Crop wild relatives to combat global warming
by K P Prabhakaran Nair on 05 Dec 2018 6 Comments

In the recently launched book, “Brief Answers to the Big Questions”, by that immortal theoretical physicist, late Lucasian Professor at Cambridge, Stephen Hawking, there is a chapter titled, “Will we survive on earth?” In January 2018, a journal founded by some physicists who had worked on the Manhattan Project to produce the world’s first hydrogen bomb, the Bulletin of Atomic Scientists, moved the Doomsday Clock, measuring the imminence of the catastrophe – both military and environmental – facing our planet, forward to two minutes to midnight. 


Interestingly, the clock was started in 1947, when the atomic age had just begun. Late Robert Oppenheimer (a German-born but domiciled American like Albert Einstein, both of whom fled Nazi Germany), Chief Scientist of the Manhattan Project, had lamented the explosion, and prophesied in 1945, when it took place, bringing the Second World War to a close, “We knew the world would not be the same. A few people laughed, a few people cried, most people were silent. I remembered the line from the Hindu scripture, the Bhagavad Gita, “Now, I am become Death, the destroyer of worlds”.


In 1947, the clock was originally set at seven minutes to midnight. It is now closer to Doomsday than at any time since then, except in the early fifties, when the Cold War between Americans and the Russians was at its peak. The clock and its movements are, of course, symbolic, but, going by what one critically observes in the world today, one has no option but to be alarmist. In retrospect, Oppenheimer had greatly lamented his involvement in the Manhattan Project, leading to the decimation of Hiroshima and Nagasaki, bringing the Japanese to their knees. It was a war won, but at what cost to humanity? Even after seven decades, the innocent Japanese still suffer the consequences – deformities both physical and mental. 


In the book, Prof Hawking puts the important question as to which is the greatest threat to the future of the planet, hence life on earth. He cites two, an asteroid collision, against which humanity has no defence, but had occurred about 66 million years ago, killing the dinosaurs, and unlikely to recur. According to him, a more immediate danger is the runaway climate change. A rise in ocean temperature would melt the ice caps and cause the release of large amounts of carbon dioxide. Both effects could make our climate like that of Venus, but, with a temperature of 250 degrees Celsius, enough to burn life on planet earth in just seconds. This piece is about the latter threat and whether humankind has a real possibility to mitigate the threat. Of most crucial consideration is the production of food for the survival of mankind.     


The plant species closely related to field crops, including their progenitors, which have the potential to contribute beneficial traits for crop improvement, such as resistance to an array of biotic and abiotic stresses, and to enrich the gene pool, leading ultimately to enhanced plant yield, thereby aiding humanity’s relentless search for production of more food to meet the ever growing needs of a burgeoning world population, are called “Crop Wild Relatives” (CWR).


CWR are known to have tremendous potential to sustain and enhance global food security, thereby contributing enormously to humanity’s well-being. Therefore, their search, characterisation and conservation in crop breeding programs assume great importance. Viewed against the recent upheavals in global climate change, the task becomes all the more important. Against the background of the disastrous after effects, especially the alarming environmental hazards of the highly soil extractive farming, euphemistically known as the “green revolution” of the 1960s, the task assumes much cruciality.


Global warming is a real threat to humanity vis-a-vis crop production. The International Panel on Climate Change (2014) had predicted dramatic changes in climate pattern in the current century, and this will inevitably affect crop production. If one juxtaposes the population increase with ambient temperature increase, a grim scenario emerges. Current projections suggest that world temperature will rise by 1.8 degree Celsius to 4 degree Celsius and the corresponding world population might touch 10 billion by 2100 – an increase of 142.9 percent from the current level at plus-minus 7 billion, which works out to about an annual increase of 1.8 per cent.


There are two kinds of “greenhouse effect” - the “natural”, which makes ambient temperature of some regions at high altitude and latitude hospitable to life forms, and the more common, extremely environmentally hazardous, occurring in the atmosphere due to emission of industrial gases, such as carbon di oxide, and those from agricultural practices like excessive use of nitrogen fertilizers, leading to huge concentration of nitrous oxide in the atmosphere, is  lethal to both human habitation and plant life.


