Effect of Growing Soybean Plants Under Continuous Light on Leaf Photosynthetic Rate and Other Characteristics Concerning Biomass Production
Titel:
Effect of Growing Soybean Plants Under Continuous Light on Leaf Photosynthetic Rate and Other Characteristics Concerning Biomass Production
Auteur:
Minobu Kasai
Verschenen in:
Journal of agronomy
Paginering:
Jaargang 7 (2008) nr. 2 pagina's 156-162
Jaar:
2008
Inhoud:
The present study investigated various characteristics concerning photosynthetic source capacity and biomass production of intact soybean plants grown under daily 10 h photoperiod as controls or under continuous light without darkness as CL plants from sowing. It was shown that while total photosynthetic source capacity and total dry matter production were larger in CL plants than in control plants, photosynthetic rate per unit leaf area and dry matter production of reproductive organs (pods) were smaller in CL plants than in control plants. It was also shown that CL plants had similar leaf intercellular CO2 concentration despite having lower leaf stomatal conductance and had lower activation state of Rubisco and similar content of leaf Rubisco as compared to control plants. With leaf microsomal membranes, three phosphatase activities, which have been found to increase under limitation of inorganic phosphate, were shown to be higher in CL plants than in control plants. Content of starch, a major photosynthetic end product in leaf was higher in CL plants than in control plants, showing that CL plants were subjected to a surplus source, an imbalance of photosynthetic source/sink balance. There are previous findings that inorganic phosphate stimulates the activation of Rubisco by promoting the binding of activator CO2 to the uncarbamylated inactive Rubisco. There is also evidence for the accumulation of starch in leaf under limitation of inorganic phosphate. Therefore, these results suggest that under continuous light that gives a surplus source, although plant total photosynthetic capacity and total biomass production are likely to increase, the efficiency of plant photosynthetic matter production is likely to decrease because of a lowered activation state of Rubisco that is likely to result from the limitation of inorganic phosphate. It is thus suggested that for the efficient improvement of plant biomass production, well-balanced improvement of source and sink would be essential.
Uitgever:
Asian Network for Scientific Information (provided by DOAJ)
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