Climate-Smart Agriculture Solutions in Rice

Rice production is a critical aspect of global food security as it is facing challenges due to climate change, which is impacting rice production in various regions of the world. In this article, you will read about rice, climate-smart agriculture solutions and the way forward.

In the Figure below, you can see how Global Rice Production was distributed in 2020. As you can see, rice is produced mainly in Asian countries, South Asian or South East Asian countries, and many other countries in Latin America, Central America, and South America, and African regions. However, countries in South East Asia, and South Asia produce more than 50 million tons. India alone produces more than 100 million tonnes of rice annually.

If you look at the climate change issues, there are many extreme climatic conditions such as drought, floods, extreme temperatures, and rising sea levels affecting rice production. Drought is one of the major issues as rice requires about 80% of the total freshwater resources in Asia. As per the latest report of the International Panel on Climate Change (IPCC), the global mean temperature is likely to increase by about 1-6 degrees Celsius compared to the pre-industrial era by the end of this century.

Source: UN Food and Agriculture Organization (FAO)

What are the trends in rice consumption among selected Asian countries?

In this histogram below it is clear that consumption of rice in terms of kilograms per person per year will be increased substantially in Bangladesh, India, Indonesia, Philippines, Vietnam, and Bangladesh by 2030, as compared to the levels of consumption in 1975-1977.

(Data source: OECD-FAO, 2021)

Climatic factors affecting rice production

• Drought affects 23 million hectares of rainfed rice in South and Southeast Asia and large areas in Africa where 70-80% of rice lands are rainfed.
• Floods cause farmers in Bangladesh and India to lose up to 4 million tons of rice annually.
• Saltwater encroachment due to rising sea levels and lower rainfall threatens rice crops in the coastal farming area. In Bangladesh, salinity affects about one million hectares of arable land.
• Climate change or extreme climate conditions are really important to tackle when we talk about global rice production, particularly in the countries that produce most of the rice.
• It is interesting to note that the lowland rice produces substantial greenhouse gas emissions as compared to sugarcane, potato, or other rainfed crops.

Three-pillar Strategy for Climate Smart Agriculture

As per the World Bank, we know that climate-smart agriculture requires building a food system that meets increasing demand while remaining sustainable and more profitable to the farmers in the face of climate change.

This requires a three-pillar strategy:

• Increasing productivity more sustainably
• Enhancing the resilience of the farmers or producers and the whole supply chain
• Reducing emissions

So, climate-smart agriculture is sustainably increasing production and adding the resilience of that particular system and minus the emissions.

Among different crops, we must try to reduce emissions from rice fields, which contributes a lot more as compared to other crops.

Climate Smart Agriculture Solutions in rice?

These solutions are based on studies by Indian rice scientists and experiments conducted over by different institutions.

• Site-specific nutrient management. It is very important as it is one of the solutions which a lot of Indian scientists have put forward to improve soil, water, and nutrient management.
• Neem-coated urea. In rice, neem-coated urea has the advantage of slow release of nitrogen from urea as compared to normal urea. Normal urea will release most of the nitrogen in the next 36 to 48 hours after application, whereas neem-coated urea is slowly released and is not immediately converted to gaseous forms. This will result fewer greenhouse gas emissions as a result of that.
• A leaf colour chart is utilized for nitrogen management.
• Microbial formulations for nutrient supplementation could be a part of integrated nutrient management along with urea and other forms of nitrogen.
• Efficient water management. There are specific methods like intermittent versus continuous flooding. Intermittent irrigation gives promising results.
• Conservation agriculture 
• Direct-seeded rice is slowly becoming very popular in India, and Indian breeders are developing improved varieties with inbuilt herbicide-tolerance.

In the Table below, you see some of the proposed solutions, showing how much they will mitigate greenhouse gas emissions through some of the technological interventions.

(Source: Pathak 2015)

For example, intermittent irrigation will reduce greenhouse gas emissions by about 25 to 30%, and direct seeding of rice will again reduce 30 to 50%, which is quite substantial. The system of rice intensification, if you use it, reduces about 25 to 30% of greenhouse gas emissions. Short-duration variety will also help because it saves a lot of water and it also contributes to a reduction of up to 15 to 20% in greenhouse gas emissions. Demand-driven nitrogen use will reduce emissions by around 15%.

