BSc-MSc (Integrated)

The impacts of climate change on agriculture are global concerns and for that
matter India, where agriculture sector alone represents 23 per cent of India’s Gross
National Product (GNP) and the livelihood of nearly 70 per cent of the population is
exposed to a great danger, as the country is one of the most vulnerable countries due
to climate change. One of the most notable characteristics of climate change is the
increase in temperature, so it has been mainly recognized as ‘global warming’. The
conclusions of the Fourth Assessment Report of the Intergovernmental Panel on
Climate Change (IPCC) published in early 2007 leave no doubt that the Earth’s
climate is changing in a manner unprecedented in the past 400,000 years. The report
substantiated that by 2100 mean surface temperatures over the earth will rise by 1.4 to
5.8 ° C, precipitation will decrease in the sub-tropics, and extreme events will become
more frequent (IPCC, 2007). However, changes in climate are already being observed
and the last 60 years were the warmest in the last 1000 years and changes in
precipitation patterns have brought greater incidence of floods or drought globally.
Climate change has negatively affected India’s millions of rice producers and
consumers. Harvest would have been 5.67 per cent higher in the absence of climate
change. Future impacts of these changes on rice yield in India would thus likely be
larger than the historical ones (Auffhammer et al., 2012). There is a huge gap between
potential and actual grain yield of rice in Kerala. The growth and yield is largely
depends on the various weather factors like temperature, rainfall, solar radiation and
relative humidity that prevail during the growing season.
Objectives of the study were to study the climate change adaptation in rice
production through fertilizer management strategies and to determine the optimum
sowing period in purview of climate change and temperature stress tolerance in
popular rice varieties of Kerala using DSSAT model. The fileld experiments were
conducted during April 2016 to September 2016 at the Regional Agricultural
Research Station of the Kerala Agricultural University at Pattambi, Palakkad district,
Kerala in variety Jyothi.
The result showed that the dates of planting, fertilizer treatment and different
growing environment had significance on yield of rice. The highest grain yield
(6324.0 kg/ha) was recorded by crop transplanted on 1st May 2016 in the open field
fertilizer application as per soil test result along with foliar application (19:19:19 NPK
5g at 15 days interval) and silica (1g per pot). Solar radiation, temperature, relative
humidity and soil temperature are the major weather parameters that influence the
yield and phenology of rice. Changes in fertilizer use, soil test based fertilizer
recommendation, application of micronutrients and additional inputs like silica
reduced the weather dependency in rice production.
High temperature stress tolerance of the popular varieties of Kerala i.e.,
Jyothi, Kanchana, Athira, Vysakh and Jaya were worked out based on the past data
generated as a part of various research programmes under KAU using DSSAT model.
Variety Jyothi showed a very slight decrease in yield when the temperature was
increased by 1°C, 2°C and 5°C. Compared to other varieties Jyothi showed high
tolerance to temperature stress. Varieties like Kanchana, Athira and Jaya had showed
continuous decrease in yield to 1°C, 2°C and 5°C increase in temperature whereas
variety Vysakh showed an increase in yield up to 2°C increase temperature compared
to the present condition but the yield were drastically reduced when the temperature
was elevated to 5°C.
Adjusting the planting time is considered one of the climate change adaptation
strategy for improving the rice production. An attempt was made to quantify the
impact of planting time on crop yield of variety Jyothi using DSSAT model. The
observed and projected yield for the first crop season for the variety Jyothi showed
more or less a continuous increase in yield starting from May 1st to August 1st. Crops
planted on August 1st (6810 kg/ha) recorded the highest grain yield and the lowest
was recorded during the May 15 planting (2212 kg/ha). During 2030, 2050 and 2080
showed a similar trend in the yield pattern corresponding to the above sowing
periods. It is interesting to notice that the yields of crops planted during the month of
May showing an increasing trend during 2030, 2050 and 2080 whereas the yields
during the conventional sowing periods showed a declining trend. The yields of late
planted crops will also going to increase as per the projected climate change
scenarios, but it will prevent the possibility of second crop rice.