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REACTIONS OF PROMISING CHICKPEA GENOTYPES TO ASCOCHYTA BLIGHT IN TWO PRODUCTION ZONES OF SYRIA
AHMED, S., C. AK.EM, and M. BELLAR

Gerinplasm Program, International Center for Agricultural Research in the Dry Areas (ICARDA) P. 0. Box 5466, Aleppo, Syria


Background and objectives
Chickpea (Cicer arietinum L.) is an important cool- season food legume in different parts of the world. In the Mediterranean region, kabuli chickpea is grown mainly in the spring after the cessation of winter rains. The main reason for delayed planting till spring is to avoid damages from ascochyta blight (Ascochyta rabiei (Pass.) Labr.) and cold. Winter chickpea planting in the Mediterranean region has been shown to produce 70% more seed yield than the spring grown crop [1]. The realization of this tremendous yield advantage of winter chickpea is only possible through the development of cultivars resistant to ascochyta blight and tolerant to cold. There is a continuous effort at ICARDA to develop high yielding winter chickpea cultivars with durable resistance to ascochyta blight. In order to ensure the durability of the resistance and yield stability, pron-iising lines are evaluated each year on research stations and in farmers fields in different production zones of Syria. Chickpea is mainly grown in zone B (annual rainfall 250-300 mm), however, due to high productivity of the winter crop, some fanners are growing the crop in zone A (annual rainfall >300 nun) in Syria. The main objectives of the multi-locational evaluations are to test promising genotypes for their resistance across enviromnents and to identify locations that consistently favor ascochyta blight development which can be used for disease evaluations under Syrian conditions.


Materials and Methods
Each year, promismg chickpea genotypes are selected from advanced breeding lines, screened for resistance to ascochyta blight under field conditions, and tested at multi-locations in the two production zones of Syria. During the 1995/96 and 1996/97 cropping seasons, three promising chickpea genotypes (FLIP 88-85, FILP 89-29 and FLIP 90-96) and the adapted cultivar Ghab 3, were evaluated in on-farm trials. The genotypes were planted at 11 locations in 8 provinces in zone A and at 5 locations in 4 provinces in zone B. The trials were planted in two replications at each location using a randoniized complete block design. The genotypes were evaluated in the on-farm trials for disease occurrence especially ascochyta blight in May of each year, on a 1-9 disease severity scale and lines with a 1-4 rating were considered resistant, those with 5 moderately resistant and 6-9 as susceptible. The degree of disease pressure in the on-farm trials were monitored using two susceptible cultivars (Ghabl and Ghab 2) planted as demonstration trials in nearby farmers fields at each location. Disease development in all the trials was dependent on natural inoculum in both seasons and at all locations.


Results and conclusions
Enviromnental conditions were favorable for ascochyta blight development m both seasons m the two production zones of Syria. Many farmers who planted chickpea in winter were forced to plough-under their fields due to early disease infections. Ghab l and Ghab 2 planted as demonstration trials in farmers fields in zone A showed disease severity ratings ranging from 6 - 9, indicating that ascochyta blight severity was very high at the trial sites. The average ascochyta blight severity on all the genotypes ranged from 2 in five locations to 9 in one location. In zone B, the average ascochyta blight severity in the on-fann and demonstration fields was lower and all the genotypes showed a resistant reaction. In zone A, the genotypes showed variable reactions by locations. with F 90-96 and F 88-85 generally more resistant than F 89-29.


Reference
1. Singh, K.B, R.S. Malhotra, M.C. Saxena and G. Bejiga. 1997. Agronomy Journal 89: 112-118.