1,721,008 research outputs found
The influence of water deficit and re-watering on flower bud morphogenesis in young apricot trees (Prunus armeniaca L.)
No full textIn deciduous fruit species, as well as in apricot, floral bud initiation, differentiation and organogenesis take place during the summer season that precedes anthesis. A number of factors (environmental conditions, cultural practices, abiotic stresses) have been identified as important triggers able to modify the regularity of floral differentiation. The water availability represents a crucial key factor, particularly under Mediterranean climates characterized by long drought periods. This investigation aimed to assess the influence of summer water deficit and re-watering treatments on floral morphogenesis, growth and quality of flower buds in apricot. Trials were carried out on two-year-old potted trees ('Portici') grown at the research station of University of Pisa. Plants were divided into three uniform groups: the first one was watered daily maintaining soil water content around 90% of field capacity, whereas second and third ones were subjected, in June or July, to 30 days of imposed water deficit followed to re-watering. In order to determine the evolution of floral bud differentiation, prior, during and after the imposed water stress, histological analyses were carried out. From autumn to spring, qualitative traits of flower buds (growth, anomalies) were also analyzed. Midday stem water potential was used to determining water status, and leaf gas exchanges were measured during trials. Both water stress periods affected the floral differentiation leading to a temporary shutdown. The plants stressed in June were able to recover the development of meristematic apices already after two weeks from the regular re-watering, while those stressed in July showed a strong delay up to the end of summer. As a consequence, variations in bud size and flower anomalies were observed. Results confirm that water stress may play an important role in flower bud differentiation and development influencing the quality of flower buds
Variazione della conducibilità del sistema xilematico del frutto di actinidia durante il ciclo di crescita
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Effects of selenate addition on selenium accumulation and plant growth of two Prunus rootstock genotypes
No full textA pot experiment was conducted with two Prunus genotypes (GF 677 and Mr.S.2/5, commercial rootstocks for peach), which are widely used in Italy and other European countries. Selenium (Se) was added as sodium selenate to 3-month-old micropropagated plants at a rate of 0 (control), 1.0, 2.5, and 5.0 mg Se (kg soil)–1. Plant growth, gas exchange, and Se accumulation were studied. Selenium added at a rate of 2.5 and 5.0 mg Se kg–1 appeared to be highly toxic for the two young peach rootstocks. Thirty-three days after the treatment, the plants showed a high mortality rate. The fast growing rootstock, GF 677, appeared to be more sensitive to Se toxicity, the mortality rate reaching 52%. The higher the Se concentration in the soil, the higher it also was in the plant. In general, both genotypes were able to take up Se and to translocate high amounts from root to leaf. After selenate addition to the soil, both GF 677 and Mr.S.2/5 plants showed reduced plant growth with the highest Se treatments. Furthermore, Se induced a partial stomatal closure, as evidenced by the values of stomatal conductance, resulting in a reduction in net assimilation, and thus a decrease in dry-matter production. Selenate applied at a low rate (1 mg Se kg–1) stimulated plant growth in GF 677. One year after the Se treatment, a remobilization of Se from the storage organs to the young shoots was detected. This study demonstrates genotypic variation in Se uptake and accumulation in peach rootstocks
Peach rootstocks as affected by selenate addition to soil.
No full textSelenium is known to be non essential for plant growth, but it may have beneficial biological functions in some species, known as ‘accumulators’, which required Se for their normal growth. Selenate and selenite are the major forms readily absorbed by plants and converted to organic Se. Both anions may be toxic at higher concentrations, reducing the plant yield, but can stimulate plant growth at low concentrations. Some soils contain Se above the normal levels and it may produce toxicity in plants. Little is known about the physiological response of fruit-tree species to selenium. The present study aimed at investigating the ability of two peach rootstocks to absorb selenium and the physiological responses to the Se accumulated in plant tissue
Changes in leaf phenolic compounds in two grapevine varieties (Vitis vinifera L.) grown in different water conditions
No full textIn 2004 growing season, at the experimental vineyard of the DCDSL of the Pisa University, located at Colignola (Pisa, Italy), two grapevine genotypes, 'Cabernet Sauvignon' and 'Sangiovese', were subjected to different water treatments (irrigated and non irrigated) under field conditions. Time-course measurements of pre-dawn leaf water potential, as well as of both leaf gas exchange performance and net carbon gain were conducted. Changes in the content and composition of leaf polyphenols were also evaluated. Identification and quantification of hydroxycinnamates and flavonoid glycosides were performed using both HPLC-DAD and HPLC-MS analyses. We show that the share of newly assimilated carbon for the synthesis of phenylpropanoids increased because of moderate water deficit. The flavonoid to hydroxycinnamate ratio markedly increased passing from well-watered to drought-stressed plants, while the quercetin to kaempferol ratio slightly increased because of drought stress. We argue that the tested genotypes did not actually suffer from a severe oxidative damage under the attempt to impose a drought stress
Determination of maturity stage and fruit quality in peach by skin ́s optical properties
No full textThe influence of rootstock and solar radiation intercepted from the branches on fruit quality is valued in peach trees. Moreover, a nondestructive method (optical properties of skin fruits) for determining the SSC, the flesh firmness and the harvest time of the fruits is examined. Trials were conducted, in 2004 growing season, at the experimental farms of the DCDSL of the University of Pisa (Italy), on a peach orchard cv. 'Flavorcrest', planted in February 2000 and grafted onto 'GF 677', 'Barrier 1', 'Mr.S. 2/5' and 'Ishtara-Ferciana'. Two summer pruning intensity treatments were applied and the solar radiation intercepted by the branches was measured. Growth of fruits and shoots inserted on the selected branches was monitored starting from the beginning of May up to harvest (middle of July). At harvest, fruit weight, diameter, SSC and flesh firmness were measured and all of the factors considered showed to be important for fruit quality. Particularly, solar radiation and medium vigour rootstocks induced a better fruit quality compared to vigorous rootstocks. The optical properties of the skin were effective to show fruit quality and predict harvest time
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
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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