Ka. Klock et al., ROOT RESPIRATION AND PHOSPHORUS-NUTRITION OF TOMATO PLANTS GROWN AT A36-DEGREES-C ROOT-ZONE TEMPERATURE, Journal of the American Society for Horticultural Science, 122(2), 1997, pp. 175-178
Growth of tomato (Lycopersicon esculentum Mill.) plants decreases at r
oot-zone temperatures (RZTs) >30 degrees C, but no research has been c
onducted on the effects of changes in root respiration on P acquisitio
n at supraoptimal RZT. We monitored the changes every 3 to 5 days in r
oot respiration, root surface phosphatase activity, and P acquisition
of 'Jet Star' tomato plants grown in Hoagland's no. 1 solution held at
25 and 36 degrees C RZT for 19 days. Root respiration rate in plants
grown at 25 degrees C increased linearly from RZT initiation to day 12
, but there was no difference in respiration between days 12 and 19. R
oot respiration at 36 degrees C, however, increased from RZT initiatio
n to day 8 and then decreased. Shoot P concentration and root phosphat
ase activity for plants grown at 25 OC did not change during the exper
iment. Shoot P concentration for plants at 36 degrees C, however, line
arly decreased over time, and root phosphatase activity linearly incre
ased over time. Decreased shoot growth and demand for P along with dec
reased root respiration after day 8 probably resulted in the decreased
P uptake and shoot P concentration in plants grown at 36 degrees C RZ
T.