Response of alfalfa to bidirectional selection for root bark area and xylem vessel diameter

1991 ◽  
Vol 71 (2) ◽  
pp. 427-435
Author(s):  
Shaoke Wang ◽  
M. A. Brick ◽  
C. E. Townsend
Keyword(s):  
Medicago Sativa ◽  
Vessel Diameter ◽  
Xylem Vessel ◽  
Root Bark ◽  
Response To Selection ◽  
Vessel Area ◽  
Medicago Sativa L ◽  
Selection For ◽  
Bidirectional Selection ◽  
Root Size

Development of alfalfa [Medicago sativa L. ssp. sativa and M. sativa ssp. falcata (L.) Arcangeli] germplasm with contrasting root bark area and xylem vessel area could be useful to evaluate relationships between anatomical root characteristics and plant functions such as drought tolerance. This study was conducted to determine the response of alfalfa to bidirectional selection for root bark area and xylem vessel area of the largest vessels as viewed in cross section. Bidirectional selection for large and small root bark area and for large and small xylem vessel area was conducted for two cycles. Selection for high root bark area resulted in an increase in root bark area in cycle one (C1), but no further response occurred in cycle two (C2). Response to selection for low bark area resulted in no response in the C1, but a response occurred in the C2. Response to selection for large xylem vessel area increased xylem area in the C1 but no further response occurred in the C2. There was no response to selection for small vessel area in either of the two cycles of selection. Asymmetrical responses to bidirectional selection were found. Root size increased significantly over the two cycles of selection and was probably due to indirect selection for large root size. Key words: Medicago sativa L., ssp. sativa and M. sativa ssp. falcata (L.) Arcangeli, root bark area, xylem vessel diameter

Effect of divergent selection for root size in field-grown alfalfa

1999 ◽  
Vol 79 (1) ◽  
pp. 93-95 ◽  
Author(s):  
O. Chloupek ◽  
M. Skácel ◽  
J. Ehrenbergerova
Keyword(s):  
Medicago Sativa ◽  
Root System ◽  
Selection Criterion ◽  
System Size ◽  
Forage Yield ◽  
Electrical Capacitance ◽  
Root System Size ◽  
Medicago Sativa L ◽  
Selection For ◽  
Root Size

The size of the root system as measured by its electrical capacitance was evaluated on two alfalfa (Medicago sativa L.) cultivars (Zuzana, Palava) for 3 yr. Plants with root system size (RSS) significantly larger or smaller than the cultivar mean were selected and their open-pollinated progenies were evaluated in the following 3 yr. Progenies of plants with large RSS tended to have larger RSS and higher forage yield than progenies of plants with small RSS. The differences for both parameters were significant (P < 0.05) in the case of Zuzana. It is concluded that RSS is a useful selection criterion in alfalfa breeding. Key words: Medicago sativa L., root system size, selection, yield, survival

scholarly journals Development of more productive and persistent lucerne by selection under frequent cutting

1994 ◽  
pp. 113-116
Author(s):  
R.G. Purves ◽  
R.B. Wynn-Williams
Keyword(s):  
Medicago Sativa ◽  
Grazing Management ◽  
Response To Selection ◽  
Selected Lines ◽  
Breeding Method ◽  
Breeding Lines ◽  
Selection Cutting ◽  
Cutting Frequency ◽  
Medicago Sativa L ◽  
Selection For

