Heritability and genotypic and environmental correlations of creeping root and persistency in Medicago sativa L.

1968 ◽  
Vol 19 (1) ◽  
pp. 27 ◽  
Author(s):  
H Daday
Keyword(s):  
Medicago Sativa ◽  
Plant Density ◽  
Genetic Correlations ◽  
Response To Selection ◽  
Environmental Correlations ◽  
Continuous Grazing ◽  
Medicago Sativa L ◽  
River Plants

This study examines the relationships between creeping-rootedness, plant diameters, and persistency in lucerne. Highly significant positive genetic correlations were found between all three plant characters among families under continuous grazing. The investigations disclosed several trends in genetic and environmental correlations, the significance of which is discussed. The heritabilities for the proportion I of creeping plants (0.41), plant diameter (0.32–0.45), and survival (0.23–0.46) were all high, indicating that response to selection is possible. The results showed that plant density decreased under continuous grazing; 66% of the creeping-rooted plants but only 8% of Hunter River plants survived after 17 months of continuous grazing.

Effects of stand age on agronomic, morphological and chemical characteristics of alfalfa

1991 ◽  
Vol 71 (2) ◽  
pp. 445-452 ◽  
Author(s):  
Michio Suzuki
Keyword(s):  
Medicago Sativa ◽  
Cold Hardiness ◽  
Plant Density ◽  
Age Groups ◽  
Stand Age ◽  
Chemical Characteristics ◽  
Total Nonstructural Carbohydrates ◽  
Vertical Extension ◽  
Shoot Number ◽  
Medicago Sativa L

Iroquois alfalfa (Medicago sativa L.) was seeded every spring from 1978 to 1988, and the established stands were maintained until the fall of 1988. Agronomic, morphological and chemical characteristics of the stands were compared among different age groups. A drastic reduction of alfalfa population occurred in the seeding year and during the first winter. There were about 40 plants m−2 in the 2nd yr which gradually decreased to 25 plants m−2 in the 8th yr, and between 12 and 24 plants m−2 in the 10th yr. There were more grass weeds in older stands. Total dry matter yield of forage, including weeds, did not decrease significantly with age of alfalfa stand Alfalfa yield, however, decreased with age, and the reduction in older stands was more evident in cut 1 than cut 2. There was little or no difference in cold hardiness among different stand ages in postseeding years. Root development pattern changed from vertical extension in the seeding year to lateral development of branched roots in postseeding years. Shoot number, crown diameter, crown decay taproot diameter, root depth, and number and spread of branched roots were associated with aging. Concentrations of total nonstructural carbohydrates (TNC) in the crown and roots decreased slightly with age. In the root, concentrations of K, Ca, B, and Fe increased, and Ca was most closely associated with age. No significant association of P, Mg, S, Mn, Cu, or Zn with age was found. Concentrations of minerals in the crown did not change with age, except B which increased slightly. Key words: Medicago sativa L., persistence, longevity, plant density, yield, minerals

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

scholarly journals Sensitivity of Winter-Active Lucerne (Medicago sativa L.) to Different Grazing Regimes

Agronomy ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 124 ◽  
Author(s):  
Vivianne Burnett ◽  
Jeff Hirth ◽  
Kym Butler ◽  
Meredith Mitchell ◽  
Steve Clark ◽  
...  
Keyword(s):  
Medicago Sativa ◽  
Plant Density ◽  
Management Practice ◽  
New South ◽  
Management Program ◽  
Grazing Management ◽  
Rotational Grazing ◽  
South Wales ◽  
Medicago Sativa L ◽  
Summer Growth

Lucerne (alfalfa; Medicago sativa L.) is the key forage for grazing in dryland temperate regions around the world. While rotational grazing of lucerne is recommended, in southern Australia the intervals between grazing events are often chosen in an opportunistic manner, to meet livestock production targets and utilise excessive spring and summer growth. To assess whether the persistence of lucerne is sensitive to variations in rotational grazing management practice, we report on an experiment with four sheep grazing treatments that was conducted for 2.5 years, including three summers, in southern New South Wales. The grazing management treatments were a crash-grazing control, frequent grazing, feed-based rotational grazing and time-based rotational grazing, replicated four times. The number of grazing events, percentage of time under grazing, lucerne top dry matter (DM) at the beginning and end of grazing periods and plant density were measured. The results relating to number of grazing events, percentage of time grazing and DM removed during grazing indicated that four grazing practices had been achieved. The treatments all had significant periods of rest for at least 73% of time and were empirically different in their approach but resulted in similar grazing pressures, in terms of overall pasture removed during grazing. Nevertheless, there was little difference in lucerne densities between grazing treatments over the life of the experiment. We conclude that there is flexibility in the rotational management of grazed lucerne provided adequate rest periods are part of the management program.

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

ALFALFA (Medicago sativa L. and M. falcata L.) CULTIVAR × ROW SPACING INTERACTION ON YIELD AT A SEMIARID ENVIRONMENT IN SOUTHWESTERN SASKATCHEWAN

1984 ◽  
Vol 64 (4) ◽  
pp. 895-900 ◽  
Author(s):  
R. B. IRVINE ◽  
P. G. JEFFERSON
Keyword(s):  
Drought Tolerance ◽  
Medicago Sativa ◽  
Plant Density ◽  
Physiological Traits ◽  
Yield Response ◽  
Row Spacing ◽  
Semiarid Environment ◽  
Medicago Sativa L ◽  
Lower Plant

Ten alfalfa (Medicago sativa L. and M. falcata L.) cultivars were grown in 30- and 90-cm row spacings on a dryland site at Swift Current, Saskatchewan. From 1979 to 1981 there was a significant cultivar × spacing interaction on yield at every harvest except the second cutting in 1981. The M. falcata cultivars, Anik and Sc MF 3713, were better able to exploit the lower plant density at the 90-cm spacing than M. sativa cultivars, Thor and Banner. Yields of Anik and Sc Mf 3713 increased with 90-cm compared to 30-cm spacing, while Thor and Banner decreased. The creeping rooted cultivars Rambler and Rangelander did not differ from Anik or Sc Mf 3713 in yield response to increased row spacing. This suggests that the observed cultivar × spacing interaction was due to morphological and/or physiological traits associated with the M. falcata cultivars, other than the creeping rooted habit.Key words: Creeping rooted, drought tolerance, WUE

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