Phenotypic Variability for Bio-Agronomical Traits in Berseem (Trifolium alexandrinum L.) Populations of the Meskawi Botanical Group

The phenotypic variability and adaptability for bio-agronomic traits in berseem populations (Trifolium alexandrinum L.), was evaluated. The number of genotypes was 32 (26 of southern Italy origin and 6 Egyptian). They were evaluated under field conditions for two years (1989–90) in Foggia (Italy) adopting different cutting regimes: at 7–8th inter-nodes stem length, beginning of flowering, and no cutting. The genotypes of the Italian origin appeared to be better adapted when the cut was applied in the early stage of development, and more productive in seed yield. The Egyptian populations were most productive in forage in the later cuts and had a higher seed weight. The range of variation among the bio-agronomical traits was higher when the cut was applied at early flowering. The traits with wider range of variation were: dry matter, plant height at cut, regrowth at the fourteenth day after cut, tiller density and seed yield. Considering a multiplicative selection index, 6 populations were well adapted and could be used as parents in breeding programs and in extended farm cultivation.     

Significance of Pollination in Seed Setting Efficiency of Berseem (Trifolium alexandrinum L.)

The Egyptian clover ( Trifolium alexandrinum L.) commonly known as berseem in India, is a predominantly self-pollinated autogamous fodder legume. It has a simple valvular type mechanism for pollination wherein tripping agencies like bees are needed for better seed setting. The seed setting efficiency and seed yield of berseem (g. m⁻²) under natural tripping or open tripping condition was extremely high (22.38) as compared to completely caged (0.52) which clearly indicates the significance of pollinators/tripping agencies in seed yield of berseem crop. Further, the influence of pollinators was well marked with diploid strains of berseem as compared to tetraploid because of difference in fertility levels (tetraploids are generally less fertile).     

Effects of harvest management on growth dynamics, forage and seed yield in berseem clover

Berseem clover (Trifolium alexandrinum L.) is an annual forage crop widely grown in Mediterranean environments. However, there is little information available on the patterns of accumulation and partitioning of assimilate in berseem and how this varies with harvest management, plant ontogeny or is influenced by genotype. Field experiments were conducted in Foggia (Italy) during three growing seasons (1991–92, 1992–93 and 1993–94), with the aim of evaluating the effects of different harvest managements on growth dynamics, forage yield and seed yield of one population of Egyptian (cv. ‘Giza 10’) as well as Italian (cv. ‘Sacromonte’) origin. Cutting treatments were applied at three different plant ages: sixth internode elongation (A), early flowering (B), and uncut control (C). The growth and development of the shoot and root systems were followed by destructive harvests made at about 5-day intervals during 9 weeks in spring in all treatments. Seasonal growth pattern, determined as dry matter accumulation, forage yield and seed production were greatly influenced by harvest management. The maximum value (20.5 g per plant on average) of dry weight was reached at about 250 days after sowing for treatment C. Defoliation induced a decrease of crown and root dry matter, however, as shown by the allometric relationships, the growth of roots and shoots was closely correlated and in most cases, shoot growth was higher than root growth and stem relative growth rate (RGR) was higher than leaf RGR. Berseem clover is a defoliation-tolerant species because after cutting, regrowth was accompanied by higher values of leaf-stem ratio (LSR), RGR and stem elongation rate (SER) than in control plants. The highest value for total forage yield (1.6 Kg m⁻²) and seed yield (60.5 g m⁻²) were obtained in treatment B and A, respectively. Plants cut at the sixth internode elongation showed a good seed yield and a small decrease (15%) in total forage yield as regards treatment B. Therefore, treatment A appeared the most favourable for obtaining double utilization (forage and seed yield) in a berseem crop. Berseem plants were greatly influenced by harvest treatments applied, but the response did not vary according to the genetic characteristics of the two cultivars examined.     

Effect of Phenological Stages on Plant Dry Matter Partitioning and Seed Production in Berseem (Trifolium alexandrinum L.)

