1,720,980 research outputs found
Coloured covering materials for peach protected cultivation
Full text linkSpectral wavelength distribution and quantity of solar radiation influence
plant photosynthesis, photomorphogenesis, phototropism and photoperiod. With
regard to photomorphogenesis, vegetative and reproductive growth processes are
influenced by the phytochrome and cryptochrome. In literature the phytochrome
response is characterized in terms of radiation rate in the red wavelengths (R, 600-
700 nm) to that in the far-red radiation (FR, 700-800 nm), i.e. the R/FR ratio. The
effects of the blue radiation (B, 400-500 nm) on the morphogenetic responses of
plants can be investigated by studying the ratio between the blue radiation and the
far-red radiation, i.e. the B/FR ratio. Aim of this paper is to investigate the influence
of coloured nets on peach trees. A BLUE net, a RED net, a YELLOW net, a PEARL
net, a GREY net and a NEUTRAL net were installed on greenhouses at the
experimental farm of the University of Bari (Italy), latitude 41°05’ N. Peach trees
were located in pots inside the greenhouses and in open field. The growth of the
peach trees cultivated in open field was lower in comparison to the growth of the
trees cultivated under the coloured nets. The RED and BLUE nets influenced the
spectrum of the solar radiation passing through the nets modifying the investigated
radiation ratios. Both nets increased the growth of the trees more than the
NEUTRAL, PEARL and GREY nets. The nets positively influenced the fruit
characteristics, such as size, colour and sugar content, in comparison to open-field
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Film foto selettivi e fotoluminescenti ed effetti sulla crescita delle piante
No full textPhotoselective and photoluminescent films and effects on the plant growth.
Photoselective and photoluminescent plastic films for protected cultivation
modify the spectral distribution of the solar radiation thus influencing plant
growth. This paper shows the results of the tests carried out at the experimental
farm of the University of Bari from December 2006 to September 2007; two
photoselective films (GREEN4% and GREEN2%), three photoluminescent films
(RED, BLUE and RED-BLUE)
and one low density
polyethylene film were used
to cover greenhouses where cherry and peach trees were grown. The lowest
vegetative activity was recorded for the trees grown in open field in comparison
with the trees grown inside the greenhouses. The photoselective films influenced
positively the growth of the trees, especially the GREEN4% film. Among the
photoluminescent films the RED film was more efficient in increasing the
vegetative activity; it was due to the film capacity of absorbing UV radiation and
re-emitting it in the wavelength band of the red radiation, which is very
efficient for photosynthesis
Caratteristiche radiometriche di film fotoselettivi e fotoluminescenti
No full textRadiometric characteristics of photoselective and photoluminescent films.
Plastic films for protected cultivation capable of modifying the spectral distribution
of the transmitted radiation can be developed with suitable radiometric characteristics
in order to influence plant vegetative activity. In order to study such films,
experimental tests were carried out at the experimental farm of the University of
Bari in Valenzano (Bari, Italy), at latitude 41° 05' N, from December 2006 to
September 2007. Two photoselective films (GREEN4% and GREEN2%), three
photoluminescent films (RED,BLUE and RED-BLUE)
and one low density polyethylene
film were used as greenhouse coverings for cherry trees and peach trees. The
photoselective films GREEN4% and GREEN2% alter the quality of solar radiation
passing through the covering materials modifying the spectral distribution of the
solar radiation in the wavelength range of the red radiation (R, 650-670
nm) and of
the far red
radiation (FR, 720-740
nm) in comparison with the natural solar
radiation recorded in open field. The photoluminescent films RED, BLUE and RED-BLUE
have the capacity to absorb UV radiation in order to re-emit it in the
wavelength of red radiation,blue radiation and red-blue radiation,
respectively.The
results showed the radiometric characteristics of these innovative plastic films.
