1,721,192 research outputs found
Bioregenerative Life Support Systems in the Space: Effects of radiation on plants
No full textIt has been discussed about the possibility to utilize the higher plants as a support to the human life in the Space in Bioregenerative Life Support Systems (BLSSs), highlighting the fundamental role of green organisms in ecosystems. The talk has been focused on the mechanisms of radioresistance in higher plants, a very useful property to counteract the harmful effect of ionizing radiation in outer Spac
The challenge of plant in Space
No full textAll the resources needed for short-term missions in Space are brought from Earth. However this will be not possible for longer missions, for economical and practical reasons. A feasible alternative would be the development of a suitable system, aiming to a continual recycling of the available resources. In this scenario, higher plants represent an optimal tool to regenerate air through the photosynthetic CO2 absorption and O2 emission, to recover purified water through the transpiration, and to recycle waste products through the mineral nutrition, while providing fresh food to integrate the crew diet. This concept is called “Bioregenerative Life Support System” (BLSS) or “Controlled Ecological Life Support System” (CELSS). In order to perform the desired functions in BLSS and produce edible biomass while recycling waste products, using light as source of energy to promote photosynthesis, plants need to be grown in precise environmental and cultural conditions. In Space plant growth is limited mainly by two space factors: microgravity and ionizing radiation. This talk explores some case study related to plants subjected to different quality of ionizing radiation
Radiation and Life Support Systems: Effects on Plants. Focus on photosynthetic apparatus.
No full textIIn Space, every organism is exposed to high levels of ionising radiation. The effects of ionising radiation on plants depend not only on the type of radiation, but also on doses, exposure conditions (either chronic or acute) and on the features of exposed organism including: species, cultivar, physiological and nutritional status, phase of the life cycle (phenological stage) at the moment of irradiation. Ionising radiation may induce responses on organisms at different scales: on cells, tissues, organs and whole organism. The consequences are not predictable and are due to several mechanism. Ionising radiation on plants may have: 1) indirect effects, as phenotypic expression of modifications induced at the genetic level; 2) direct damages due either to the interaction between the radiation itself with specific cellular structures (for example, the various components of cell walls) or to the production of Reactive Oxygen Species that can damage structural and functional macromolecules such as lipids, proteins and nucleic acids. In this talk were explored the radiosensitivity and the radioresistance of different plant categories
Water acidification: effects on the macroalgal community
No full textRecent researches, performed in a naturally acidified site (Castello Aragonese d’Ischia - Gulf of Naples, Italy) where volcanic carbon dioxide vents cause long-term changes in seawater carbonate chemistry, lowering the pH from 8.17 down to 6.57, reveal winners and losers within the benthic community. In the same site, we chose to address the impact of ocean acidification on the algal community with an integrated approach by means of ecological, physiological and molecular tools. Qualitative and quantitative changes in algal composition have been detected. Results showed a less structured community at low pH, characterized by few dominant species and the lack of calcareous taxa. Due to their different tolerance to pH variations, three target species (Sargassum vulgare, Dictyota dichotoma and Jania rubens) have been selected to carry out transplant experiments in order to detect short term stress signals. Variations in fluorometry-derived parameters of the photosynthetic performance of these species were detected in situ at different pH conditions by means of a Diving-PAM. In order to understand if the chronic lowering of pH of this site has promoted any local adaptations (morphological and/or genetic), the Dictyota complex species have been selected. Results indicate that our integrated approach is the key factor leading to understand how these changes can drive deteriorations in the structure and function of algal assemblages under the effects of water acidification
Regulation of photosynthetic activity of crop species subjected to abiotic environmental stresses
No full textThis thesis aimed to study regulations of photosynthetic activity of plants under two of the most important abiotic stresses: water stress and salt stress. We mainly focused on the physiological and biochemical mechanisms that regulate growth and productivity under limiting conditions, in order to acquire a better understanding of the complex defense responses of plants to environmental abiotic stresses, which represent the greatest global constraints for agriculture. In order to tackle such broad aim, an integrated approach was necessary. This study was carried out on some specific crops with the peculiar purpose to test cultivars that are tolerant to drought or salinity used under harsh environments. Although abiotic stresses have been largely studied for tomato, pepper and grape species, the specific behavior of many local and typical cultivars and landraces to cope with drought and salinity problems is still new. Hence, the general aim of this work was pursued through three main experimental activities, illustrated in chapters 2-4. Chapter 2 focuses on two typical long-storage tomato landraces grown in greenhouse under extreme (gs< 0.01mol m-2 s-1) water stress conditions ; chapter 3 focuses on two pepper cultivars - grown in a soilless system differently behaving under severe (15.6 dS m-1) long-term salt stress conditions; chapter 4 focuses on a wine grape cultivar, typical in Southern Italy, grown in two soils with contrasting hydrological properties for retaining water
Variazioni stagionali dell’attività fotosintetica di tre specie della macchia mediterranea
No full textPer valutare come le condizioni climatiche influenzano la ripartizione dell’energia luminosa assorbita tra fotosintesi e processi dissipativi, misure di scambi gassosi e fluorescenza sono state effettuate su foglie di Quercus ilex L., Phillyrea angustifolia L. e Laurus nobilis L. in inverno ed in primavera. I risultati ottenuti hanno mostrato, per tutte le specie indagate, valori più elevati di fotosintesi e di efficienza fotochimica in primavera rispetto all’inverno facendo registrare per Q. ilex i valori più alti. In primavera, inoltre, per tutte le specie è stato evidenziato un minor contributo dei processi di dissipazione termica e fotochimica dell’energia luminosa assorbita rispetto all’inverno. Durante l’inverno il contributo significativamente più elevato dei processi di dissipazione termica e fotochimica, ha permesso, nonostante la forte riduzione della fotosintesi, di mantenere in tutte le specie una elevata efficienza fotochimica
Influenza dell'irradianza sull'attività fotosintetica di piante di Q. ilex L. cresciute su compost verde ed esposte ad elevata concentrazione di CO2
No full textMisure di scambi gassosi ed emissione di fluorescenza sono state effettuate su piante di Quercus ilex L. impiantate su terreno sabbioso (controllo) e su una miscela di compost verde 65% ed argilla espansa 35% (CV) per valutare l’influenza del substrato di crescita sulla fotosintesi all’aumentare dell’irradianza a 390 e a 800 ppm di CO2. A 800 ppm di CO2 le piante hanno mostrato rispetto a 390 ppm, un incremento significativo della fotosintesi e dell’attività di trasporto elettronico ed una diminuzione della foto-assimilazione fogliare di nitrati e dei processi di dissipazione termica e fotochimica dell’energia luminosa su entrambi i substrati di crescita. Inoltre, poiché sia a 390 che a 800 ppm di CO2 l’impianto sulla miscela di compost verde ha determinato una fissazione di carbonio ed un’attività di trasporto elettronico significativamente più elevate rispetto alle piante controllo, in tutto l’intervallo di intensità luminose, si può concludere che non solo l’esposizione ad elevate concentrazioni di CO2, ma anche il substrato di crescita influenza notevolmente la risposta fotosintetica di Q. ilex all’aumentare dell’irradianza
- …
