Agricultural Research Management Information System

Home
Research Summary
Search
About Us
- ARMIS
- Brochure
Contact Us
Report
User Request
Data Input
Help
- Operation Manual
  - PDF
  - Video
- Program Area & Commodity
We have reached 37600 number of research entries at this moment.

- Logout

Research Detail

Home
Research
Detail

Understanding Physiological and Morphological Traits Contributing to Drought Tolerance in Barley

Md. Hasanuzzaman
Department of Agronomy, Faculty of Agriculture, Sher-e-Bangla Agricultural University, Sher-e-Bangla Nagar, Dhaka, Bangladesh

Lana Shabala
Tasmania Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia

Timothy J. Brodribb3
School of Biological Science, University of Tasmania, Hobart, Tasmania, Australia

Meixue Zhou
Tasmania Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia

Sergey Shabala
Tasmania Institute of Agriculture, University of Tasmania, Hobart, Tasmania, Australia

Abstract/ Executive Summary:

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 trials. The experiment was conducted in large soil tanks subjected to drought treatment of eighty barley genotypes at the three-leaf stage and gradually brought to severe drought by withholding irrigation for 30 days under glasshouse conditions. Also, the 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.

Keywords: Biomass, Ionic relation, Residual transpiration, Root length, Stomatal conductance, Stomatal density

Location:

Start Date:

End Date:

Program Area: Crop-Soil-Water Management

Commodity: Barley

Objectives:

In this work, we aimed to fill the above gaps in our knowledge by answering three specific questions: (a) do the stomatal density and stomatal conductance of barley genotypes grown under control conditions correlate with drought tolerance (b) Does the residual transpiration of well-irrigated plants correlate with drought tolerance (c) Is the root length an important component of the drought tolerance mechanism in barley.

Methodology:

2.1 Plant materials and growth conditions Seeds of eighty barley genotypes (Hordeum vulgare L.) were obtained from the Australian Winter Cereal Collection and China and multiplied in the field at Tasmanian Institute of Agriculture (TIA) facilities in Launceston. Seeds were sown at 10 mm depth in 432 L (1.2 × 0.6 × 0.6 m) Poly (vinyl) chloride (PVC) tanks using soil mixture with slow releasing mixed fertilizers in a glasshouse at the Mount Pleasant Laboratory facilities in Launceston, Australia. The experiment was conducted in 2015 (September–December) under controlled glasshouse conditions (day length 14 hr, average day/night temperatures 25/15°C, relative humidity 65%). After germination, barley seedlings were thinned to four uniform and healthy plants for each variety in each tank. The drought was imposed on 15-day-old seedlings (3-leaf stage) after germination. Plants were gradually brought to severe drought by withholding irrigation for 30 days. The experiment was conducted as a complete random design (CRD) with each tank as a replication. Thus, the experiment was carried out with four replications for each cultivar for each of the drought and control treatments. Control plants were grown in the normal irrigated conditions in the soil tank under control glasshouse conditions. 2.4 Residual transpiration measurement Three fully expanded leaves at an intermediate position from each genotype from control plants were selected for sampling. The leaves were excised and sealed with vacuum grease on the cut end immediately. Collected leaves were then immediately transported to the laboratory and placed in the darkroom at 20 ± 1°C and 50% relative humidity for stomatal closure. Fresh weights were measured by an electronic balance immediately after the excision of leaves. The leaves were then weighed at 2, 4 and 6 hr intervals. The leaves were then placed in a dry oven at 60°C for 24 hr after which the dry weight was measured. The residual transpiration was measured and calculated as described in our previous publications (Hasanuzzaman, Davies, et al., 2017a). 2.7 | Drought stress tolerance index After 30 days of withholding irrigation, the extent of the leaf injury was scored for each plant and ranked on 1 to 9 scales (1 = completely dead plants; 3 = more than 75% of all leaves dried; 5 = more than 25% of all leaves dried; 7 = about ¼ of the leaf length is dry; 9 = no damage symptoms) (Supporting Information in Figure S1). The average values of four replications were used for the quantitative estimation of drought tolerance. The drought tolerance index estimated as per the above scale was used to determine the effectiveness of different morphological and physiological parameters in screening for drought tolerance. 2.8 | Seedling test All eighty barley genotypes were screened for root length under control conditions in hydroponics experiments. Fifteen seeds of each genotype were germinated in a two-layer wet paper towel inserted into a plastic pot containing a small amount of distilled water. Seeds were grown in dark conditions at 25°C. After six days, the root length of the germinated seeds was recorded and correlated with the drought stress tolerance index. For each of the genotypes, 10 seedlings from three biological replicates were analyzed. 2.9 | Statistical analysis Data were analyzed using IBM SPSS Statistics 21 (IBM Corp., Armonk, NY, USA). All results are given as means ± SE. The significance of the correlations between different parameters was determined by bivariate correlations based on Pearson's correlation (two-tailed).

Source of Information: J Agro Crop Sci. 2018;1–12.

Article Link (Online Journal):

Funding Source:

1.

Budget:

Total Budget (Tk.) :

Achievement/Findings:

In conclusion, the study suggested that the tolerant barley genotypes contain less water in their tissues under control conditions and are more efficient in conserving water under drought stress. The latter trait is achieved by the more pronounced reduction in stomatal conductance. The stomatal density and residual transpiration of barley genotypes grown under control conditions were not correlated with drought tolerance, suggesting that these two traits are not constitutive but rather inducible. The drought-tolerant genotypes had naturally lower Na+ , K+ and Cl− contents in their tissues compared with their drought-sensitive counterparts and, thus, relied more on organic osmolytes for osmotic adjustment. These osmolytes most likely played a dual role protecting stressed plants against the oxidative stress imposed by the water deficit.

Knowledge Management: Journal