T. Burgess et al., INFLUENCE OF LOW-OXYGEN LEVELS IN AEROPONICS CHAMBERS ON EUCALYPT ROOTS INFECTED WITH PHYTOPHTHORA-CINNAMOMI, Plant disease, 82(4), 1998, pp. 368-373
Aeroponics root chambers were designed to evaluate the influence of lo
w oxygen on disease development in clones of Eucalyptus marginata susc
eptible or resistant to infection by Phytophthora cinnamomi. Actively
growing 7-month-old clones of E. marginata were transferred into the a
eroponics chambers, into which a nutrient solution was delivered in a
fine spray, providing optimal conditions for root growth. Prior to ino
culation by zoospores of P. cinnamomi under normal oxygen, the roots w
ere exposed to four treatments: (i) normal oxygen, approximately 8 mg
of O-2 liter(-1); (ii) 6 days of hypoxia, 2 mg of O-2 liter(-1); (iii)
anoxic acclimatization 2 days at 2 mg of O-2 liter(-1), 2 days at 1 m
g of O-2 liter(-1), 2 days at 0.5 mg of O-2 liter(-1), 2 days at 2 mg
of O-2 liter(-1), and 6 h at <0.05 mg of O-2 liter(-1); and (iv) 6 h o
f anoxia, <0.05 mg of O-2 liter(-1). Root extension during hypoxia was
greatly reduced, Lesion development was least for roots exposed to hy
poxia and greatest for roots exposed to anoxia for 6 h, suggesting inc
reased resistance of E. marginata to P. cinnamomi following hypoxia.