Help us to improve the salinity tolerance of rice

Salinization of arable land is a huge challenge in many areas of the world. Saline soils can occur naturally due to geochemical processes such as mineral weathering, atmospheric deposition, and the origin of soils from marine sediments. However, salinization may also result from human activities such as land clearing and poor agricultural practices. Salinization and the resulting land degradation threatens global food production and as a result, up to 1.5 million ha are lost annually.

Plants generally respond to salinity stress in two phases: (1) a rapid and short osmotic phase and (2) a slower ionic phase where the ions accumulate in the shoot to toxic levels. The first phase is the result of osmotic effects that start immediately after the salt concentration in the root zone reaches a threshold level. The salt lowers the water potential in the soil so that the water, which is still present in the soil, becomes less accessible to the plant. The reduced water uptake results in stomatal closure and therefore also reduced photosynthesis with subsequent impact on growth. The second phase develops over time and is a result of salt entering the transpiration stream of the plant; however, only water escapes from the open stomata so that the ions accumulate in the shoot. Sodium and chloride can accumulate to toxic concentrations resulting in premature senescence, reduced growth and ultimate death of the plant.

If you choose to conduct your BSc or MSc thesis with ur, you will be part of the large Danida-funded research project. We aim at developing new rice cultivars to help African farmers meet the challenging future where flooding and salination of productive rice paddies will undermine their livelihood. See more on

Some varieties of rice possess higher tolerance to soil salinity than others. The sensitive varieties are wilting even if they grown in stagnant water; however, the salt content of the water make the water itself inaccessible to the plants and then the shoot is wilting after some time of exposure to toxic levels of salt. In contrast, the more tolerant varieties remain green for much longer but in the end they also perish. Photo kindly provided by IRRI.

In our lab, we have the latest technology to study responses to salt stress including an osmometer to measure osmotic potential of solutes and a flame photometer to measure sodium (and potassium). Data from the osmometer can help us understand how the plants attempt to adjust internal solutes so that salt intrusion is restricted. This can be done by producing osmolytes which are large organic molecules that serve to ramp up cell osmolarity so the influx of ions are reduced. Sodium (Na) and potassium (K) analyses are useful as we can follow Na accumulation in the shoot but also loss of K from the roots, which is a common response during the early phases of salinization.

We are currently working on a root trait that seems to reduce radial uptake of salt; help us to unravel the possible benefits of this trait by joining our lab when conducting your BSc or MSc thesis work!

See the list of publications for articles on this exciting topic!

Contact Ole Pedersen for more information.