468 research outputs found
Advances in irrigation management in greenhouse cultivation
The advantages of greenhouse include the ability to secure better conditions than outdoor environment for crop growth and development, increased off-season production and autonomy from external weather conditions. This chapter provides an up-to-date critical overview of scientific advances in irrigation management for greenhouse vegetables and ornamentals. The chapter presents a technical design of a typical greenhouse irrigation system, before covering water balance and crop evapotranspiration techniques as well as the use of high-tech moisture sensors for irrigation scheduling. In the context of enhancing the water use efficiency of greenhouse crops, the chapter also discusses innovative management practices such as biostimulants and grafting. Finally, the chapter concludes by looking ahead to future prospects and research breakthroughs
Ameliorating a Complex Urban Ecosystem Through Instrumental Use of Softscape Buffers: Proposal for a Green Infrastructure Network in the Metropolitan Area of Naples
Green Infrastructure (GI) definition, deriving from the United States green infrastructure
for hydro-geological rebalancing through imitating the nature stormwater management,
was consolidated in Europe by GI Planning Guide. Nowadays GI can be considered
a valid and meaningful approach for ameliorating urban complex ecosystems, and
could also be considered as mitigation action of land consumption, according to the
guidelines on the soil sealing of the European Commission (2012). The metropolitan
area of Naples located in south Italy is characterized by an unauthorized and chaotic
urban development. The land-use map reported an average of 30% of urbanization in
the metropolitan area, rising up to 50â60% and as high as 98% in the north core area of
the city. This high level of urbanization is directly related to the habitat fragmentation. The
National Biodiversity Conservation Strategy defines several challenges and targets to
counteract the biodiversity loss in Italy, identifying urban areas as places exposed to the
greatest pressures on ecosystems. Therefore, the integration of different policies limiting
habitat fragmentation, heat island effect and natural soil hydro-geological degradation
into spatial planning, especially through green corridors and ecosystem enhancement
in urban areas is an urgent need for the society. Spatial planning has to be renewed
in metropolitan areas, where threats and weaknesses to biodiversity conservation are
stronger than in any other place, according to the Law n. 56/2014, (Gazzetta Ufficiale
della Repubblica Italiana, 2014) committing metropolitan cities to the enactment of
General Territorial Plan. In the current paper, we aim at designing an ecological network
for the metropolitan area of Naples one of the biggest city of southern Italy. The analyses
include the adopted methodological procedure, i.e., ecological network analysis and
design, and the introductory elements of a spatial analysis on a pilot ecological network
of several patches. Finally, the paper illustrates the network analysis conceived as a
monitoring system and also in future perspective, as a planning support system
Characterization of the first eukaryotic cold-adapted patatin-like phospholipase from the psychrophilic Euplotes focardii: Identification of putative determinants of thermal-adaptation by comparison with the homologous protein from the mesophilic Euplotes crassus
The ciliated protozoon Euplotes focardii, originally isolated from the coastal seawaters of Terra Nova Bay
in Antarctica, shows a strictly psychrophilic phenotype, including optimal survival and multiplication
rates at 4e5 C. This characteristic makes E. focardii an ideal model species for identifying the molecular
bases of cold adaptation in psychrophilic organisms, as well as a suitable source of novel cold-active
enzymes for industrial applications. In the current study, we characterized the patatin-like phospholipase
from E. focardii (EfPLP), and its enzymatic activity was compared to that of the homologous protein
from the mesophilic congeneric species Euplotes crassus (EcPLP). Both EfPLP and EcPLP have consensus
motifs conserved in other patatin-like phospholipases.
By analyzing both esterase and phospholipase A2 activity, we determined the thermostability and the
optimal pH, temperature dependence and substrates of these enzymes. We demonstrated that EfPLP
shows the characteristics of a psychrophilic phospholipase. Furthermore, we analyzed the enzymatic
activity of three engineered versions of the EfPLP, in which unique residues of EfPLP, Gly80, Ala201 and
Val204, were substituted through site-directed mutagenesis with residues found in the E. crassus homolog
(Glu, Pro and Ile, respectively). Additionally, three corresponding mutants of EcPLP were also generated
and characterized. These analyses showed that the substitution of amino acids with rigid and bulky
charged/hydrophobic side chain in the psychrophilic EfPLP confers enzymatic properties similar to those
of the mesophilic patatin-like phospholipase, and vice versa.
