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Sustainable rice production

Feb 28 2017

February 27, 2017 ( by The Daily Star )


Bangladesh has more than tripled the production of rice in the space of 45 odd years. PHOTO: Anurup Kanti Das

Last time the world witnessed a phenomenal growth in agricultural productivity was back in the 60s. What American biologist Norman Borlaug initiated in Mexican wheat fields during the mid-20th century, the first breeder of then newly established International Rice Research Institute (IRRI), Dr Peter Jennings, did the same for rice. Together, these two men brought a phenomenal change in rice and wheat production thereby ushering in a Green Revolution, long being credited for averting a billion deaths.

Dwarfing of wheat and rice plants, thereby turning the world's two of the most consumed staples highly yielding, was a game changer. It saw Mexico becoming a net wheat exporter by 1963, India and Pakistan literally doubling their wheat baskets between 1965 and 1970, Borlaug winning a deserving Nobel in peace in 1970 and nations across Asia, Africa, Latin America and elsewhere benefiting from semi-dwarf 'Miracle Rice' IR8.

IRRI's hand in helping the rice-eating world through breeding better varieties of rice began shortly after the Ford and Rockefeller Foundations established the Institute with the help of the Philippine government in 1960. IRRI scientists sought to replicate in rice what had been done in wheat in Mexico, and successfully bred IR8—a semi-dwarf variety that journalists dubbed 'Miracle Rice' because it could produce twice the amount of rice grains that tall varieties produced. IR8 has been credited with averting a humanitarian crisis that would have otherwise plunged the world's poor into abject hunger. Since then, more than 900 IRRI varieties have been released in 78 countries, across five continents. Some of these were bred to be resistant to insects or diseases, and they can withstand poor soils.

In November 2016, IRRI celebrated the 50th anniversary of the official release of the semi-dwarf rice variety IR8 to Asia and the world. It became popular with farmers because it had short growth duration and a high-yield capacity related to its response to nitrogen fertiliser.

Since that time (the mid-20th century) the world has seen its population grow from 2.5 billion (1950) to 7.4 billion (2016) and its per capita arable land nearly halve from 0.37 hectares (1961) to 0.197 (2013).

Half of today's world population depends on rice for survival, and, owing to predicted population increases and a general trend towards urbanisation, per hectare of land that currently provides enough rice to feed 27 people will need to support 43 by 2050.

In December 2021, Bangladesh will celebrate 50 years of independence. Keeping that timeframe in consideration, Bangladesh's Vision 2021 rightly set goals: a) to become a participatory democracy; b) to have an efficient, accountable, transparent and decentralised system of governance; c) to become a poverty-free middle-income country; d) to have a nation of healthy citizens; to develop a skilled and creative human resource; e) to become a globally integrated regional economic and commercial hub; and f) to be environmentally sustainable; and to be a more inclusive and equitable society.

In 1971, we had a population of 75 million and our food production was a little over 10 million metric tonnes. Thanks to adoption of modern farm technologies, policy support, better breeds and inputs and above all a hard working farming community, today we grow over 35 million metric tonnes of cereal crops.

So it's true that since the Borlaug and Jennings days, the world's food production grew dramatically keeping pace with an alarmingly faster rate of population growth. To cite a country-specific example, we can easily refer to the Bangladesh scenario. Over the past four decades, Bangladesh succeeded outpacing the population growth rate with its growth in rice output. The country has more than tripled the production of its staple in the space of 45 odd years.

But questions arise whether we have reached a plateau - where any further growth in farm outputs would be too hard to achieve. We have a large population base and despite a falling population growth rate, it'll take a few more years before we get stabilised by the time farmlands continue to get scarcer thanks to rapid urbanisation, industrialisation and infrastructure developments.

Achieving self-sufficiency in rice at this point of time is no way perpetual. History shows we have reached such points in a few occasions in the past when output matched the demands but again we did slip back - not because of any production decrease rather, because of population increase.
More importantly, attaining autarky in rice, the staple, is not enough to proclaim ourselves food self-sufficient. We need a reality check here. After rice, maize emerges as the second most important cereal crop relegating wheat into third position in Bangladesh. We're still not able to meet the total domestic requirements of maize thanks to a huge feed demand triggered by a burgeoning fish and poultry industry. And over 75 percent of our annual wheat demands are met by imports.

Currently, more than 790 million people in the world do not have enough to eat, and over 280 million, in other words, nearly a third of food-starved people, live in our part of the world (South Asia). Producing enough food does not necessarily guarantee people's right to food. To make sure people have rightful access to food all the time, ensuring its availability, stability, accessibility, sustainability and adequacy is equally important.

Standing at this crossroads, we need to revisit the whole range of farming issues - how sustainable the heavily input-driven production system is, how prudent it is to overexploit our fast depleting groundwater table and what would be our coping mechanisms to face impacts of climate change in the farm sector.

