Plant breeders are in the need for a convenient, reproducible, reliable and rapid screening methods to be used as a proxy for drought tolerance for a large number of genotypes. Addressing this need, we compared different physiological measures of stress in six barley (Hordeum vulgare L.) genotypes subjected to different drought treatments under glasshouse conditions. Genotypes were evaluated by measuring transpiration rate, quantum yield of PSII (chlorophyll fluorescence F_v/F_m ratio), SPAD chlorophyll meter reading, dry biomass and shoot water content. The accuracy of different methods for quantifying water stress tolerance was evaluated by measuring the rates of surviving and death in plants and leaves, and newly grown leaves after rewatering. In another experiment, the same genotypes were evaluated by applying 18% (w/v) of polyethylene glycol (PEG) to germinating seeds grown in paper rolls to induce osmotic stress, using relative root and shoot lengths as a measure of tolerance. The results suggest that transpiration measurements at the recovery stage could be the most sensitive method for separating contrasting genotypes. However, the method is time-consuming and laborious for large-scale screening. Chlorophyll content, dry biomass, shoot water content and stomatal density did not correlate with plant drought tolerance. At the same time, chlorophyll fluorescence F_v/F_m ratio showed a strong correlation with drought tolerance and could be recommended as suitable proxy for screening. Measuring relative root growth rate (length) using PEG-treated paper roll-grown seedlings also seems to be a highly suitable and promising method for screening a large number of genotypes in breeding programs.

Item Type:	Refereed Article
Keywords:	chlorophyll fluorescence, Fv/Fm, polyethylene glycol, SPAD reading, stomatal density, transpiration rate.
Research Division:	Biological Sciences
Research Group:	Plant biology
Research Field:	Plant physiology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the environmental sciences
UTAS Author:	Hasanuzzaman, Md (Mr Md Hasanuzzaman)
UTAS Author:	Shabala, L (Associate Professor Lana Shabala)
UTAS Author:	Brodribb, TJ (Professor Tim Brodribb)
UTAS Author:	Zhou, M (Professor Meixue Zhou)
UTAS Author:	Shabala, S (Professor Sergey Shabala)
ID Code:	112463
Year Published:	2017 (online first 2016)
Funding Support:	Australian Research Council (DP140100666)
Web of Science® Times Cited:	15
Deposited By:	Plant Science
Deposited On:	2016-11-11
Last Modified:	2017-11-02
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