Whole plant photosynthesis, development, and carbon partitioning in potato as a function of temperature

Knowledge of temperature effects on whole canopy photosynthesis, growth, and development of potato (Solanum tuberosum L.) is important for crop model development and evaluation. The objective of this study was to quantify the effects of temperature on canopy photosynthesis, development, growth, and partitioning of potato cv. Atlantic under elevated atmospheric CO2 concentration (700 mu L L-1 CO2)Potato plants were grown in day-fit plant growth chambers at six constant day/night temperatures, (12, 16, 20, 24, 28, and 32 degrees C) during a 52-d experimental period in 1999 in Beltsville, MD. Main stem length and main stem expanded leaf number were measured nondestructively at 4 d intervals while leaf, stem, root, and tuber weights were obtained by destructive harvesting at biweekly time intervals. Canopy level net photosynthesis (P-N) was obtained from gas exchange measurements. The optimum temperature for canopy photosynthesis was 24 degrees C early in the growth period and shifted to lower temperatures as the plants aged. Total end-of-season biomass was highest in the 20 degrees C treatment. End-of-season tuber mass and the ratio of tuber to total biomass decreased with increasing temperature above 24 degrees C. Accumulated biomass was a linear function of total C gain with a common slope for all treatments. However, the proportion of C allocated to tubers decreased with increasing temperatures. High respiration losses decreased total C gain at higher temperatures. When simulating photosynthesis and C assimilation in crop models, source-sink relationships with temperature and photosynthesis need to be accounted for.