Climate change has mixed impact on crops: ICAR study

Global warming has both adverse and beneficial impact on agricultural production through their impact on plant nutrition and the spread of diseases, according to an assessment study conducted by the Indian Council of Agricultural Research (ICAR).
Rise in temperature reduces crop duration, increases crop respiration rates, affects the equilibrium between crops and pests, hastens nutrient mineralisation in soils, decreases fertiliser use efficiencies and increases evapo-transpiration, an official release on the study said.

Increase in carbon dioxide, however, is beneficial for several crops such as wheat, rice, legumes and oilseeds, the study said.

Crops such as maize, jowar, bajra and sugarcane do not benefit from increased carbon dioxide.

A study conducted on onion crop in Maharashtra indicates that the crop failed in 1997 Rabi due to high temperatures in bulb formation stage and in 1998 Kharif due to Purple Blotch and Stemphylium Blight diseases, which were induced by high rainfall, the release said.

The study also found an upward shift in the apple belt in the apple growing areas of Himachal Pradesh due to decreasing chilling hours and increasing temperature during November to March. New areas of apple cultivation have appeared in Lahaul and Spiti and upper reaches of Kinnaur district of Himachal Pradesh.

The analysis of data for the period 1901 to 2005 indicates increase in the annual mean temperature by 0.5 o degree C. The long-term variation of the mean annual temperature of the country for the period 1875 to 2004 was in the order of 0.03 degree C per decade while for the period 1971 to 2004 it was around 0.22 degree C per decade, indicating greater warming in the recent decades.