps. The continuous emission spectrum, combined with high spectral selectivity and adjustable optical power, can be used to optimize plant growth and development. Thus, perennial ryegrass (Lolium perenne L.) plants, commonly used for lawns, were primarily grown at three different intensities (200, 300, and 400 μmol m−2 s−1) of cool white light. Despite the higher water and energy consumption, 400 μmol m−2 s−1 maximizes the plant’s efficiency, with higher photosynthetic rates and foliar pigment concentration, and more foliar soluble sugars and aboveground biomass accumulation. Then, it was evaluated the perennial ryegrass (Double and Capri cultivars) response to different spectral compositions [100% cool white (W), 80% Red:20% Blue (R80:B20), 90% Red:10% Blue (R90:B10), and 65% Red:15% Green:20% Blue (R65:G15:B20)] at 400 μmol m−2 s−1. Both cultivars exhibited similar responses to light treatments. In general, W contributed to the better photosynthetic performance and R90:B10 to the worst one. Water consumption and aboveground biomass were equal in all light treatments. R80:B20 allows energy savings of 24.3% in relation to the W treatment, showing a good compromise between physiological performance and energy consumption

Toxicological evaluation of pterospartum tridentatum flower water

Pterospartum tridentatum Willk. (prickled broom) is an autochthonous plant, common in Portuguese territory. The yellow flowers are widely used in traditional medicine, as a potential cure for all body illnesses, mainly for throat irritation treatment or for diabetes, hypertension and hypercholesterolemia therapy. Despite its wide traditional use, no toxicological assessment of this plant has been performed, as far as we know. The major goal of this work was the P. tridentatum water extracts safety assessment. Methodology: Chemical characterization of MS analysis of P. tridentatum flower extract was performed by ESI-MS spectroscopy; phenols and quercetins content were also determined. Antioxidant activity was evaluated through -carotene bleaching test and ABTS radical-scavenging activity. Oxygen consumption of isolated mitochondria was determined polarographically with a Clark oxygen electrode and mitochondrial respiratory rates evaluated accordingly to Chance and Williams (1956) and mitochondrial swelling was evaluated the apparent absorbance changes at 520 nm. Results and discussion: A high antioxidant activity of P. tridentatum flower water extract was assessed in good agreement with its ESI-MS spectrum that revealed the presence of several flavonoids, as luteolin-O-(O-acetyl)-glucuronide, luteolin-Oglucuronide or isorhamnetin-O-hexoside. Mitocondrial respiratory rates (state 4, state 3 and FCCP-stimulated respiration) and respiratory indexes (respiratory control and P/O ratios) showed no consistent decrease of respiratory and phosphorylative efficiencies for the concentrations tested (up to 500 μg.mL-1). In conclusion, for the concentration range commonly used P. tridentatum flowers usage can be regarded as harmless and trustworthy and due to its great antioxidant properties it is useful to counteract diabetes mellitus associated diseases

Use of kaolin as a summer stress alleviating product in olive orchards under rainfed conditions

In a changing world, where is expected the temperatures rising and the reduction in precipitation in some semi-arid areas of the globe, the search for new agronomic practices that help crops to maintain and/or increase yields and quality is a continuous challenge. Kaolin (KL) exogenous application has been considered a short-term solution to alleviate the adverse effects of summer stress. The formed particle film increases the reflection of excess radiation reducing the risk of leaf damage from heat load accumulation and solar injury. Olive trees (Olea europaea L.) cultivated under rainfed conditions were sprayed with KL (5%) during two consecutive years in the beginning of the summer season. In general, relatively to the control group, KL-sprayed plants showed an enhancement in leaf water status, stomatal conductance and photosynthetic capacity and a reduction in leaf sclerophylly. In the severest period analyzed, at the end of the second-year summer, KL has lost the effectiveness of keeping gas exchange above the control measurements. However, in both years, allowed a faster restauration of the physiological functions in early autumn and contributed to higher crop yield. Overall, the results of the present investigation revealed that KL were effective in preventing the adverse effects of summer stress on crop performance and yield.Doctoral fellowship under the Doctoral Program “Agricultural Production Chains – from fork to farm” (PD/00122/2012) provided by the FCT-Portuguese Foundation for Science and Technology to C. Brito (PD/BD/52543/2014). Institution CITAB, for its financial support through the European Investment Funds by FEDER/COMPETE/POCI– Operational Competitiveness and Internationalization Program, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.info:eu-repo/semantics/publishedVersio

Polyphenols characterization and toxicological evaluation of pterospartum tridentatum leaf water extracts

