| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
a P.O. Box 110500, Dep. of Agronomy, Univ. of Florida, Gainesville, FL 32611-0500
b North Florida REC-Marianna, 3925 Hwy 71, Marianna, FL 32446-7906
c West Florida REC, P.O. Box 3634, Milton, FL 32572-3634
d Range Cattle REC, 3401 Experiment Station, Ona, FL 33865-9706
* Corresponding author (clover{at}ifas.ufl.edu)
‘Southern Belle’ red clover (Trifolium pratense L.) (Reg. no. CV-27, PI 638505) was released by the Florida Agricultural Experiment Station in 2002. This population was developed through cooperative research between the Agronomy Department, North Florida Research and Education Center (REC), West Florida REC, and Range Cattle REC at the University of Florida. The population was evaluated under the experimental designation Florida Meloidogyne Resistant Cycle 7 (FLMR7).
The breeding procedure for development of Southern Belle included a combination of recurrent genotypic and phenotypic selection using ‘Cherokee’ (Quesenberry et al., 1993) as the base population. In spring of 1986, plants with low gall and egg mass scores from three distinct red clover populations derived from Cherokee which had undergone selection for resistance to Meloidogyne arenaria race 1 (Ma), M. incognita race 3 (Mi), or M. javanica (Mj) were selected and intercrossed to develop one root-knot nematode (RKN) resistant population, designated "FLMR3." Numbers of plants intercrossed from each population were 38 for Ma, 41 for Mi, and 27 for Mj, for a total of 106 plants. Each of these individual populations had undergone two cycles of selection for low gall and egg mass numbers in response to its specific nematodes before intercrossing selected individuals as one population. Seed was harvested from individual plants to produce half-sib lines.
In winter 1986–1987, about 1750 plants representing the 106 half-sib lines from Cycle 3 were evaluated for galling and egg mass response when inoculated with Mi. A total of 149 plants from the top 26 families were intercrossed to produce Cycle 4 (FLMR4). Seed was again harvested from individual plants to produce half-sib families.
In winter 1987–1988, about 1100 plants from 84 of the half-sib lines from Cycle 4 that had adequate seed amounts were again evaluated for galling and egg mass response when inoculated with Mi. A total of 114 plants from the 16 top families were intercrossed to produce Cycle 5 (FLMR5). At this point, an equal amount of seed from each of the 114 plants was bulked to produce a composite population of all lines.
Mass selection was then used for additional selection for RKN resistance. About 3300 plants from FLMR5 were evaluated for low galling and egg mass response when inoculated with Mi. This evaluation was conducted in two stages during 1988 and 1989, with a total of 100 plants selected during the 2 yr. These plants were cloned and intercrossed in spring 1990 with a bulk harvest to produce FLMR6. This population was tested in various locations, including a location with high RKN populations at the Range Cattle REC, Ona, FL. In this research (Mislevy et al., 1994), FLMR6 had the least response to methyl bromide fumigation of any clover tested, supporting the finding of higher levels of RKN resistance.
In winter of 1993–1994, three groups of 300 FLMR6 plants each were inoculated with Ma, Mi, or Mj (Call et al., 1996, 1997a, 1997b). From these groups, plants were selected based on low gall and egg mass responses. These plants were cloned, and ramets of each plant were inoculated with the same species of nematode as was done previously. Only those plants that consistently had low gall and egg mass scores were selected. From this double screening, the following numbers of plants were selected: Ma = 25, Mi = 20, Mj = 36. Cuttings were made of each plant, and an average of three ramets were transplanted to the field for an isolated intercross. Seed was bulk harvested in spring 1994 to produce Cycle 7 (FLMR7).
In early spring 1995, about 5000 plants of FLMR7 were transplanted to the field to produce a seed increase nursery of this population. From this nursery, about 8.6 kg of clean seed were harvested. A sample of this seed was sent to California and used to establish a 0.3-ha pre-Breeder seed field in spring 1996. Seed was harvested from this field in late summer 1996 and entered into regional tests as FLMR7.
Southern Belle was superior to Cherokee and all other known red clover cultivars in resistance to the above RKN species. In a greenhouse evaluation experiment in 1996, Southern Belle had lower (P < 0.05) galling and egg mass scores than Cherokee when inoculated with Ma, Mi, or Mj. Nevertheless, Cherokee had lower (P < 0.05) ratings than ‘Kenstar’ in response to these same RKN. Although not specifically selected for resistance to M. hapla (Mh), Southern Belle also had lower (P < 0.05) galling and egg mass scores in response to this species than Kenstar or Cherokee (Quesenberry et al., 1997). Disease ratings taken on plots grown at Quincy, FL, show that Southern Belle had lower powdery mildew (caused by Erysiphe polygoni DC) ratings than Cherokee, Kenstar, and ‘Marathon’. In a greenhouse test at Madison, WI, Southern Belle was equal to Cherokee in northern anthracnose susceptibility (Quesenberry et al., 2002).
Southern Belle has been evaluated for seasonal distribution and total dry matter yield at multiple locations in Florida and across the southeastern USA. At Gainesville, FL, annual and 5-yr mean total seasonal dry matter yields of Southern Belle were not different (P > 0.05) from Cherokee. Similar results are demonstrated in yield performance data from Jay, FL, Popular, MS, and Franklin, LA. The primary yield advantage of both Southern Belle and Cherokee over other red clover cultivars when grown at more southern locations has been in first harvest yields, because of the nondormancy (earlier spring growth) of Southern Belle and Cherokee. First harvest yields of Southern Belle averaged across four growing seasons were approximately 1000 kg ha–1 greater than cultivars developed at more northern locations. It typically was not different from Cherokee in first-harvest yields, but usually was superior to cultivars developed at more northern locations such as Kentucky, Indiana, Iowa, and Wisconsin. Total seasonal yields of Southern Belle at southeastern locations usually equaled or exceed central- and northern-USA-developed cultivars.
At Gainesville, FL, more than 70% of Southern Belle spaced plants flowered before any plants of cultivars developed at more northern locations had flowered. This approximately 3-wk earlier growth and production of Southern Belle comes during a time in the growing season when Florida and southeastern USA beef cow-calf producers are generally experiencing a critical deficit in both quantity and quality of winter pastures.
Production and marketing rights for Southern Belle have been granted to Allied Seed, LLC., 9311 Hwy 45, Nampa, ID 83686. Breeder seed will be maintained by the Agronomy Department, University of Florida under controlled environmental conditions. Allied Seed LLC will conduct Foundation and Certified seed increases. Certified seed may be produced from Breeder or Foundation seed on stands not more than 3 yr old.
NOTES
Florida Agricultural Experiment Station Journal Series number R-10160. Registration by CSSA.
Accepted for publication March 31, 2005.
REFERENCES
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| 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 | |||
