Agro-biodiversity as a Resource

Economic and Political Weekly (2019) Vol. 54, No. 28

The ravages of climate change will be particularly harsh in South Asia and India, posing serious challenges to its agriculture and related livelihoods and to its food and nutrition security. Though the high level of uncertainty about its manifestation makes it difficult to deal with climate change, one of the most effective tools to deal with it is agro-biodiversity. It is important to move away from an exclusive focus on techno-fixes and towards time-tested resources like genetic diversity and indigenous knowledge.

Climate change is upon us. The bad news is that there are winners and losers in the climate change game. The worse news is that South Asia, especially India, is likely to bear the worst brunt of climate change on its agriculture. Agriculture production will be affected by factors like higher temperatures, uncertain and reduced water availability, reduced soil fertility, increased incidences of floods and droughts, and different kinds of pests and diseases. Crops, livestock, and fisheries are all going to be affected by these sudden, unpredictable changes.

With respect to agriculture and food production, those who destroyed the environment and laid the foundation of global warming, the “polluters” in other words, will be its greatest beneficiaries. In a perverse reversal of natural justice, the polluter instead of paying, will get paid. There is a threat that the fertile regions like India and others in South Asia, which are currently three crop zones, will get reduced to one crop zones in many parts. Whereas large tracts of Europe which are essentially one crop zones today, will become two or maybe three crop zones. This is patently unjust, but there it is.

According to studies (Parry et al 2004; Parry et al 2007), rising temperatures will result in as much as 10% to 40% reduction in crop production by 2080–2100. Indian studies (Aggarwal and Sinha 1993; Saseendran et al 2000) show that for every 1ºc rise in temperature, wheat production will go down by four to five million tonnes. Additional studies (Aggarwal et al 2000) show that rice yields have been decreasing in the Indo–Gangetic belt, as also in the Philippines (Peng et al 2004). Other crops like mustard, peas, tomato, onion and garlic, all show a decline in yields as temperatures rise. The increased carbon dioxide (CO₂) in the atmosphere due to global warming could result in higher levels of photosynthesis, and hence some yield advantage in certain crops like wheat, rice, and soybean (Long et al 2005). However, this advantage is likely to be nullified by the much higher temperatures that will accompany the CO₂
increase (Aggarwal 2008).

Knowledge of Varied Varieties

So how do we cope with the onslaught of climate change and its impact on food security? The best bet appears to be agro-biodiversity and the indigenous knowledge associated with it. Agro-
biodiversity or the genetic diversity of crop plants becomes a valuable resource only if its properties are known. Fortunately for us, our farming and tribal communities have retained a significant amount of knowledge about the properties of different crop varieties. This knowledge is accessed by scientists when they are looking for varieties with certain traits, for example, drought tolerance, to breed new varieties. The farming community knows which varieties are drought or flood tolerant, which are early or late maturing, which varieties are resistant or vulnerable to specific pests or diseases, etc.

Our genetic diversity is still formidable despite our negligence in allowing it to be destroyed. At one stage, it is estimated, India, which is the birthplace of rice, had close to 3,00,000 varieties of this crop. A diminished number is still being conserved by farming communities in different parts of the country and fortunately, many are conserved in national and international gene banks. Similarly, Mexico, which is the birthplace of maize, has hundreds of varieties of it carrying a range of valuable traits that will help to overcome production challenges thrown up by climate change.

This genetic diversity of any crop is a valuable tool to cope with climate turbulence and the kinds of stresses it brings. China, which is the birthplace of soybean, can use its genetic diversity of soybean to find varieties that will allow it to cope with such stresses or other problematic conditions. Wheat originated in what is modern-day Iraq and Middle East, the region of the Tigris–Euphrates basin. The many varieties of wheat found in these areas will help local farmers to tide over the flood, drought or new pests and diseases, with varieties that are adapted to such situations.

How do we have this genetic wealth, and who has created and maintained it? It is the farming communities of the country that have created and maintained this genetic diversity. Over millennia, farmers have faced adverse situations like disease, pest attacks, high heat and drought, floods and excessive humidity, salinity or acidic soils. Every time they have faced adversity, they have noted that although some
varieties of the crop went under, others survived.