The area of luceme (Medicago sativa L.), regarded as the best adapted legume for dry areas of New Zealand, has declined by 67% over the last 2 decades. The major reason for the decline has been the effect of pests, diseases and poor grazing management on productivity and persistence. The development of disease- and pest-resistant cultivars has allowed plant breeders to investigate methods for developing grazing-tolerant lucernes. It has been suggested that frequent cutting is harder on plants than grazing and that it could be used to rapidly identify the survival characteristic of breeding lines. Lines surviving cutting every 4 m weeks for 2 seasons have been selected at Lincoln. To evaluate the breeding method these selected lines were compared with their parents, under 4- weekly cutting (frequent), 8-weekly cutting (infrequent) and frequent grazing. Frequent grazing was less severe on plants than frequent cutting and evaluation by this treatment was discontinued after 3 years. There was a trend towards increased production through selection under both frequent and infrequent cutting and there appeared io be line differences in response to selection. Persistence of lines after 7 years of frequent and infrequent cutting was significantly improved by selection for most lines. The different degrees of improvement between lines indicate that lines responded differently to selection. Cutting frequency had little effect on the final plant numbers of lines. The differences between cultivars and lines can be attributed to disease and pest resistance and adaptability of lines. The trial showed that selecting plants tolerant of frequent cutting can improve production and persistence. Keywords: frequent cutting, grazing, Medicago sativa, persistence, production, selection

SELECTION FOR SEED SET IN NONINBRED AND PARTLY INBRED POPULATIONS OF ALFALFA

1977 ◽  
Vol 57 (3) ◽  
pp. 873-881 ◽  
Author(s):  
R. MICHAUD ◽  
T. H. BUSBICE
Keyword(s):  
Medicago Sativa ◽  
Seed Set ◽  
Exponential Model ◽  
Seed Setting ◽  
Medicago Sativa L ◽  
Selection For ◽  
Inbred Populations ◽  
The Relationship ◽  
Advanced Generation ◽  
Coefficient Of Inbreeding

Alfalfa (Medicago sativa L.) is a highly heterozygous cross-pollinating species, and most breeding efforts have been conducted on noninbred populations. The purpose of this study was to determine whether greater breeding progress could be made by selecting within partly inbred populations rather than within noninbred ones. One hundred and twenty F1 (noninbred) and 120 S1 (partly inbred) plants that were issued from crossing and selfing four alfalfa clones were evaluated for self-fertility. The most self-fertile 10% of the plants from each family were selected in each population. The selected plants within each level of inbreeding were intercrossed to produce an advanced generation in which the effectiveness of the selection was evaluated. Selection increased both self- and cross-fertility in the advanced generation. Selection was more effective at the F1 level than at the S1 level. Fertility was reduced drastically by inbreeding. The average self-fertility of the S1’s was only about 7% of the cross-fertility of their parental clones. An exponential model was proposed to describe the relationship between seed setting and the coefficient of inbreeding in the developing zygote. This model explained 95% of the variation among 11 unselected populations having differing levels of inbreeding.

Identification and selection for salt tolerance in lucerne (Medicago sativa L.)

1984 ◽  
Vol 35 (2) ◽  
pp. 239 ◽  
Author(s):  
CL Noble ◽  
GM Halloran ◽  
DW West
Keyword(s):  
Salt Tolerance ◽  
Medicago Sativa ◽  
Recurrent Selection ◽  
Leaf Damage ◽  
Shoot Number ◽  
Two Generations ◽  
Medicago Sativa L ◽  
Selection For ◽  
Efficiency Of Selection ◽  
Chloride Concentrations

Variation existed between plants of the lucerne (Medicago sativa L.) cultivar CUF 101 for dry matter production, shoot number and length, and leaf damage when grown for 70 days under 250 mM NaCl (15 h photoperiod, 20�C day, 10�C night). Salt tolerance evaluation using the criteria percentage leaf damage (percentage of total number of leaves with complete or partial necrosis) and length of the main shoot, isolated plants which showed salt tolerance of reasonably high heritability (h2=0.41). Two generations of recurrent selection for tolerance significantly increased the mean population tolerance without decreasing production under non-saline conditions. While both sodium and chloride concentrations of the shoot were lower in the tolerant than in less tolerant plants, chloride was more closely associated with salt tolerance than sodium. Sodium and chloride concentrations in the roots did not vary with the level of salt tolerance. No association of shoot and root potassium concentration with tolerance was evident. Selection for salt tolerance in lucerne plants using percentage leaf damage of less than 10% as the main criterion should give a rapid response to selection. The efficiency of selection may be increased if selection is based on the efficiency of chloride exclusion from the shoots and/or the level of chloride tolerated by the shoots prior to leaf damage becoming evident.

