
TY  - JOUR
A1  - Sale, PJM 
T1  - Productivity of Vegetable Crops in a Region of High Solar Input. III. Carbon Balance of Potato Crops
JF  - Functional Plant Biology
JO  - Functional Plant Biol.
Y1  - 1974
VL  - 1
IS  - 2
SP  - 283
EP  - 296
KW  - 
UR  - https://doi.org/10.1071/PP9740283 
N2  - The carbon balance of potato crops has been studied by measuring canopy net photosynthesis and dark respiration losses with a field assimilation chamber and semi-closed gas analysis system. Results are given for the latter part of growth in both a spring-planted and a summer-planted crop. Net CO2 uptake increased with solar input to reach 35&ndash;40mg dm-2 (ground area) h-1 at 400&ndash;450 W m-2, but light saturation then occurred and little or no further uptake resulted from increases in solar input up to 1000 W m-2. This supports the previous conclusion that net photosynthesis in the potato is determined by the size of the 'sink' provided by the developing tubers. The imposed experimental variables of reduced solar input (21 and 34% shade) and soil moisture were found not to affect the relation between solar input and CO2 uptake, and the effect of chamber temperature was also very small. Dark respiration rates of the canopy were markedly sensitive to temperature, and also to the solar input prior to measurement. Respiration from the below-ground plant parts accounted for a considerable part of the total plant respiration. In all, 15&ndash;20 % of the net assimilation during daylight hours was lost by night respiration. There was little variation in CO2 efflux from uncropped soil during the experiments. Dry weight changes calculated from the gasometric measurements were in accordance with those found from previous growth analysis. * Part II, Aust. J. Agric. Res., 1973, 24, 751&ndash;62. 
ER  -