Berseem clover ( Trifolium alexandrinum L.) is an annual forage crop widely grown in Mediterranean environments. Dry matter partitioning in the leaf, stem and root and seed production of three populations of Egyptian as well as Italian origin were evaluated under four cutting regimes. The cutting treatments were applied to the plants at different stages of plant development: at the fourth (A) and eighth nodes elongation (B), at early flowering (C) and physiological maturity of seeds (D), After herbage, harvest plants were utilized for seed yield and evaluation of its seed yield components. Higher dry matter and seed yield was obtained in treatments D and B, respectively. In the other treatments, dry matter content was lower than in treatment D and related to the phenological development of the plant. Dry matter content in the root was higher when the cut was applied at early flowering. Cutting regimes influenced plant mortality, with the number of dead plants increasing from the cut applied in early (A) to that in the final treatment (D). Cuts applied at early stage of development depleted root reserves causing plant death. This peculiarity could be a tool for selecting populations with higher persistence and with a more tolerant physiological response to stress imposed by cuts. The populations of Egyptian origin, in comparison with the Italian ones, were more productive in dry matter in the early stage of growth and in all treatments were higher in seed weight.     

Variation for dry matter yield,seed yield and other agronomic traits in Ladino white clover landraces and natural populations

Summary A set of Ladino white clover ecotypes including the last available landraces and some natural populations collected from old permanent meadows, together with some white clover varieties of various origins, were evaluated as monocultures for dry matter (DM) and seed yield assessed in separate field experiments. Other agronomic traits were also recorded. The best performing variety, Espanso, was significantly outyielded by some ecotypes for DM and seed production. Compared to landraces, natural populations yielded on average far less seed but as much DM and tended towards higher persistence indicating that domestication of the native Ladino at the farm level only improved seed yield of the crop. Natural populations showed, besides lower values of most seed yield components, a distinct canopy architecture characterized by smaller leaves, longer internodes and denser stolons. Seed weight proved the best character discriminating between the two ecotype groups. Significant variation for most traits was found both among landraces, in which it was mostly relatable to differences among provenances, and among natural populations. The relations between the main multivariate patterns of phenotypic variation and a set of environment collecting variables suggested that evolutive adaptation to different agronomic practices was a major determinant of the overall variation found in landraces. Evidence is provided that a relevant part of the variation observed among ecotypes for some important traits could be genetic.Abbreviations DM dry matter - DMY dry matter yield - NRH number of ripe heads - NFH number of florets per head - PL petiole length - LS leaf size - IL internode length - NS number of stolons - PRO protein content - SY seed yield - TSW thousand seed weight - NSF number of seeds per floret - PCA principal components analysis - PC principal component     

Selection for Seed Yield Production of Egyptian Clover (Trifolium alexandrinum L.) C. V. Fahl

Modified mass and family selection for seed yield production of berseem clover (Trifolium alexandrinum L.) c.v. ‘Fahl’ were applied for two generations. Two hundred plants (5 % intensity of selection) were selected for seed yield in the first season, 1985/86. In the second season, 1986/87, selection between and within half-sib families was practiced. In addition, equal parts of seeds from each of the 200 selected plants were bulked to form the C₁ modified mass selection; after establishing, the same procedure was adopted to form the C₂ generation. The cycles 1 and 2 of half-sib families and modified mass selection along with the base population family were evaluated for forage and seed yields. The realized gains from modified mass selection were 6.03 and 9.51 % for fresh forage yield, 5.57 and 10.86 % for protein yield and 13.23 and 16.19 % for seed yield in cycles 1 and 2, respectively, over the base population. The realized gain from family selection in cycle 2 as a percentage of the base population mean amounted to 11.32, 13.35, 17.47 and 3.15% for forage, protein, and seed yield and seed index, respectively. The broad sense heritability, as estimated from the variance components was 89.63, 63.03, and 76.67 % for dry forage, seed yield and seed index, respectively. Although, all these five traits (fresh, dry, protein, and seed yield and seed index) had positive correlation with each other, weak correlations were found between seed yield and forage yields. Furthermore, close associations were found among forage yield traits.     