Farmers had the wisdom to save these varieties, knowing that adverse weather conditions would come again. Similarly, they have seeds of varieties that mature early or late or in between, can grow submerged in deep water as the rice varieties of Bihar, or in extremely saline soils as in the Sundarbans. The farmers of Rajasthan have crop diversity suited to extremely high heat and arid conditions of the desert and the farmers of Ladakh have maintained crop varieties that can withstand the biting cold and low moisture conditions of that cold desert area.

It is now known that the traditional farming practice of planting a mixture of varieties (never a monocrop) had a sound scientific basis. Scientific proof that genetic diversity controls crop disease comes from a study done in Yunnan, China. This showed that when rice fields were planted with a mixture of varieties, the incidence of disease decreased significantly. When this was done year for year, the fields became practically disease-free (Zhu et al 2000).

Irrespective of the googly that climate change throws at us, be it high heat, low moisture, unusual cold or untimely pests and disease, it is likely that we will find suitable varieties that are adapted to such conditions. Scientists need to look at this repository of genetic diversity and chances are that they will find varieties to deploy in the altered weather conditions brought about by climate change, and keep agriculture viable in the face of these new stressors.

Changing Pest Profiles

It is not just crop cycles that will go awry with changes in the climate. The fear is also from the new pests and diseases that will affect our crops. Pests and pathogens may come at unexpected times and throw existing crop protection strategies to the wind. Farmers know the pests and diseases that are likely to affect their crops. They also know in which seasons these will possibly manifest, so they have had appropriate coping strategies. Unfortunately, Integrated Pest Management has been given the go-by in official circles, and instead, tonnes of poisonous pesticides get recommended to the farmer. But even these come with a package of practices and a seasonality that is now often not in tune with the changes in pest profile and the timing of the pest/disease attacks. For instance, unseasonal rain and unexpected humidity will suddenly invite pests and diseases like fungal wilt which were hitherto not known in that period.

What is apparent is that the uncertainty and unpredictability associated with climate change make preparedness difficult (Chalam and Khetarpal 2010). This coupled with our scanty knowledge of insect and pathogen behaviour and the wide range of pests present in tropical countries, compounds the problem. Nevertheless, there are some indicators. Studies show that cereals become more susceptible to rust diseases as temperatures increase and an early onset of summer could cause fungal diseases like “late blight” to appear early, thus increasing the potential for more severe epidemics. Warmer temperatures are also helpful to pests improving their survival rates and increasing their geographical range which results in their overall larger numbers (Coakley et al 1999; Khetarpal and Chalam 2008).

Similarly, moisture changes affect the appearance and behaviour of disease-causing pathogens. For instance, higher humidity makes pathogens, such as late blight and root rot in vegetables, extend their damage, and also increases their virulence. On the other hand, powdery mildew species which can attack crops as diverse as grapes, cucumbers, mango, and wheat are not so aggressive at lower moisture levels. Increased concentrations of CO_2, similar to temperature and humidity, also create unpredictable impacts on pest and pathogen performance. Higher CO₂ levels combined with higher photosynthesis can cause physiological changes in the host plant that can increase resistance to pests, but other impacts could include faster evolution in the insect pests which helps them to overcome the host’s resistance.

The evolution of new pests and pathogens, changes in pest–pathogen virulence, and altered timings of pest and disease attacks are all features of pest and disease behaviour under changed climatic conditions. It has become imperative to have early warning systems in place that can detect pest and disease changes in time to enable preventive or control actions. In addition, we will have to reintroduce Integrated Pest Management as a dominant pest control strategy. India’s wealth of indigenous knowledge about pest and disease control should be revived. The strategy to use friendly insects should be restored because they attack disease-causing organisms without causing environmental harm.

