Effects of temperature on virulence of Didymella rabiei pathotypes affecting chickpea
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Seid Ahmed Kemal, Muhammad Imtiaz. (28/3/2014). Effects of temperature on virulence of Didymella rabiei pathotypes affecting chickpea. Cordova, Spain.
Abstract
Chickpea (Cicer aritienum) is one of the most important food legumes grown
around the world in more than 50 countries. The yield gap of chickpea is high due
to abiotic and biotic constraints where Ascochyta blight (Didymella rabiei) causes
yield instability in different regions. High yielding chickpea varieties were
developed and released in many countries; however some varieties were taken out
of production due to susceptibility to new virulent pathotypes of the pathogen.
Knowledge of the interactions of Didymella-Cicer with the environment has
practical significance because the environment may alter the performance of
cultivars and pathogen populations in the field (1, 2). Little is known on how
temperature may affect the virulence of different pathotypes of D. rabiei. The
effects of temperature (10, 15, 20 and 25oC) on the virulence of four Pathotypes (PI,
P-II, P-III and P-IV) were studied using six chickpea genotypes (Ghab-1,Ghab-2,
Ghab-3, Ghab-4, Ghab-5 and ICC-12004) with varying levels of blight resistance
under controlled conditions. The results showed that the interactions of temperature
with pathotypes as measured by virulence index were statistically significant but
without changes in the ranking of the pathotype virulence on the host genotypes.
The mean virulence index of the four pathotypes ranged from 3.3 in P-I to 7.2 in PIV.
P-4 showed high mean virulence index under all temperature regimes followed
by P-3 compared with the other two. The least virulent P-1 among the tested
pathotypes showed high average virulence index at 10oC on the test genotypes.
Similar results were obtained for the chickpea genotypes where significant
genotype by temperature interactions were detected but no changes in the ranking
of resistance to Ascochyta blight. Except for Ghab-1, which is the most susceptible
genotype, the remaining genotypes showed high disease severity at temperature 10
and 15oC. This study showed that D. rabiei population has developed pathotypes
that can cause disease epidemics irrespective of temperature regimes in Syria and
there is a need to further investigate the response of pathogen populations to
temperature from similar Mediterranean environments.
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Kemal, Seid Ahmed https://orcid.org/0000-0002-1791-9369