Chromosomal Location of Traits Associated with Wheat Seedling Water and Phosphorus Use Efficiency under Different Water and Phosphorus Stresses

The objective of this study was to locate chromosomes for improving water and phosphorus-deficiency tolerance of wheat at the seedling stage. A set of Chinese Spring-Egyptian Red wheat substitution lines and their parent Chinese Spring (recipient) and Egyptian Red (donor) cultivars were measured to determine the chromosomal locations of genes controlling water use efficiency (WUE) and phosphorus use efficiency (PUE) under different water and phosphorus conditions. The results underlined that chromosomes 1A, 7A, 7B, and 3A showed higher leaf water use efficiency (WUEl = Pn/Tr; Pn = photosynthetic rate; Tr = transpiration rate) under W-P (Hoagland solution with 1/2P), -W-P (Hoagland solution with 1/2P and 10% PEG). Chromosomes 7A, 3D, 2B, 3B, and 4B may carry genes for positive effects on individual plant water use efficiency (WUEp = biomass/TWC; TWC = total water consumption) under WP (Hoagland solution), W-P and -W-P treatment. Chromosomes 7A and 7D carry genes for PUE enhancement under WP, -WP (Hoagland solution with 10% PEG) and W-P treatment. Chromosome 7A possibly has genes for controlling WUE and PUE simultaneously, which indicates that WUE and PUE may share the same genetic background. Phenotypic and genetic analysis of the investigated traits showed that photosynthetic rate (Pn) and transpiration rate (Tr), Tr and WUEl showed significant positive and negative correlations under WP, W-P, -WP and -W-P, W-P, -WP treatments, respectively. Dry mass (DM), WUEP, PUT (phosphorus uptake) all showed significant positive correlation under WP, W-P and -WP treatment. PUE and phosphorus uptake (PUT = P uptake per plant) showed significant negative correlation under the four treatments. The results might provide useful information for improving WUE and PUE in wheat genetics

Towards a Spatial Planning Framework for the Re-naturing of Cities

This chapter presents a framework for the spatial planning of re-naturing cities. There is today a lively debate about re-naturing cities, since it can address multiple societal challenges and generate benefits such as the enhancement of health and wellbeing, sustainable urbanisation, ecosystems and their services and resilience to climate change. Yet, further consideration of the roles that positive spatial planning and planning models in particular have to play in fostering the integration of urbanisation with nature is needed. This chapter, thus, focuses on representative models with such potential, including the grid, the linear, the concentric and the radial. Initially, it identifies major principles for the spatial re-naturing of cities. Secondly, it analyses the main characteristics of each of the four models, concentrating in particular on their suitability to deliver on the re-naturing principles discussed previously. The chapter then centres on how a hybrid approach can maximise the systemic integration of natural and urban systems. Finally, the conclusions offer insights into the potentialities of planning models in bridging the city–nature dichotomy and potential future directions of development