Hs. Dungey et al., MYCOSPHAERELLA LEAF DISEASE - GENETIC-VARIATION IN DAMAGE TO EUCALYPTUS NITENS, EUCALYPTUS-GLOBULUS, AND THEIR F1-HYBRID, Canadian journal of forest research, 27(5), 1997, pp. 750-759
Severity of Mycosphaerella leaf disease was assessed on the adult and
juvenile foliage of both controlled crossed and open-pollinated famili
es of Eucalyptus globulus ssp. globulus Labill., Eucalyptus nitens (De
ane & Maiden) Maiden, Eucalyptus globulus ssp. bicostata (Maiden, Blak
ely & J. Simm.) Kirkpatr., and their F-1 hybrids in a trial in northwe
st Tasmania, Australia. Within ssp, globulus, disease was more severe
on one provenance, Taranna, than another, King Island. For interproven
ance hybrids, differences between parents were inherited in an additiv
e manner, whereas interspecific hybrids were generally more susceptibl
e than predicted intraspecific midparent values and occasionally, were
more susceptible than the more susceptible parent. Within populations
, the narrow-sense heritabilities for Mycosphaerella disease severity
were low to moderate (0.004-0.506), but were consistently higher for a
dult than for juvenile foliage despite disease severity being higher o
n juvenile foliage. Parental breeding values and heritabilities estima
ted from open-pollinated progeny were similar to estimates obtained fr
om controlled crosses involving the same parents. Complex genetic inte
ractions were detected between growth, vegetative phase change, and di
sease severity. It is possible that selection for rapid growth in an e
nvironment without disease may result in indirect selection for suscep
tibility.