Closed flow solar dehydration with the use of silver nanoparticles: Application for the production of Pouteria lucuma flour

In this research, a closed-flow solar dehydrator with a refrigeration moisture extraction system was evaluated, likewise, the dehydration temperature time was optimized by evaluating three types of heat transfer fluids. The dehydration equipment included devices to absorb thermal energy from incident sunlight, such as a trombe wall and a parabolic cylindrical collector, and a thermo bank system. In addition, the influence of three types of heat transfer fluids (water, oil and oil nanofluidþsilver nanoparticles) was evaluated. This dehydration system was applied to process the Pouteria lucuma fruit. The results indicate the reduction of the dehydration time by 58.19% using nanofluid. This treatment prevents the modification of the physicochemical properties of the product and helps preserving its organoleptic propertiesinfo:eu-repo/semantics/publishedVersio

Deficit Irrigation in Mediterranean Fruit Trees and Grapevines: Water Stress Indicators and Crop Responses

In regions with Mediterranean climate, water is the major environmental resource that limits growth and production of plants, experiencing a long period of water scarcity during summer. Despite the fact that most plants developed morphological, anatomical, physiological, and biochemical mechanisms that allow to cope with such environments, these harsh summer conditions reduce growth, yield, and fruit quality. Irrigation is implemented to overcome such effects. Conditions of mild water deficit imposed by deficit irrigation strategies, with minimal effects on yield, are particularly suitable for such regions. Efficient irrigation strategies and scheduling techniques require the quantification of crop water requirements but also the identification of pertinent water stress indicators and their threshold. This chapter reviews the scientific information about deficit irrigation recommendations and thresholds concerning water stress indicators on peach trees, olive trees, and grapevines, as case studies

Updated single and dual crop coefficients for tree and vine fruit crops

ReviewThe present study reviews the research on the FAO56 crop coefficients of fruit trees and vines performed over the past twenty years. The main objective was to update information and extend tabulated single (Kc) and basal (Kcb) standard crop coefficients. The selection and analysis of the literature for this review have been done to consider only studies that adhere to FAO56 method, computing the reference ET with the FAO Penman– Monteith ETo equation and field measuring crop ET with proved accuracy. The crops considered refer to vine fruit crops, berries and hops, temperate climate evergreen fruit trees, temperate climate deciduous fruit trees and, tropical and subtropical fruit crops. Papers satisfying the conditions expressed above, and that studied the crops under pristine or appropriate eustress conditions, were selected to provide for standard Kc and Kcb data. Preference was given to studies reporting on the fraction of ground cover (fc), crop height (h), planting density, crop age and adopted training systems. The Kc and Kcb values obtained from the selected literature generally show coherence relative to the crop biophysical characteristics and reflect those characteristics, mainly fc, h and training systems. The ranges of reported Kc and Kcb values were grouped according to crop density, particularly fc and h, and were compared with FAO56 (Allen et al., 1998) previously tabulated Kc and Kcb values, as well as by Allen and Pereira (2009) and Jensen and Allen (2016), which lead to define update indicative standard Kc and Kcb values. These values are aimed for use in crop water requirement computations and modeling for irrigation planning and scheduling, thus also aimed at supporting improved water use and saving in orchards and vinesinfo:eu-repo/semantics/publishedVersio

Drought-induced embolism in current-year shoots of two Mediterranean evergreen oaks

threatened by the increasing water deficits related to climate change. To contribute to the understanding of the capacity of these oaks to withstand severe drought we assessed the vulnerability to xylem embolism and the anatomical traits in current-year shoots. Data were collected in mature trees at two sites, in central/ coastal and southern/inland Portugal. In situ safety margins to hydraulic failure were evaluated from long-term predawn and midday leaf water potential records. Results showed that xylem vulnerability to embolism was similar in Q. ilex and Q. suber. The 50% loss in hydraulic conductivity (Wxyl,50PLC) was observed at xylem water potentials of 2.9 and 3.2 MPa in shoots of Q. suber and Q. ilex, respectively. Values of mean vessel diameter of Q. suber shoots at both sites suggest an intra-species adaptation to the local water availability, with larger vessels at the more mesic site. In situ hydraulic safety margins observed in shoots showed that, even during the driest periods, both oaks lived comfortably above the most critical embolism thresholds. However, the hydraulic safety margins were narrower in the driest site. Results are relevant to the understanding of survival, growth, and functional behaviour of evergreen oaks in Mediterranean climates, under recurrent/seasonal drought condition

