A field survey revealed infestations of broomrape, Orobanche aegyptiaca (syn. Phelipanche aegyptiaca), on sesame (Sesamum indicum L.) plants in the province of Khorasan (36°12'N, 57°39'E, 972 m above sea level) in northeastern Iran in November 2011. About 5% of total sesame fields in this area were infested, and the estimated average yield losses were approximately 30 to 40%. The annual mean air temperature and the average maximum and minimum air temperatures were 17.5, 24.2, and 10.6°C, respectively. In a pot experiment that was also conducted at the Isfahan University of Technology to study the effect of sesame as a trap crop for managing broomrape, a total of 20 genotypes of sesame were infested with broomrape. The infestation of sesame was confirmed by verifying the attachment of the broomrape to the sesame roots. Broomrape plant heights were between 20 and 35 cm, with flowering stems 15 to 20 cm. The stems were erect, usually branched, slender, glandular-pubescent, pale yellowish, and inflorescent rather than lax. Flowers had one bract and two bracteoles. The bracts measured 6 to 8 mm, had ovate lanceolates shorter than the calyces, and filiform, lanceolate bracteoles measuring 8 mm. The calyces measured 10 to 11 mm, and were gamosepalous, entire, whitish, hairy, and glandular. Corollas measured 32 to 35 mm, and were blue violet or sky blue with darker veins and cream proximally, straight or slightly curved, conspicuously infundibuliform in distal parts, and glandular-pubescent with two lips. Stamens were epipetalous, inserted 4 to 5 mm above the corolla base, with filaments hairy below, sparsely so above; anthers were villous or spidery hairy along sutures. Stigma lobes were white. The Botanists Group of the College of Agriculture of IUT confirmed the plants' identity. Sesame has been mentioned before as a trap crop for broomrape (1); however, to our knowledge, this is the first report of broomrape parasitism on sesame in Iran.
Reference: (1) B. M. Chittapur et al. Allelopathy J. 8:147, 2001.
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