Cryptic improvement for fertility by continuous selfing of diploid potatoes using Sli gene

While a diploid potato was continuously selfed by a function of Sli gene, the level of heterozygosity reduced, and the fertility also reduced (inbreeding depression), which might be improved because continuous selfing could eliminate undesirable recessive alleles. To explore what was occurring as advancing self-generations in terms of fertility, 51 plants of an S₃ diploid potato family were evaluated for fertility-related traits and analyzed by RFLP markers. The level of heterozygosity was positively correlated with any of fertility-related traits (r = 0.108−0.333). At least six loci on six chromosome sections were associated with fertility-related quantitative trait loci (QTLs), of which three performed better in the heterozygotes and three in the homozygotes. By further continued selfing, QTLs performing better in heterozygotes were likely fixed to homozygotes with secondly better performance, and those performing better in homozygotes were fixed to the best genotypes. Thus, the selfed progenies were cryptically being improved for fertility by genetic fixation to the best or better genotypes in fertility-related QTLs.     

Genetic variability and interrelationships of seed yield and yield components in switchgrass

Information on the genetic variability of seed yield and yield components is limited and no information is available on correlations among seed yield and yield components and direct and indirect effects of the yield components on seed yield in switchgrass, Panicum virgatum L. Accordingly, we conducted replicated experiments at Chickasha and Perkins, OK, in 1998 involving 11 lowland type switchgrass populations to assess genetic variation for seed yield and yield components, quantify interrelationships among them, and determine direct and indirect effects of yield components on seed yield through path coefficient analysis to identify traits for indirect selection of seed yield. Significant (P ≤ 0.01) variation existed among the 11 populations over locations for percent seed set and 100-seed weight. Seed yield/plant and the seed yield components panicle number/plant, spikelet number/panicle, and seed number/panicle had significant (P ≤ 0.05) population × location interactions, indicating substantial environmental influence on these traits for these populations. Accordingly, data for these traits were analyzed separately for each location revealing significant (P ≤ 0.01) differences among populations at both locations for each of these traits. Phenotypic correlation between seed yield/plant and seed number/panicle was positive (r = 0.76** at Chickasha and r = 0.72** at Perkins). Path coefficient analyses revealed that seed number/panicle had the highest positive direct effect on seed yield at both locations. Ample genetic variability was present among the switchgrass populations studied to allow breeding improvement of seed yield. Selection for increased seed number/panicle would be the most effective means of indirectly selecting for higher seed yield within this germplasm. Correlation and path coefficient analyses among biomass yield, seed yield, and harvest index indicated that, at least within the switchgrass germplasm studied, it would be possible to breed switchgrass cultivars with enhanced biomass yielding ability and sufficient seed production capability for their commercial propagation.     

Response of a new IR50/Moroberekan recombinant inbred population of rice (Oryza sativa L.) from an indica × japonica cross for growth and yield traits under aerobic conditions

Genetic variability, correlation, path coefficient analysis and test of normality was conducted in an F₈ recombinant inbred aerobic rice population developed by single seed descent method to evaluate its potential as a mapping population. Estimates of genotypic variance, phenotypic variance, genotypic coefficient of variance (GCV), phenotypic coefficient of variance (PCV), heritability in the broad sense (H) and expected genetic advance at 5% selection index (GA) for grain yield and other attributing characters were computed. In all the cases, PCV was higher than GCV indicating the influence of environment on the characters. High heritability coupled with high GA was observed for several plant traits; number of tillers, plant height, total number of spikelets panicle⁻¹, biomass plant⁻¹, straw weight, harvest index and grain yield plant⁻¹ and hence offered good scope for selection. Grain yield plant⁻¹ was found to be positively correlated with plant height, number of tillers, panicle length, panicle exsertion, number of panicles plant⁻¹, single panicle weight, test weight, number of fertile spikelets panicle⁻¹, straw weight, biomass plant⁻¹, harvest index and grain breadth both at genotypic and phenotypic levels. Harvest index exerted maximum positive direct effect, followed by biomass plant⁻¹ and straw weight on grain yield plant⁻¹ at phenotypic level. Shapiro-Wilks “W test of normality” indicated that the population was skewed towards female parent IR50 for some traits and for some others towards Moroberekan, the male parent. Most of the characters that showed skewness were platykurtic with a kurtosis value of less than 3.     