The photoselective films GREEN4% and GREEN2% were characterised by a
reduction of the R/FR ratio of the photon fluence rate in the red to that in the
far red
in comparison to the natural solar radiation.Film plastici utilizzati per la protezione delle colture in grado di influenzare la
distribuzione spettrale della radiazione solare che li attraversa con opportune
caratteristiche radiometriche sono stati recentemente sviluppati per condizionare
la crescita delle piante. Allo scopo di valutare gli effetti di tali film sono
state condotte, da dicembre 2006 a settembre 2007, prove sperimentali in
ambiente protetto su alberi di pesco e ciliegio presso il centro sperimentale
dell’Università di Bari utilizzando due film sperimentali fotoselettivi (GREEN4% e GREEN2%), tre film sperimentali fotoluminescenti (RED, BLUE e REDBLUE)
e, per confronto, un film standard in polietilene a bassa densità. I filmfotoselettivi
GREEN4% e GREEN2% filtrano particolari lunghezze d’onda della radiazione
solare, cioè variano la distribuzione spettrale della radiazione solare nel
rosso e nel rosso lontano rispetto alla radiazione solare in pieno campo. I film
fotoluminescenti Red, Blue e RedBlue hanno la capacità di assorbire le radiazioni solari incidenti nell’ultravioletto per riemetterle in corrispondenza
delle lunghezze d’onda rispettivamente della radiazione rossa, blu e della
combinazione di entrambe. I risultati presentati riguardano la caratterizzazione
radiometrica dei film plastici innovativi. I film fotoselettivi Green4% e Green2% hanno mostrato un’elevata capacità di ridurre il rapporto R/FR tra radiazione presente nel rosso (R: 650- 670 nm) e nel rosso lontano (FR: 720- 740 nm) rispetto al valore calcolato in presenza di radiazione solare naturale.Plastic films for protected cultivation capable of modifying the spectral distribution of the transmitted radiation can be developed with suitable radiometric characteristics
in order to influence plant vegetative activity. In order to study such films,
experimental tests were carried out at the experimental farm of the University of Bari in Valenzano (Bari, Italy), at latitude 41° 05' N, from December 2006 to September 2007. Two photoselective films (GREEN4% and GREEN2%), three photoluminescent films (RED,BLUE and REDBLUE)
and one low density polyethylene film were used as greenhouse coverings for cherry trees and peach trees. The photoselective films GREEN4% and GREEN2% alter the quality of solar radiation
passing through the covering materials modifying the spectral distribution of the
solar radiation in the wavelength range of the red radiation (R, 650- 670
nm) and of the farred
radiation (FR, 720- 740
nm) in comparison with the natural solar radiation recorded in open field. The photoluminescent films RED, BLUE and REDBLUE
have the capacity to absorb UV radiation in order to retransmit it in the
wavelength of red radiation, blue radiation and redblue radiation, respectively.The
results showed the radiometric characteristics of these innovative plastic films.
The photoselective films GREEN4% and GREEN2% were characterised by a
reduction of the R/FR ratio of the photon fluence rate in the red to that in the
farred in comparison to the natural solar radiation
On the apple proliferation symptom display and the canopy colonization pattern of “Candidatus Phytoplasma mali” in apple trees
No full textNotwithstanding the availability of several different real time PCR protocols for "Candidatus Phytoplasma mali", it is still unclear how informative is the estimation of the concentration of phytoplasma cells in the leaves of apple proliferation infected trees, and how the reliability of the estimations may be affected by an erratic and uneven distribution of the pathogen in the host. Here we investigated these issues systematically and showed that phytoplasma concentration varies significantly among seasons, but not between two cultivars that appeared to have different degree of susceptibility on the basis of the symptoms displayed. In fully symptomatic trees sampled at the end of the season the phytoplasmas were detectable in most leaves, but in more than half of the leaves at low concentrations. Both the pattern of colonization of the canopy and the amount of phytoplasmas varied greatly in trees that show symptom remission, although a direct relation between symptom severity and colonization could not be established. The sampling of the apple canopy for the purpose of evaluation of concentration of "Candidatus Phytoplasma mali" should take into consideration the complex pattern of colonization and seasonal variation
Evaluation of coloured nets in peach protected cultivation
No full textThe aim of this paper is to investigate the influence of the radiometric properties of coloured nets on peach tree photomorphogenesis. The modification of the spectral distribution of the transmitted radiation and thus the effects on the tree vegetative and productive activity were studied. A field experimental test using coloured nets for the protection of peach trees was carried out during 2008 at the experimental farm of the University of Bari, latitude 41° 05' N. A blue net and a red net, characterised by a nominal shading factor of 40%, and a neutral net with a nominal 12% shading factor were tested. Peach trees in open field conditions were used as control. The effects of the nets on the trees growth were correlated with the radiometric properties of the nets, which were evaluated by means of laboratory tests. The red and blue nets influenced mainly the B/FR ratio: the former net decreased and the latter increased the B/FR ratio. The nets influenced the quantity as the quality of the yield. The red net increased the shoot growth of the trees more than the blue one. The nets influenced positively the fruit weight and skin colour in comparison to the open-field
La coltivazione protetta nell’Italia centro-meridionale
No full textThe technique of growing cherry under protected
cultivation, proposed experimentally in the ‘70s and ‘80s, is attracting new interest because
of the need to extend the marketing periods
and to improve the quality of the product. In the
last years, the CRA–Tree Fruit Research Center
has developed an intense experimental activity
aimed at evaluating the most innovative plastic
films suitable for early cultivation in the “cold
greenhouse”, the study of photoselective nets for
higher efficiency in the management of plants,
the protection of plants against biotic and abiotic
adversity, and the improvement of fruit quality
- …
