November 2010

Source: CGIAR News

Dry root rot affects a field of chickpea.

Recent studies conducted by researchers at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) in India indicate that drought caused by prolonged high temperatures make chickpea (Cicer arietinum) more vulnerable to dry root rot caused by the fungus Rhizoctonia bataticola. “The revelation vindicates ICRISAT’s stand that climate change has far-reaching impact on food security and the lives of the poorest of the poor,” comments ICRISAT Director General William Dar. “It also reminds us of our responsibility to further study the behavior of pathogens at different levels of temperature and soil moisture.” Chickpea is grown in over 50 countries in a wide range of environments and cropping systems. It is a major food legume grown mostly by the poor and subsistence farmers in the semi-arid tropics of Asia and Africa.

This popular pea is used to make dal (a thick, spicy soup), curries and sweets in Africa and Asia, as well as salads and hummus in Mediterranean and Western countries.

The studies indicated that, under emerging climate change, high temperatures and the resultant rapid loss of soil moisture at the reproductive stage of growth predispose chickpea to outbreaks of dry root rot. This is one of the two diseases that affect chickpea production; the other is Fusarium wilt.
 

Dry root rot infection at 60%, soil moisture level at 35C.

There are substantial sources of chickpea resistance to Fusarium wilt but none against dry root rot. Interestingly, dry root rot symptoms can easily be mistaken for those of Fusarium wilt. The confusion raises questions about why chickpeas resistant to Fusarium wilt are dying? Is resistance to Fusarium wilt breaking down? Or has a new disease emerged?

The incidence of dry root rot shows clear association with high temperatures and the absence of rainfall.

Studying data taken in India after the rainy season from 2005 to 2010, scientists found that there is higher incidence of dry root rot in chickpea varieties that resist Fusarium wilt in years when temperatures exceed 33ºC. Research under different soil moisture and temperature conditions revealed that the pathogen infected chickpea plants and manifested dry root rot faster at 35ºC with soil moisture levels less than or equal to 60%. Fusarium wilt occurs at 25ºC and soil moisture levels above 60%.

ICRISAT’s studies clearly demonstrate the combined roles of drought plus the pathogen that infects chickpea and causes the development of dry root rot.

For more information, contact Suresh Pande at s.pande@cgiar.org or Mamta Sharma at mamta.sharma@cgiar.org. 

Website: http://www.cgiar.org

Published: November 23, 2010