Role of xanthophyll and water-water cycles in the protection of photosynthetic apparatus in Arbutus unedo and Arabidopsis thaliana

Photosynthetic organisms have sought out the delicate balance between efficient light harvesting under limited irradiance and regulated energy dissipation under excess irradiance. One of the protective mechanisms is the thermal energy dissipation through the xanthophyll cycle that may transform harmlessly the excitation energy into heat and thereby prevent the formation of damaging active oxygen species (AOS). Violaxanthin deepoxidase (VDE) converts violaxanthin (V) to antheraxanthin (A) and zeaxanthin (Z) defending the photosynthetic apparatus from excess of light. Another important biological pathway is the chloroplast water-water cycle, which is referred to the electrons from water generated in PSII reducing atmospheric O2 to water in PSI. This mechanism is active in the scavenging of AOS, when electron transport is slowed down by the over-reduction of NADPH pool. The control of the VDE gene and the variations of a set of physiological parameters, such as chlorophyll florescence and AOS content, have been investigated in response to excess of light and drought condition using Arabidopsis thaliana and Arbutus unedo.. Pigment analysis showed an unambiguous relationship between xanthophyll de-epoxidation state ((A+Z)/(V+A+Z)) and VDE mRNA amount in not-irrigated plants. Unexpectedly, gene expression is higher during the night when xanthophylls are mostly epoxidated and VDE activity is supposed to be very low than during the day. The importance of the water-water cycle in protecting the chloroplasts from light stress has been examined through Arabidopsis plant with a suppressed expression of the key enzyme of the cycle: the thylakoid-attached copper/zinc superoxide dismutase. The analysis revealed changes in transcript expression during leaf development consistent with a signalling role of AOS in plant defence responses but no difference was found any in photosynthesis efficiency or in AOS concentration after short-term exposure to excess of light. Environmental stresses such as drought may render previously optimal light levels excessive. In these circumstances the intrinsic regulations of photosynthetic electron transport like xanthophyll and water-water cycles might modify metabolism and gene expression in order to deal with increasing AOS.

Development Aid to Water Management in Mali: The Actors, ‘Global’ Paradigms, and ‘Local’ Translations

Development aid involves a complex network of numerous and extremely heterogeneous actors. Nevertheless, all actors seem to speak the same ‘development jargon’ and to display a congruence that extends from the donor over the professional consultant to the village chief. And although the ideas about what counts as ‘good’ and ‘bad’ aid have constantly changed over time —with new paradigms and policies sprouting every few years— the apparent congruence between actors more or less remains unchanged. How can this be explained? Is it a strategy of all actors to get into the pocket of the donor, or are the social dynamics in development aid more complex? When a new development paradigm appears, where does it come from and how does it gain support? Is this support really homogeneous? To answer the questions, a multi-sited ethnography was conducted in the sector of water-related development aid, with a focus on 3 paradigms that are currently hegemonic in this sector: Integrated Water Resources Management, Capacity Building, and Adaptation to Climate Change. The sites of inquiry were: the headquarters of a multilateral organization, the headquarters of a development NGO, and the Inner Niger Delta in Mali. The research shows that paradigm shifts do not happen overnight but that new paradigms have long lines of descent. Moreover, they require a lot of work from actors in order to become hegemonic; the actors need to create a tight network of support. Each actor, however, interprets the paradigms in a slightly different way, depending on the position in the network. They implant their own interests in their interpretation of the paradigm (the actors ‘translate’ their interests), regardless of whether they constitute the donor, a mediator, or the aid recipient. These translations are necessary to cement and reproduce the network.

