September 1, 2008
By Syed Akbar
Hyderabad, Aug 29: There will be severe shortage of rice as average temperature goes up due to global warming.
A study on the "effect of climate change on rice" carried out by the city-based Directorate of Rice Research has revealed that global warming will reduce the potentiality of photosynthesis in paddy, thereby bringing down the overall yield. Photosynthesis is a natural process through which plants use the sunlight to prepare
their food. Any change in the photosynthesis process will affect flowering and thus yields.
This is the first time that a study has been conducted on how global warming and consequent climate change will hit rice yields. The study was conducted by DRR in association with the Central Research Institute for Dryland Agriculture.
The DRR-CRIDA team selected one month old seedlings of rice genotypes (Krishna Hamsa, rice hybrid DRRH2). They then raised them in pots in ambient atmosphere. Later, the saplings were transferred into open top chambers with control (ambient) or 550 ppm carbon dioxide enriched atmosphere using the automated system facility developed in the CRIDA.
The team imposed carbon dioxide treatment everyday from 9.30 am 4.30 pm and continued the process till flowering. At flowering, they measured leaf characteristics such as photosynthesis, stomatal (leaf opening) conductance, transpiration, air and leaf temperatures. Soil samples were also analysed for differences in nematode (useful worms) population.
The results showed that, irrespective of genotypes, there was a reduction in photosynthesis by about 25 per cent. There was also reduction of 36-38 per cent in leaf conductance and transpiration rates under elevated carbon dioxide condition as compared with the control. Differences between air and leaf temperatures under
ambient and elevated carbon dioxide conditions were eight per cent and 12 per cent,
respectively.
The study found that with increased concentration of carbon dioxide, there was a reduction in nematodes in the soil.
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