Understanding physiological and morphological traits contributing to drought tolerance in barley

Abstract

Drought stress is a major limiting factor for crop production in the arid and semi‐arid regions. Here, we screened eighty barley (Hordeum vulgare L.) genotypes collected from different geographical locations contrasting in drought stress tolerance and quantified a range of physiological and agronomical indices in glasshouse trails. The experiment was conducted in large soil tanks subjected to drought treatment of eighty barley genotypes at three‐leaf stage and gradually brought to severe drought by withholding irrigation for 30 days under glasshouse conditions. Also, root length of the same genotypes was measured from stress‐affected plants growing hydroponically. Drought tolerance was scored 30 days after the drought stress commenced based on the degree of the leaf wilting, fresh and dry biomass and relative water content. These characteristics were related to stomatal conductance, stomatal density, residual transpiration and leaf sap Na, K, Cl contents measured in control (irrigated) plants. Responses to drought stress differed significantly among the genotypes. The overall drought tolerance was significantly correlated with relative water content, stomatal conductance and leaf Na+ and K+ contents. No significant correlations between drought tolerance and root length of 6‐day‐old seedling, stomatal density, residual transpiration and leaf sap Cl− content were found. Taking together, these results suggest that drought‐tolerant genotypes have lower stomatal conductance, and lower water content, Na+, K+ and Cl− contents in their tissue under control conditions than the drought‐sensitive ones. These traits make them more resilient to the forthcoming drought stress.

Comparative physiological attributes of cultivated and wild relatives of barley in response to different water environments

“…When plants are subjected to drought stress, a number of physiological responses have been observed (Hasanuzzaman, Shabala, Brodribb, Zhou, & Shabala, 2019: Kebede et al., 2019; Lu et al., 1999). In some wild cereals such as barley, osmotic adjustment has been found to be one of the most effective physiological mechanisms underlying plant resistance to water deficit (Binott, Owuoche, & Bartels, 2017; Zhang, Jin, & Zhao, 2015).…”

“…Osmotic adjustment, as a process of active accumulation of compatible osmolytes in plant cells exposed to water deficit, may enable a continuation of leaf elongation, though at reduced rates. Stomatal and photosynthetic adjustments maintained root development and soil moisture extraction, delayed leaf senescence, and provided better dry matter accumulation and yield production for plants in stressful environments (Hasanuzzaman et al., 2019; Lu et al., 1999). In the present study, water deficit decreased RWC, whereas proline content significantly increased RWC.…”

Signaling Role of Glutamate in Plants

“…Drought stress caused by the decline in soil water potential interferes with many physiological processes at different levels, such as water uptake, transpiration, photosynthesis, seed germination, plant growth, and development (Deinlein et al, 2014;Tardieu et al, 2018;Hasanuzzaman et al, 2019;Laxa et al, 2019). Under severe conditions, drought stress lead simultaneously or successively to osmotic and oxidative stress.…”

“…Under severe conditions, drought stress lead simultaneously or successively to osmotic and oxidative stress. Therefore, the regulation of water balance by controlling stomata movement is one of the major strategies that resist and adapt to drought stress in plants (Deinlein et al, 2014;Tardieu et al, 2018;Hasanuzzaman et al, 2019;Laxa et al, 2019).…”

“…For land plants, stomata is indispensable structure to control water balance and gas exchange, its movement is regulated by a coordinated action of a series of signaling molecules, such as Ca 2+ , ROS, NO, H 2 S, and ABA (Tardieu et al, 2018;Hasanuzzaman et al, 2019;Laxa et al, 2019). In Arabidopsis and fava bean (Vicia faba L.), Glu treatment increased [Ca 2+ ] cyt in guard cells, which in turn led to stomata closure.…”