Search for resistance to crenate broomrape (Orobanche crenata Forsk.) in pea germplasm

Orobanche crenata Forsk. is a major constraint for pea production in Mediterranean and East Asian countries. To solve the problem of the lack of resistance in pea cultivars, a screening for resistance was performed under field conditions in a germplasm collection of 575 accessions of Pisum sativum L. No complete resistance was found but varying levels of resistance were identified and confirmed in further field seasons and in pots experiments in the greenhouse. Resistance was quantitative resulting in a reduction in the number of emerged broomrapes per pea plant. Broomrape infection and expression of resistance proved to be highly influenced by environmental conditions. Resistance is the consequence of the combination of several resistance mechanisms preventing or hampering establishment of broomrape and/or development of established tubercles. Resistance identified could suffice to prevent broomrape damage in normal years, but might need to be implemented with other control measures in very conducive years. Resistant accessions have been crossed with pea cultivars and submitted to a breeding programme in which accumulation of levels of resistance to broomrape is a priority.