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ABSTRACT

At the current scenario, the health of plants in the globe has been challenged by major threats like climate change, invasive alien species, pollutions and many more. The United Nations (UNs) has designated 2020 as ‘International Year of Plant Health’ to create awareness and seek attention across the globe. This awareness of protecting plant health can lead a hunger-free world protecting environment.

The health of plants is vital to represent healthy ecological parameters. Healthy plants being aided by both intrinsic and extrinsic mechanisms such as resistance, tolerance and escape face various types of stresses in the environment (biotic and abiotic). The economic resources of a country primarily depend on its healthy crop cultivars grown by various farmers in different states. Various factors like the plant genetics, abiotic or environmental factors and associated micro or macro-organisms in the agro-ecosystem affect plant health and ultimately to the crop yield.

Importance of plant health

Plant health is very important as it affects the profitable crop yield and ultimately to the sustenance of a farmer. The crop products used directly for consumption or any other purpose like food, ornamental purpose, medicinal values etc. are sensibly related to the plant health. A healthy plant represents a healthy environment. At the current scenario, the use of modern biotechnology and molecular technology is boosting the branch of crop improvement. New cultivars of crops are being developed more tolerant to water stress conditions and losses by biotic stresses. 

All over the globe plant, health is increasingly under threat. Simultaneously both the global population and the demand for food from limited cultivable land resources are increasing over time. The current 7.7 billion world population will increase to 9.5 billion in the next 30 years. The impact of climate change on plants is well visible to all. Both human interventions and a changing climate have imparted negative effects on various agro-ecosystems and biodiversity. New favourable niches have supported newly emerged insect pests. The outbreak of desert locust (Schistocera gregaria Forskal) in 2019 and first half 2020 over Eastern Africa to the west and central India (till part of Madhya Pradesh) along with the infrequent attack of brown plant hopper (Nilaparvata lugens Stal) in paddy ecosystem in Aisa in recent years is a clear picture of the effect of climate change. Also, the boost in international trade and travels, which have tripled in function in the last decade are the major loopholes for the spreading of various pests and diseases around the globe. The extent of various kinds of pollutions is also affecting the full biological potential of various crops at field level.

 International years

The United Nations (UNs) designate specific days or weeks or years or decades to mark and promote occasions which need attention across the globe. Generally, Member States propose these designations and the General Assembly creates those with a resolution. Sometimes these occasions are also being declared by the specialized agencies of the UNs like UNESCO, UNICEF, FAO, etc. when the concerned issues fall within their scope. Since the year 1959 UNs has designated various International Years to grab the attention of the world onto main problems of global importance.

The kingdom Plantae constitutes the basis for all life forms on earth. About 80% of our food comes from it and we survive through oxygen which is the major constituent for metabolism in our body. It has been reported that plant health will play a major role in sustainable agriculture which can be able to feed to the growing population by 2050. Thus recognition and advocacy for the promotion of plant health are of utmost importance in the current scenario. In July 2017, the FAO Conference approved a draft resolution pursuing the General Assembly of the UNs to consider declaring 2020 as the International Year of Plant Health (IYPH). In December 2018, the UNs general assembly declared 2020 as the International Year of Plant Health (IYPH). The year is a once in a lifetime opportunity to raise global awareness on protecting plant health which can lead a hunger-free and poverty-free world along with protecting the environment. This also aims to promote responsible practices that decrease the spread of different phytophagous pests and scientific innovations to address pest threats.

 Objectives of celebrating International Year of Plant Health 2020 

The general objective of celebrating IYPH 2020 is to raise awareness among the people regarding the importance of plant health. This will be fulfilled by addressing issues like hunger, poverty and environmental threats which may be amplified because of lesser concern to plant health. Followings are the objectives under the resolutions.

1. To raise awareness among the public and policymakers on global and national levels about plant health and how it is efficiently related to promoting sustainable agriculture, protecting the environment and facilitating economic and trade development.
2. To Promote and strengthen global and national plant health efforts which are currently threatened by increasing trade and travels between countries and also an invasion of alien species aided by climate change.
3. To bring together the political support of global, regional and national governments for plant health.
4. To increase global and regional resources for plant health policies and systems.