Animal Husbandry

Apart from crops, an integral part of Indian agriculture is animal husbandry. This is of special relevance to small farmers and landless agriculture labourers who depend on animal outputs for their income. Although small ruminants like sheep and goats are popular, it is largely cattle and buffaloes that bring assured incomes, because of the milk chains that have been set up to collect milk practically from the farmer’s doorstep. Dairying gives landless agriculture labour 2.5 times more returns than crop-based agriculture.

India is the world’s largest producer of milk. The milk revolution is based on high-performance cattle like the crossbreds of Holstein-Friesian and Jersey. Although they are good milk yielders, such cattle are also extremely sensitive to high heat and water stress and are thus very vulnerable to climate change. Climate change reduces the performance of hybrid cattle significantly due to a number of reasons. These are raised body temperature and increased panting, lowered feed intake and lower metabolic efficiency which results in lower nutrient utilisation by the animal. This, in turn, reduces milk yield and milk quality. Milk yield in such cattle can go down by as much as 40%. Drinking water demand, already high, rises when it is hot, and is not always easy to meet in dryland areas. 

The answer to coping with climate change and maintaining dairying incomes also comes from animal genetic diversity. India has a number of indigenous cattle and buffalo breeds adapted to the hot, dusty conditions of scrub and dryland agriculture. Such animals have a low water requirement, have good tolerance to high temperatures and are resistant to many diseases. Compared to the sensitive hence vulnerable cross-bred cattle, indigenous breeds are hardy and far better equipped to withstand the ravages brought about by a changing climate. Our strategy to maintain milk output should be to deploy locally adapted cattle and buffalo breeds and protect and enhance their performance. Careful genetic selection to pick out high performers in the native breeds, as well as breed improvement programmes should be undertaken without losing any genetic diversity (Garg 2010).

The Sahiwal cows of Punjab and the Murrah buffalo of Punjab and Haryana, the Gir, Kankrej cattle as well as Jafarabadi and Surti buffalo from Gujarat, as also the Tharparkar and Rathi cows of Rajasthan will continue to yield well in dry areas. Similarly, the Red Kanthar and Deoni cattle breeds of Maharashtra and the Pandharpuri buffalo can be adapted in dairy units with similar climates. There are several other breeds classified as “nondescript” that have valuable genetic properties and strong adaptive features which make them important milch cattle in a period of climate turbulence. Some indigenous cattle breeds like the Gir, Sindhi, Tharparkar, and Sahiwal are reasonably high-yielding but many well-adapted native breeds are low milk yielders. Scientific research is being used to improve milk output despite temperature stress by balancing the feed, increasing protein and fat in the feed mixtures and adding location-suited mineral mixtures.

In Conclusion

Clearly, the challenge before India is to adapt as fast as possible to the unpredictable and largely negative changes in the climate that are threatening its food and nutrition security, as well as the livelihoods of its people. One of the greatest assets we have in combating the impacts of uncertain, unpredictable weather/climate is agro-biodiversity. This great resource of genetic wealth, enviable in its range and  sophistication should be one of the main pillars to rest our adaptation strategies on and yet, it remains neglected and abandoned by the scientific research establishment of the country.

Genetic diversity distributes risk and the greater the genetic variability in hand, the better the coping capacity of farmers. Genetic diversity gives all species the ability to adapt to changing environments and combat biotic and abiotic stresses like pests, disease, drought and flood, salinity and submergence. It has become more important than ever to collect and conserve as much agro-biodiversity as possible, of plants, animals, and fish, and bring it into breeding programmes and direct use.

It is telling that the National Mission for Sustainable Agriculture highlights the use of biotechnology, that is, genetically modified (GM) crops to adapt to climate change but fails to mention agro-biodiversity as an important coping strategy. We need to correct this mindless techno-fix approach and look at the time-tested resources like genetic diversity and indigenous knowledge that has delivered solutions in the past and will do so again. The farmers over millennia have faced adverse situations before; and they have the tools to face these again.

References

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Suman Sahai (mail@genecampaign.org) is with the Gene Campaign, New Delhi, a research and advocacy organisation working on issues related to food, nutrition, and livelihoods.