INHERITANCE OF DRY MATTER YIELD IN A HETEROZYGOUS POPULATION OF ALFALFA

1981 ◽  
Vol 61 (2) ◽  
pp. 313-318 ◽  
Author(s):  
STEVE R. BOWLEY ◽  
B. R. CHRISTIE

Additive and digenic variances for dry matter yield were estimated from a population of F1 lines of alfalfa (Medicago sativa L.). The F1 lines and their polycross (PX) progenies were both evaluated over three harvests in a simulated sward in a growth room. From the analyses of variance, the genetic variances of the F1 and PX lines were estimated and the covariance between the F1 and PX performance calculated for dry matter yield. Correlations between relatives were used to partition these variances into additive and digenic effects. Narrow-sense heritabilities and the expected response to selection were estimated for the F1 population and broad-sense heritabilities were calculated from the F1 and PX trials. The pooled estimates of additive variance were significantly greater than zero for the second harvest and total yield while all estimates of digenic variance were nonsignificant. This indicated that the genetic variance for dry matter yield was mainly additive. The expected response to selection for total dry matter yield, if the top 10% of the F1 lines were recombined, was 23% of the F1 population mean. Based on these results, it was concluded that selection gains for yield could be made in this population of alfalfa.

1992 ◽  
Vol 72 (2) ◽  
pp. 593-598
Author(s):  
B. R. Christie ◽  
J. L. Townshend

A study was conducted to evaluate response of alfalfa (Medicago sativa L.) to selection for resistance to the root-lesion nematode (Pratylenchus penetrans (Cobb) Filipjev and Sch.-Stek.) under growth-room facilities. Six hundred plants of the cultivar Vernal were inoculated with root-lesion nematodes. Counts were made 13–14 wk later of the number of nematodes g−1 root. Selections were made for relatively low counts (resistant) and high counts (susceptible). Selections were self-pollinated, and the S1 progeny of nine plants (five resistant and four susceptible) were evaluated. The S1 progenies from both types of selections had similar counts. The S2 progenies of resistant S1 parents, however, had lower counts than those of susceptible parents. The F1 crosses generally reacted as expected on the basis of the S2 parents. Results of this study suggest that progress can be made in breeding for resistance to the root-lesion nematode in alfalfa.Key words: Nematode, Pratylenchus penetrans, alfalfa, selection


1984 ◽  
Vol 64 (2) ◽  
pp. 309-317
Author(s):  
L. BELZILE ◽  
R. RIOUX

The effects of cultivars, seeding rates and dates on alfalfa (Medicago sativa L.) yield and quality in the seeding year were studied from 1971 to 1975 on a Kamouraska clay. Results showed the importance of seeding alfalfa before the end of May. Seedings made in early and in mid-May resulted in equivalent yield. Differences between cultivars were more important on the second than on the first cut. Regrowth was an important factor in the seedling year. The total yield of the Alfa cultivar is higher than Vernal and Narragansett and it is also higher for every combination of rates and seeding dates. Seeding rates were not an important factor except at the first cut where a rate of 6.7 kg/ha gave a lower yield than a rate of 13.4 kg/ha. Dry matter digestibility of Alfa is sometimes higher than for the other cultivars in the study. Late seeding generally increased the digestibility of the second cut dry matter, whereas rates of seeding have no effect on either first or second cut material. The crude protein content is not affected by seeding rates and the effects of cultivars are generally very small. With a delay in seeding dates the crude protein content of the second cut material is sometimes increased.Key words: Medicago sativa L., cultivar, date, rate