Prior to Green Revolution we had rain-fed rice like Aman and Aus but thanks to introduction or irrigated dry season rice Boro during the winter there has been phenomenal growth in the staple output. But for that to happen we started sinking millions of shallow and deep-set pumps to draw water from underground and irrigate the Boro rice. At the same time we started using chemical fertilizers and pesticides. We had also advanced in farm mechanisation thereby dwindling the numbers of our draft animals, which were also a big source of dung, the natural manure.

Climate-induced stresses are becoming all the more challenging. Extreme weather conditions like prolonged flood, shorter winter, drought and salinity pose huge challenges. Too much mining of groundwater in the north (greater Rajshahi, Rangpur-Dinajpur region) for irrigating rice lands creates vacuums underneath, giving more inroads for the southern saline water to seep in. To some count a tenth of our cultivable lands are saline-prone to varied levels.

To address these challenges scientists have taken up an uphill task of developing various crop varieties that can withheld stress conditions and are genetically better bred giving extra vigour and higher productivity.

Growing rice with less water

It takes 14 million litres of irrigation water to produce six tonnes of Boro rice on one hectare of typical farmland in Bangladesh. A farmer has to burn 250 litres of diesel to run a shallow pump, owned or hired, to irrigate this single hectare of paddy field. If translated into minuscule unit, each kilogram of rice reaches our plates from the farm at the expense of 3,500 litres of immensely valuable fresh water.

One Bangladeshi agronomist took it upon himself to see what difference he could make in terms of water conservation and save the country from an ecological disaster. Irrigated-rice Boro contributes 55 percent of Bangladesh's nearly 35 million tonnes of yearly rice output and heavily sucks on a rapidly depleting groundwater.

Professor Moshiur Rahman, who teaches agronomy at Bangladesh Agricultural University (BAU) in Mymensingh, negated the notion that rice in dry season has to grow in puddle condition, soaked field and in standing water. Rahman wanted to challenge the notion and began with an on-campus experiment back in 2006-07. In the last 10 years, Rahman reached out to plots of many farmers in six rice-rich districts, and reached a conclusion—rice can be grown using less than half the irrigation water in Boro season.

Rahman and his team conserved water by not growing seedlings in the nursery. They, rather, directly sowed in the dry field by plowing furrows and did not puddle or soak the field with water, thereby saving some water as well. They didn't keep standing water in the paddy field during the period between panicle initiation and grain-filling. In the direct-seeded Boro rice technology, Professor Rahman said, what farmers are required to do is keep the seeds soaked in water for 24 hours and then incubate the soaked seeds for another 30 to 40 hours prior to sowing in the paddy field. From the results of his experiments with the direct-seeded rice technology in Rajshahi, Rangpur, Dinajpur, Tangail, Netrokona and Mymensingh over the last 10 years, Rahman showed statistical evidence that in the most conservative estimate, 50 percent less water was required for growing rice with equally productive yield.

If further tweaking makes the water-conserving rice production system work fine, then it will definitely be a great relief for rice-rich northern region of Bangladesh that has long over-exploited groundwater in irrigation. Around 88 percent of total fresh water is used for agriculture in the country and rice production accounts for 73 percent of that water. The UN Food and Agriculture Organization (FAO) stated in a report, “In some parts of the country, particularly the Barind Tracts in the northwest region, there are already symptoms of deterioration in the natural hydrological regime. Declining groundwater levels have affected water quality causing it to affect soils, the growth of agricultural crops, flora and fauna and to increase health hazards.”

Rice going southbound

It couldn't have been better timed for rice breeders in Bangladesh to come up with more solutions for southern farmers when the government is all out in its efforts to make rice southbound giving relief to the north that has long been over mined for groundwater to irrigate winter rice Boro. Scientists have come up with a solution for southern farmers who have long been deprived of the benefits of high-yield modern rice varieties (MVs) that cannot grow on tidal wetlands. After 12 years of arduous breeding process, they succeeded in developing two modern varieties suitable for cultivation in the tidal floodplain ecosystem of the southern delta region, with the promise of an additional yield of one million tonnes a year.

Against 2.5 to 3 tonnes of rice per hectare, which farmers reap from traditional varieties, the new modern varieties - BRRI dhan77 and BRRI dhan78 - will bring about 4 tonnes of crops a hectare during the Aman season in July-December, according to Helal Uddin Ahmed, a chief scientific officer at Bangladesh Rice Research Institute (BRRI). While farmers elsewhere have already switched to MVs from low-yield traditional varieties, rice growers in over a million hectares of tidal wetlands have had to remain satisfied with homegrown varieties.

For so long indigenous varieties have performed better than modern varieties on tidal floodplains because seedlings of the former are taller than the latter. As the region is at the proximity of the sea and inland estuaries, shorter seedlings often fail to survive the water flowing in and out with high tide and low tide twice a day.

