Soil salinity poses a serious threat for agriculture industry steeply decreasing cultivated area every year all over the world. Pakistan is situated in arid to semi-arid climate having high temperature and a low rainfall accumulating salts at the surface and sub-surface soils causing salinization. Salt affected area in Pakistan is more than7 mha and about an area of 4000 ha is increasing every year. Majority of farmers with poor resource and suffering from economic loss due to stagnant yield on salt-affected soils. Farmers are not meeting their basic needs and struggling to and fro the poverty line. On the other hand the linear increase in population is demanding more food to meet their nutritional requirements. The universal solution of food security is to utilize the available resources more efficiently on sustainable basis. The ultimate desire of our country is to remediate the salt-affected soils and get comparable yields from these soils.
Numbers of options are available to remediate salt affected soils including physical, chemical and biological processes. Most of these techniques are time dependent, costly or less eco-friendly which demands to find out some new means to combat with the problem economically in a very short period of time. Silicon (Si) application is one of the best available options to remediate salt affected soils. Exogenous silicon application increases salt tolerance in agricultural crops like wheat, maize, rice sorghum, soybean and barley. Silicon maintains water contents of plant which diluted salts present in plants, thus reducing salt toxicity and improves plant growth. Seed germination is the most important phase during seedling establishment which is adversely affect by salinity as a result of restricted water uptake in the presence of excessive salts. The application of silicon reduces this salinity problem and germination percentage is increased. Silicon application decreases sodium uptake and accumulation by a plant and promotes K+ to Na+ ratio in plants. Silicon regulates the mineral nutrition of plants under salt stress by enhancing the uptake and translocation of mineral elements like K, P, Mg and Ca in plants. Photosynthesis is also increased with silicon fertilization which helps the plants to assimilate more food results and increased the ultimate yields on salt-affected soils. Silicon is second most abundant element constituting about 28 % of the earth crust. Silicon is present in the form of insoluble alumino-silicates in the soil. In spite of plenty of Si reserves in the soils its availability to plant is a concerned question due to low solubility which depends on different soil factors like organic compounds, pH, cations and water contents. This question can be addressed by applying Si exogenously in the form of sodium, calcium, magnesium and potassium silicates. Different raw form of silicon includes wood biochar, cotton stick biochar, rice husk biochar, rice husk ash, fly ash, sugarcane baggas and sugarcane baggas ash.
Hence, it can be concluded from above discussion, exogenous silicon is the best option to overcome salinity stress and increase production of crop plants. The need of the time is to educate farmers to adopt new technologies to enhance crop production. Therefore, as scientists we are focusing on the best method of silicon application i.e. soil or foliar and which critical stage of plants is producing maximum yield with silicon application.
This article is collectively authored by Zia-ur-Rehman1*, Arslan Rauf1, Mehwish Zafar1 and Zahoor Ahmad2 1Institue of Soil and Environmental Sciences, University of Agriculture Faisalabad 2Cholistan Institute of Desert Studies, The Islamia University of Bahawalpur.