Inbreeding depression in diploid and autotetraploid sugarbeet,Beta vulgaris L.

Summary The effect of inbreeding on vegetative vigor, as measured by root yield, was evaluated in two diploid (2x) and equivalent autotetraploid (4x) sugarbeet strains, and one additional 2x and one 4x strain. Root yields of the 2x and 4x S₁ progenies each averaged 86.7% of their comparable open-pollinated progeny. Inbreeding depression of root yield was variable from strain to strain. The selfed 4x populations, when compared with their 2x equivalents, suffered more yield depression than was expected on the basis of the theoretic approach to homozygosity associated with selfing in autotetraploids. The inbreeding depression was partly attributed to (a) the approach to homozygosity, and (b) the fact that partially homozygous 4x S₁ individuals were probably unable to make compensating growth when located adjacent to a low vigor aneuploid plant. A major part of root yield depression remained unexplained. Sucrose content within strains and within ploidy levels was not significantly affected by one generation of selfing.Joint contribution of the Crops Research Division, Agricultural Research Service, US Department of Agriculture, the Colorado Agricultural Experiment Station, and the Beet Sugar Development Foundation. Published with the approval of the Director of the Colorado Agricultural Experiment Station as Scientific Series No. 1582.     

Selection of snap bean recombined inbred lines by using EGT and SSD

With the objective of selecting superior recombinant lines of snap bean, four segregating F₂ populations were selected by early generation testing and advanced by single seed descent. In a randomized complete block design with two replications within sets 120 F_6:7 lines were obtained and evaluated for seven traits of agronomic interest. The mean pod yield of the F_6:7 generation was 72% higher than in generation F₂, confirming the efficiency of early selection. There was genetic variability in the F_6:7 lines within the sets. The selection of superior genotypes was possible by the high estimates of narrow-sense heritability. Highest gains in simultaneous selection of traits were expressed by the indices proposed by Mulamba & Mock for the genetic standard deviation and by Williams, based on tentatively attributed arbitrary weights. Line 3 of the F_6:7 generation, with a yield of 8,050.0000 kg ha⁻¹ and pod fiber content of 0.3650% is highly promising to be release as new cultivar.     

Differences in nitrogen fixation among field-grown red clover strains at different levels of 15N fertilization

Summary Genetic variation in fixed nitrogen (N) yield of red clover (Trifolium pratense L.) strains and cultivars was investigated using the ¹⁵N isotope dilution method under three regimes of N fertilization: 0.5, 30, and 60 N (kg N ha^–1 per cut). The yield of fixed N per cut (the mean of eight cuts over 2 production years) varied among the strains (progenies of crosses between inbred parents) from 148 to 443 mg per plant at 0.5 N, from 76 to 324 mg at 30 N, and from 69 to 300 mg at 60 N. There were significant and consistent strain differences in the percentage of clover N derived from the atmosphere (% N_dfa). However, %N_dfa was positively correlated with dry mass yield. Consequently, ranking of the strains according to fixed N yield reflected that of dry mass yield. There were only minor strain × N fertilizer interactions, suggesting that selection for enhanced N fixation can be carried out at a single rate of fertilizer N. For a selected pair of strains, the difference in yield of fixed N was confirmed in an Italian ryegrass-red clover mixture, both without and with the addition of N fertilizer (50 kg N ha^–1 per cut). Results with 7-week-old seedling plants in a growth chamber, although obtained in the presence of mineral N and with the isotope dilution method, did not adequately predict field performance. It is concluded that selection for dry matter or total N yield is likely to result in an enhanced yield of fixed N at any level of mineral N availability.Abbreviations % N_dfa percentage of clover nitrogen derived from the atmosphere by symbiotic nitrogen fixation - S₂-F₁-n progeny of pair cross between inbred parents obtained after two generations of selfing     