Automobile emission is an important one contributing hugely to carbon di oxide (CO2) concentration in the atmosphere, which has changed from the pre-industrial value of 20 ppm (parts per million) to 400 ppm, a 2000 per cent increase. This is a phenomenal increase. But more worrying is the production of nitrous oxide (N2O), commonly known as “laughing gas” (dinitrogen monoxide), a major scavenger of stratospheric ozone leading to global warming.


Nitrous oxide is ranked third behind carbon di oxide and methane (CH4) in its effect on global warming as a “Greenhouse Gas”. It is 310 times more effective in trapping heat compared to CO2. Average lifetime of N2O is 120 years. 30% of N2O in the atmosphere is due to agricultural practices, primarily due to application of excessive nitrogen carrying fertilizers like urea. A steep ramp-up in N2O in the atmosphere coincided with the green revolution of the 1960s. When higher food production is targeted through excessive use of nitrogen fertilizer, like urea, soil microbes convert N in the fertilizer urea to N2O at a faster rate than normal. This has been a major factor leading to global warming with all its attendant environmental fallouts like low precipitation, soil degradation, ground water depletion etc. Punjab, “cradle” of the green revolution, where thousands of acres of cultivable soil have been ruined is a living example of this environmental disaster.  


The growing concern over the potentially devastating impacts of climate change on biodiversity and food security, juxtaposed with the burgeoning global population, implies that immediate measures have to be taken to preserve the CWRs and derive from them potentially usable genes to enhance crop yield. CWRs are a key tool to address the limits of genetic variation in domestic crops to adapt them to climate change. However, extension of their conservation and promotion of more systematic exploitation are hindered by lack of understanding of their current and potential value, their diversity, and, practically how they might be conserved.


There is no scope to discuss the modalities of utilising CWRs, in entirety, in this piece, as it is a very vast subject. But a passing remark on two vital aspects connected to CWRs vis-à-vis the current status of Indian agriculture will help the reader understand the importance and gravity of the situation. The entire green revolution in the Asian subcontinent, in particular India, rests on three pillars – an array of the “dwarf” “miracle” varieties of wheat and rice, inherently with alien blood, copious (I would say unbridled) use of chemical fertilisers, primarily nitrogenous, like urea, and liberal use of irrigation water. Many of these dwarf miracle varieties are now found to be non-resistant to both biotic and abiotic stresses. This has been the reason for a shift of emphasis from green revolution to “gene revolution”.  


India had its first genetically modified cotton (Bt cotton) available for commercial cultivation in 2002, which was developed primarily to contain the attack of American Pink Bollworm. This author had clearly predicted then that the Bt cotton would fail in India, as the pests would get smarter than the plant. And fail it did. Thousands of acres of cotton in the cotton belt, the Vidarbha region, miserably failed succumbing to newer pests like sucking insects and aphids. The same is true of Punjab and Rajasthan. And, the number of cotton farmers who were rendered penniless, and sadly took their own lives to escape bankruptcy, especially in Vidarbha, is countless.


The economic value of CWR genetic contribution at current value is US$ 68 billion, and the potential value is close to 200 billion (PriceWaterHouseCooper, 2013). The entire spectrum of food, fibre, sugar, fruit, root and vegetables crops have their CWRs, and widely distributed in the country, be it the forests, hills or mountains. Locating them, growing them in situ or ex situ for introgression into currently domesticated cultivars to overcome biotic or abiotic stresses like global warming is a challenge Indian agricultural scientists need to girdle up for. Are they up to this challenge to save India, or content doing inconsequential “research” is a million dollar question.


Excerpted from the invitational chapter, titled “Crop Wild Relatives to Combat Global Warming”, just published and online in ADVANCES IN AGRONOMY, the magnum opus of agricultural science and an invitational lecture to the American Crop and Soil Science Societies. The author was formerly Professor, National Science Foundation, The Royal Society, Belgium and currently Senior Fellow, Alexander von Humboldt Foundation, The Federal Republic of Germany; he can be contacted at

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