THEME


 

Rice is the most important cereal food crop of India. It occupies about 19.2% of gross cropped area of the country. It plays vital role in the national food grain supply. Rice contributes 40.8% of total food grain production. In India presently the area under rice cultivation is 41.85 million ha with an annual production of 89.13 million tonnes with an average productivity of 2.13 tonnes/ha (2009-10) (http://www.agricoop.nic.in/). In 2009-10 area under rice cultivation declined drastically compared to the previous years. Analysis of past 10 year data revealed that productivity varied greatly on year to year basis depending on the climatic conditions prevailed during the year (Figs.).  To increase total production, only sustainability of productivity is not sufficient, rather a great leap is required in per unit production due to the decrease of arable land in future.

 

 

Rice, grown on flooded soils – both irrigated and rainfed, is significant in terms of trace gas emissions. Methane (CH4) and nitrous oxide (N2O) are major greenhouse gases (GHGs) both having significant fluxes from rice-ecosystems. Rice have been identified as one of the major sources of atmospheric CH4, contributing about 10–15% to global CH4 emissions. Rice is also known to emit high N2O fluxes under certain water management regimes. Agricultural soils are subjected to a great deal of management practices including tillage, fertilization, irrigation, weeding and manure amendments. Management practices can thus affect trace gas emissions and play an important role in the atmospheric balance of the trace gases. Estimates of regional GHG emissions from rice differ largely, depending on the techniques, approaches and databases used for extrapolation. One of the principal causes of uncertainties is the large spatial and temporal variability in CH4 and N2O emissions. Over the past few decades, numerous field experiments identified the magnitude, temporal pattern and influencing factors of CH4 and N2O emissions from rice fields. The large amount of site-specific information is of great value for improved understanding of the variability in GHG emissions if it is done with improved methods. Global estimates of trace gas fluxes cannot be derived simply from the extension of results from field-plot measurements of trace gases because of the magnification errors obtained from field-plot measurements. Identification of important parameters and functional relationships between environmental variables and trace gas fluxes are required in order to provide more accurate and spatially explicit information on current trace gas fluxes and to estimate past and future changes in trace gas fluxes as a function of global change scenarios.

 

Excessive flooding poses risks to human life and is a major contributor to the poverty and vulnerability of marginalized communities especially women and children in poor families. It is estimated that the flood-affected area has more than doubled in size from about 5% (19 million hectares) to about 12% (40 million hectares) of India’s geographic area (http://web.worldbank.org). Adding to these already high risk areas, the climate projections suggest that temperatures, precipitation and flooding, and sea level rise are likely to increase, with adverse impacts on crop yields and farm income. Among the more substantial effects is a spatial shift in the pattern of rainfall towards the already flood-prone coastal areas. As an example of the implied magnitudes, the probability of discharge exceeding 25,000 cubic meters per second at the measuring station at Naraj on the Mahanadi River in Orissa, India is projected to increase dramatically from the current level of about 2 % to over 10 % (World Bank Report, 2008). Climate changes already start influencing the monsoon and tropical cyclones, the two prime drivers of flood events in India. Looking at the pattern of rainfall in Orissa, one can easily sense the impact of climate change. While costal districts like Balasore, Puri, Cuttack and Ganjam are receiving more rainfall, the hinterlands like Bolangir and Nuapada are experiencing less rainfall. Average annual precipitation of Orissa is around 1500 mm and 75 % of it is received through South-west monsoon during June to September (Table 1). If we look at the rainfall pattern of the last decade, we find that there is a huge deviation from the normal, and 300 - 400 mm rainfall is received within a span of 1-2 days, causing severe flood and drought in subsequent days. The rainfall has become irregular and unpredictable. Therefore, a number of interacting problems threaten future and present sustainability and food security. Present and anticipated global food demands further necessitate a significant increase in crop productivity on less favorable farmlands and under the adversary of climate change.

 

Living without rice is unimaginable. So we have to increase rice productivity that is also with limited resources under variable climatic conditions. Reduction of the Global Warming Potential of rice is another aspect so that rice cultivation becomes more sustainable and climate friendly. We have following two way strategies so that in one hand GHG emission reduces from Rice cultivation in general and in another hand identify rice germplasm with greater tolerance to submergence, drought and salinity. It would be of greater aid to develop rice cultivars proof to climate change with reduce Global Warming Potential. Improved estimates of GHG emissions in rice based production systems would lend a hand to make a balance sheet related to Global Warming Potential of rice cultivation accurately.

 

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