RESPONSE TO SELECTION FOR STEM LENGTH IN RED CLOVER EVALUATED AT WIDE AND NARROW SPACINGS

1984 ◽  
Vol 64 (4) ◽  
pp. 925-934 ◽  
Author(s):  
S. R. BOWLEY ◽  
N. L. TAYLOR ◽  
P. L. CORNELIUS ◽  
C. T. DOUGHERTY

Six cycles of phenotypic recurrent selection for stem length were conducted in a 91-cm-spaced planted population of red clover (Trifolium pratense L.) as a means of increasing herbage yield. The objectives of this investigation were (1) to compare the effectiveness of selection for stem length tested in transplants at wide (91 cm) and narrow (7 cm) spacings, and in row seedings and (2) to determine the effect of selection for stem length on herbage yield. Response to selection for stem length was obtained under all plantings; however, greater gains were observed at the wide transplant spacing (3.3 cm∙cycle−1) compared to the narrow transplant spacing (0.7 cm∙cycle−1) and row seeding (0.8 cm∙cycle−1). Densely spaced transplants gave performance similar to row seedings and may be of value to forage crop breeders in situations where yield or quality assessment is desired but seed supplies are insufficient for the establishment of seeded plots, such as in the early stages of breeding programs. Selection for stem length was effective in increasing herbage yield at first harvest but was associated with reduced persistance, decreased regrowth yields, and increased partitioning of dry matter towards the shoot rather than the root during seedling development. Selection for stem length in the regrowth or in the second year, rather than in the primary (seedling) growth, might have avoided the declines in persistence and regrowth yields.Key words: Trifolium pratense L., red clover, recurrent selection, stem length, density, herbage yield

1988 ◽  
Vol 68 (1) ◽  
pp. 103-114 ◽  
Author(s):  
S. R. BOWLEY ◽  
C. T. DOUGHERTY ◽  
N. L. TAYLOR ◽  
P. L. CORNELIUS

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


1999 ◽  
Vol 79 (3) ◽  
pp. 357-359 ◽  
Author(s):  
B. R. Christie ◽  
R. A. Martin

To increase the persistence of red clover (Trifolium pratense L.), phenotypic recurrent selection was conducted under field conditions. After three cycles of selection, a strain designated as CRS-16, was developed. This strain has better persistence than the check cultivars, Florex and Marino, and has a more fibrous root system. Among 4-yr-old plants, about 10% initiated new shoots from below the crown. Key words: Red clover, Trifolium pratense L. persistence, root type


2003 ◽  
Vol 60 (3) ◽  
pp. 447-452 ◽  
Author(s):  
Daniel Portella Montardo ◽  
Miguel Dall'Agnol ◽  
Nilton Rodrigues Paim

Red clover (Trifolium pratense L.) is one of the most important temperate legume species, used to lessen the lack of forage during the critical fall-winter period in Rio Grande do Sul, RS, Brazil. However, its utilization has been restricted mainly because of its lack of persistence. This work evaluates the dry matter yield and persistence of red clover half-sib progenies in two physiographic regions of RS: "Depressão Central", in Eldorado do Sul and "Encosta Superior do Nordeste", in Veranópolis. Experiments were carried out for two growing seasons and results were compared to two red clover commercial checks, Qüiñequeli and Estanzuela 116. The region of Veranópolis was more adequate for red clover forage production, enabling better yield and persistence. The best check for both locations was cultivar Estanzuela 116. At Eldorado do Sul persistence was highly affected and some progenies were superior to the best check. At Veranópolis the best check was very productive, with good persistence. The best progenies at both locations were selected to be propagated and submitted to additional recurrent selection cycles.


1999 ◽  
Vol 79 (3) ◽  
pp. 351-356 ◽  
Author(s):  
B. C. Venuto ◽  
R. R. Smith ◽  
C. R. Grau

In Wisconsin, Fusarium oxysporum, Schlect., a pathogen causing vascular wilt, is the most prevalent fungal pathogen recovered from diseased red clover (Trifolium pratense L.) plants. This study was conducted to determine the mode of inheritance for red clover resistance to this pathogen and to develop resistant germplasm. Virulent isolates of this pathogen, collected from red clover plants at the Ashland Research Station, Ashland, Wisconsin, were used to screen three populations, the red clover cultivars Arlington and Marathon and the C11 germplasm, for resistant plants. Plants were inoculated with the pathogen and evaluated for reaction, using a disease-severity index (DSI) score from 1 to 5 (1 = no reaction, 5 = plant dead). Selected plants from each cycle were intercrossed to produce subsequent generations. After two and three cycles of selection, the developed populations were simultaneously evaluated for gain from selection. The gain from selection for resistance in these populations (cycle 0 minus cycle 2) ranged from 0.31 to 0.48, 0.12 to 0.75, and 0.13 to 0.83 DSI units, respectively, for Arlington, Marathon, and C11. Estimated narrow-sense heritabilities, based on cycle-1 and cycle-2 progeny, were, respectively, 0.20 and 0.37 for Arlington, 0.15 and 0.13 for Marathon, and 0.06 and 0.17 for C11. These results indicate that resistance is a quantitative trait controlled by many loci, each contributing some portion to overall resistance in the host. Key words: Red clover, Trifolium pratense L., Fusarium oxysporum, vascular wilt, resistance


1964 ◽  
Vol 12 (1) ◽  
pp. 1 ◽  
Author(s):  
GJ Hindmarsh

Development of the male and female gametophytes is traced in detail, and departures from the normal sequence of events are found at several points. Among these are pollen abortion, failure of the archesporial cell to develop in the ovule, and collapse of the embryo sac during its development. The formation of two embryo sacs per ovule is of relatively common occurrence, and this is followed by the breakdown of one or both of them. In addition, either the egg apparatus degenerates before fertilization or the nucellar plug may fail to disintegrate and so form a barrier to the passage of the pollen tube through the micropyle. The occurrence of an ovule in which an embryo sac was developing apomictically suggests that a breeding programme based on selection for somatic apospory, rather than high seed yield from sexually reproducing plants, would probably produce a strain of red clover which could maintain itself in pastures.


