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Sink strength regulates photosynthesis in sugarcane
A J McCormick1, M D Cramer, D A Watt
1South African Sugarcane Research Institute (SASRI), Crop Biology Resource Centre, Private Bag X02, Mt Edgecombe, 4300, South Africa. Alistair.mccormick@sugar.org.za
Sugarcane source-leaf photosynthesis increases when sink tissue is shaded, indicating a link between sugar availability and photosynthetic capacity. This research explores carbon partitioning in Saccharum spp.
Area of Science:
- Agricultural Science
- Plant Physiology
- Biochemistry
Background:
- Sugarcane (Saccharum spp.) productivity relies on efficient carbon partitioning between source (leaves) and sink (culm) tissues.
- Understanding the regulation of photosynthesis in response to sink demand is crucial for crop improvement.
Purpose of the Study:
- To investigate the relationship between source photosynthetic capacity and sink strength in field-grown sugarcane.
- To determine how altering the sink:source ratio affects carbon assimilation and partitioning.
Main Methods:
- Field-grown sugarcane (Saccharum spp. hybrid cv. N19) had its sink strength manipulated by shading leaves.
- Measurements included leaf gas exchange, chlorophyll fluorescence, and 14CO2 uptake and translocation.
- Sucrose, glucose, and fructose concentrations were analyzed in source and sink tissues.
Main Results:
- Shading treatments led to decreased sucrose concentrations in young internodes and shaded leaves.
- Unshaded leaves exhibited increased CO2-saturated photosynthetic rate (Jmax), carboxylation efficiency (CE), and electron transport rate after 8 days.
- A significant correlation was found between source hexose concentration and photosynthetic activity.
Conclusions:
- Up-regulation of source-leaf photosynthetic capacity is linked to reduced assimilate availability to the culm sink.
- Sugarcane photosynthetic activity is significantly influenced by source hexose concentration, highlighting a feedback mechanism.
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