Estimation and mapping transpiration with basal and stress crop coefficients derived from remote sensing and ground-based plant water stress indicator

The use of remote sensing for obtaining evapotranspiration (ET) from natural and agricultural surfaces is already widely used. For irrigated agriculture the two basic approaches are: (1) the solution of the energy balance equation, using remotely sensed surface temperatures and reflectances to estimate variables and components of this equation, and (2) the crop coefficient and reference evapotranspiration (ETo) approach where the crop coefficient is obtained through canopy reflectance measurements. For the latter, theoretical and field studies have shown that satellite reflectance-derived vegetation indices (VIs) are closely relate to carbon and moisture fluxes and, when combined with ground data or appropriately calibrated models, they can produce valuable estimates of crop transpiration and related processes at the canopy or ecosystem scale (D ́Urso and Calera, 2006). In this study the crop coefficient approach was used. For estimation of actual transpiration of irrigated and very high tree-density hedgerow orchards grown in Alentejo the procedure correlates (a) the basal crop transpiration coefficients (Kcb = Tmax/ETo) of the unstressed full irrigated treatment to the normalized difference vegetation index (NDVI) values assessed from Landsat5 TM and Landsat7 ETM+ (r2 = 0.86) and (b) the crop stress coefficient (Ks = Ta/KcbETo), obtained from the ratio of the sustained deficit irrigation (Ta) and fully irrigated (Tmax) daily transpiration rates, to a plant stress indicator, in the case, the basal leaf water potential (r2= 0.85). Daily tree transpiration rates on both treatments were obtained from sap flow measurements. The unstressed crop status of the full irrigation treatment was warranted from the high Willmott index of agreement (IA = 0.88) obtained with transpiration values simulated with the Penman-Monteith “big leaf” model (Willmott, 1982). In this algorithm, a specific model of bulk daily canopy conductance (Gc) for unstressed olive canopies was used (Orgaz et al., 2007). From the resulting relationship equations, known field values of leaf basal water potential and satellite-derived NDVI ́s suffice to get estimates of Ks and Kcb, respectively and from them derive and map the actual olive tree transpiration (Ta = Kcb Ks ETo) rates. The study is under way, and thus further validation applications are planned prior to using the approach for mapping olive transpiration orchards of different tree density and scale areas

Lettuce Production under Mini-PV Modules Arranged in Patterned Designs

The growing need for clean energy and food production are favoring the use of underused spaces, such as rooftops. This study aims to demonstrate the compatibility of the use of rooftops both for the production of photovoltaic energy and for the production of food, despite the fact that both compete for the same resource, sunlight (rooftop agrivoltaic). In the experiment reported in this study, which was carried out in Almería (Spain) during the spring and summer of 2021, three shade treatments were tested for a lettuce crop, produced by photovoltaic modules with different arrangements: concentrated shade (CS), scattered shade (SS) and full sun (FS). This experiment was repeated in two seasons with high radiation levels and temperature. The results show that in these environmental conditions, the cultivation of plants that demand little sunlight, such as lettuce, is compatible with the shading produced by photovoltaic panels. In addition, it is shown that the same percentage of the area covered with shade (22%), but using mini-PV modules arranged in patterns, improves the productivity (fresh weight, dry matter, number of leaves, maximum length and dry matter of roots) of lettuce cultivation, both in spring and summer

