Partitioning and mobilization of photoassimilate in alfalfa subjected to water deficits. [Medicago sativa L]

Journal Article · · Crop Science; (USA)

OSTI ID:7194659

Hall, M H ^[1]; Sheaffer, C C; Heichel, G H ^[2]

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1. Univ. of Idaho, Moscow (USA)
2. Univ. of Minnesota, St. Paul (USA)

Faster regrowth of a stressed alfalfa (Medicago sativa L.) crop compared to an unstressed crop after rewatering has been reported. The bases of this compensatory response are unknown, but they may be important to understanding adaptation to water stress and to developing crop water management strategies. The authors objectives was to determine the effect of stress induced by water deficit on photoassimilate partitioning and the utilization of stored assimilates during regrowth of alfalfa. Field and greenhouse experiments were conducted using cultivars differing in winterhardiness. Plants were subjected to water stress, pulse-labeled with {sup 14}CO{sub 2}, and sampled following 0, 1, 14, 21, and 28-d translocation periods. Following the 14-d sampling, herbage was harvested and water stress was removed. Cultivars contrasting in winterhardiness responded similarly to water stress. Stressed plant roots contained 73 and 114% more total plant radioactivity (TPR) than the control at the 1 and 14-d translocation periods, respectively. Water stress significantly increased root starch and TPR percentage in the starch fraction, but had much smaller effects on root soluble-sugar concentration and TPR percentage of the root sugar fraction. Herbage regrowth mass following harvest and rewatering of the water-stressed plants was similar to that of the control. Compared to the control, water-stressed alfalfa has greater total nonstructural carbohydrates in the roots, apparently due to increased photoassimilate partitioning to the roots. However, the greater root carbohydrate concentrations did not result in compensatory herbage regrowth following rewatering.

• OSTI ID: 7194659
• Journal Information: Crop Science; (USA), Journal Name: Crop Science; (USA) Vol. 28:6; ISSN CRPSA; ISSN 0011-183X
• Country of Publication: United States
• Language: English

Related Subjects

551001* -- Physiological Systems-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ALFALFA
CARBON 14 COMPOUNDS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
GROWTH
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LEGUMINOSAE
MAGNOLIOPHYTA
MAGNOLIOPSIDA
METABOLISM
OXIDES
OXYGEN COMPOUNDS
PHOTOCHEMICAL REACTIONS
PHOTOSYNTHESIS
PHYSIOLOGY
PLANT GROWTH
PLANTS
ROOTS
SYNTHESIS
TRACER TECHNIQUES
TRANSLOCATION