All the measures mentioned above keep the yield level almost the same as the conventional practices, as confirmed by experiments in India on rice.

What is the potential of Direct-seeded Rice?

• It has a major impact on saving resources as it can save 25-30% on irrigation water, 40-45% on energy and 25-30% on Labour.
• Time-saving because of early maturity, 8 to 10 days could be saved.
• It can reduce greenhouse gas emissions by 60 to 70%.
• Grain yield will be up to 90-100%.

Further, the intermittent flooding in rice reduced global warming potential (GWP) BY 25-30% over continuous flooding. The short-duration variety, Pusa Basmati 1509 reduced global warming potential (GWP) by 15-20% compared to the long-duration variety, Pusa Basmati 1121.

How to adapt to climate change?

Developing varieties more resilient to heat, drought, flood, salinity, and pest and diseases is required as given below:

Drought

There are 30 drought tolerant varieties released by the Consultative Group for International Agricultural Research (CGIAR) and their partners in several countries. For example, for India, we have the Sahbhagi Dhan variety; for Philippines, we have Sahod Ulan; and for Nepal, it’s the Sukkha Dhan. These varieties produce 0.8 to 1.2 tonnes more yield over drought susceptible cultivars.

Floods

Flood-tolerant varieties such as Swarna-Sub1 in India, Samba Mahsuri-Sub 1 in Bangladesh, IR64-Sub1 in Philippines and Coherang-Sub1 in Indonesia and Nepal, and FARO 66 and 67 in Nigeria are stress-tolerant varieties that the CG centers have developed, which provide advantages of one to three tonnes more yield over the original varieties after complete submergence up to 10 to 18 days.

Salinity

Similarly, International Rice Research Institute (IRRI) and Africa Rice developed twenty salt-tolerant rice varieties. Examples of these varieties include BRRI Dhan 11, 28 and 29 for Bangladesh and many others for India and West Africa.

How to move forward with adaptation to climate change?

1. Develop varieties with increased yield potential and resistance to multiple environmental stresses.
2. Develop varieties with higher input use-efficiency, for example, using less land, less water, less labour, fewer chemical inputs so as to achieve reduction in greenhouse gas emissions.
3. Develop varieties with high nitrogen use efficiency, as low nitrogen use efficiency as is a serious problem in some rice production areas, including China and India.
4. Engineering to curtail dependence on synthetic fertilizers. We can use more of microbial formulations and integrated nutrient management.
5. Engineering carbon dioxide responsive rice to sustain higher productivity under a CO₂ rich, warmer climate.

As rightly pointed out by Matthew Reynolds of CIMMYT: “Climate change has not been sufficiently addressed in the current breeding”.  Hence, there is much more that we can do via conventional breeding for adaptation to climate change.

We have large collections of plant genetic resources around the globe, and we need to enhance their use for targeted breeding efforts particularly keeping in view the climate change scenario.

As you can see in the picture below, apart from conventional breeding, improved agronomy is important. However, biotechnologies including genome editing have recently emerged as new plant breeding technologies for developing crops with high adaptation to climate change.

What are the crop traits associated with climate resilience? Can we bring them together in a single variety?

• Tolerance to drought, heat, and soil salinity through multiple genome editing,
• Enhanced flooding tolerance
• Improved nutrient acquisition and use efficiency
• Increased radiation-use and photosynthesis efficiency
• Improved pests and pathogen resistance because there are new threats emerging with the climate change.
• Symbiotic nitrogen fixation in cereals, oil seeds, and millets.

There are some examples of how genome editing has been used to develop crop varieties with the above-mentioned traits. For example, genome editing in India has been used to silence one drought and salinity tolerance gene (OsDST) in one of the mega varieties of Indian rice (Santosh Kumar, 2020). This resulted not only in enhancing drought and salt tolerance but also in increased water use efficiency by 20 to 25%. However, more research and efforts are needed to combine more stress-tolerant traits in rice or other crops.

