Spontaneous hybridisation between vegetable crops and weeds. 1: Garden radish (Raphanus sativus L.) and wild mustard (Sinapis arvensis L.)

In order to assess the risk of commercial Fl hybrid seed contamination due to outcrossing on male sterile radish line pollinated by wild mustard, two isolated field experiments were performed in the presence or absence of gar den radish pollen. Additionally, spontaneous wild radish plants were observ ed under 200 m away from both fields. Seeds were harvested on the female ra dish line and sieved. Isozyme analyses combined with cytogenetical characte risation revealed that morphological observations were not efficient enough to distinguish the interspecific hybrids among the seedlings obtained. The radish-wild mustard interspecific hybrid production was higher without tha n with radish pollen competition: 42 and 3 interspecific hybrid seeds per 1 000 seeds were observed, respectively. Numerous cultivated-wild radish hyb rids were observed from the two experiments without and with radish pollina tor: 551 and 144 per 1 000 seeds, respectively. Sieving seems to be efficie nt in preventing the commercialisation of cultivated radish-wild mustard hy brids. (C) Inra/Elsevier, Paris.