The in vitro digestibility (IVD) of timothy (Phleum pratense L.) declines with advance in maturity. Forage quality reductions resulting from late harvesting could be minimized by developing cultivars with reduced IVD decline during maturation. This study examines variation for IVD decline among timothy genotypes. Clones originating from a single population were grown in simulated swards (100 plants m−2) at two Ontario locations in 1980 and 1981. Harvests were made every 5–6 d from early heading to late anthesis. Relative IVD declines were determined by regressing genotype performance on the population mean over several harvests. Considerable variation was found for relative IVD decline, but this parameter was not associated with IVD at early heading. Genotypes were identified which showed high IVD at heading and a 20% reduction in digestibility decline from heading to late anthesis. Changes in IVD were not associated with changes in the leaf content of forage. It is concluded that selection for reduced IVD decline, in addition to high digestibility at heading, might result in a 2–3% unit increase at anthesis.Key words: Timothy, Phleum pratense L., in vitro digestibility, IVD, IVD decline

Flowering time is an important component in the adaptation of oat to sub-tropical environments. Genotypes differ in their response to photoperiod and to vernalization. The objectives of this study were to identify photoperiod insensitive oat genotypes and then investigate the response of different oat genotypes to a period of vernalization (cold treatment), and to evaluate F6 recombinant inbred lines from two oat crosses in two different environments (day-length increases and day-length decreases). The genotypes used in the studies were from the UFRGS Oat Breeding Program: UFRGS 8, UFRGS 881971 and UFRGS 930605 and from the University of Minnesota, USA: Amagalon/*Ogle, Coker 492/Starter-1 and PC68/5*Starter, and F6 lines from the crosses UFRGS 8×UFRGS 930605 and UFRGS 8×PC68/5*Starter. UFRGS 8 showed no photoperiod sensitivity by flowering early regardless of the photoperiod length. Late flowering in the winter and early flowering in the summer characterize day-length-dependent genotypes like PC68/5*Starter. UFRGS 881971 responded to vernalization. Genotypes showed variability that can be used in the selection of lines/varieties that more effectively use the complete season.

Desirable qualities of milling oat varieties include low hull content (high groat content), high beta-glucan content, high groat protein, low oil concentration, low kernel breakage, high grain yield, and superior yield stability. The objective of this study was to develop a graphical method for understanding the influence of environment on genetic relationships among traits. Associations among agronomic and quality traits in 67 oat (Avena sativa L.) performance trials conducted during 1996-2003 across Canada and some northern US states were studied using a trait-association by environment biplot, which allows visual study of pair-wise trait associations in multiple environments (year-location combinations). Based on the differential association of yield with days to heading and plant height, the North American spring oat growing regions can be divided into Northern mega-environment (Canadian Prairies plus North Dakota and Idaho) and Southern megaenvironment (Minnesota, South Dakota, and Ontario). We also found that the following trait associations were relatively stable across environments: (1) negative association of protein content vs. oat yield, (2) positive association of beta-glucan vs. groat oil, (3) positive association of beta-glucan vs. protein content, and (4) negative association of beta-glucan vs. breakage. All trait-associations were of moderate magnitude and were responsive to the environment. This suggests that breeding for superior oat varieties with desired trait combinations is possible, but it must be achieved through direct selection for multiple traits in representative environments.

