In this study, butterhead lettuce (Lactuca sativa L. cv. Baby Butter) plants were grown at three root-zone temperatures
(RZTs): 25°C, 30°C and ambient-RZT (A-RZT) ranging from 26°C-42°C while their shoots were maintained at
hot ambient temperature ranging from 26°C-42°C. Three phosphorus (P) concentrations: -25% P (minus P, 23.25ppm),
control (31.00ppm) and +25% P (plus P, 38.75ppm) were supplied to the plants at each RZT using Netherlands Standard
Nutrient Solution. Interactions between RZT and P concentrations on productivity, root morphology, maximum photosynthetic
O2 evolution (Pmax), P uptake and its partitioning between shoot and root were studied. Lettuce plants grown with
the plus P concentration at 25°C-RZT had the highest productivity, highest Pmax, highest shoot and root P concentrations.
However, all the root morphological parameters studied were the greatest in plants grown with the minus P at 25°C-RZT.
Higher P concentration in the solution and 25°C-RZT resulted in higher portion of the absorbed P partitioned to the
shoots. Integrated effects of RZT and P concentration on the productivity, root morphology, photosynthesis and P uptake