 Climate change and plant health

Over the next 100 years, with increasing levels of carbon dioxide (CO2) and Ozone (O3), global temperatures are predicted to rise by 2°to 4°C. Disasters like droughts, erratic rainfall patterns and heat waves may be more common in coming years. There are reports of the negative impact of climate change on food production across the world. The elevated mean seasonal temperature can shorten the crop cycle and ultimately the yield (IPCC, 2007, Mukherjee et al., 2016). Also, the crop productions in tropics will be significantly affected by this. These are also speculations that the crop production may no longer be possible due to increased heat and drought in case of marginal and semi-arid areas of sub-Saharan Africa and South Asia. 

Under changing climate scenario, the global crop yields may decline 10-25% or more by 2050 at a global level (IPCC, 2018). The effect of climate change on yield through biotic factors is still in infancy and not well documented. Various arthropod pests and diseases cause at least 10% losses in food grain around the world. There is a direct impact of climate change on various pest species composition and interactions. There is a risk to have novel pests and pathogens emerging from new climate conditions (under changing temperature and precipitation patterns). Also, the risk involved in the increase of the geographical range of various crop pests with climate change can’t be ignored. Climate change also has an impact on plant genetic resources directly. There is an increased risk of emergence and spread of pests, diseases or pathogens. In future lack of genetic diversity in crops may occur and they may become uniformly susceptible. In turn, this can increase vulnerability and may create congenial situations for widespread crop losses. In recent years, many works of literature show how climate change is likely to affect plant diseases (Pautasso, 2011). Most of these kinds of literature predict that plant pathogen and respective diseases will become more severe.

It has been speculated that in this current century India will experience comparatively warmer temperature than that of the average global value. The temperature extremities in various seasons will be significant and winter will be warmer than summer. In the current trend, the longevity of heat waves across India has extended with warmer night temperatures. The average global temperature change is predicted to be 2.33°C to 4.78°C. The CO₂ concentrations will also be doubled. These heat waves will cause erratic rainfall, which ultimately may affect the agriculture sector.

Out of a US$1.3 trillion annual food production capacity worldwide, the biotic stresses caused by insects, diseases and weeds cause 31 to 42% loss (US$500 billion). The extent of post-harvest losses ranges from 6 to 20% (US$120 billion) which are majorly caused by insects, fungus and bacterial infections. In developing countries crop losses due to diseases are more comparing to developed countries (Oerke et al., 1994). Weeds are also a major hindrance affecting cropping systems worldwide. In addition to these various abiotic causes such as drought, flood, frosts, nutrient deficiencies, various soil and air toxicities cause around 6 to 20% losses.

 International trades, Invasive alien species and plant health

Invasive alien species (IAS) are the non-native species which are introduced into new locality via intentional or unintentional introductions. They are a major challenge to the sustenance of biological diversity. They compete for a similar kind of resources with the native organisms. It has been seen that the impact is tremendous in many cases. The impact may be on human health, agricultural sectors etc. There is a loss of hundreds of billions of dollars annually worldwide due to invasive alien species. The rapid increase in various invasive species is recognized as a primary cause of global biodiversity loss and is affecting the flora and fauna of the world (Mooney & Hobbs, 2000). The rapid increase of these IAS is causing bio-invasion. Bio-invasion is a type of biological pollution and is significantly leading to global biodiversity change and extinction of species (Mooney and Drake, 1987; Drake et al., 1989).

In this 21st century, the threat of emerging invasive alien species is significant and distributed throughout the world. About 17% of the global land area is highly vulnerable to invasion. The threat is similarly high in countries like Africa, South America and Asia. About 16% of global biodiversity hotspots including endemic plant, bird Areas and WWF`s Global 200 Ecosystems, are highly vulnerable to invasion.

Recently in 2019-20, the invasiveness of fall armyworm (Spodopterafrugiperda) has created havoc throughout the world. FAO has periodically warned the affected countries. This noctuid moth is native to America. Since 2016 it has been aggressively migrating to eastwards. It has crossed across Africa and started infesting for the first time in Asia last summer. In India, this moth was first detected in July 2018 and by January 2019, it had spread to neighboring countries like Sri Lanka, Bangladesh, Myanmar, Thailand and China’s Yunnan Province.

 Pollutions and plant health

The global pollution is the result of additive effects of various sources, located on the entire surface of the globe. These are ozone depletion in the stratosphere, greenhouse effect mediated by the release of greenhouse gases (GHGs such as CO2, methane, CFCs, etc.), the formation of aerosols in the atmosphere (suspended pollutant clouds).

