Global warming may hit maize, wheat production

In the coming years, Gujarat's wheat and maize production might suffer because of rising temperatures.

Results of an experiment carried out by the department of Agricultural Meteorology, B A College of Agriculture, Anand Agricultural University says that global warming and greenhouse effect will have an impact on the yield of wheat and maize in the state. Wheat and maize yield will go down manifolds if the temperatures keep rising or falling.

Vyas Pandey, head, department of Agricultural Meteorology, B A College of Agriculture, Anand Agricultural University, told Business Standard, "We have used the crop growth simulation model to prepare this report. Crop growth simulation models have been recognised in environmental characterisation and agro-ecological zoning defining research priority, technology transfer, estimate production potential, strategic and tactical decision-making and for predicting the effects of climate change and variability."

The wheat yield fell under elevated maximum temperature under experimental conditions. The wheat yield was 4,000 kg per hectare when the temperature was raised by one Celsius, this fell to 3,600 kg per hectare under two degree Celsius temperature which further fell to 3,250 kg per hectare when temperature was raised three degree Celsius.

The yield under temperature of four degree Celsius was only a little above 2,800 kg per hectare and a little above 2,500 kg per hectare under 5 degree Celsius. The base yield was fixed a little above 5,700 kg per hectare.

The wheat yield under reduced maximum temperature was best under minus five degree Celsius. Against the base yield fixed at little over 5,700 kg per hectare the wheat yield was almost 6,250 kg per hectare under minus five degree Celsius temperature.

This production decreased to 5,600 kg per hectare under minus four degree Celsius temperature. The yield took a further dip to a little below 5,500 kg per hectare mark under minus three degree Celsius.

While, under minus two degree Celsius the yield was only 5,250 kg per hectare and under minus one degree Celsius it was 4,700 kg per hectare. So, wheat will suffer tremendously under the increasing temperatures in the forthcoming years. The decrease in cultivation of wheat may further worsen the situation as more and more farmers are turning towards cash crops like cotton.

On the other hand, maize varieties like GS-2 and GM-3 gave different results under this simulation. Maize GM-3 found more vulnerable to elevated temperature (3-4 degree Celsius as compared to GS-2.

Both the cultivators responded well at elevated temperature of two degree Celsius. The GS-2 variety of maize production per hectare was 4,200 kg under the elevated maximum temperature of one degree Celsius against the normal yield of 4,000 kg per hectare. However, it increased to almost 4,800 kg per hectare under two degree Celsius temperature. The yield fell to 3,900 kg per hectare under five degree Celsius temperature.

Similarly, in GM-3 variety the yield was 3,700 kg per hectare under the elevated maximum temperature of one degree Celsius which increased to 3,850 kg per hectare under two degree Celsius temperature. The normal yield was 3,550 kg per hectare. The yield went down to normal (3,550 kg per hectare) at four degree Celsius. The report says that gradual temperature reduction pose a negative impact on maize yield.

Pandey said, "Earth's temperature is increasing by human activities, like burning coal, oil and natural gas. This releases carbon dioxide, methane and other greenhouse gases into the atmosphere. Greenhouse gases form a blanket around the Earth, trapping heat and raising temperatures on the ground. This is steadily changing our climate."

"In the 21st century, temperature will have increased by 1.5 to 5 degree C depending on population and economic growth. This climate change will affect agricultural yield directly because of alterations in temperature and rainfall, and indirectly through changes in soil quality, pests, and diseases."

"Moreover, tropical countries are more vulnerable to climatic effects in agricultural productivity. Simulation models provide a scientific approach to study the impact of climate change on agricultural production and world food security. The weather parameters selected for the purpose were maximum temperature (1 to 5 degree C) and concentration of carbon dioxide (1.2 and 2.4 per cent higher concentration of 330 ppm) along with doubled carbon dioxide concentration with elevated temperatures," Pandey added.