| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Dep. of Agronomy, Lilly Hall of Life Sciences, Purdue Univ., West Lafayette, IN 47907-1150
* Corresponding author (bjoern{at}dept.agry.purdue.edu).
Recent studies suggest that alfalfa (Medicago sativa L.) root carbohydrate concentrations are not correlated closely with shoot regrowth, and that root N reserves may influence shoot regrowth after harvest. The objectives of this greenhouse study were to (i) determine the effects of supplemental N on alfalfa regrowth and N uptake, (ii) quantify N remobilization from roots to regrowing shoots, and (iii) determine if certain root N pools, including vegetative storage proteins (VSPs), were utilized preferentially as N sources during early shoot regrowth. Four cultivars with contrasting fall dormancy reaction were defoliated and supplied with 85 mg N (kg soil)–1 as 15N-enriched (NH4)2SO4 or KNO3. Samples were taken immediately and once weekly for 28 d. After 28 d, plants were again defoliated and shoots, crowns, and roots of one-half of the plants sampled immediately. Intact crowns and roots of remaining plants were transplanted into sand, and shoots, crowns, and roots sampled 10 d after transplanting. Taproot N from these samples was partitioned into four specific pools. Nitrate-N uptake was greater than NH4-N uptake at 7 and 28 d after N application. Ten days after transplanting, 25% of crown and root total N and 35% of crown and root 15N was remobilized to regrowing shoots. Fifty-five percent of total root N was soluble in phosphate buffer. The buffer-soluble N pool was fractionated into a low molecular weight N pool (
30% of total root N), a non-VSP protein N pool (20% of total root N), and a VSP-enriched protein N pool (5% of total root N). The low molecular weight N and VSP-enriched protein N pools in roots were utilized preferentially as N sources for regrowing shoots 10 d after transplanting. Accumulation of these root N pools may be important for rapid early shoot regrowth after defoliation.
Received for publication June 7, 1995.
This article has been cited by other articles:
|
|
 |
|
  F. MEURIOT, J.-C. AVICE, J.-C. SIMON, P. LAINE, M.-L. DECAU, and A. OURRY Influence of Initial Organic N Reserves and Residual Leaf Area on Growth, N Uptake, N Partitioning and N Storage in Alfalfa (Medicago sativa) during Post-cutting Regrowth Ann. Bot., August 1, 2004; 94(2): 311 - 321. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. M. Haagenson, S. M. Cunningham, B. C. Joern, and J. J. Volenec Autumn Defoliation Effects on Alfalfa Winter Survival, Root Physiology, and Gene Expression Crop Sci., July 1, 2003; 43(4): 1340 - 1348. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. M. Haagenson, S. M. Cunningham, and J. J. Volenec Root Physiology of Less Fall Dormant, Winter Hardy Alfalfa Selections Crop Sci., July 1, 2003; 43(4): 1441 - 1447. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
C. Dhont, Y. Castonguay, P. Nadeau, G. Belanger, and F.-P. Chalifour Alfalfa Root Nitrogen Reserves and Regrowth Potential in Response to Fall Harvests Crop Sci., January 1, 2003; 43(1): 181 - 194. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 E. Justes, P. Thiebeau, J.-C. Avice, G. Lemaire, J. J. Volenec, and A. Ourry Influence of summer sowing dates, N fertilization and irrigation on autumn VSP accumulation and dynamics of spring regrowth in alfalfa (Medicago sativa L.) J. Exp. Bot., January 1, 2002; 53(366): 111 - 121. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. D. Redfearn, B. C. Venuto, and W.D. Pitman Nutritive Value Responses of Rhizoma Peanut to Nitrogen and Harvest Frequency Agron. J., January 1, 2001; 93(1): 107 - 112. [Abstract] [Full Text]
|
|
|
|
|
|
R.H. Skinner, J. A. Morgan, and J. D. Hanson Carbon and Nitrogen Reserve Remobilization Following Defoliation: Nitrogen and Elevated CO2 Effects Crop Sci., November 1, 1999; 39(6): 1749 - 1756. [Abstract] [Full Text]
|
|
|
|
 |
|
 J. A. Gana, N. E. Kalengamaliro, S. M. Cunningham, and J. J. Volenec Expression of beta -Amylase from Alfalfa Taproots Plant Physiology, December 1, 1998; 118(4): 1495 - 1506. [Abstract] [Full Text]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| The SCI Journals | Agronomy Journal | Vadose Zone Journal | |||
| Journal of Natural Resources and Life Sciences Education |
Soil Science Society of America Journal | ||||
| Journal of Plant Registrations | Journal of Environmental Quality |
The Plant Genome | |||