Challenges, gaps, and opportunities

UID/AGR/04129/LEAF UIDB/04647/2020 UIDP/04647/2020Urban agriculture (UA) plays a key role in the circular metabolism of cities, as it can use water resources, nutrients, and other materials recovered from streams that currently leave the city as solid waste or as wastewater to produce new food and biomass. The ecosystem services of urban green spaces and infrastructures and the productivity of specific urban agricultural technologies have been discussed in literature. However, the understanding of input and output (I/O) streams of different nature-based solutions (NBS) is not yet sufficient to identify the challenges and opportunities they offer for strengthening circularity in UA. We propose a series of agriculture NBS, which, implemented in cities, would address circularity challenges in different urban spaces. To identify the challenges, gaps, and opportunities related to the enhancement of resources management of agriculture NBS, we evaluated NBS units, interventions, and supporting units, and analyzed I/O streams as links of urban circularity. A broader understanding of the food-related urban streams is important to recover resources and adapt the distribution system accordingly. As a result, we pinpointed the gaps that hinder the development of UA as a potential opportunity within the framework of the Circular City.publishersversionpublishe

Unveiling biological activities of marine fungi: the effect of sea salt

There is an urgent need for new substances to overcome current challenges in the health sciences. Marine fungi are known producers of numerous compounds, but the manipulation of growth conditions for optimal compound production can be laborious and time-consuming. In Portugal, despite its very long coastline, there are only a few studies on marine fungi. From a collection of Portuguese marine fungi, we screened for antimicrobial, antioxidant, enzymatic, and cytotoxic activities. Mycelia aqueous extracts, obtained by high pressure-assisted extraction, and methanolic extracts of culture media showed high antioxidant, antimicrobial, and cytotoxic activities. The mycelium extracts of Cladosporium rubrum showed higher antioxidant potential compared to extracts from other fungi. Mycelia and culture media extracts of Aspergillus affinis and Penicillium lusitanum inhibited the growth of Staphylococcus aureus, Kocuria rhizophila, Enterococcus faecalis, Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa, including multiresistant strains. Penicillium lusitanum and Trichoderma aestuarinum inhibited the growth of clinical strains of Candida albicans, C. glabrata, C. parapsilosis, and C. tropicalis. All extracts from culture media were cytotoxic to Vero cells. Sea salt induced alterations in the mycelium's chemical composition, leading to different activity profiles.info:eu-repo/semantics/publishedVersio

Response of intensive and super-intensive olive grove to two different irrigation regimens: physiological parameters, production and quality

Olive grove irrigation has substantially increased in the past years on the region of Alentejo (southern Portugal). The correct determination of the plant water requirements is one of the key factors on the orchard management. This work evaluates the response of two varieties of Olea europaea, Cobrançosa in an intensive grove (hereafter named FEA) and Arbequina in a hedgerow orchard (hereafter named OSul), subject to two water regimes, the one usually practiced by the farmer (emitters with flow rate 1.6 or 2.3 l h-1 on FEA or OSul, respectively) and an excessive water supply on FEA or a deficit irrigation in OSul. The main water relation parameters, chlorophyll content and spectral emission were determined on adult and young leaves, at solar mid-day, three times over the year, spring, late summer and winter 2011. In October, fruits were harvested and total production, oil content and quality were assessed. The results show that in the intensive grove of Cobrançosa (FEA), water supply above the one practiced by the farmer did not improve fruit production neither oil content or quality. There were also no significant differences between the water relation parameters of plants subject to the two irrigation regimes. As to the hedgerow orchard of Arbequina (OSul), deficit irrigation induced lower production and also lower leaf water content, lower water potential and lower stomatal conductance at the end of summer and winter, although oil content and quality remained similar. Chlorophyll content and vegetation indexes were only occasionally affected by the irrigation regime. In both olive groves and irrigation regimes, oil quality was not affected, always attaining the characteristics of an extra virgin olive oil. This research continues in 2012