Research topic

Drought and Salt Stress

As population increases worldwide, the arable land per caput also decreases, while more land is becoming degraded. It is estimated that about 15 % of the total land area of the world has been degraded by soil erosion and physical and chemical degradation, including soil salinization. Drought and salt stresses are important abiotic factors which are the more severe and wide-ranging environmental stresses that significantly affect crop growth and productivity.

A sunflower with symptoms of salt stress. These are identifiable by rolling-up of leaves, chloroses and necrosis. Sunflower leaves are serrated; this characteristic will be less pronounced in case of salt stress, and leaf edges appear smoother. (Photo: IAPN)

A sunflower with symptoms of salt stress. These are identifiable by rolling-up of leaves, chloroses and necrosis. Sunflower leaves are serrated; this characteristic will be less pronounced in case of salt stress, and leaf edges appear smoother. (Photo: IAPN)

Drought stress adversely affects crop growth and productivity. Agricultural drought stress is imposed when the required amount of moisture is not provided by rainfall or irrigation to the plant for its growth and development. Water scarcity, mainly due to the shortage of rain which is often erratic, heavier rainfalls leading to lower storage capacity and improper water resource management practices, will increase drought periods.

 

Salt stress is caused by the accumulation of excessive salts in the soil which eventually results in the inhibition of plant growth (phase I) and leads to plant death (phase II), decreasing agricultural productivity. In phase I, the availability of water for plants decreases due to negative water potential in the rhizosphere inhibiting plant growth. In phase II, the ion toxicity takes place when the exclusion mechanisms and internal compartmentalization processes are overloaded. Salt-affected soils occur in all continents and under almost all climatic conditions. Worldwide, the major factor in the development of saline soils is the lack of precipitation. Most salt-affected soils are found in the arid and semiarid regions compared to the humid regions.

Quinoa (Chenopodium quinoa Willd.) cultivated in an IAPN experiment on the effect of potassium on salt stress resistance. (Photo: IAPN)

Quinoa (Chenopodium quinoa Willd.) cultivated in an IAPN experiment on the effect of potassium on salt stress resistance. (Photo: IAPN)

These abiotic stresses affect plants in multiple ways including nutritional disorders, oxidative stress, reduction of cell division and expansion, alteration of metabolic processes and synthesis of photosynthetic pigments.

 

Due to water scarcity and salinization, new cultivation techniques, the use of alternative potential crops to exploit areas that are not suitable for growing traditional crops, and the development of new strategies of fertilization management, are necessary. At IAPN we are conducting research on the importance of potassium (K+) and magnesium (Mg2+) in abiotic stress. K+ and Mg2+ are cations that can compete with sodium ions (Na+), the latter being in high concentrations in saline soils. Since Na+ interfere with K+ homeostasis, particularly given its involvement in numerous metabolic processes, maintaining a balanced cytosolic Na+/K+ ratio has become a key mechanism for salinity tolerance.

 

 

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