Giorgio Gianquinto

Beyond the ionic and osmotic response to salinity in Chenopodium quinoa: functional elements of successful halophytism

Chenopodium quinoa Willd. (quinoa) is a halophyte for which some parameters linked to salt tolerance have been investigated separately in different genotypes and under different growth conditions. In this study, several morphological and metabolic responses were analysed in parallel after exposure to salinity. In vitro seed germination was initially delayed by a 150mM NaCl treatment but eventually reached the same level as the control (0mM NaCl), whereas seedling root growth was enhanced; both parameters were moderately inhibited (~35-50%) by 300mM NaCl. In pot grown plants, plant size was reduced by increasing salinity (0-750mM NaCl). Transpiration and stomatal conductance were decreased at the highest salinity levels tested, consistent with reduced stomatal density and size. The density of epidermal bladder cells (EBCs) on the leaf surface remained unaffected up to 600mM NaCl. Tissue contents of Na+ and Cl- increased dramatically with salt treatment, but resulted in only a 50% increase in Na+ from 150 to 750mM NaCl. Internal K+ was unaffected up to 450mM NaCl but increased at the highest salinity levels tested. Excretion through sequestration into EBCs was limited (generally ≤20%) for all ions. A modest dose-dependent proline accumulation, and concomitant reduction in total polyamines and putrescine efflux occurred in NaCl-treated plants. Results confirm the importance of inorganic ions for osmotic adjustment, the plants ability to maintain K+ levels and the involvement of putrescine efflux in maintaining ionic balance under high salinity conditions. Conversely, ion excretion and proline appear to play a minor role. Taken together these results indicate which parameters could be used for future comparison among different genotypes.

Salinity thresholds and genotypic variability of cabbage (Brassica oleracea L.) grown under saline stress

BACKGROUND Two botanical varieties of cabbage, namely Savoy (Brassica oleracea var. Sabauda L.) and White (Brassica oleracea var. Capitata L.) were used in order to understand the morphological, physiological and biochemical elements of functional salt stress response. Thirteen salt concentrations (range, 0 to 300 mmol L(-1) NaCl) were considered in Experiment 1 and, of these 13, three (0, 100 and 200 mmol L(-1) NaCl) were used in Experiment 2. RESULTS Experiment 1 enabled the definition of two salinity thresholds (100 and 200 mmol L(-1) NaCl), associated with morphological and physiological adaptations. In Experiment 2, moderate salinity (100 mmol L(-1) NaCl) had lower effects on Savoy than in White cabbage yield (respectively, -16% and -62% from control). Concurrently, 100 mmol L(-1) NaCl resulted in a significant increase of antioxidant enzymes from control conditions, that was greater in Savoy (+289, +423 and +88%, respectively) as compared to White (+114, +356 and +28%, respectively) cabbage. Ion accumulation was found to be a key determinant in tissue osmotic adjustment (mainly in Savoy) whereas the contribution of organic osmolites was negligible. CONCLUSIONS Higher antioxidative enzymatic activities in Savoy versus White cabbage after treatment with 100 mmol L(-1) NaCl were associated with improved water relations, thus suggesting a possible physiological pathway for alleviating perceived salt stress.

Morphological and Physiological Plant Responses to Drought Stress in Thymus citriodorus

Water availability is considered as a determinant factor that affects plant growth. The commercial medicinal values of an aromatic plant rely on the presence of secondary metabolites that are affected under water shortage. Two-year-old Thymus citriodorus plants were subjected to different polyethylene glycol (PEG-6000) levels (0, 2%, and 4%) under greenhouse condition. PEG treatment lasted for 15 days. Thyme plant showed a morphological drought avoidance mechanism by maintaining the root system development through shoot fresh weight reduction resulting in promoted root absorption capacity and sustained plant growth. Moreover, stressed plants were able to maintain water use efficiency and root : shoot ratio suggesting a strong relation between root water uptake and water use saving strategies. Furthermore, thyme plants reduced tissue dehydration through stomatal closure and improved root water uptake. Content of volatile oil constituents of geraniol and diisobutyl phthalate increased upon drought stress while pseudophytol was reduced. Unexpectedly, thymol was not reported as a main oil element under either control or mild stress condition, while it was increased upon high drought stress in measure of 4.4%. Finally, carvacrol significantly accumulated under high drought stress (

Onion Seed Germination as Affected by Temperature and Light

Producers need to know whether the germination rate will produce sufficient numbers of seedlings needed for field production of onion (Allium cepa L.). The influence of temperature (5.0, 7.5, 10, 15, 20, 25, 30, 35, or 40°C) and continuous light or continuous dark was tested for effects on percentage germination of normal, abnormal, or diseased seed; production of normal seedlings; and percentage of ungerminated solid and soft seeds of onion. Temperatures from 7.5 to 30°C generally assured a high germination percentage and a high percentage of normal seedlings. The most rapid germination occurred at 25°C in the dark. At 5, 35, and 40°C normal germination was only about 10%. The model from the Weibull function indicated that temperature influenced the time between the beginning of imbibition to germination. Onion seed exposed to temperatures between 10 and 30°C under field conditions could produce a high germination percentage, which should lead to development of normal seedlings.

Managing Mineral Nutrition in Soilless Culture

In most cases, rooftop agriculture uses soilless cultivation (or hydroponics) of plants, as the yield and the quality of the soilless-grown crops are often higher than those grown in the agricultural soil. In soilless culture, the elements that are essential or beneficial for plant growth and development are supplied through: (i) the addition of organic and/or synthetic fertilisers to the substrate before and after crop plantation; (ii) the supply of a nutrient solution, which is prepared dissolving one or more soluble fertilisers in the raw water and thus is delivered with the irrigation system (fertigation). In this chapter, the basic aspects of the mineral nutrition of hydroponically-grown plants and the methods that could be used for a sustainable management of fertigation in rooftop soilless culture and to improve the organoleptic and nutritional quality of rooftop food crops are described.

