BSc-MSc (Integrated)

The rate of global warming is expected to continue increasing if no mitigation
efforts take place to reduce the carbon intensity of the world economy and the
consequent emission of green-house gases (Raupach et al., 2007). Agricultural
production, and thus global food security, is directly affected by global warming
(Ainsworth and Ort, 2010).
Rice production plays an essential role in feeding the world’s population and
will continue to be in the future, because rice is the most important global staple food
in many countries. The production of rice, along with other agricultural crops, will be
impacted by climate change. There is still great uncertainty about how climatic and
atmospheric changes will affect the future productivity of food crops. Major future
impacts of climate change are expected on food security and agricultural incomes,
including shifts in production areas across the world.
In addition to affecting rice production, climate change may alter pathogen
dissemination and development rates, and modify the resistance, growth and
metabolism of host plants. The geographical distributions of pathogens are very likely
to change, and losses can be expected, in part due to altered effectiveness of control
strategies. Thus climate change is a serious threat to agriculture because it can lead to
significant changes in the occurrence and severity of plant diseases. All phases of the
disease cycle, from the germination of spores to the development of lesions, are
considerably influenced by climatic factors. The most important climatic factors are
temperature and precipitation. These factors may be modified by the coming climate
changes. Recent research indicates that the monsoon has changed in two significant
ways during the past half-century: it has weakened (less total rainfall during June–
September; Ramanathan et al. 2005; Dash et al. 2007), and the distribution of rainfall
within the monsoon season has become more extreme (Goswami et al. 2006; Dash et
al. 2009).
Rice blast caused by Pyricularia oryzae an important disease of rice
worldwide is known to cause severe yield losses in rice production area where high
inputs of nitrogen fertilizer and favourable climatic conditions occur. Sometimes the
yield losses reach as high as 50% in upland cultivations.
Objectives of the study were to Study the effect of various weather parameters
and climate change on incidence and development of leaf blast disease of rice and
evaluation of disease forecasting models for leaf blast of rice. The field experiments
were conducted during May 2016 to October 2016 at the Regional Agricultural
Research Station of the Kerala Agricultural University at Pattambi, Palakkad district,
Kerala.
Crops sowing June showed a higher disease incidence compared to other dates
of sowing. It was also noticed that variety Kanchana is more susceptible to Leaf blast
incidence compared to Jyothi. The effect of weather on LAI significantly varied with
varieties. The effect of weather on grain yield was significant. Under upland condition
the sheath blight disease incidence was not observed even after artificial
inoculation.The effects of weather and varieties on leaf blast incubation period were
significant.
EPRICE model developed by Savary et al., (2012) was used to forecast the
disease severity of leaf blast disease in rice after transplanting. The model works on
daily weather parameters particularly rainfall, maximum and minimum temperature,
morning and afternoon relative humidity. RMSE for Kanchana prediction is 0.265.
This shows that the predicted leaf blast severity was in good agreement with the
observed values. So this model can be used for forecasting the rice blast severity
under Kerala conditions.
The future climatic projections have taken from Ensemble of 17 General
Circulation Models (GCMs). The future carbon dioxide concentrations and climate
data has been incorporated into disease simulation model-EPIRICE and predicted the
future disease incidence possibility of blast for the years 2030, 2050 and 2080 in all
the 14 districts of Kerala. The climate data for the years 2030, 2050 and 2080 under
different RCPs. The impact of climate change on leaf blast severity in the various
districts of Kerala showed a varying trend. Except in the northern districts
(Malappuram, Wayanad, Kannur and Kasaragod) the disease severity showed a
decreasing trend.