Effects of Light Intensity, CO2 Concentration, and Temperature on Photosynthesis of Asparagus officinalis L
1989 Volume 58 Issue 2 Pages 369-376
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1989 Volume 58 Issue 2 Pages 369-376
In order to establish a reasonable culture procedure for edible asparagus (Asparagus officinalis L.) in the warm regions of Japan, it is necessary to determine its physiological and ecological characteristics.
This paper reports on the photosynthesis of asparagus, which plays the basal role for growth, development, and dry matter production for the following season.
1. Photosynthesis in asparagus was mainly observed on cladophylls into which stems turned. The main stem, and lateral shoot to which cladophylls were not attached also photosynthesized. Especially, the net photosynthetic rate of lateral shoots of 0.5-1mm diameter reached about 30% of that of cladophylls measured as mg CO2 per 1g dry weight per hour. The net photosynthetic rate of main stem was 0-3% of that of cladophylls.
2. Respecting the effect of light intensity on net photosynthesis, net photosynthetic rate of most plants at the early and middle stages, and at the late stage of development was saturated at 40-50klx and 10-20klx of light intensity respectively. Light compensation points of them were ranged from 1.5 to 2klx.
3. Respecting the effect of CO2 on net photosynthesis, when measured by increasing the CO2 concentration (400→1400ppm), CO2 saturation was observed between 400 and 1000ppm. On the other hand, when measured by decreasing the CO2 concentration (1400→400), CO2 saturation was not observed in the range from 400 to 1400ppm. The photosynthetic rate measured with the latter procedure was less than that of the former, compared at each of the same CO2 concentrations.
4. The favorable range of temperature for photosynthesis was 20±5°C.
5. The response to light, CO2 and temperature for net photosynthesis was similar among plants at early, middle and late stages of development. Diurnal fluctuation of net photosynthesis was clearly observed when intact plants were measured, and the net photosynthetic rate decreased in the afternoon. On the other hand, cut plants did not show this fluctuation.