Pterospartum tridentatum Willk. (prickled broom) is an autochthonous and common plant in Portugal. Leaves and stems are normally used in cooking, to flavour rice, roast meat or hunting animals. Leaves are also used as a condiment in fresh salads and, despite of its traditional use, no toxicological evaluation has been performed. P. tridentatum leaves aqueous extract ESI-MS spectrum revealed the presence of several luteolin and isorhamnetin derived phenolic compounds, which can be associated to the health benefits claimed for this plant species. Still, P. tridentatum leaves extract (up to 100 µg plant extract.mg-1 protein) stimulated state 4 and FCCP-stimulated liver mitochondria respiratory rates and inhibited the state 3 respiratory rate. Respiratory control ratio was diminished, indicating a decrease in phosphorylative efficiency due to inner mitochondrial membrane induced by P. tridentatum leaves extract. Nevertheless, previous results, cytotoxicity evaluation by MTT assay (50 and 125 µg plant extract) showed no significant decrease on HepG2 cell viability. Overall, the present study suggests that the consumption of P. tridentatum leaves should be regarded as safe

Weather year-to-year variations determine the influence of kaolin and salicylic acid in olive fruits and oil phenolic composition

Olive tree (Olea europaea L.) growing area is threatened by the current and predicted adverse environmental conditions, affecting negatively the quality of the olive products, largely known for its benefits in human diet. Thus, agronomic strategies may be implemented to offset those negative effects. During two consecutive years young olive trees under rainfed conditions were sprayed in the beginning of the summer season with 100 M salicylic acid (SA), a stress signaling phytohormone, or with kaolin 5% (KL), a heat and irradiance reflecting clay. The distinct weather conditions during the fruit development stage, with higher rainfall close to the harvest and the early frost events, in the first year, and the warmer and drier summer, in the second year, contributed to the increase in phenolic compounds in fruits and in olive oil from the first to the second year. Both KL and SA increased crop yield, while, in general, phenolics concentrations of both olives and oil were increased and decreased by the applied products in the first and second year, respectively. This dissimilar response was modulated by the distinct weather conditions, demonstrating the effectiveness of the applied products in attenuating the frost-promoted degradation of phenolic compounds in the first year and in mitigating the extreme adverse conditions felt in the summer of the second year. The phenolic composition was also distinctly affected, since total phenols, ortho-diphenols and flavonoids exhibited different trends. It is hard to conclude a specific influence of the applied products on olives and oil phenolic composition, since the weather year-to-year variations determine different plant responses.Doctoral fellowship under the Doctoral Program “Agricultural Production Chains – from fork to farm” (PD/00122/2012) provided by the FCT-Portuguese Foundation for Science and Technology to C. Brito (PD/BD/ 52543/2014). Institution CITAB, for its financial support through the European Investment Funds by FEDER/COMPETE/POCI– Operational Competitiveness and Internationalization Program, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.info:eu-repo/semantics/publishedVersio

Salicylic acid improves the tolerance of olive trees against the Mediterranean adverse summer conditions

The projected climate changes in the Mediterranean region, that include low rainfall, excessive heat load and high daily irradiance, are of utmost relevance for rainfed olive orchards, since are expected negative consequences on physiology, growth, productivity and quality. In this sense, agronomic strategies may be implemented to offset those negative effects. Rainfed young olive trees (Olea europaea L.) cv. Cobrançosa were sprayed with 100 M salicylic acid (SA), a signaling phytohormone with diverse regulatory roles in abiotic stresses responses. The results demonstrate that SA influenced positively the leaf water status, stomatal conductance and photosynthetic capacity of rainfed trees. The protective action of SA is associated with the induction of some stress tolerance indicators, as the increase in soluble proteins and ascorbate concentrations, and the improvement of plant nutritional status. This more comfortable conditions during the summer period allowed a faster restauration of the physiological functions in the early autumn. Finally, the sprayed plants exhibited higher yields than the control ones. In summary, SA seems to be an efficient strategy to improve olive tree tolerance against the adverse summer conditions of Mediterranean region.Doctoral fellowship under the Doctoral Program “Agricultural Production Chains – from fork to farm” (PD/00122/2012) provided by the FCT-Portuguese Foundation for Science and Technology to C. Brito (PD/BD/52543/2014). Institution CITAB, for its financial support through the European Investment Funds by FEDER/COMPETE/POCI– Operational Competitiveness and Internationalization Program, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013.info:eu-repo/semantics/publishedVersio

Kaolin and salicylic acid foliar application modulate yield, quality and phytochemical composition of olive pulp and oil from rainfed trees

Olive orchards, rainfed managed, are threatened by the current and predicted adverse environmental conditions, which change the yield and quality of olive products, largely known for its benefits to human health. To mitigate these problems, it is highly recommended to perform some adjustments in agronomic practices, such as the use of foliar sprays that cloud help the trees to cope with climate change. During two consecutive years, olive trees were pre-harvest sprayed with kaolin (KL) and salicylic acid (SA) to attenuate the adverse effects of summer stress. Olive yield was increased by 97% and 72% with KL and SA, respectively. Phenolics and antioxidant capacity of both olives and olive oil increased and decreased in the first and second year, respectively, in a closely association with the prevailing climatic conditions. The foliar sprays did not significantly affect the oil quality indices, free acidity, peroxide value and K232 coefficient and decreased the K270 coefficient. This study strongly suggests that the applied products might be effective in mitigating the adverse environmental conditions, without substantial changes in fruit and olive oil quality.Doctoral fellowship under the Doctoral Program “Agricultural Production Chains – from fork to farm” (PD/00122/2012) provided by the FCT-Portuguese Foundation for Science and Technology to C. Brito (PD/BD/ 52543/2014). Institution CITAB, for its financial support through the European Investment Funds by FEDER/COMPETE/POCI– Operational Competitiveness and Internationalization Program, under Project POCI-01-0145-FEDER-006958 and National Funds by FCT - Portuguese Foundation for Science and Technology, under the project UID/AGR/04033/2013. INTERACT project - "Integrative Research in Environment, Agro-Chains and Technology", no. NORTE-01-0145- FEDER-000017, in its lines of research entitled ISAC, co-financied by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020).info:eu-repo/semantics/publishedVersio

