Date of Award:

1991

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Plants, Soils, and Climate

Advisor/Chair:

Bruce Bugbee

Abstract

Plant breeders often examine leaf size, plant height and photosynthetic capacity in an effort to increase wheat yield. This study was concerned with the relationship between these parameters in dwarf and semidwarf wheat cultivars (Triticum aestivum L.) with a wide range in flag leaf size. Photosynthetic capacity was measured at anthesis using photosynthesis versus intercellular CO2 response curves to determine maximum photosynthetic rate and ribulose-1,5- bisphosphate carboxylase efficiency. Leaf area, chlorophyll concentration, stomatal density, interveinal distance and dry mass partitioning were also examined. Smaller flag leaves had greater carboxylation efficiency and closer vein spacing. Dwarf wheat had higher chlorophyll concentrations and maximum photosynthetic rates at anthesis than the taller semi-dwarfs. Dwarf cultivars had lower photosynthetic rates before anthesis, suggesting preanthesis feedback inhibition of photosynthesis, possibly due to a smaller sink capacity of its stem.

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