Photosynthate partitioning in alfalfa before harvest and during regrowth. [Medicago sativa L]
- Texas A and M Univ., College Station (USA)
- Dept. of Agriculture, St. Paul, MN (USA)
During the harvest regrowth cycle of alfalfa (Medicago sativa L.) plants, factors such as source to sink distance, sink size, and inter-organ competition continually change. However, consequent changes in the pattern of photosynthate partitioning from leaves to other organs are poorly understood. The authors objective was to examine photosynthate partitioning from upper and lower alfalfa leaves at intervals before herbage harvest and during regrowth after harvest. The uppermost or lowest fully expanded leaf on the longest or dominant stem was labeled with {sup 14}CO{sub 2}. After a 24-h translocation period, the plants were divided into various organs to determine distribution of the radiocarbon. At that time, the upper leaf preferentially partitioned photosynthate to the shoot apex, unexpanded leaves and auxillary shoots of the dominant shoot, whereas the lower leaf preferentially distributed photosynthate to the crown shoots, crown, root, and nodules. Expressions of {sup 14}C partitioning were affected differently by organ mass. While the smallest organs such as nodules and unexpanded leaves always ranked higher for {sup 14}C based on relative specific activity, the largest organs such as roots and crown shoots accumulated the largest percentage of total plant recovered radioactivity. The results illustrate the importance of growth stage and leaf position in photosynthate partitioning in alfalfa and the dominance of herbage meristems for current photosynthate during regrowth.
- OSTI ID:
- 7066284
- Journal Information:
- Crop Science; (USA), Vol. 28:6; ISSN 0011-183X
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ALFALFA
PHOTOSYNTHESIS
CARBON 14 COMPOUNDS
CARBON DIOXIDE
PLANT GROWTH
TRACER TECHNIQUES
TRANSLOCATION
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
GROWTH
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEGUMINOSAE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PLANTS
SYNTHESIS
551001* - Physiological Systems- Tracer Techniques