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In Mediterranean regions drought is the major factor limiting spring barley and durum wheat grain yields. This study aimed to compare spring barley and durum wheat root and shoot responses to drought and quantify relationships between root traits and water uptake under terminal drought. One spring barley (Hordeum vulgare L. cv. Rum) and two durum wheat Mediterranean cultivars (Triticum turgidum L. var durum cvs Hourani and Karim) were examined in soil-column experiments under well watered and drought conditions. Root system architecture traits, water uptake, and plant growth were measured. Barley aerial biomass and grain yields were higher than for durum wheat cultivars in well watered conditions. Drought decreased grain yield more for barley (47%) than durum wheat (30%, Hourani). Root-to-shoot dry matter ratio increased for durum wheat under drought but not for barley, and root weight increased for wheat in response to drought but decreased for barley. The critical root length density (RLD) and root volume density (RVD) for 90% available water capture for wheat were similar to (cv. Hourani) or lower than (cv. Karim) for barley depending on wheat cultivar. For both species, RVD accounted for a slightly higher proportion of phenotypic variation in water uptake under drought than RLD.Keywords: Barley; Mediterranean; root architecture; root length density; root traits; root volume density; water; wheat Citation: Carvalho P, Azam-Ali S, Foulkes MJ (2014) Quantifying relationships between rooting traits and water uptake under drought in Mediterranean barley and durum wheat.

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(2016) Relationships between δ13C, δ18O and grain yield in bread wheat genotypes under favourable irrigated and rain-fed conditions. Field Crops Research, 196 . pp. 237-250. ISSN 1872-6852 Access from the University of Nottingham repository: http://eprints.nottingham.ac.uk/46334/1/Foulkes%20et%20al%202016%20FCR%20196237-50.pdf Copyright and reuse:The Nottingham ePrints service makes this work by researchers of the University of Nottingham available open access under the following conditions. This article is made available under the University of Nottingham End User licence and may be reused according to the conditions of the licence. For more details see: http://eprints.nottingham.ac.uk/end_user_agreement.pdf A note on versions:The version presented here may differ from the published version or from the version of record. If you wish to cite this item you are advised to consult the publisher's version. Please see the repository url above for details on accessing the published version and note that access may require a subscription. Abstract 19In previous investigations, carbon isotope composition (δ 13 C) has been used in C 3 cereals to 20 screen for genotypes with high transpiration efficiency and oxygen isotope composition 21 (δ 18 O) has been shown to correlate with transpiration rate. We examined associations of δ developed to maintain food security. In the UK, water deficits can commonly limit wheat 51 yields in some years, where, typically, the onset of drought is post-anthesis, and losses are c. 52 20-30% (Foulkes et al., 2002). 53Plants discriminate against the heavier carbon isotope ( 13 C) during photosynthesis and 54 the extent of this discrimination depends on the ratio of intercellular versus external CO 2 55 concentration (C i /C a ) in photosynthetic organs (Farquhar et al., 1982). The carbon isotope 56 composition (δ 13 C) is negatively related to Ci/Ca (δ 13 C) (Farquhar et al., 1982) , which, in 57 turn, is negatively related to the transpiration efficiency (TE) at the stoma (CO 2 assimilation/ 58 transpiration). Therefore, carbon isotope composition (δ 13 C; frequently expressed as 59 discrimination from the source air, Δ 13 C) is positively associated with TE. When measured in 60 dry matter, δ 13 C provides information on the long-term transpiration efficiency of C 3 plants 61 (Farquhar and Richards 1984). Conditions that induce stomatal closure, such as water deficit, 62 restrict the CO 2 supply to carboxylation sites, which then increases the δ 13 C (or decreases 63 Δ 13 C) of plant matter (Farquhar et al., 1989). The carbon isotope signature has been used as a 64 selection indicator for high TE in commercial wheat breeding for water-limited environments 65 (Rebetzke et al., 2002;Condon et al., 2002;Condon et al., 2004). Selection for Δ 13 C was used 66 to develop the Australian spring-wheat cultivars Drysdale and Rees (Richards, 2006). Under 67 severe drought in Australia, Δ 13 C of grain was negatively correlated with aerial biomass and 68 grain yield for wheat (Rebetzke et al., 200...

Currently, the genus Populus is one of the favourite objects for research of molecular genetics of woody plants. A high growth rate and the broadly applicable timber as raw material for different types of products made of wood make poplar attractive for industrial usage. Despite the positive aspect of its growth capacity and wood composition, one major problem in cultivating fast-growing tree species in a forestry plantation system is the comparably high water demand of the plants. In this context, a rapid development of an efficient adventitious root system from dormant hardwood cuttings is an essential requirement for the successful establishment of short-rotation cultures. It reduces the establishment costs of plantations, and the developing plant can be transferred into favourable conditions due to varying environmental conditions. Results of greenhouse pot and soil-column experiments on the development of shoots and adventitious roots from hardwood cuttings of seven hybrid poplar cultivars and the reaction of the plants performance on varying water availability will be presented. We estimated root and shoot length, root and shoot growth and biomass accumulation over time, root-to-shoot length ratio, and root morphological traits.