New water use efficiency strategies to cope with climate change

Crop water requirements are important elements for food production, especially in arid and semiarid regions. These regions are experience increasing population growth and less water for agriculture, which amplifies the need for more efficient irrigation. Improved water use efficiency is needed to produce more food while conserving water as a limited natural resource. Evaporation (E) from bare soil and Transpiration (T) from plants is considered a critical part of the global water cycle and, in recent decades, climate change could lead to increased E and T. Because energy is required to break hydrogen bonds and vaporize water, water and energy balances are closely connected. The soil water balance is also linked with water vapour losses to evapotranspiration (ET) that are dependent mainly on energy balance at the Earth’s surface. This work addresses the role of evapotranspiration for water use efficiency by developing a mathematical model that improves the accuracy of crop evapotranspiration calculation; accounting for the effects of weather conditions, e.g., wind speed and humidity, on crop coefficients, which relates crop evapotranspiration to reference evapotranspiration. The ability to partition ET into Evaporation and Transpiration components will help irrigation managers to find ways to improve water use efficiency by decreasing the ratio of evaporation to transpiration. The developed crop coefficient model will improve both irrigation scheduling and water resources planning in response to future climate change, which can improve world food production and water use efficiency in agriculture.

Assimilation of Meteosat Second Generation (MSG) satellite data in a regional numerical weather prediction model using a one-dimensional variational approach

The quality of temperature and humidity retrievals from the infrared SEVIRI sensors on the geostationary Meteosat Second Generation (MSG) satellites is assessed by means of a one dimensional variational algorithm. The study is performed with the aim of improving the spatial and temporal resolution of available observations to feed analysis systems designed for high resolution regional scale numerical weather prediction (NWP) models. The non-hydrostatic forecast model COSMO (COnsortium for Small scale MOdelling) in the ARPA-SIM operational configuration is used to provide background fields. Only clear sky observations over sea are processed. An optimised 1D–VAR set-up comprising of the two water vapour and the three window channels is selected. It maximises the reduction of errors in the model backgrounds while ensuring ease of operational implementation through accurate bias correction procedures and correct radiative transfer simulations. The 1D–VAR retrieval quality is firstly quantified in relative terms employing statistics to estimate the reduction in the background model errors. Additionally the absolute retrieval accuracy is assessed comparing the analysis with independent radiosonde and satellite observations. The inclusion of satellite data brings a substantial reduction in the warm and dry biases present in the forecast model. Moreover it is shown that the retrieval profiles generated by the 1D–VAR are well correlated with the radiosonde measurements. Subsequently the 1D–VAR technique is applied to two three–dimensional case–studies: a false alarm case–study occurred in Friuli–Venezia–Giulia on the 8th of July 2004 and a heavy precipitation case occurred in Emilia–Romagna region between 9th and 12th of April 2005. The impact of satellite data for these two events is evaluated in terms of increments in the integrated water vapour and saturation water vapour over the column, in the 2 meters temperature and specific humidity and in the surface temperature. To improve the 1D–VAR technique a method to calculate flow–dependent model error covariance matrices is also assessed. The approach employs members from an ensemble forecast system generated by perturbing physical parameterisation schemes inside the model. The improved set–up applied to the case of 8th of July 2004 shows a substantial neutral impact.

Light energy management in peach: utilization, photoprotection , photodamage and recovery. Maximizing light absorption in orchard is not always the best solution