This is the first report on the isolation and characterization of a cold-adapted patatin-like phospholipase
from eukaryotes. The results reported in this paper support the idea that enzyme thermaladaptation
is based mainly on some amino acid residues that influence the structural flexibility of
polypeptides and that EfPLP is an attractive biocatalyst for industrial processes at low temperatures
Effect of long-term irrigation water salinity on soil properties and microbial biomass
We assessed the effects of saline water irrigation on soil properties and microbial activity. Increasing salinity microbial activity decreased. 1% salinity strongly affected soil biochemical properties and microorganisms. Our results indicate that 0.5% salinity may be tolerated by soil microorganisms suggesting a possible use of brackish water in agriculture soils
Changes in Morpho-Anatomical and Eco-Physiological Responses of Viburnum tinus L. var lucidum as Modulated by Sodium Chloride and Calcium Chloride Salinization
Salinity in water and soil is among the major constraints to the cultivation of ornamental
crops since it can affect their growth and aesthetic value. A greenhouse experiment was carried out to
assess whether the application of two different salts (80mM NaCl or 53.3mM CaCl2, with a final ionic
concentration of 160 mM) could differently modulate the anatomical and physiological acclimation
of an important ornamental species such as Viburnum tinus L. var. lucidum. Eco-physiological
analyses (e.g., leaf gas exchange and chlorophyll a fluorescence emission) were performed and
leaves were subjected to light microscopy analysis to quantify functional anatomical traits through
digital image analysis. Results showed that the two iso-osmotic solutions induced different structuremediated
physiological alterations in V. tinus plants. Photosynthesis was lowered by CaCl2 treatments
(-58%) more than by NaCl (-37%), also due to the occurrence of photodamage apart from stomatal
limitations. Neither Na+ nor Cl- exhibited toxic effects in leaf lamina structure which was reflected
in the limited reduction in dry matter accumulation. Overall data were interpreted focusing on the
coordination among leaf structural and functional traits suggesting that the fine control of functional
anatomical traits contributes to physiological acclimation to both stressful condition
An appraisal of urine derivatives integrated in the nitrogen and phosphorus inputs of a lettuce soilless cultivation system
Reinforcing and optimizing sustainable food production is an urgent contemporary issue. The depletion of natural mineral resources is a key problem that is addressed by recycling mined potassium and phosphorus, and nitrogen, whose production depends on very high energy input. A closed-loop approach of fertilizer use asserts the necessity for efficient management and practices of organic waste rich in minerals. Human-derived urine is an underutilized yet excellent source for nitrogen fertilizer, and, in this study, processed urine fertilizer was applied to greenhouse soilless cultivation of lettuce (Lactuca sativa L.) cv. Grand Rapids. Biomass increase, biometric parameters, soil plant analysis development (SPAD) index, minerals, and organic acids content of lettuce were analyzed. From eight different urine fertilizer products generated, K-struvite, urine precipitate-CaO, and the liquid electrodialysis (ED) concentrate supported the growth of lettuce similar to that of commercial mineral fertilizer. ED concentrate application led to the accumulation of potassium (+17.2%), calcium (+82.9%), malate (+185.3%), citrate (+114.4%), and isocitrate (+185.7%); K-struvite augmented the accumulation of magnesium (+44.9%); and urine precipitate-CaO induced the highest accumulation of calcium (+100.5%) when compared to the control, which is an added value when supplemented in daily diet. The results underlined the potential of nitrogen- and phosphate-rich human urine as a sustainable source for the fertilization of lettuce in soilless systems
the role of biostimulants and bioeffectors as alleviators of abiotic stress in crop plants
Abstract The use of bioeffectors, formally known as plant biostimulants, has become common practice in agriculture and provides a number of benefits in stimulating growth and protecting against stress. A biostimulant is loosely defined as an organic material and/or microorganism that is applied to enhance nutrient uptake, stimulate growth, enhance stress tolerance or crop quality. This review is intended to provide a broad overview of known effects of biostimulants and their ability to improve tolerance to abiotic stresses. Inoculation or application of extracts from algae or other plants have beneficial effects on growth and stress adaptation. Algal extracts, protein hydrolysates, humic and fulvic acids, and other compounded