1997 ◽  
Vol 77 (4) ◽  
pp. 601-605 ◽  
Author(s):  
P. H. Martin ◽  
B. E. Coulman ◽  
J. F. Peterson

Virus diseases are known to reduce the yield and persistence of stands of red clover (Trifolium pratense L.). Alfalfa mosaic virus (AMV) is one of the causes of mosaic in red clover and may also cause mottling and leaf distortion. The goals of this study were to identify genotypes resistant to AMV within commercial red clover cultivars and to determine the inheritance of this resistance. Cultivars and progenies were screened for resistance by means of mechanical inoculations. Plants showing no symptoms after three successive inoculations were assayed for the presence of the virus using ELISA (enzyme-linked immunosorbent assay). Resistant plants were detected at a frequency of just over 1% in the five cultivars screened. Crosses among and between resistant (R) and susceptible (S) plants were carried out over two successive cycles of selection. In cycle 1, R × R crosses produced a higher frequency of resistant plants (19.8%) in the progenies than R × S crosses (10.9%). S × S crosses produced no resistant progeny. For crosses of resistant plants from cycle 1 progeny, (R × R) × (R × R) produced 47.8%, (R × R) × (R × S) produced 31.4% and (R × S) × (R × S) produced 29.3% resistant cycle 2 progeny. Crosses of resistant and susceptible cycle 1 plants resulted in resistance frequencies in cycle 2 which were not significantly (P < 0.05) greater than cycle 1. When only resistant plants were selected for further crossing, the percentage of resistant plants increased from 1.3 to 47.8 over the two cycles of selection. It was concluded that resistance to AMV in red clover is under polygenic control and that it should be relatively simple to select a highly resistant population through recurrent selection. Key words: Red clover, Trifolium pratense L., virus disease, alfalfa mosaic virus, recurrent selection


1997 ◽  
Vol 77 (1) ◽  
pp. 77-81 ◽  
Author(s):  
Y. K. Soon

This study was conducted on a P-deficient Dark Grey Solod to compare the effects of the rate (0, 45, 90 kg P ha−1 cumulative), placement method (broadcast vs. banding), and frequency (preplant only vs. annually) of P fertilizer application on herbage production by a bromegrass (Bromus inermiss Leyss)–red clover (Trifolium pratense L.) mixture. The preplant broadcast application was incorporated by rototilling, and subsequent broadcast applications were topdressings. Annual applications continued for 3 yr only and dry matter (DM) yields were taken for 4 yr following the establishment year in 1991. Rate of P applied had the greatest effect on herbage yield, but its effect was influenced by the frequency of application. When P fertilizer was applied annually, herbage yields increased linearly with application rates. When P was applied preplant only, herbage yields reached a plateau with 45 or more kg P ha−1. Broadcasted P yielded slightly more than banded-in P in the first year harvest only. Annual application of 30 kg P ha−1 gave the highest cumulative herbage yield, suggesting decreasing P availability with time. This was supported by soil P analysis in 1994 and by herbage P concentrations. Herbage P concentration was significantly correlated with herbage yields of the second year and subsequent harvests. It is concluded that a preplant broadcast-incorporated application of 30 to 45 kg P ha–1, followed by at least one subsequent surface application of 30 kg P ha–1 was required for optimum herbage production by a legume-grass mixture. Key words: Application method, P fertilizer management, bromegrass-red clover, Grey Luvisol, soil P distribution


1982 ◽  
Vol 98 (1) ◽  
pp. 99-102 ◽  
Author(s):  
F. I. Sant ◽  
D. Wilson

SUMMARYCell walls of three bloat-causing legumes, lucerne, red clover and white clover tended to be thinner and disintegrated significantly (P < 0·05) faster during cellulase digestion than those of two non-bloat-causing legumes, sainfoin (reported to contain tannins) and cicer milkvetch (reported not to contain tannins). Response to one generation of selection for speed of mesophyll cell-wall disintegration was marked in a diploid red clover (h2 = 0·66, 1·13) but slight in a tetraploid (h2 = 0·10, 0·13).


1994 ◽  
Vol 74 (4) ◽  
pp. 825-826 ◽  
Author(s):  
T. M. Choo ◽  
B. R. Christie ◽  
G. F. Bélanger ◽  
Y. A. Papadopoulos ◽  
S. Kilyanek

The red clover (Trifolium pratense L.) cultivar, AC Charlie, is a diploid of the early or double-cut type. It was developed by two cycles of mass selection for persistence and vigour. Forage yields after severe winter conditions indicate that AC Charlie is more winterhardy than Florex in Atlantic Canada. It is similar in maturity to Florex and 3–4 d later than Marino. Key words: Cultivar description, red clover, AC Charlie


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