The relation between the intercepted light and orchard productivity was considered linear, although this dependence seems to be more subordinate to planting system rather than light intensity. At whole plant level not always the increase of irradiance determines productivity improvement. One of the reasons can be the plant intrinsic un-efficiency in using energy. Generally in full light only the 5 – 10% of the total incoming energy is allocated to net photosynthesis. Therefore preserving or improving this efficiency becomes pivotal for scientist and fruit growers. Even tough a conspicuous energy amount is reflected or transmitted, plants can not avoid to absorb photons in excess. The chlorophyll over-excitation promotes the reactive species production increasing the photoinhibition risks. The dangerous consequences of photoinhibition forced plants to evolve a complex and multilevel machine able to dissipate the energy excess quenching heat (Non Photochemical Quenching), moving electrons (water-water cycle , cyclic transport around PSI, glutathione-ascorbate cycle and photorespiration) and scavenging the generated reactive species. The price plants must pay for this equipment is the use of CO2 and reducing power with a consequent decrease of the photosynthetic efficiency, both because some photons are not used for carboxylation and an effective CO2 and reducing power loss occurs. Net photosynthesis increases with light until the saturation point, additional PPFD doesn’t improve carboxylation but it rises the efficiency of the alternative pathways in energy dissipation but also ROS production and photoinhibition risks. The wide photo-protective apparatus, although is not able to cope with the excessive incoming energy, therefore photodamage occurs. Each event increasing the photon pressure and/or decreasing the efficiency of the described photo-protective mechanisms (i.e. thermal stress, water and nutritional deficiency) can emphasize the photoinhibition. Likely in nature a small amount of not damaged photosystems is found because of the effective, efficient and energy consuming recovery system. Since the damaged PSII is quickly repaired with energy expense, it would be interesting to investigate how much PSII recovery costs to plant productivity. This PhD. dissertation purposes to improve the knowledge about the several strategies accomplished for managing the incoming energy and the light excess implication on photo-damage in peach. The thesis is organized in three scientific units. In the first section a new rapid, non-intrusive, whole tissue and universal technique for functional PSII determination was implemented and validated on different kinds of plants as C3 and C4 species, woody and herbaceous plants, wild type and Chlorophyll b-less mutant and monocot and dicot plants. In the second unit, using a “singular” experimental orchard named “Asymmetric orchard”, the relation between light environment and photosynthetic performance, water use and photoinhibition was investigated in peach at whole plant level, furthermore the effect of photon pressure variation on energy management was considered on single leaf. In the third section the quenching analysis method suggested by Kornyeyev and Hendrickson (2007) was validate on peach. Afterwards it was applied in the field where the influence of moderate light and water reduction on peach photosynthetic performances, water requirements, energy management and photoinhibition was studied. Using solar energy as fuel for life plant is intrinsically suicidal since the high constant photodamage risk. This dissertation would try to highlight the complex relation existing between plant, in particular peach, and light analysing the principal strategies plants developed to manage the incoming light for deriving the maximal benefits as possible minimizing the risks. In the first instance the new method proposed for functional PSII determination based on P700 redox kinetics seems to be a valid, non intrusive, universal and field-applicable technique, even because it is able to measure in deep the whole leaf tissue rather than the first leaf layers as fluorescence. Fluorescence Fv/Fm parameter gives a good estimate of functional PSII but only when data obtained by ad-axial and ab-axial leaf surface are averaged. In addition to this method the energy quenching analysis proposed by Kornyeyev and Hendrickson (2007), combined with the photosynthesis model proposed by von Caemmerer (2000) is a forceful tool to analyse and study, even in the field, the relation between plant and environmental factors such as water, temperature but first of all light. “Asymmetric” training system is a good way to study light energy, photosynthetic performance and water use relations in the field. At whole plant level net carboxylation increases with PPFD reaching a saturating point. Light excess rather than improve photosynthesis may emphasize water and thermal stress leading to stomatal limitation. Furthermore too much light does not promote net carboxylation improvement but PSII damage, in fact in the most light exposed plants about 50-60% of the total PSII is inactivated. At single leaf level, net carboxylation increases till saturation point (1000 – 1200 μmolm-2s-1) and light excess is dissipated by non photochemical quenching and non net carboxylative transports. The latter follows a quite similar pattern of Pn/PPFD curve reaching the saturation point at almost the same photon flux density. At middle-low irradiance NPQ seems to be lumen pH limited because the incoming photon pressure is not enough to generate the optimum lumen pH for violaxanthin de-epoxidase (VDE) full activation. Peach leaves try to cope with the light excess increasing the non net carboxylative transports. While PPFD rises the xanthophyll cycle is more and more activated and the rate of non net carboxylative transports is reduced. Some of these alternative transports, such as the water-water cycle, the cyclic transport around the PSI and the glutathione-ascorbate cycle are able to generate additional H+ in lumen in order to support the VDE activation when light can be limiting. Moreover the alternative transports seems to be involved as an important dissipative way when high temperature and sub-optimal conductance emphasize the photoinhibition risks. In peach, a moderate water and light reduction does not determine net carboxylation decrease but, diminishing the incoming light and the environmental evapo-transpiration request, stomatal conductance decreases, improving water use efficiency. Therefore lowering light intensity till not limiting levels, water could be saved not compromising net photosynthesis. The quenching analysis is able to partition absorbed energy in the several utilization, photoprotection and photo-oxidation pathways. When recovery is permitted only few PSII remained un-repaired, although more net PSII damage is recorded in plants placed in full light. Even in this experiment, in over saturating light the main dissipation pathway is the non photochemical quenching; at middle-low irradiance it seems to be pH limited and other transports, such as photorespiration and alternative transports, are used to support photoprotection and to contribute for creating the optimal trans-thylakoidal ΔpH for violaxanthin de-epoxidase. These alternative pathways become the main quenching mechanisms at very low light environment. Another aspect pointed out by this study is the role of NPQ as dissipative pathway when conductance becomes severely limiting. The evidence that in nature a small amount of damaged PSII is seen indicates the presence of an effective and efficient recovery mechanism that masks the real photodamage occurring during the day. At single leaf level, when repair is not allowed leaves in full light are two fold more photoinhibited than the shaded ones. Therefore light in excess of the photosynthetic optima does not promote net carboxylation but increases water loss and PSII damage. The more is photoinhibition the more must be the photosystems to be repaired and consequently the energy and dry matter to allocate in this essential activity. Since above the saturation point net photosynthesis is constant while photoinhibition increases it would be interesting to investigate how photodamage costs in terms of tree productivity. An other aspect of pivotal importance to be further widened is the combined influence of light and other environmental parameters, like water status, temperature and nutrition on peach light, water and phtosyntate management.