In spring-type oat (Avena sativa L.), quantitative trait loci (QTLs) detected in adapted populations may have the greatest potential for improving germplasm via marker-assisted selection. An F6 recombinant inbred (RI) population was developed from a cross between two Canadian spring oat varieties: ‘Terra’, a hulless line, and ‘Marion’, an elite covered-seeded line. A molecular linkage map was generated using 430 AFLP, RFLP, RAPD, SCAR, and phenotypic markers scored on 101 RI lines. This map was refined by selecting a robust set of 124 framework markers that mapped to 35 linkage groups and contained 35 unlinked loci. One hundred one lines grown in up to 13 field environments in Canada and the United States between 1992 and 1997 were evaluated for 16 agronomic, kernel, and chemical composition traits. QTLs were localized using three detection methods with an experiment-wide error rate of approximately 0.05 for each trait. In total, 34 main-effect QTLs affecting the following traits were identified: heading date, plant height, lodging, visual score, grain yield, kernel weight, milling yield, test weight, thin and plump kernels, groat β-glucan concentration, oil concentration, and protein. Several of these correspond to QTLs in homologous or homoeologous regions reported in other oat QTL studies. Twenty-four QTL-by-environment interactions and three epistatic interactions were also detected. The locus controlling the covered/hulless character (N1) affected most of the traits measured in this study. Additive QTL models with N1 as a covariate were superior to models based on separate covered and hulless sub-populations. This approach is recommended for other populations segregating for major genes. Marker-trait associations identified in this study have considerable potential for use in marker-assisted selection strategies to improve traits within spring oat breeding programs.

Genetic variation for forage yield of orchardgrass is abundant, but there are few reports of progress from selection for increased forage yield. The objective of this study was to estimate direct effects of selection from one cycle of half-sib family selection for forage yield in orchardgrass, Eleven selected populations were compared with their parent populations within three maturity groups. Populations were evaluated under hay management at three locations and management-intensive rotational grazing at two locations. Nine of the I I selected populations differed, by an average of 7.4%, from their parent population in forage yield. Nine of the selected populations also showed changes in Drechslera leafspot reaction, all indicating a negative genetic correlation with forage yield. Selection for high forage yield tended to result in greater ground cover and later relative maturity. However, changes in net herbage accumulation (NHA) under rotational grazing were generally not significant and were uncorrelated with changes in forage yield, indicating that forage yield of hay plots is not correlated with the NHA of grazed plots. Although genetic gains in forage yield measured under hay management were very favourable relative to other reports from the literature, the lack of correlated progress under grazing management indicates that directed selection for NHA of orchardgrass should be conducted under grazing management.

There has been considerable activity in breeding orchardgrass (Dactylis glomerata L.) cultivars in North America during the latter half of the 20th century, but little effort devoted to quantification of breeding progress. The objectives of this study were to quantify changes in mean cultivar performance for that time compared with the progress achieved from one cycle of half-sib progeny selection within the USDA population of orchardgrass accessions. Forty-two cultivars (32 North American cultivars and 10 European cultivars) were tested at three locations (Arlington, WI and Rock Springs, PA, and Ottawa, Ontario, Canada) in 1995 through 1997. Cultivars were grouped into three experiments by maturity class: early, medium, and late. North American cultivars averaged 3,9, and 12 % higher in forage yield than European cultivars for early, medium, and late maturity groups, respectively. Between 1955 and 1997, forage yield and ground cover of early-maturity cultivars increased by 2.5 Mg ha -1 decade -1 and 4.0% decade -1 , respectively. Forage nutritional value of medium-maturity cultivars increased during that time, although this was probably not due to direct selection. Significant gains were made in forage yield and Drechslera spp. leafspot reaction of cultivars derived from two individual breeding programs, although the majority of orchardgrass cultivars lack improvements in forage traits.

Various preconditioning treatments of alfalfa (Medicago sativa L.) somatic embryos to improve embryo quality and conversion were studied. Four different regenerating genotypes were compared. Embryogenic cultures were established in liquid culture. Globular embryos were collected and plated on an embryo development medium until they reached cotyledonary stage. They were then exposed to three treatments: a standard embryo development medium (control), media supplementation with 1 μM abscisic acid (ABA), 50 mM glutamine and 5% sucrose (T), additional supplementation with 50 μM ABA (TT), and additional supplementation followed by desiccation (TTD). Treatments affected embryo conversion, but not uniformly for all genotypes. Embryo conversion was increased (P<0.05) by pretreatment (T), while only one exhibited any response to additional ABA (T vs. TT). Desiccation decreased (P<0.05) conversion of pretreated embryos (TT vs. TTD) of all genotypes. The effect of treatments on plantlet weight was less pronounced and inconsistent across genotypes.