Sustainable Water Management in Green Roofs

In this chapter, the contribution of green roofs in management of the urban water cycle is addressed. Primarily, proper water management strategies are presented, with specific regard to the sustainable practice of irrigation and the definition of water quality standards. We reference the application of alternative water sources, such as rainwater harvesting and gray water regeneration. Then, the environmental, ecological, and financial benefits associated with rooftop greening are described, including reference to life cycle cost assessment. Ecosystem service provision is analyzed in specific relation to the role played by water in improving urban microclimate and air quality and promoting resilience to climate change.

Social acceptance and perceived ecosystem services of urban agriculture in Southern Europe: The case of Bologna, Italy

Urban agriculture has become a common form of urban land use in European cities linked to multiple environmental, social and economic benefits, as well as to diversified forms (from self-production allotments to high-tech companies). Social acceptance will determine the development of urban agriculture and specific knowledge on citizens’ perception is required in order to set the basis for policy-making and planning. The ecosystem services provided by urban agriculture can be determinant in this process. The goal of this paper is to evaluate the social acceptance and the perceived ecosystem services of urban agriculture in the city of Bologna (Italy), as an example of a Southern European city. In particular, we evaluated the preferences for urban land uses, for different typologies of urban agriculture and for the resulting products, the perceived provision of ecosystem services and the willingness to engage in new initiatives. A survey that investigated these topics (including open questions, closed questions and Likert-scale evaluation) was performed on the citizens of Bologna (n = 380) between October and November 2016. Results showed that urban agriculture is widely accepted by the inhabitants of Bologna, particularly regarding vegetable production. Although intensive farming systems were the least preferred forms to be implemented in Bologna, citizens highly accepted a large variety of urban agriculture goods, with preference for those obtained from plants as compared to animal products. The willingness-to-pay for urban food products was mostly the same as for conventional ones, although the participants recognised the social values, proximity and quality of the former. Socio-cultural ecosystem services were perceived as more valuable than environmental ones. Policy-making recommendations can be extracted from the results to facilitate the development of urban agriculture plans and policies.

Toward the Creation of Urban Foodscapes: Case Studies of Successful Urban Agriculture Projects for Income Generation, Food Security, and Social Cohesion

Urban agriculture (UA) is a strategic means of achieving sustainable urban food security now and into the future. While a number of different models of agriculture will be required to provide food for the concentrated number of people in urban spaces, UA can be key tool in helping urban residents meet micronutrient requirements, whose deficiency is now recognized as the most important cause of “hidden hunger” globally. UA, or the cultivation of crops for food in small and irregular spaces within a city and its periphery, has been practiced for as long as cities have existed. However, it is gaining increased attention for both its limited scale, its effects on nutrition and community building, the associated possibilities for employment and social mobility, its relevance in a vibrant and diverse food system and for all of these reasons, its sustainability. UA projects are springing up in cities all over the world, always engaging the collaboration of multiple urban stakeholders and increasingly with a focus on the most vulnerable people in society: the poor, the elderly, children, and those suffering malnutrition and chronic disease. For all city dwellers, UA improves livelihoods within the city environment by reducing city ecological footprint, strengthening city resilience to climate change and environmental hazards, reducing noise, improving air quality and the city microclimate, minimizing drought by improving storm water management, and contributing to solid waste management. It increases human health and well-being through stress recovery, encouragement of exercise, reduction of urban violence, facilitating social contact, and providing sources of added employment and income. Using the concept of urban political ecology as a foundation for understanding food dynamics, this chapter will describe a range of different UA initiatives across the globe, giving special attention to their multifunctionality in the context of social vulnerabilities within urban spaces. In so doing, it will present UA as an important platform for community engagement and sustainability building toward increased food security. Turning concrete into green productive lands results in changes in physical, psychological, environmental, and community health. At the same time, the application of social leftovers (abandoned lands, unused rooftops, plastic and wood containers, etc.) onto productive means creates a new model for adding micronutrition to urban diets that integrates and takes seriously social, cultural, nutritional, and economic outcomes.

A Geography of Rooftop Agriculture in 20 Projects

In this chapter, selected cases of rooftop agriculture across the world will be presented, explaining their organisation, technical design and operation, their business model and main functions, lessons learned during establishment and operation, their productive and societal results and their policy relevance. The owner or manager of the rooftop garden or farm and an independent researcher were involved in documenting the cases, When selecting the cases, we tried to include examples of the various types of rooftop agriculture presented in previous chapters. We also sought to include cases from all continents. Accordingly, a comprehensive list of most relevant rooftop agriculture experience across the world is presented, following an alphabetical order by city. For each case, the names of main informants (case study representatives) are listed altogether with the name of the author that coordinated data collection.

Rooftop Urban Agriculture

In a world characterised by growing urbanisation, urban agriculture is gaining relevance due to its potential for increasing resource efficiency, contributing to city food security and enhancing associated ecosystem and social services. In cities, however, spaces available for cultivation are limited, thus leading to the need to explore innovative growing solutions, such as cultivating building rooftops. Rooftop agriculture can also contribute to addressing specific city challenges such as climate change. Experiences are sprouting all over the world, scientific evidence on most suitable growing solutions, policies and potential benefits is growing. The present review will address the main features of rooftop agriculture, providing an interdisciplinary assessment of different approaches for development and the multifaceted forms that rooftop agriculture may assume in different contexts, bringing together existing experiences as well as suggestions for planning of future sustainable cities.