mixtures have properties beyond basic nutrition, often enhancing growth and stress tolerance. Non-pathogenic bacteria capable of colonizing roots and the rhizosphere also have a number of positive effects. These effects include higher yield, enhanced nutrient uptake and utilization, increased photosynthetic activity, and resistance to both biotic and abiotic stresses. While most biostimulants have numerous and diverse effects on plant growth, this review focuses on the bioprotective effects against abiotic stress. Agricultural biostimulants may contribute to make agriculture more sustainable and resilient and offer an alternative to synthetic protectants which have increasingly falling out of favour with consumers. An extensive review of the literature shows a clear role for a diverse number of biostimulants that have protective effects against abiotic stress but also reveals the urgent need to address the underlying mechanisms responsible for these effects. Graphical abstract Biostimulants have protective effects against abiotic stress
Cold Treatment Modulates Changes in Primary Metabolites and Flowering of Cut Flower Tulip Hybrids
Tulip is one of the most important bulbous genera in the worldâs floriculture. It is known that cold exposure of bulbs before planting is required to break the bulb dormancy and to promote the plantâs flowering. Preparation procedures performed by breeders differ in the duration and the thermal level, and the choice of the procedure depends on the genotypeâs sensitivity to temperature; however, little is known about the metabolic responses underlying the different behaviours of the numerous commercial hybrids. We evaluated the influence of two bulb-preparation procedures, 15â18 weeks at 5 Ă· 9 °C, and 9â14 weeks at 2 Ă· 5 °C, in two hybrids of tulip (Tulipa gesneriana L.), âRoyal Virginâ and âAd Remâ, grown hydroponically in a floating system. Tulip plants of the two hybrids responded differently to bulb exposure to low temperatures in terms of early flowering, as this was unaffected by the preparation procedure in âRoyal Virginâ (27.1 days from transplanting, on average), while it was earlier after treatment at higher temperatures compared with lower temperatures in âAd Remâ (24.1 vs. 26.7 days at 5 °C vs. at 9 °C). This different flowering earliness may be related to the diverse metabolic responses enacted by the bulbs for cold acclimation that depended on hybrid x thermal treatment. Plant leaf area and flower stem characteristics were similar in the hybrids and were unaffected by the bulb-preparation procedure
High Light Intensity from Blue-Red LEDs Enhance Photosynthetic Performance, Plant Growth, and Optical Properties of Red Lettuce in Controlled Environment
Plant factories using artiïŹcial light to produce vegetables have high energy costs due to
the high demand for electricity for lighting. Compared to conventional light sources, light-emitting
diodes (LEDs) offer the possibility of tailoring the light spectrum and regulating light intensity
and are more energy-efïŹcient in terms of energy conversion regardless of the levels of lighting
intensity. Optimal light intensity and daily light integral (DLI) requirements are key factors for plant
growth; however, their values vary among species and varieties. Our experiment aimed to identify
the best light intensity to produce lettuce plants in controlled environment. Lettuce plants of the
type Batavia cv âBlackhawkâ were grown in plastic pots ïŹlled with perlite and peat (20:80 v/v) for
33 days in a growth chamber under blue (B, 20%) and red (R, 80%) LED light at a photosynthetic
ïŹux density of 130 ”mol m
â2
s
â1
(BR 130, DLI 7.49 mol m
â2
d
â1
), 259 ”mol m
â2
s
â1
(BR 259, DLI
14.92 mol m
â2
d
â1
), and 389 ”mol m
â2
s
â1
(BR 389, DLI 22.41 mol m
â2
d
â1
). Our results showed
that increasing light intensity and DLI promotes net photosynthesis, sustains the electron transport
rate (ETR), and stimulates the synthesis of anthocyanins and carotenoids, with positive results for
plant photoprotection. Furthermore, the decreases in vegetation indexes (photochemical reïŹectance
index (PRI), greenness, and modiïŹed chlorophyll absorption in reïŹectance index (MCARI1)) also
indicate changes in photosynthetic pigment content in response to plant acclimation to different DLIs.
Among the three light intensities, 389 ”mol m
â2
s
â1
(DLI 22.41 mol m
â2
d
â1
) gave the best results
for growing Batavia red lettuce cv âBlackhawkâ, since it enhances both production and qualitative
traits. These results highlight the importance of a proper light intensity to promote plant growth
and qualitative traits and to reach high production targets. Hence, preliminary screening of plant
performance under different light treatments is recommended to optimise plant response to artiïŹcial
lighting
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