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Abstract

Miscanthus ×giganteus Greef et Deu. (Poaceae), a hybrid of Miscanthus sinensis and M. sacchariflorus native to Japan, is an ornamental and a highly lignocellulosic bioenergy crop, cultivated in the European Union as an alternative source of energy. This grass reproduces exclusively vegetatively, by rhizomes or via expensive in vitro micropropagation. The present study was aimed at finding the barriers that prevent sexual seed production, based on detailed embryological analyses of the whole generative cycle, including microsporogenesis, pollen viability, megasporogenesis, female gametophyte development, and embryo and endosperm formation. Sterility of M. ×giganteus results from abnormal development of both male and female gametophytes. Disturbed microsporogenesis (laggard chromosomes, univalents, micronuclei) was further highlighted by low pollen staining. The frequency of stainable pollen ranged from 13.9% to 55.3% depending on the pollen staining test, and no pollen germination was observed either in vitro or in planta. The wide range of pollen sizes (25.5-47.6 μm) clearly indicated unbalanced pollen grain cytology, which evidently affected pollen germination. Only 9.7% of the ovules developed normally. No zygotes nor embryos were found in any analyzed ovules. Sexual reproduction of M. ×giganteus is severely hampered by its allotriploid (2n=3x=57) nature. Hybrid sterility, a strong postzygotic barrier, prevents sexual reproduction and, therefore, seed formation in this taxon.
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Abstract

The paper presents the concept of vital cities in the context of mechanisms of sustainable development, networking and creativity. The vital city was presented as: - a city belonging to the inhabitants – a city managed and developed with advanced processes of participation, - a city of reasonable management – a city that uses and at the same time protects its key potentials, - a city of creation – a city of creating and implementing new ideas, - a city of opportunities – a city that creates the conditions for the use of energy and creativity residents, - a city in the surround – a city with a strong position in the environment.
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Abstract

The paper presents a review of concepts for the development of city centres in response to social and culture processes, economic, technical and environmental developments taking place at present on those areas. This review proves that concepts tend to change over time from those based on economic dynamics to those based on collaborative commons and on governance. On the example of a few city centres situated in the Silesian Region an analysis was carried out of the concepts being presently applied and with the use of which projects Silesian cities strive to maintain and strengthen the dynamics and vitality of city centres.
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