'Defending the rights'. An integrated model of collective action for "public water" in Italy

In many communities, supplying water for the people is a huge task and the fact that this essential service can be carried out by the private sector respecting the right to water, is a debated issue. This dissertation investigates the mechanisms through which a 'perceived rights violation' - which represents a specific form of perceived injustice which derives from the violation of absolute moral principles – can promote collective action. Indeed, literature on morality and collective action suggests that even if many people apparently sustain high moral principles (like human rights), only a minority decides to act in order to defend them. Taking advantage of the political situation in Italy, and the recent mobilization for "public water" we hypothesized that, because of its "sacred value", the perceived violation of the right to water facilitates identification with the social movement and activism. Through five studies adopting qualitative and quantitative methods, we confirmed our hypotheses demonstrating that the perceived violation of the right to water can sustain activism and it can influence vote intentions at the referendum for 'public water'. This path to collective action coexists with other 'classical' predictors of collective action, like instrumental factors (personal advantages, efficacy beliefs) and anger. The perceived rights violation can derive both from personal values (i.e. universalism) and external factors (i.e. a mobilization campaign). Furthermore, we demonstrated that it is possible to enhance the perceived violation of the right to water and anger through a specifically designed communication campaign. The final chapter summarizes the main findings and discusses the results, suggesting some innovative line of research for collective action literature.

Life Cycle Assessment of Peach Nectar: a comparative analysis between conventional and bioenergy-from-waste integrated food chains

Modern food systems are characterized by a high energy intensity as well as by the production of large amounts of waste, residuals and food losses. This inefficiency presents major consequences, in terms of GHG emissions, waste disposal, and natural resource depletion. The research hypothesis is that residual biomass material could contribute to the energetic needs of food systems, if recovered as an integrated renewable energy source (RES), leading to a sensitive reduction of the impacts of food systems, primarily in terms of fossil fuel consumption and GHG emissions. In order to assess these effects, a comparative life cycle assessment (LCA) has been conducted to compare two different food systems: a fossil fuel-based system and an integrated system with the use of residual as RES for self-consumption. The food product under analysis has been the peach nectar, from cultivation to end-of-life. The aim of this LCA is twofold. On one hand, it allows an evaluation of the energy inefficiencies related to agro-food waste. On the other hand, it illustrates how the integration of bioenergy into food systems could effectively contribute to reduce this inefficiency. Data about inputs and waste generated has been collected mainly through literature review and databases. Energy balance, GHG emissions (Global Warming Potential) and waste generation have been analyzed in order to identify the relative requirements and contribution of the different segments. An evaluation of the energy “loss” through the different categories of waste allowed to provide details about the consequences associated with its management and/or disposal. Results should provide an insight of the impacts associated with inefficiencies within food systems. The comparison provides a measure of the potential reuse of wasted biomass and the amount of energy recoverable, that could represent a first step for the formulation of specific policies on the integration of bioenergies for self-consumption.