1,720,969 research outputs found
Posidonia-based compost as a growing medium for the soilless cultivation of tomato
No full textHigh quality compost could be used as an environmentally friendly and renewable component for soilless growing media. Beached residues of posidonia (Posidonia oceanica (L.) Delile), a marine phanerogam endemic to the Mediterranean Sea, can be used as raw material for compost production. The aim of this study was to evaluate a posidonia-based compost as a soilless growing medium component for the cultivation of tomato. Beached residues of posidonia (20% in weight) and green wastes were composted. The compost, alone (Compost 100%) or mixed with perlite at the rate of 50% in volume (Per-Comp 50:50), was used as growing medium and compared with traditional perlite (Perlite 100%). Tomato plants (cv. ‘Ikram’ ungrafted, ‘Ikram’ grafted onto ‘Beaufort’ and ‘Ikram’ grafted onto ‘Arnold’) were grown in the three growing media. A complete nutrient solution (EC = 1.7 dS/m; pH = 5.0) was used for fertigation. A system composed by EC5 soil moisture sensors, a data logger and a rely controller, and tensiometers to check water potential was used to manage fertigation, with the aim to maintain easily available water. Forty five days after transplanting, the plants grown in 100% compost as well as in the compost/perlite mix resulted in higher growth. Leaf area, total fresh and dry weight increased with increasing amounts of compost in the substrate. The tomato yield in Compost 100% and Per-Comp 50:50 treatments resulted higher than Perlite 100%, in terms of weight and number of fruits (15 and 7%, respectively). Grafted plants, regardless of the rootstock, showed a higher total yield if compared with ungrafted plants (11%, on average). The quality profile of fruits was only slightly influenced by growing media, while was not by the grafting combination. The results show that the compost-based posidonia could be successfully used as soilless substrate component for growing tomato
The compost of posidonia residues: a short review on a new component for soilless growing media
No full textPosidonia oceanica (L.) Delile is the main marine seagrass endemic of the Mediterranean Sea. From September on, leaves and rhizomes detach off the marine plant and accumulate on beaches in huge amounts, forming banks on the foreshore and backshore of beaches. Offshore residues represent an environmental, economical, social and hygienic problem, because of the great disturbance to the touristic activities, citizens life in urban areas and high costs that the public administrations have to support for managing them (beach cleaning, transport and disposal of such a biomass). Nowadays, current Italian legislation (n. 75/2010) allows the use of posidonia residues as raw material for the production of compost although at a maximum rate of 20% by fresh weight of the composting mixture. High presence of sand mixed to residues after removing from beaches and high salinity levels represent at the moment the main obstacles to the large use of this biomass as raw material for composting. Studies have been conducted, in the framework of the Life09 “Posidonia Residues Integrated Management for Eco-sustainability” (P.R.I.M.E.) project, with the aim to increase the application of posidonia residues for compost production, demonstrating the possibility to effectively separate the sand from the organic material and reduce the salinity levels.
Several tests have been carried out with the objective to assess the posidonia-based compost quality. Posidonia-based compost proved to be a good peat substitute for lettuce transplant production and a good growing media component for green-house tomato and lettuce in soilless conditions. According to our studies, beached posidonia wastes could represent a low cost and renewable raw material for com-posting. Posidonia-based compost presents interesting properties and can be used as horticultural growing media component
Open-cycle drip vs closed-cycle subirrigation: Effects on growth andyield of greenhouse soilless green bean
No full textClosed-cycle management of soilless cultivation is one of the promising strategies to prevent pollution,while increasing the efficiency of water and fertilizer use. However, in order to encourage the adoptionof closed-cycle cultivation even in countries characterized by a low-tech greenhouse industry, effectiveeasy-management systems need to be developed.A greenhouse experiment was carried out to determine the influence of two irrigation methods (dripirrigation open-cycle and subirrigation closed-cycle) and two nutrient solution (NS) concentrations (100and 80% of the macro-element concentration normally used for soilless cultivation) on substrate electricalconductivity (EC), plant growth, gas exchange, yield, fruit quality, and water-use efficiency of green bean(Phaseolus vulgaris L., cv. Saporro).Subirrigated plants showed higher substrate EC and higher Na+and Cl−concentrations, especially inthe upper layer of the growing medium, while moisture distribution throughout the substrate profileshowed an opposite trend and was more uniform in drip irrigation. The total fresh and dry biomass ofthe drip-irrigated plants were higher than in those grown in subirrigation, while whole plant dry matterpercentage