Some variants of genome editing technology include base editing and prime editing. By using base editing or prime editing, there is a possibility of not only increasing the input use efficiency per se but also the uptake, transport, and responsiveness of the plants. With less amount of water, nitrogen or phosphorus, there is a possibility of having the same amount of yield in varieties developed through the process of genome editing.

Another example that is gaining momentum through genome editing is Rapid domestication. In the case of tomatoes, it has already been demonstrated with one of the wild species of tomato (Solanum pimpinellifolium), that through multiple genome editing, modification of about five or six genes can be achieved, altering the phenotype or increasing the fruit yield while retaining all the traits related to climate resilience. So, rapid de novo domestication can be applied to convert the wild rice to cultivated rice in possibly two to four years (Molla et al, 2021).

As an example, it has been demonstrated by Yu et al. (2021) that the wild allotetraploid rice, which is adapted to the environment and has many other resilience traits can be converted to cultivated rice. However, we need to bring traits such as grain quality, seed shattering, grain size or even photoperiod sensitivity and others into the wild rice through genome editing. Traditionally this would take thousands of years, and there is a loss of genetic diversity, but if you can put all these genes through genome editing into the wild type of rice, it could be done in two to four or five years and retain genetic diversity. This process is called De novo domestication by genome editing. 

How important is the conservation and use of wild relatives of cultivated plants in India?

Collections of crop wild relatives are important as they have genetic traits that can be used in developing well-adapted crops for use in climate change-affected production systems.

As per the FAO, United Nations, more emphasis is needed to explore and use the natural genetic variation. Farmers will need to protect their own indigenous varieties. They also need to have these improved crop varieties suited to a range of agroecological systems and farming practices.

What are the activities proposed to use plant genetic resources optimally and cope with climate change?

• Genebanks to screen and evaluate all germplasm to enhance the use in breeding for climate change adaptation.
• Ensure that the process of crop improvement and breeding activities are relevant to climate change.
• Strengthen policies to promote the establishment of community-based seed enterprises or community seed banks at strategic locations with information awareness to the farmers.
• Ensuring collections of stress-adapted genetic material that can contribute to adaptation to climate change.

I would like to close this article with a quote by the Nobel Laureate, Jennifer Doudna: “CRISPR- based solutions will allow farmers to adapt to a changing climate and sequester more carbon while preserving prized regional varieties. There is an incredibly important role for CRISPR in the protection of small farmers”.

References

Pathak, H. (2015). Greenhouse gas emission from Indian agriculture: Trends, drivers and mitigation strategies. Proceedings of Indian National Science Academy, 81(5), 1133–1149.

Yu H, Lin T, Meng X, Du H, Zhang J, Liu G, Chen M, Jing Y, Kou L, Li X, Gao Q, Liang Y, Liu X, Fan Z, Liang Y, Cheng Z, Chen M, Tian Z, Wang Y, Chu C, Zuo J, Wan J, Qian Q, Han B, Zuccolo A, Wing RA, Gao C, Liang C, Li J. A route to de novo domestication of wild allotetraploid rice. Cell. 2021 Mar 4;184(5):1156-1170.e14. doi: 10.1016/j.cell.2021.01.013. Epub 2021 Feb 3. PMID: 33539781.

Molla, Kutubuddin, Sretenovic, Simon, Bansal, KC and Qi, Yiping. (2021). Precise plant genome editing using base editors and prime editors. Nature Plants. 7. 1-22. 10.1038/s41477-021-00991-1.

Santosh Kumar VV, Verma RK, Yadav SK, Yadav P, Watts A, Rao MV, Chinnusamy V. CRISPR-Cas9 mediated genome editing of drought and salt tolerance (OsDST) gene in indica mega rice cultivar MTU1010. Physiol Mol Biol Plants. 2020 Jun;26(6):1099-1110. doi: 10.1007/s12298-020-00819-w. Epub 2020 May 10. PMID: 32549675; PMCID: PMC7266915.

K Pradheep, DC Bhandari, KC Bansal, 2014, Wild Relatives of Cultivated Plants in India, ISBN: 9788191038880.