A study on the respiration of Cymbidium

1. Ultrastructure of root and leaf mitochondria: the crest structure in root mitochondria is denser than that in leaves, and leaf mitochondria are basically distributed near chloroplasts, which has important biological significance.

2. The pathways of material metabolism and energy metabolism: the determination of the key enzyme activities of glycolysis pathway, tricarboxylic acid cycle and phosphate hexose branch and the application of various respiratory inhibitors show that the catabolism of carbon-water complex mainly takes the EMP pathway-TCA cycle, while HMP is the secondary pathway. EMP pathway and HMP pathway were highly active in roots and leaf buds, and decreased with the increase of leaf age. The activity of TCA cycle in roots and young leaf buds was lower than that in mature leaves. Energy metabolism mainly follows the normal respiratory electron transport chain, and there is no cyanide-resistant respiration.

3. The effect of temperature on respiratory rate and respiratory quotient: the respiratory rate of leaves and roots increased with the increase of temperature, and the temperature coefficient Q10 was between 2 and 3. The optimum temperature of leaf respiration was about 35 ℃, and that of root respiration was about 30 ℃. When the temperature exceeded 35 ℃, the root respiratory system was damaged. The respiratory quotient (RQ) of roots and leaves were lower when the temperature was less than 25 ℃, and approached to 1 with the increase of temperature. The respiration rate of leaves in CO2-free air was 1.5 times higher than that in normal air and 0.7 times higher in roots.

4. The effect of light on the root respiration rate of several orchids: light can obviously stimulate the respiration of the "etiolated roots" of some aerial orchids. However, it had little effect on the respiration of rooting. (Ye Qingsheng, Pan Ruichi)