Silicon Phyto-Nutrition For Climate Smart Agriculture

The world population is continuously increasing and converting forests and fertile lands in to shelter. Humans directly or indirectly are responsible for climate change e.g. afforestation, burning of crop residues, electrical appliances, flooded rice, and automobiles etc.

By Muhammad Azhar

Climate change and its consequences on crops

Environmental stresses mainly; temperature, water, and salt stress, are the consequences of climate change compromising natural systems, human health, and agriculture production worldwide¹. The progressively increasing intensities of these stresses are responsible to restrict crops to achieve their potential yields². Temperature fluctuations adversely affect crop yield viz. heat stress reduces grain yield whereas cold stress results in sterility. The average temperature of the earth is expected to increase from 2 to 4.5 °C by 21^st century³. During the last century, the annual temperature in the wheat, rice, maize, and soybean growing areas has increased by approximately 1 °C and will continue to increase in the next century with continuous greenhouse gas emissions⁴.

Water stress in cereals badly affects flower initiation and inflorescence⁵. Rice suffers disturbances in fertilization and anthesis processes under drought stress⁶. Drought stress also decreases the harvest index by 60% and reduces grain set⁷. Wheat yield is observed to be reduced from 1-30% under mild drought stress while the reduction increased to 92% where stress prolonged⁷.  Mash bean and soybean yield was also found to be decreased by drought stress^8,9. Soil salinity impairs plant growth and productivity because of water stress, cytotoxicity, and nutritional imbalance. In addition, salinity generates reactive oxygen species (ROS) which produce oxidative damage in plants^10,11. In Pakistan, pollination and grain filling of maize and rice crops was badly affected from last two years due to temperature fluctuations at reproductive stage. The shift in temperature and rainfall patterns due to climate change also deteriorates the cotton crop productivity and quality.  

Maize and rice pollination is negatively affected by high temperature (climate change) at reproductive stage

Silicon Phyto-nutrition

The detrimental consequences of above-mentioned environmental stresses, i.e. temperature, water, and salt stress, can be mitigated using silicon (Si). Si, previously considered as a non-essential but beneficial element, is the second largest element, in terms of abundance, found in Earth’s crust. However, smaller fraction of earth’s Si is phyto-available while most is locked up in silicate minerals not available for plants. The phyto-availability of Si is dependent on pH and redox reactions. Recently, it has been termed as “quasi-essential” element by International Plant Nutrition Institute. It is up-taken by plants in the form of soluble silicic acid [Si(OH₄)]¹². Si helps to tolerate abiotic stress conditions through enhanced plant growth dynamics and molecular physiology by the regulation of antioxidant defense system and hormone signaling under heat stress¹³. It is effective to alleviate salinity stress by regulating root development changes, redox equilibrium, photosynthesis and nutrient dynamics¹⁴. In terms of drought stress tolerance, Si strengthens plant biochemical attributes and facilitates to absorb nutrients for plant growth enhancement¹⁵.

Conclusion and recommendations

Silicon (Si) can be attributed as an element which has a broader advantageous impact on plants to mitigate environmental stresses. Owing to its beneficial role in multiple stress tolerance, it can be considered as a regular element particularly for cereals and monocots. Application of Si can be included in plant nutrition plan especially in the areas affected by environmental stresses because Si boosts plant tolerance against stresses. Along with climate resilient varieties, smartly manage water and nutrition (balanced nutrition) and add beneficial nutrients like Si to increase yield and quality of produce under changing climate.  

Effect of Si nutrition on abiotic stresses (Image taken from Malhotra and Kapoor 2019; Doi; http://doi.org/10.1007/978-3-030-06118-0_14)

References

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Author : Muhammad Azhar, Assistant Research Officer, Engro Fertilizers Ltd. Pakistan