Kaolin and salicylic acid alleviate summer stress in rainfed olive orchards by modulation of distinct physiological and biochemical responses

In a changing world, the search for new agronomic practices that help crops to maintain and/or increase yields and quality is a continuous challenge. We aim to evaluate kaolin (KL) and salicylic acid (SA) effectiveness as summer stress alleviating agents through physiological, biochemical and immunohistochemical analysis. Olive trees (Olea europaea L. cv. Cobrançosa) grown under rainfed conditions were sprayed with 5% KL and 100 μM SA, at the beginning of summer, during two consecutive years. KL enhanced relative water content (RWC), stomatal conductance (gs) net photosynthesis (A) and leaf indole-3-acetic acid (IAA) signal, and decreased leaf sclerophylly, secondary metabolites and non-structural carbohydrates accumulation and abscisic acid (ABA).The trees treated with SA showed changes on IAA and ABA dynamics, and an enhancement in RWC, gs, A, soluble proteins, and leaf P and Mg concentrations during the summer. Notably, KL and SA also allowed a faster restauration of the physiological functions during stress relief. In sum, KL and SA foliar sprays alleviated the negative effects induced by summer stress in olive trees performance, by modulation of distinct physiological and biochemical responses.info:eu-repo/semantics/publishedVersio

Kaolin spray induces changes in ABA and IAA immunodistribution in olive leaves.

The climate change scenarios predicted the accentuation of drought and high temperature events during the summer season in the Mediterranean region, coming up harmful consequences to important crops of this region, such as olive tree (Olea europaea L.). Stress conditions often stimulate changes in plants production, distribution or signal transduction of phytohormones as a response, then modifying their physiology and biochemistry. Kaolin (KL) is a reflecting clay that applied on leaves surface reduce the common damages promoted by heat load and high irradiance levels, being important to test its effect on olive tree hormonal dynamics and physiological parameters. Olive trees of a rainfed orchard in Northeast Portugal, were sprayed with kaolin 5% (KL) and water (C). The immunodistribution of two hormones, abscisic acid (ABA) and indoleacetic acid (IAA), and some physiological and growth responses were accessed. The ABA signal was substantially more pronounced than the IAA signal in all the analyzed leaves, concomitant with the stressful conditions of which these plants were subjected. In general, ABA signal showed a uniform distribution throughout the leaf in both treatments. However, its intensity was higher in C than in KL-sprayed leaves, reflecting the better water status and higher stomatal conductance of the last plants. While in C leaves was observed a uniform distribution of IAA signal trough the leaf limb and an almost absence of signal in the main vascular tissues, in KL-sprayed leaves was observed a higher signal intensity in the main vascular tissues and upper palisade parenchyma. These data suggest its transport and an active growth in KL plants, concomitant with the higher increase of canopy volume. Thus, immunodetection appears to be an efficient tool to understand the translocation of IAA and ABA in plants treated with abiotic stress alleviating products and clarify their role in regulating the physiological responses.info:eu-repo/semantics/publishedVersio

Kaolin and salicylic acid alleviate summer stress effects on rainfed olive orchards through distinct physiological and biochemical processes

In a changing world, the search for new agronomic practices that help crops to maintain and/or increase yields and quality is a continuous challenge. Olive trees cultivated under rainfed conditions were sprayed with 5% kaolin (KL) and 100 μM salicylic acid (SA) during two consecutive years in the beginning of the summer season. Exogenous KL enhanced relative water content (RWC), stomatal conductance (gs) net photosynthesis (A) and IAA immunodetection, and decreased leaf sclerophylly, secondary metabolites and non-structural carbohydrates accumulation, ABA signal and DNA methylation, contributing to higher growth and yield. The plants treated with SA showed an enhancement in RWC, gs, A, soluble proteins, IAA, ABA and DNA methylation immunodetection and leaf P and Mg concentrations during the summer, leading to higher yield. Thus, KL and SA alleviated some of the negative effects induced by summer stress in olive tree performance, allowing a faster restauration of the physiological functions during the stress relief and leading to higher yieldsThis work was funded by the INTERACT project – “Integrative Research in Environment, Agro-Chains and Technology”, no. NORTE-01-0145-FEDER-000017, in its lines of research entitled ISAC, co-financed by the European Regional Development Fund (ERDF) through NORTE 2020 (North Regional Operational Program 2014/2020).info:eu-repo/semantics/publishedVersio