Production of small-seeded natto soybean [Glycine max (L.) Merr.] has increased in eastern Canada during the past decade, Improved natto quality characteristics are important for maintaining and increasing this market. This study was conducted to examine environmental and genotype x environment effects on quality characteristics. Two data sets were used for statistical analysis: seven lines grown at five locations in 1989 and 1990 (Data Set 1) and fifteen lines grown at the same five locations in 1993 and 1994 (Data Set 2). Quality characteristics important in natto production were measured: small-seed fraction, percentage of seeds with impermeable seed coats, water uptake, seed shape, and levels of the seed constituents, Ca, oil, and sugar, Genotypes were significantly different for most traits in both data sets, Location effects were not significant for any quality traits, Year effects were significant only for seed shape and sugar levels in Data Set 2. Year x location interactions were often significant, but no patterns were apparent in these interactions. Genotype x environment interactions were often significant, but these variance components were usually an order of magnitude smaller than the main effects of genotype, These results indicate that it is possible to develop natto soybean cultivars that are broadly adapted to the short-season areas of eastern Canada.

Stem strength, as an estimate of forage intake potential, could be a useful selection parameter in alfalfa (Medicago sativa L.) breeding programs, but there is little information on sampling techniques or the effect of tissue weakening by bacterial or fungal incubation. This study investigated the effect of stem position (top, middle, bottom) and incubation with a water control, Ruminococcus flavefaciens or Neocallimastix MC-2 on stem shear strength of four alfalfa genotypes. Stem diameter was closely associated with shear force in all treatments and was used as a covariate in statistical analyses. Shear strength increased from the top to the bottom of all genotypes regardless of incubation. Both bacterial and fungal incubation reduced (P < 0.01) shear strength, with the fungus reducing shear strength to the greatest extent. Genotype differences (P < 0.05) across incubation treatments were detected in the bottom stem portions only. There were no genotype × incubation treatment interactions within any stem position, but genotype × position effects (P < 0.01) were detected in the water incubation control. The bottom sections of alfalfa showed the largest differences and would provide the best sample material to estimate forage intake potential. Stem diameter should be used as a covariate.

Improving the nutritive value of timothy (Phleum pratense L.) through breeding is dependent on selecting for genetic traits which directly contribute to ruminant digestibility. The identification of these traits is the goal of many forage researchers. The objectives of this research were to evaluate the leaf and stem digestibility of six timothy genotypes under different temperature conditions using two methods of estimating digestibility. Correlations between leaf and stem digestibility were not significant, suggesting that separation of these components is nessessary to clearly evaluate genotypic differences. Temperature had an important effect on digestibility, particularly for the stem fraction. Isolating leaf from stem and evaluating genotypes individually across temperatures may permit the identification of more simple genetic factors which control digestibility in timothy. Genotypic differences were observed at all temperatures. The rumen fluid digestion resulted in a much greater range within and among genotypes for both stem and leaf fractions. Genotypes tended to follow the same trends with respect to temperature using both techniques suggesting that only a portion of the dry matter digested by rumen fluid is available to the cellulases used in these experiments. Lignin content was measured for two of the most variable genotypes and the results showed that while levels increased with higher growth temperature, differences between genotypes are more pronounced at 10 °C for both leaf and stem. Key words: Digestibility, forage quality, lignin, temperature, timothy, Phleum pratense L.

AC Splendor is a late-maturing orchardgrass (Dactylis glomerata L.) cultivar. It was developed by phenotypic selection within cv. Rideau for winter hardiness, yield, persistence and absence of stem rust (Puccinia graminis) at the Plant Research Centre. Agriculture and Agri-Food Canada, Ottawa. Its forage yield was 103.2% of cv. Kay over 15 station years in Ontario. Yield in second and subsequent production years was 101.7% of cv. Kay over 8 station years. Key words:Dactylis glomerata L., orchardgrass

AC Graze, tested as Syn-A, is a late-maturing forage-type tall fescue (Festuca arundinacea Schreb.) cultivar. It was developed by mass selection for vigor, persistence, leafiness and uniform maturity at the Plant Research Centre, Agriculture Canada, Ottawa. AC Graze yielded 105.3% of the test mean (seven cultivar, six station years) in Ontario Forage Crop Committee trials. Key words: Tall fescue, Festuca arundinacea Schreb.

