Ascochyta blight (AB), caused by Ascochyta rabiei is a major disease of chickpea (Cicer arietinum L.), especially in areas where cool, cloudy, and humid weather persists during the crop season. Several epidemics of AB causing complete yield loss have been reported. The fungus mainly survives between seasons through infected seed and in infected crop debris. Despite extensive pathological and molecular studies, the nature and extent of pathogenic variability in A. rabiei have not been clearly established. Accumulation of phenols, phytoalexins (medicarpin and maackiain), and hydrolytic enzymes has been associated with host-plant resistance (HPR). Seed treatment and foliar application of fungicides are commonly recommended for AB management, but further information on biology and survival of A. rabiei is needed to devise more effective management strategies. Recent studies on inheritance of AB resistance indicate that several quantitative trait loci (QTLs) control resistance. In this paper we review the biology of A. rabiei, HPR, and management options, with an emphasis on future research priorities.

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Ascochyta blight of chickpea (Cicer arietinum L.): a review of biology, pathogenicity, and disease management

A collection of 114 Cicer accessions including 95 wild Cicer accessions from four different species (C. bijugum K. H. Rech., C. echinospermum P. H. Davis, C. pinnatifidum Jaub. & Sp. and C. reticulatum Ladiz.) was screened in glasshouse trials for resistance to ascochyta blight (caused by Ascochyta rabiei (Pass.) Lab.). Resistance was identified in accessions from all four wild Cicer species. There was variation for resistance within accessions of C. echinospermum, C. pinnatifidum and C. reticulatum, with only C. bijugum containing accessions in which all plants were completely resistant. Resistant accessions from C. echinospermum and C. reticulatum may offer accessible sources of resistance because fully fertile hybrids with cultivated chickpea can be readily obtained.

Prospecting for sources of resistance to ascochyta blight in wild Cicer species

https://pubag.nal.usda.gov/download/45766/PDF

Evidence of unique and shared responses to major biotic and abiotic stresses in chickpea

Rainfed farming systems in southern Australia have changed during recent decades from a traditional mixed crop–livestock system towards more intensive cropping. New technologies and greater economies of scale have increased productivity and have been accompanied by the adoption of more environmentally sustainable land management systems. Despite intensification of cropping, medium-term farm business profits vary less with the proportion of the area cropped than with the management skill of individual farmers. Many consultants believe that trends toward higher cropping intensity on mixed farms may have weakened recently as a result of prolonged drought, herbicide-resistant weeds, higher crop input costs, and higher prices for livestock products. These adjustments demonstrate the benefits of the reversible integration of mixed crop–livestock systems. Optimism for the future of broadacre farming, re-ignited in 2008 by high world grain prices and increasing demand for meat, is tempered by concerns over rising energy and input costs, the possible impacts of climate change, and slowing productivity trends. Case studies in this chapter illustrate the development of mixed farming systems in contrasting regions: (1) the equiseasonal rainfall area of southern New South Wales with clay loam soils, and (2) the winter-dominant rainfall area of the northern sand plain of Western Australia.

Diversity and Evolution of Rainfed Farming Systems in Southern Australia

Ascospores of Didymella rabiei were trapped from chickpea stubble containing naturally occurring pseudothecia Ascospores produced typical Ascochyta rabiei cultures on potato-dextrose agar plus gentamicin Ascochyta blight developed on chickpea plants inoculated with conidia derived from single-ascospore cultures This is the first record of the teleomorph, D rabiei, in Australia Its presence has implications in the long distance dispersal and epidemiology of ascochyta blight

Didymella rabiei, the teleomorph of Ascochyta rabiei, found on chickpea stubble in Western Australia

The ascochyta blight resistance of 14 chickpea cultivars, 29 imported chickpea lines and 38 local breeding lines to four Australian isolates of Ascochyta rabiei was investigated. Each isolate was tested individually on each chickpea genotype. There were no differences between the four isolates in their pathogenicity. However, there were large differences between chickpea genotypes in the expression of disease symptoms. All of the Australian chickpea cultivars tested were susceptible to A. rabiei. Seven imported lines and three local breeding lines were found to be resistant to A. rabiei. The eight isolates of A. rabiei tested in these studies were all the same mating type, i.e. MAT1-1.

K. A. Meredith

Papers

Screening chickpea germplasm for ascochyta blight resistance