Effects of Temperature on Photosynthesis and CO₂ Evolution in Light and Darkness by Green Leaves

Abstract

Abstract.Using an open and a closed system of gas analysis, it was found that CO., evolution in light and in darkness from plant leaves (sunflower, soybean, watermelon, eggplant, and jackbean) have a different response to temperature. While the rate of CO, evolution in light increased with incre-asing temperature from 17 to 350 and then declined, the rate of CO, evolution in darkness increased continuously up to 400. The rate of CO, evolution in light was affected by light intensity. At 1800 ft-c and below 350 the rate of CO2 evolution in light was greater than in darkness, but above 350 it beoame lower than in darkness. The Q10 for CO2 evolution in light was consistently lower than that in darkness.Apparent photosynthesis decreased with increasing temperature, from 20 to 400 and its rate was affected 'by both light intensity and oxygen concentration. In leaves of dicotyledonous plants studied 'the decrease in apparent photosynthesis between 20 to 300 at 21 % 02 was shown to be due primarily to an increase in CO. evolution in light with relatively little effect on photosynthesis.In corn which does not evolve CO2 during illumination there was little effect of increasing temperature on the rate of apparent photosynthesis.The different response to temperature of CO., evolution in light and in darkness support the earlier conclusion that these are 2 different processes.It has been reported that the rates of CO2 evolution by green leaves in light are affected by both O, concentration (6, 9, 11, 14, 29) and light intensity (3,6,15, 17,18,27). Decker (3) has shown that the post-illumination CO., outburst from tobacco at 33.5' was 3 times as large as that at 17.50 and Zelitch (34) has also shown that CO., evolution in light increases with a temperature increase from 250 to 350. Further data on the effect of temperature on CO. evolutioni in light is scanity although the response of CO.2 evolution in darkness has been well documented (19). Additional knowledge would be of interest since there is increasing evidence to in.dicate that in green 'leaves the processes leading to the evolution of CO., in light and in darkness mav be different (6,9,11, 17,23 35-day old watermelon and eggplants were used. The closed and the open systems of gas analysis were the same as described previously ( 15, 16). The closed system was used to study the magnitude of the post-illumination CO. outburst, the CO., compen'sation point, and the effect of CO) concen,tration on -the rate of apparent photosynthesis at various temperattures. The open system. was used to studv the effect of temperature on the steadv rates of apparent photosynthesis at 0.03 % CO2 in air anid CO., evolution into CO-free air in light and in darkness.The various leaf temperatures were obtained by circulating water (Hakke temperature controller) of the desired temperature around the leaf chamber.

Effect of high temperature on photosynthesis and transpiration of sweet corn (Zea mays L. var. rugosa)

“…These results are corroborated by a research of Hew et al (1969) who reported that P N of a sunflower leaf in a closed system exhibited a proportional decrease with temperature increases from 19 to 34 ºC. Baker et al (1992) reported that grain yield of rice decreased from 10.4 to 1.0 Mg ha -1 with increasing temperature from 28/21/25 °C to a 37/30/34 °C, a decrease of about nine productivity units per increase of 9 °C.…”

On the nature of the oxygen uptake in the light by Chondrus crispus. Effects of inhibitors, temperature and light intensity

“…In agreement with Hew et al [21] we found a higher optimum temperature for dark respiration compared to in vivo Rubisco activity. At 330/A CO2.1 -1 , dark respiration increased linearly with temperature up to 25 °C at least, whereas net O2 evolution started to decrease above 17°C, ( Figure 4B).…”

Dead or Alive? Using Membrane Failure and Chlorophyll a Fluorescence to Predict Plant Mortality from Drought

“…1A). The difference between night R and the recorded day R is likely explained by the significant difference in temperature (32 6 2°C and 25 3 4°C) between the day and night conditions in the greenhouse and the metabolic pathways activated by light during day time (Hew et al, 1969). In the droughted cohort some plants showed near-zero A after 6 d to 8 d of drought when their soil moisture was still close to 20% (Supplemental Fig.…”