2017 ◽  
Vol 5 (2) ◽  
pp. 107
Author(s):  
Doohong Min ◽  
Iryna McDonald

The objective of this study was to evaluate the effect of planting alfalfa (Medicago sativa L.) with- and without cover crops on forage dry matter yield and nutritive values of alfalfa in Kansas, USA. In the first production year 2014, dry matter yield of mono-culture alfalfa appears to be compatible or even higher than planting with certain species of winter annual forages as a cover crop. Alfalfa planted with a combination of four different multi-species winter annual forages such as oats (Avena sativa L.), oilseed radish (Raphanus sativus L.), annual ryegrass (Lolium multiflorumL.), and turnip (Brassica rapa L.) had the highest dry matter yield of alfalfa in 2014.Dry matter yield of alfalfa in 2nd production year 2015 was similar to alfalfa + oats and alfalfa + oats + oilseed radish + annual ryegrass + turnip or significantly higher than alfalfa planted with annual ryegrass, oilseed radish, and turnip together. Based on two year of data in 2014 and 2015, the highest alfalfa yield occurred when alfalfa was planted with a combination of oats, oilseed radish, annual ryegrass, and turnip. The lowest dry matter yield of alfalfa occurred when alfalfa was planted with annual ryegrass.No significant differences in crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) were found when comparing alfalfa monoculture with alfalfa + oats, alfalfa + oilseed radish, alfalfa + oats + oilseed radish + annual ryegrass + turnip, and alfalfa + turnip treatments. When considering both dry matter and nutritive values of alfalfa, planting alfalfa with cover crops appears to be compatible or better practice than planting alfalfa monoculture.


1985 ◽  
Vol 40 (2) ◽  
pp. 267-277 ◽  
Author(s):  
T. A. Stewart ◽  
I. I. McCullough

ABSTRACTSilage cut twice annually (June and August) from a tetraploid red clover/grass sward and three times annually (May, July and September) from a low nitrogen (N) and high N perennial ryegrass/white clover sward was fed in proportion to dry-matter yield from each cut, over a 10-week period, each winter for 3 years to castrated male cattle of initial live weight 401 kg in year 1 and 425 kg in years 2 and 3. The silages were supplemented with 0, 1, 2 and 3 kg concentrate per head daily.Total dry-matter yield from the red clover/grass sward was similar to that from the perennial ryegrass/white clover sward (high N grass) receiving 360 kg N per ha but the digestibility, particularly of first cut material was much lower. Dry-matter production of the low N grass/white clover sward was 0·73 of high N grass sward and produced silages of similar digestibility and fermentation.Dry-matter intakes by the cattle were higher on the legume-based silages in years when clover made a worthwhile contribution to total yield, but this did not significantly improve utilization or animal performance compared with high N grass silage. Mean daily carcass gain per head on red clover/grass silage was 0·41 kg which was significantly less than the 0·61 kg on white clover/grass silage and 0·59 on high N grass (P < 0·001). Carcass output from red clover/grass silage was 618 kg/ha and 629 kg/ha from white clover/grass, both of which were significantly less than the 863 kg/ha from the high N grass silage (P < 0·001). Dressing proportion was also significantly poorer in animals fed red clover/grass silage compared with the other silage types.


1968 ◽  
Vol 48 (2) ◽  
pp. 167-173 ◽  
Author(s):  
D. A. Cooke ◽  
S. E. Beacom ◽  
W. K. Dawley

Two 6-year-old grass–alfalfa mixtures were compared when fertilized with 0, 84 and 168 kg nitrogen per hectare and grazed by yearling Hereford steers. The effect of stocking rate, fertilization, forage mixture and year on the cumulative liveweight gain per hectare was also determined. The bromegrass (Bromus inermis L.) and alfalfa (Medicago sativa L.) mixture showed a linear increase in dry matter yield, but the nitrogen requirement of the intermediate wheatgrass (Agropyron intermedium L.) and alfalfa mixture was fully met by the 84-kg/ha N treatment. In 1960, the addition of 84 and 168 kg/ha N to the bromegrass–alfalfa increased animal production by 61 and 98% respectively. Corresponding increases of 53 and 56% were obtained from the fertilized intermediate wheatgrass–alfalfa mixture. Similar percentage increases were obtained in 1961. The 84-kg/ha N treatment reduced the alfalfa content of both mixtures by more than 40%. The 168-kg/ha N treatment practically eliminated the alfalfa from the stands. Nitrogen recovery by the bromegrass–alfalfa was similar at both fertility levels and amounted to 62% in 1960, and 24% in 1961. Recovery of nitrogen by intermediate wheatgrass–alfalfa was 62 and 36% from the 84- and 168-kg/ha N treatments in 1960, and 23 and 12% respectively in 1961.


