During the summer, I had the chance to work with the International Rice Research Institute (IRRI) offices in Los Banos, Philippines, on genetically breeding rice varieties with low CH4 and nitrous oxide (N2O) emissions. The goal was to contribute in reducing the amount of greenhouse gases (GHG) released into the atmosphere.
Background
Rice production is a major source of GHG emissions. The Intergovernmental Panel on Climate Change (IPCC) estimates that rice production is responsible for about 55% of the total GHG emissions from agricultural soils (Nicholaisen et al., 2021). Because rising temperatures are expected to cause rice fields to emit more GHGs in the future, drastic changes are required to grow rice in a way that minimises environmental damage while improving food security. It is important to breed rice varieties with high yields and low GHG emissions if we want to make more food and have less of an effect on the climate.
Figure 1: Low Carbon Rice in Latin America. (Photo credit: CCAFS Research on Low Emission Development)
Methodology
The study used a randomised complete block design (RCB) experiment, a manual closed chamber approach and gas chromatography for CH4 and N2O gas sample analysis.
Figure 2: Collection of greenhouse gas fluxes, by using a Manually Operated Closed Chamber. (Photo credit: Prachin Buri Rice Research Center)
Through my research, I learned about advanced methods used in plant breeding for managing and analysing plants. It also helped me get in touch with world-famous research institution and scientists who study the genetics of rice.
The United Nations (2019) says that the number of people on earth will reach 9.4 billion by 2050 and an additional 2.7 billion by 2100. So, it is clear that global food production must rise to meet the needs of a growing population, but the question is by how much? Where will it be made in the world? The problem could be solved by breeding plants to make F1 hybrids, which are good for the environment, the economy, and society. But what do these advantages look like? How important are they to achieving the Sustainable Development Goals (SDGs)?
What are hybrid varieties?
Genetics and selective breeding use the term “hybrid” (Khan, 2017). A hybrid plant is the offspring of two parent plants that work well together. Then, the hybrid has the best parts of both parents. But to make good parents, you have to make sure their genes are as similar as possible (homozygous). You can do this by crossing the parents with themselves, which is called selfing or inbreeding.
Social, economic and environmental benefits of hybrid varieties
Breeding hybrid varieties of plants can give them good plant health and high yields, which may help farmers deal with the low grain prices right now. When growing conditions are right, hybrid varieties can help farms make more money because the gains from more crops or lower costs for other inputs can cover the cost of the seed. Breeding for hybrid varieties can also have a big effect on how much farmers get paid. If new varieties can grow crops that meet certain quality standards (such as size and taste), they can give farmers access to new markets.
New plant breeding techniques which emerged as an innovative solution: Image credit Shutterstock
The great thing about hybrid varieties is that they have a positive impact on yield. The way families eat can also be affected by how much their crops produce. Hybrid varieties lead to higher yields, especially when the crop is stressed by the environment, like when there is a drought or temperature shock early in the season or when there is heat and drought during grain fill later in the season (Lu et al., 2020). Also, the roots of hybrid varieties are deeper and stronger, which helps them get water and nutrients very quickly. In this way, they make it easier to use less water and nutrients.
Plant breeding of hybrid varieties may help reduce the expansion of agricultural land by helping farmers get higher yields. This could reduce land use change (LUC) and the greenhouse gas (GHG) emissions that come with it, as well as help keep natural biodiversity. This is especially important in places where converting carbon-rich and biologically diverse landscapes to farmland is part of the process of making more land for farming.
Performance of hybrid rice F1 plant population at milling stage. Image credit: Delin Hong.
Lastly, the COVID-19 pandemic showed how fragile the world’s food system is and how important it is to change it to make it more environmentally and economically resilient. Cereal crops like rice, wheat, and maize can help a lot if they are better bred. Also, any food security plan that wants to attain Sustainable Development Goal 2 (zero hunger) must include larger system-wide changes, like zero-emissions agriculture.
Sources
Khan, N. U. (2017). F1 hybrid. Reference Module in Life Sciences. doi:10.1016/b978-0-12-809633-8.06413-x
Lu, J., Wang, D., Liu, K. et al. (2020). Inbred varieties outperformed hybrid rice varieties under dense planting with reducing nitrogen. Sci Rep10, 8769. https://doi.org/10.1038/s41598-020-65574-0
United Nations (2019). World population prospects: The 2019 revision. Department of Economic and Social Affairs, Population Division, United Nations. Online Edition. Rev. 1. Available from https://population.un.org/wpp/Download/Standard/Population/.
Greenhouse Gas (GHGs) emissions have been going up around the world, even though there have been a lot of multilateral institutions and national policies aimed at reducing them. The World Resources Institute (WRI) says that emissions reached almost 50 gigatonnes of CO2 equivalents per year (GtCO2eq/yr) on a global scale (WRI 2021). Eighteen percent of these GHG emissions are caused by agriculture. At the United Nations Climate Summit, people talked about estimates that put this number closer to 50%.
The status of meeting the goals of the Paris Agreement on Climate Change
The world is a long way from meeting the GHG emissions goal set in the 2016 Paris Agreement on Climate Change. This goal is to keep the global temperature rise between 1.5 and 2ºC. For this to happen, efforts to cut emissions would have to be much bigger. By 2030, emissions would have to be anywhere from 25% to 50% lower than what is promised in the current Nationally Determined Contributions (NDCs).
Agriculture Emissions
Most of the time, GHGs emissions from farming are different from other industries. Most of them come from the production of nitrous oxide (N2O) and methane (CH4). Both of these GHGs are made by biological processes (Molla 2014). Nitrous oxide comes from manure, and methane comes from ruminant livestock, mostly cattle, and sheep. Even though the use of energy in agriculture is important, it only accounts for less than 1.5% of all GHGs emissions.
The main on-farm agricultural greenhouse gas emission sources, removals, and processes in managed ecosystems (Source: IPCC 2006).
The way to cut down on emissions from agriculture
Meeting a goal for lowering CH4 emissions is, only a small part of what needs to be done to lower overall emissions and slow down global warming (UNEP 2021). Especially for agriculture, we need to cut back on N2O, which is an even stronger GHG. When choosing between the possible ways to cut down on CH4, it would be smart to also think about how they would affect other GHGs emissions and environmental issues. For instant, if the number of livestock was cut, there would be less animal manure, which could lead to a rise in the use of artificial fertilisers, which emit other GHGs.
An integrated cropping-livestock system for emission reduction (Infographic: R. Kenn/IAEA)
Also, small-scale farming and decentralised food systems are a way to cut down on emissions from agriculture. Small farmers’ emissions are more localised, so they don’t add much to the overall emissions from agriculture. This is because they use less chemical fertiliser, which is a major source of emissions, and sell more of their crops locally. Cover crops, low tillage, and organic fertiliser are all ways to cut down on carbon in the air without adding a lot more.
Conclusion
As COP26 agreed, cutting down on CH4 would help in the short term. Even if CH4 is cut in other areas, the policies and practises of agriculture need to change quickly and in a big way for the overall reduction to be around 25%.