COMPARISON OF YIELD COMPONENTS OF RED CLOVER AND ALFALFA

1988 ◽  
Vol 68 (1) ◽  
pp. 103-114 ◽  
Author(s):  
S. R. BOWLEY ◽  
C. T. DOUGHERTY ◽  
N. L. TAYLOR ◽  
P. L. CORNELIUS
Keyword(s):  
Medicago Sativa ◽  
Yield Components ◽  
Trifolium Pratense ◽  
Total Yield ◽  
Red Clover ◽  
Herbage Yield ◽  
Trifolium Pratense L ◽  
Medicago Sativa L ◽  
Stem Development ◽  
Selection For

Yield components of five regrowth cycles, two in 1981 and three in 1982, of three red clover (Trifolium pratense L.) populations and three alfalfa (Medicago sativa L.) cultivars were compared in swards. Red clover left more stubble but produced less herbage and accumulated total yield (herbage, stubble and 10 cm depth root) at a slower rate than alfalfa during most regrowths. The percent leaf at flowering of red clover was similar to that of alfalfa. Maximum LAI declined during successive regrowths each year. Maximum crop growth rates were 30 and 34 g m−2 d−1 for red clover and alfalfa, respectively. Stem development (canopy height) followed patterns of accumulation of herbage yield. The initiation of stems was slower in red clover and stem populations were less than that of alfalfa. Selection for faster stem initiation rates, higher stem populations, and reduced partitioning of dry matter towards stem bases which would be left as stubble were suggested as ways of increasing the herbage yield of red clover.Key words: Trifolium pratense L., Medicago sativa L., yield components, growth analysis clover (red), alfalfa

Alfalfa resistance to post-harvest Aspergillus species: Response to selection

2000 ◽  
Vol 80 (4) ◽  
pp. 755-763
Author(s):  
C. A. Kimbeng ◽  
S. R. Smith Jr. ◽  
V. Babij ◽  
K. M. Wittenberg
Keyword(s):  
Medicago Sativa ◽  
Leaf Area ◽  
Forage Yield ◽  
Fungal Resistance ◽  
Aspergillus Species ◽  
Response To Selection ◽  
Post Harvest ◽  
Species Response ◽  
Sib Families ◽  
Selection For

Alfalfa (Medicago sativa L.) cultivar development programs routinely incorporate resistance to fungal diseases that limit forage yield, quality and stand longevity. "Hay molding", caused by saprophytic fungi, reduces forage quality during the post-harvest period, but genetic resistance has not been reported. The objective was to determine the response to selection for post-harvest fungal resistance in alfalfa. Initially, 1144 genotypes from 22 alfalfa cultivars were screened for post-harvest fungal resistance with a combination of Aspergillus species. Forty resistant and 40 susceptible genotypes were selected by measuring percentage of leaf area with fungal coverage. The selected genotypes and their maternally derived half-sib families were screened for resistance to Aspergillus repens. Mean leaf area with fungal coverage was significantly (P < 0.05) lower for resistant than susceptible parental genotypes and maternal half-sib families. Percent leaf area with fungal coverage ranged from 13.2 to 70.5% (mean, 41.7 ± 1.7) among resistant and 28.2 – 83.4% (mean, 50.2 ± 1.7) among susceptible parental genotypes. Among the maternal half-sib families, resistant families ranged from 14.0 to 51.3% (mean, 32.1 ± 1.8) and susceptible families from 18.8 to 60.1% (mean, 40.3 ± 1.9). These results show a positive response to selection for post-harvest fungal resistance in alfalfa. Key words: Alfalfa, Medicago sativa, post-harvest fungi, Aspergillus species, breeding, divergent selection

Sign in / Sign up

Export Citation Format

Share Document