1970 ◽  
Vol 21 (4) ◽  
pp. 583 ◽  
Author(s):  
GJ Leach

Lucerne (Medicago sativa L.) plants grown to two stages of maturity were cut at 2, 5, or 10 cm above the crown. In addition, the leaf on the stubble and on basal shoots was either removed or retained. The change in the number and size of the regrowth shoots growing from different heights above the crown, and the total yield of dry matter, were observed for 4 weeks after cutting. Nearly all the regrowth shoots arose from very near to the crown, either on the crown itself or from within the first 2 cm above it, so that cutting at higher levels increased shoot numbers only slightly. Also most of the shoots arising from near the crown resumed extension growth earlier, and therefore grew larger, than the shoots arising from higher positions. In general the growth of shoots from one stubble segment was not influenced by whether segments were still present above. Increasing the cutting height above 2 cm consequently produced little effect on the yield of dry matter 2 and 4 weeks after cutting. Retaining stubble leaf and basal shoot leaf increased the shoot yield 2 and 4 weeks later, because the basal shoots resuming growth first grew larger than those on plants from which leaves were removed. The effect of retaining leaves was independent of the stage of maturity when the plants were cut and of the cutting height.


1970 ◽  
Vol 21 (2) ◽  
pp. 195 ◽  
Author(s):  
PC Whiteman ◽  
A Lulhan

Plantings of D. uncinatum and P. atropuvpureus were made in October and December 1965 and February and April 1966, and subsequently the plots were either rotationally grazed by sheep, cut with a mower at 3 inches, or left undefoliated. Monthly samples were taken to determine individual plant dry weight, nodule weight per plant, nodule number, and mean weight per nodule. Three samples for plot dry matter yield were also taken. Individual plant dry weight was higher in the October and December sowings, although by the end of the second growing season dry matter yield per plot was higher in the December and February sowings. Dry matter yield of legume was depressed by April planting. D. uncinatum began regrowth in spring 2 months earlier than P, atropurpureus, when minimum temperatures exceeded 48-50�F compared with 57' for P. atropurpureus. Both species had marked seasonal peaks in nodule and plant dry weight. The rapid decline in nodule weight could not be directly related to the onset of flowering or frosts. Grazing caused a greater reduction than cutting in terms of plant and nodule weight and legume yield. In P. atropurpureus nodule weight per plant was reduced through a decline in mean weight per nodule, while in D. uncinatum grazing and cutting reduced nodule number per plant.


1980 ◽  
Vol 20 (105) ◽  
pp. 447 ◽  
Author(s):  
JAG Irwin ◽  
DL Lloyd ◽  
RA Bray ◽  
PW Langdon

Seedlings of lucerne (Medicago sativa) with increased resistance to anthracnose caused by Colletotrichum trifolii, were obtained from cvv. Hunter River and Siro Peruvian by selection through two generations under laboratory conditions. Glasshouse screening of half sib F1 and F2 families confirmed that rapid progress was made in increasing the level of resistance in both populations. In the field, after two years, F1 derivatives had lower percentages of plant mortality and disease indices than their parent cultivars, and F2 derivatives had lower values than their F1 parents. The F2 population of Siro Peruvian, in the second year, yielded 55% and 45% more dry matter than the unselected populations of Siro Peruvian and Hunter River respectively. However, the level of resistance in the field of the Siro Peruvian F2 population was only the equivalent of the unselected Hunter River population, and was inferior to the F1 and F2 populations of Hunter River.


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