93Chapter 5
Tolerance to Combined Stress of Drought
and Salinity in Barley
Imrul Mosaddek Ahmed, Umme Aktari Nadira, Noreen Bibi, Guoping Zhang
and Feibo Wu
© Springer International Publishing Switzerland 2015
R. Mahalingam (ed.), Combined Stresses in Plants, DOI 10.1007/978-3-319-07899-1_5
F. B. Wu () · I. M. Ahmed · N. Bibi · U. A. Nadira · G. P. Zhang
Department of Agronomy, College of Agriculture and Biotechnology, Zijingang Campus,
Zhejiang University, Hangzhou 310058, China
e-mail: [email protected]
5.1 Introduction
Drought and salinity stresses occur naturally (Dai 2011 ), and have been expanding
worldwide due to human activities such as deforestations, salt mining (Ghassemi
et al. 1995 ), poor irrigation water (Marcum and Pessarakli 2006 ), and escalating
emissions of greenhouse gases (IPCC 2000 ). Currently, more than 800 million hect-
ares (ha) of land are affected by salinity (Munns 2005 ), and about one third of the
world’s arable land has experienced yield reduction due to cyclical or unpredict-
able drought (Chaves and Oliveira 2004 ), which are causing a great threat to crop
production. For example, China, India, and the USA, the world’s three major grain
producers and exporters, have been suffering serious water shortages in many major
agricultural regions. In China, according to the survey by the Ministry of Water Re-
sources, over 25.67 million ha of farmland was annually affected by drought stress
during the 15th 5-year plan, which caused production reduction of 3.5 × 1010 kg and
economic losses of more than 230 billion Chinese Yuan (http://mt.china-papers.
com/1/?p=185213).
Generally, the co-occurrence of several abiotic stresses, rather than an individual
stress condition, is even worse for crop production (Mittler 2006 ). For example,
the combined effects of salinity and drought on yield are more detrimental than the
effects of each stress alone, as observed in potato (Levy et al. 2013 ), wheat (Yousfi
et al. 2012 ), and barley (Yousfi et al. 2010 ). However, most studies to date have ad-
dressed the effects of single stresses on plant (Zhao et al. 2010 ; Wu et al. 2013 ), and
little is known about the physiological and molecular mechanisms underlying the
acclimation of plants to a combination of salinity and drought (Mittler 2006 ). Recent
studies have revealed that the response of plants to a combination of different abiot-
ic stresses is unique and cannot be directly extrapolated from the response of plants