Nine different Lycopersiconspecies—twoL. esculentumgenotypes, one L. pennellii, and six L. pe-
ruvianum—were used in a comparative study conducted on 15 host plants per species. Six weeks after in-
oculation of 20 germinated Orobancheseeds per host plant, all host plants were harvested. Measurements
of the photosynthesis of the host, leaf area of the tomato leaves, stem length of the tomatoes, and fresh
and dry weight of leaves, stems, and roots of the host plants as well as of the whole Orobancheplants
were performed. Several physiological parameters—shoot/root ratio, specific leaf area, leaf area ratio,
leaf weight ratio, stem weight ratio, root weight ratio—were calculated to get an idea of the effect of the
interaction.
Data show that there are significant differences between the tomato host reactions at every level of
the physiological interaction with Orobanche[117]. Differences were also found with respect to the two
different species of the parasite, O. aegyptiacabeing more virulent than O. ramosa. As both parasitic
species are quite similar in their habitat, morphology, and host range, this study is good proof that they
should not be treated as one species.
REFERENCES
- E Kuiper. Comparative Studies on the Parasitism of Striga asperaandStriga hermonticaon Tropical Grasses.
The Netherlands: Edam, 1997.
PARASITIC FLOWERING PLANTS OF GENUS OROBANCHE 797
Figure 6 Southern blot of Orobanchesp. DNA digested by EcoRI, probed with mitochondrial gene 18 rrn.
1, Lambda HindIII; 2,3, O. ramosa, Spain; 4,5, O. aegyptiaca, Egypt; 6,7, O. oxyloba, Egypt; 8,9, O. ramosa,
Bulgaria; 11, O. ramosa, North America; 12,13, L. esculentum.