BRRI dhan77 and BRRI dhan78 are bred in a way in which their seedlings would be tall in size and survive the tidal wetland condition. The newly developed breeding lines will meet southern farmers' aspiration for higher yields in the Aman season.

Nationwide modern varieties coverage in rice cultivation has increased from 25 percent in 1972 to over 80 percent now, but their penetration in the tidal regions of Barisal, Patuakhali, Jhalakathi, Pirojpur, Bhola, Bagerhat and Gopalganj has remained at 15 percent for all these years. The new MVs come as a breakthrough offering the southern farmers a good choice to shift from low-yield homegrown varieties like Sadamota, Lalmota, Moulata, and Dudhkalom.

Meanwhile, as saline water continues to creep in, scientists are also continuing their efforts to develop rice varieties that can withstand a certain degree of salinity. In recent years, Bangladeshi scientists developed four transgenic rice varieties capable of production in high soil salinity, far better than the ones derived through conventional breeding.

A particular pea gene – helicase – was infused into four high yielding rice varieties (HYVs) that helped rice plants have higher salt tolerance and higher yield potential. A team led by Dhaka University's Biochemistry and Molecular Biology Professor Zeba Islam Seraj made it possible after a decade of research. In lab and net house, the transgenic varieties had shown potential to yield up to 50 percent more than the available salt-tolerant HYVs in saline-stressed soil.

In Bangladesh, one million hectares out of a total nine million hectares of cultivable land are salinity affected, and the vulnerability is more profound during the dry season. That's why the scientists chose the dry season Boro rice varieties first for the gene transfusion.

Climate change is a reality and so is the farming sector's resilience to it in Bangladesh. With limited resources at hand and a rapidly increasing population to feed, some 18 million farming households in Bangladesh have shown fortitude against all odds. Farmers never called it quits in their constant fight against natural calamities, shrinkage of farmland, market irregularities, and all sorts of resource limitations.

From Green Revolution to Gene Revolution

Given the fact that world population would continue to increase for many more years to come and farm resources - land, water, etc. - would continue to get scarcer, the global food regime would definitely require a big push to the scale of mid-20th century.

Green Revolution was to some extent chemical-driven - the increased productivity was gained largely by use of chemical fertilisers and pesticides. While it was widely recognised that Green Revolution came as a blessing for mankind when fear of famine was haunting a large part of developing economies, there is no denial that injudicious applications of chemicals had long-term bearings on environment and ecology.

Currently, a lot of the efforts of scientists are centred on biological maneuvering so that better breeds can be derived which are more productive and less susceptive to stresses like cold, drought, submergence, salinity, etc.

What scientists and journalists sometimes tout as Gene Revolution has to come through scientific advancement, better understanding of genetic structures and functioning of different plant species and sub-species. In recent months, genomes of 186 Bangladeshi rice varieties have been sequenced in Beijing Genomics Institute, China as part of a global collaborative project, opening up new opportunities for varietal developments. These include rice germplasms, high yielding varieties (HYVs) and advanced lines. Germplasm is the living genetic resources such as seeds or tissue that is maintained for the purpose of animal and plant breeding, preservation and other research uses.

C4 - The next big thing

An IRRI literature reads, “Only 29 percent of the earth's surface is land and only a little over a third of that is suitable for agriculture; the rest is ice, desert, forest or mountain and is unsuitable for farming. More simply stated, only 10 percent of the surface of the earth has topographical and climatic conditions suitable for producing the food requirements of human beings.” It further reads, “Sixty percent of the world's population lives in Asia, where each hectare of land used for rice production currently provides food for 27 people, but by 2050 that land will have to support at least 43 people. Nonetheless, the area for rice cultivation is continually being reduced by expansion of cities and industries, to say nothing of soil degradation.”

For the past few year scientists have embarked upon an uphill task of changing the biophysical structure of the rice plant, making it a much more efficient user of solar energy. Solar energy captured in photosynthesis over the duration of a crop gives it the capacity to grow. Rice has what is known as a C3 photosynthetic pathway, less efficient than that of maize, which has a C4 pathway.

A galaxy of scientists drawn from IRRI to Oxford University, from Chinese Academy of Sciences to Cambridge University, is now working on an ambitious project so that rice can be converted into a C4 plant from a C3 plant. An Oxford University release said, “If rice could be 'switched' to use C4 photosynthesis, it would theoretically increase productivity by 50 percent.” As well as an increase in photosynthetic efficiency, introduction of C4 traits into rice is predicted to improve nitrogen use efficiency, double water use efficiency, and increase tolerance to high temperatures, according to Oxford University, as the C4 rice project entered, what the scientists say into third phase in December 2015.

The writer is Assignment Editor, The Daily Star