Evaluation of the World Safflower Collection for Resistance to Phytophthora1

Abstract

The World Safflower (Carthamus tinctorius L.) Collection was tested 5 years in the field for resistance to root rot induced primarily by Phytophthora drechsleri Tucker, P. parasitica Dast., and P. cryptogea Pethyb. and Laff. Resistance of 1,547 entries of the World Safflower Collection obtained from 35 different countries was evaluated. Nurseries were planted on a heavy clay soil following a crop of rice (Oryza sativa L.). In order to maximize disease incidence, plants were stressed for water prior to flood irrigation. Disease readings were made 10 to 20 days after irrigation. Seeds (achenes) from individual open‐pollinated plants which appeared resistant were harvested and planted the following year. After 5 years of testing, 15 of the most resistant lines which had been originally obtained from the following countries were released: Turkey, five; Egypt, Afghanistan, and Iran, two each; Sudan, India, Iraq, and Australia, one each. The released genotypes were designated UC‐150 to UC‐164, respectively.