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Physiological responses to waterlogging in barley (Hordeum vulgare L.)

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Pang, Jiayin (2006) Physiological responses to waterlogging in barley (Hordeum vulgare L.). PhD thesis, University of Tasmania.

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Abstract

Waterlogging is a major environmental constraint severely limiting crop production
both in Australia and worldwide. In Australia, the problem is especially acute in
higher rainfall areas with poorly draining soils. With most Australian commercial
barley cultivars being waterlogging sensitive, waterlogging tolerant genetic material
has to be selected and used in the breeding programs. Of specific interest is Chinese
germplasm collection. However, lack of appropriate screening methodology makes
selection ofwaterlogging tolerant cultivars difficult. Also, waterlogging is a
complex abiotic stress encoding a large number of physiological and biochemical
mechanisms and complicated by many confounding factors. Accordingly, the aims
of this project were three-fold: (1) to develop an efficient screening methodology
for waterlogging tolerance in barley breeding programs; (2) to select some
waterlogging tolerant cultivars among existing barley germplasm; and (3) to
understand the physiological, morphological and anatomical mechanisms encoding
waterlogging tolerance in barley. The project was an integral part ofGRDC-funded
collaboration between Australia and China on barley genetics.

Barley plant growth was adversely affected by waterlogging. As waterlogging stress
developed, chlorophyll content, net C02 assimilation and maximal photochemical
efficiency of PSil (Fv/Fm) decreased significantly. Among these, chlorophyll
fluorescence of dark-adapted samples (Fv/Fm values) was found to be the most
efficient screening parameter for large-scale programs for waterlogging tolerance.
Among studied genotypes, the Chinese cultivar TX9425 was found to be the most
waterlogging tolerant, with the least reduction of plant growth, chlorophyll content,
chlorophyll fluorescence and photosynthetic parameters. Naso Nijo (a Japanese
cultivar) and Franklin (an Australian cultivar) were found to be the most susceptible
to waterlogging. The adverse effects in stressed plants were alleviated following 2
weeks recovery in all cultivars. These contrasting genotypes were used later in all
physiological studies.

Overall, this study suggests that substantial genetic potential exists to improve
waterlogging tolerance in barley. Measuring chlorophyll fluorescence of darkadapted
samples (Fv/Fm values) is recommended as an efficient screening tool for
waterlogging tolerance in barley breeding program. Key features targeted by
breeding should include both morphological (production of more adventitious roots
and formation of larger aerenchyma area in adventitious roots) and physiological
(high ability of 0 2 uptake and K+ acquisition in plant roots) traits, as well as the
plant's ability to withstand soil-borne phytotoxins. Foliar application of nutrient c~
be used in practice to alleviate the adverse effects ofwaterlogging.

Item Type: Thesis (PhD)
Keywords: Barley, Barley
Copyright Holders: The Author
Copyright Information:

Copyright 2006 the author

Additional Information:

Chapter 4 is post print.

Chapter 5 is post print and is the equivalent of the peer reviewed version of the following article: ANG, J. Y., NEWMAN, I., MENDHAM, N., ZHOU, M. and SHABALA, S. (2006), Microelectrode ion and O2 fluxes measurements reveal differential sensitivity of barley root tissues to hypoxia. Plant, Cell & Environment, 29: 1107–1121, which has been published in final form at http://dx.doi.org/10.1111/j.1365-3040.2005.01486.x This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.

Chapter 6 formed the basis of an article later published as: Jiayin Pang, Tracey Cuin, Lana Shabala, Meixue Zhou, Neville Mendham and Sergey Shabala, (2007) Effect of secondary metabolites associated with anaerobic soil conditions on ion fluxes and electrophysiology in barley roots, Plant physiology, 145 (1) 266-276

Chapter 7 formed the basis of an article later published as: Jiayin Pang, John Ross, Meixue Zhou, Neville Mendham, Sergey Shabala (2007) Amelioration of detrimental effects of waterlogging by foliar nutrient sprays in barley, 34 (3) 221-227

Available for library use only and copying in accordance with the Copyright Act 1968, as amended. Thesis (PhD)--University of Tasmania, 2006. Includes bibliographical references

Date Deposited: 03 Feb 2015 03:09
Last Modified: 11 Mar 2016 05:54
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