(cumulative Fv/Fm at 0.3 ranging from 2% to 8%) and the susceptible
batavia lettuce cultivars i4, i5 and i6 (cumulative Fv/Fm at 0.3 ranging
from 1% to 3%) could be clearly separated from the resistant
butterhead lettuce cultivars i1, i8, i9 and i10 (cumulative Fv/Fm at
0.3 < 1%) as well as from the controls (cumulative Fv/Fm at
0.3 < 0.5%). The newly breed resistant line 92 (i7; c.f. Table 1), however,
showed very early symptoms of senescence and, therefore
had a low average Fv/Fm and, correspondingly a very high cumulative
Fv/Fm at 3% (4%).