RESPONSES OF WILD AND CULTIVATED BARLEY FROM WEST ASIA TO NET BLOTCH AND SPOT BLOTCH

Wild species and cultivated landraces from the center of crop origin may provide new sources of resistance to a variety of plant diseases that plague genetically uniform crops around the world. This study was conducted to assess resistance to Canadian isolates of three foliar pathogens [Cochliobolus sativus (Ito and Kurib.) Drechsl. ex Dastur., Pyrenophora teres (Died.) Drechsl. f. teres, and P. teres, f. maculata] in wild and cultivated landrace barley [Hordeum vulgare L. subsp. spontaneum (C. Koch) Thell. and H. vulgare L. subsp. vulgare] from Turkey and Jordan and to determine whether disease resistance was preserved by in situ conservation of the two barley species. Seedlings were inoculated separately with the pathogens in growth cabinet tests. More wild barley accessions were resistant to C. sativus (4.5% vs 0.3%) and P. teres f. teres (21.8% vs. 0.5%) than cultivated barley. An equal number of wild and cultivated barley accessions was resistant to P. teres f. maculata. A larger percentage of wild barley accessions (10.5%) had at least moderate resistance to all three leaf diseases as compared to only 1.3% in cultivated barley. The average disease rating on these accessions was lower for wild barley (65%) but not significantly different from cultivated barley (73%). Chi-square statistics showed significant associations for disease reactions of (i) C. sativus with P. teres f. maculata, and (ii) P. teres f. teres with P. teres f. maculata that were larger in cultivated barley, indicating stronger associations due to agricultural selection. Disease reactions were independent for C. sativus and P. teres f. teres In both wild and cultivated barley. In situ conservation of cultivated barley in the Middle East was successful in preserving resistance in either single or multiple combinations in cultivated landrace populations, but it was less effective in preserving the diversity for resistance than in wild barley.