A transplant plug technique was developed that uses in vitro somatic embryogenesis techniques to mass-multiply alfalfa plants in a form suitable for direct transplanting. The plug contains potting media covered with an agar nutrient cap. Plants develop from embryos placed on the cap and then establish in the potting media.Key words: Hybrid alfalfa, Medicago sativa L., tissue culture, transplant plug, somatic embryogenesis

Previous studies have indicated that individual timothy (Phleum pratense L.) genotypes being evaluated for quality should be grown under competition. There is little information on the effect of differential plant competition on the precision of yield or quality estimates. In a series of three experiments, timothy genotypes of uniform maturity were grown in field simulated swards with a population density of 100 plants m−2. The objectives were (i) to investigate the effect of planting patterns (1, 2 or 4 plants per experimental unit) on the precision of DM yield and a quality parameter, acid-pepsin digestibility (APD) estimates; (ii) to determine if adjusting for differential competition would increase the precision of yield estimates; and (iii) to evaluate the adequacy of a two-replicate simulated sward for commercial screening of timothy genotypes for yield and APD. Wide ranges among genotypes for DM yield indicated that plants within the sward were under strong competitive pressure. The highest precision for DM yield was obtained with the four-plant experimental unit but was marginally better than the two-plant unit. Size of experimental unit had little effect on the precision of APD estimates. Differential competitive pressure had no effect on either DM yield or APD estimates. Including the yield of neighbouring plants in the statistical model as a covariate did not improve the precision of yield estimates. It is concluded that a two-replicate sward with a two-plant experimental unit is adequate for routine screening of yield and APD in a breeding program.Key words: Competition, Phleum pratense L., simulated swards, timothy

Improved in vitro digestibility (IVD) is an important goal in timothy (Phleum pratense L.) breeding. This study examines the effect of genotype × environment (GE) interactions on individual genotypes and examines two methods for identifying superior parental genotypes. Fifteen genotypes of similar maturity were grown in simulated swards (100 plants m−2) at five locations. IVD was determined at early heading. Highly significant effects were found for genotype, year, location and all their interactions. A regression stability analysis indicated that most genotypes responded in a predictable manner to environment. Genotypes which performed relatively well in all environments were identified. However, some useful genetic material, being "unstable", would be discarded using this approach. Genotypes with consistently high IVD were identified using a technique developed for grouping corn (Zea mays L.) hybrids. This approach is considered the more efficient for identifying superior parental genotypes. Although genotype (IVD should be based on performance in several environments, it is suggested that selection for IVD stability is important in developing narrow-based but not wide-based synthetics.Key words: Timothy, Phleum pratense L., genotype × environment interaction, in vitro digestibility, IVD

Fifteen timothy (Phleum pratense L.) genotypes of similar maturity were grown in simulated sward (100 plants m−2), spaced-plant (1 plants m−2) and growth room nurseries for 2 yr or harvests. The whole plant in vitro digestibility (IVD) was determined at early heading. IVD values were strongly influenced by growing conditions and highly significant [Formula: see text] year × genotype and harvest × genotype interactions were found. The precision of IVD determination was similar in all nurseries. Correlation between genotype means of simulated sward and other nurseries, although significant [Formula: see text] is some cases, was too low to be of predictive value. Some genotypes tended to rank relatively high in all nurseries, but the relative performance of most genotypes was inconsistent. It is concluded that the choice of nursery techniques used to predict the sward performance of timothy genotypes is more critical than is generally assumed.Key words: Timothy, Phleum pratense L., in vitro digestibility, IVD, nursery competition