was lower. Differences in terms of plant height, number of leaves, leaf area, root growth,chlorophyll content, net photosynthesis, stomatal conductance and transpiration rate were recorded,with higher values in drip-irrigated plants. With closed-cycle subirrigation, green bean total and mar-ketable yield (598 and 574 g plant−1, respectively) were, on average, 33% lower than for drip irrigation, butfruit quality was higher in terms of “extra class” number of pods (93.6 vs 88.3%) and dry matter percent-ages. On average, both total and marketable yield were 9% higher with NS 80%, with a 13% higher waterconsumption, while slight or no effects were observed on net photosynthesis, stomatal conductance andshoot growth. The highest WUE (11.2 kg m−3) was obtained with subirrigation, where recirculating NSwas never discharged, compared to drip irrigation (8.5 kg m−3). The green bean response to closed-cyclesubirrigation showed a general decrease in productive performance. Detrimental effects were reducedby reducing the NS concentration. Lower yield could be compensated by savings of water and fertilizersand lower environmental impact
Supplemental lighting with LED for efficient year-round production of soilless tomato in a Mediterranean greenhouse
No full textSupplemental lighting (SL) is currently arising increasing interest in Mediterranean greenhouse for efficient year-round production. Compared to traditional high-pressure sodium lamps, light-emitting diode (LED) grow lights provide important advantages [a generally touted higher efficiency in terms of micromoles of photosynthetic photon flux (PPF) produced per unit of electricity; a provided light with a spectral distribution used efficiently by plants; the possibility to provide specific spectra able to induce specific responses by plants]. In this research we compared the effects of inter-light LEDs ['R+B': red (660 nm) + blue (450 nm) + red (660 nm) light; 'FR': red blue + blue red + infrared (730 nm) light] toward natural light growing conditions ('C', control) on the performance of soilless greenhouse tomato ('DRW 7723' and 'Diamantino' cultivars, both grafted on 'Maxifort'). The experiment was carried out at the experimental farm “La Noria” (Mola di Bari, South Italy). SL was operated automatically by a system composed by a CR1000 datalogger and a quantum sensor: for 16 h d-1, the system evaluated every 4 s the incoming sunlight in the greenhouse, and turned on the LED light bars whenever the ambient PPFD dropped below 200 μmol m-2 s-1 until the PPFD from sunlight rose above the set-point again. The duration of the supplemental light activation ranged from about 7 to 16 h d-1 (values registered in October 2018 and November-December-January 2019, respectively) depending on the ambient light conditions during the growing cycle. Model equations describing daily light integral (DLI) trends inside the greenhouse and power consumption as affected by light conditions were obtained. Plants grown without SL showed, on average, 19% lower yield and 16% lower fruits number than tomato plants grown with SL. Also, water use efficiency and fruit quality traits were positively affected, but the response can be highly dependent on the cultivar
Effects of municipal solid waste- and sewage sludge-compost-based growing media on the yield and heavy metal content of four lettuce cultivars
Full text linkCompost has been recently suggested as an alternative to peat for the preparation of growing substrates in soilless cultivation systems. However, some physico-chemical properties of compost may reduce plant performance and endanger the quality of productions, in particular for possible heavy metal accumulation in edible parts. This study aims at evaluating the suitability of a municipal solid waste compost (MSWC) and a sewage sludge compost (SSC) as components of growing media for the soilless cultivation of lettuce (Lactuca sativa L.). Heavy metal content of SSC complied with legislation limits but, in MSWC, it exceeded (Cu, Pb) or was very close (Cd, Zn) to safe limits. A greenhouse experiment was carried out by cultivating four lettuce cultivars (“Maximus,” “Murai,” “Patagonia,” and “Aleppo”) in pots containing a mixture of MSWC and perlite (MSWC + P), SSC and perlite (SSC + P), or peat and perlite (peat + P), the latter used as control. Plant biometric parameters measured after 72 days of growth revealed that the yield of plants cultivated on SSC + P was similar to control plants, independently of the cultivar. Conversely, MSWC + P suppressed in general the biomass production, especially for Murai and Patagonia cultivars. Compared to peat + P, both compost-based substrates reduced the leaf accumulation of heavy metals, with a major effect in Maximus plants. The levels of Cd and Pb in the edible part were always below the safe limits imposed by European regulation. Therefore, risks of heavy metal intake in food chain associated with the replacement of peat with compost in the growing media are negligible, even when a compost with a significant amount of heavy metals is used. Besides compost quality monitoring, also an appropriate varietal choice is crucial to obtain good yields and safe products
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
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