Dust pollution usually blocks the stomata of leaves and decrease their conductance to CO₂, interfering with photosystem II. Polluting gases such as SO₂ and NO_x enter leaves through stomatal openings, following a diffusion pathway like that of CO₂. In cells, NO_x dissolves to nitrite ions (NO^2-) (toxic at high conc.) and nitrate ions (NO^3-) which enter into nitrogen metabolism. Other pollutants like SO₂ when are exposed to plants, cause stomatal closure, that protects the leaf surface against the further entry of the pollutant but simultaneously it also ceases photosynthesis. In the cells, SO₂ dissolves to give bisulfite and sulfite ions. Out of these sulfite is toxic. At low concentrations, both bisulfite and sulfite are detoxified by plants. But in urban areas, these gases sometimes present in huge concentrations that they are unable to be detoxified by plants.

The ozone pollution also has a significant detrimental effect. As per a finding, the combined yields of soybean, maize, wheat, and cotton decreased by 5, 10 and 16 per cent respectively wherever the mean daily ozone concentration reaches 40, 50 or 60 ppb. Being highly reactive, Ozone binds to plasma membranes and further, it alters cellular metabolism. The effects are poor regulation of stomatal openings and damaged thylakoid membranes. Also, rubisco is degraded and the photosynthesis process is ceased. Sometimes reactive oxygen species (ROSs) are formed when ozone reacts with oxygen. Some ROSs are hydrogen peroxide (H₂O₂), superoxide (O^2-), singlet oxygen ¹(O₂), hydroxyl radical (-OH) etc. These ROSs can denature proteins, can damage nucleic acids (mutations) or can cause lipid peroxidation.

 Recommendation

 The awareness should spread to each sector of society. Every sector of the society such as a farmer, a policymaker, a researcher, a politician, a bureaucrat, an academician everyone should rethink about this resolution and should incorporate in their respective works. To promote these public-private partnership and convergence approaches can be useful (Mukherjee and Maity 2015; Mukherjee et al. 2012).The relationship between plants and animals are being evolved for million years ago. So in the modern trends of scientific advancement and technological innovation we should not forget to keep the plants around us healthy. Because, our existence and survival is mutually inclusive.

 

References

 

Drake, J.A, Mooney, H.A., di Castri, F., Groves, R., Kruger, F., Rejmanek, M and Williamson, M. (1989). Biological Invasions: A Global Perspective. John Wiley and Sons, New York. Environment 1987,  29(5),12

IPCC (2018). Impact of Climate Change on Plant Health ZitouniOuld Dada IPPC Seminar – Plant Health, Climate Change and Environmental Protection 10th October 2018, Rome, Italy.

IPCC (2007). Climate Change 2007: Synthesis Report. Contribution of Working Groups I, II and III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, Pachauri, R.K and Reisinger, A. (eds.)]. IPCC, Geneva, Switzerland.

Mooney, H.A and Drake, J.A., (1987). The ecology of biological invasions. Environment, 29(5), 12.

Mooney, H.A and Hobbs, R.J. (2000). Invasive Species in a Changing World. Island Press, Washington DC.

Oerke, E.C., Dehne, H.W., Schonbeck, F and Weber, A. (1994). Crop production and crop protection estimated losses in major food and cash crops. Elsevier Science, Amsterdam, 808, pp 95-313.

Pautasso, M., Doring, T.F., Garbelotto, M., Pellis, L., and Jeger, M.J., (2011). Impacts of climate change on plant diseases—opinions and trends. European Journal of Plant Pathology. 133,

Mukherjee, A., Rakshit, S., Nag, A., Ray, M.,  Kharbikar, H.L., Shubha, K., Sarkar, S., Paul, S., Roy, S., Maity, A., Meena, V.S., Burman, R.R., (2016). Climate Change Risk Perception, Adaptation and Mitigation Strategy: An Extension Outlook in Mountain Himalaya. Conservation Agriculture: an approach to combat climate change in Indian Himalaya (JK Bisht, VS Meena, PK Mishra and A Pattanayak. Springer. Pp 257-292. http://link.springer.com/chapter/10.1007/978-981-10-2558-7-10

Mukherjee, A., Bahal, R., Burman, R.R., Dubey, S.K., Jha, G.K., (2012) Conceptual convergence of pluralistic extension at Aligarh District of Uttar Pradesh. Journal of Community Mobilization and Sustainable Development, 7(1), pp. 85-94.

Mukherjee, A., Maity, A., (2015). Public–private partnership for convergence of extension services in Indian agriculture. Current Science, pp. 1557-1563.

 

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INTERNATIONAL YEAR OF PLANT HEALTH 2020 1.pdf