Recurrent selection for maturity and percent seed protein in Glycine max based on S0 plant evaluations

Summary Progress was evaluated after four cycles of recurrent selection among S₀ plants of Glycine max (L.) Merr. in which selection was either for maturity (MAT) or seed protein (PRO). The two populations, MAT and PRO, were developed from an initial population that was a combination of a line with 48.4% seed protein and two F₂ populations segregating for male sterility. Intermating was facilitated by genetic male-sterility and the selection intensity was 20% in each cycle of the two populations. Selection for early maturity advanced the average maturity a significant 2.7±0.34 days cycle^–1 and reduced seed yield a non-significant 9.1±2.95 g plant^–1 cycle^–1. Selection increased mean seed protein a significant 0.8±0.15 percentage points cycle^–1 and decreased percent seed oil a non-significant 0.5±0.17 percentage points cycle^–1. Correlation coefficients between seed protein and seed yield varied from 0.18 to –0.21 in the four cycles indicating plants with favorable combinations of seed yield and seed protein could be identified. Selection in these two populations would be effective for early maturity and for increased seed protein.     

Effects of inbreeding on nodal root system morphology and architecture of white clover (<Emphasis Type="Italic">Trifolium repens</Emphasis> L.)

Plants of white clover (Trifolium repens L.) cultivar Crau, a self-fertile Crau genotype, and nine generations of inbred progeny were raised in sand culture in a glasshouse experiment. Digital images of the root systems were made and root morphological characteristics were determined on all the plants. Root architectural parameters were measured on the Crau parent and the S₁, S₄, S₆, and S₉ inbred lines. The clover roots became shorter and thicker with inbreeding but the number of root tips per plant was unchanged. Root architecture (branching pattern) was largely unaffected by inbreeding. It is concluded that inbreeding white clover will lead to shorter, thicker roots, and reduced nutrient uptake efficiency compared with the parent clover. The degree to which these deleterious traits are overcome during the development of F₁ hybrids needs to be determined.     

Sources of variation for sustainable field pea breeding

The pea crop (Pisum sativum L.) is a convenient source of plant protein for animal feeding. The objective of this research was to evaluate field pea breeding lines for agronomic performance and seed quality focussed to their use in a sustainable production. Thirty-five field pea breeding lines and six elite cultivars were evaluated for their agronomic value in field in Spain upon 20 traits related to flower, cycle, plant architecture, productivity and seed quality. The lines showed significant differences in all the quantitative traits evaluated and three of them, namely MB-0307, MB-0308, and MB-0319 were chosen to be evaluated, together with the advanced cultivar ZP-1233, in field and in growing chamber for agronomic performance, seed quality and ability for sustainable production. The four accessions displayed high seed protein content that had significant effect of cropping density with averages of 253.6 g kg⁻¹ under low cropping density of 60 plants m⁻² and 259.1 g kg⁻¹ under high cropping density of 90 plants m⁻², therefore, the low cropping density should be regarded as the most convenient. Average yield of the lines MB-0307, MB-0308 and MB-0319 and the cultivar ZP-1233 was fair (197.5 g m⁻²), probably due to the absence of fertilizers and irrigation, aiming for the sustainability of the crop. Intercropping with rye and herbicide application resulted in no differences on the seed yield; therefore, the ability of the breeding lines to grow without herbicide seems to be demonstrated, while the germination of the seeds at low temperature was very good. These results indicate that field pea could be a new protein crop in the North of Spain to satisfy the demand of plant protein for animal feed, based upon adapted breeding lines that combine the ability for growing under sustainable conditions with other desirable agronomic traits maintaining an adequate productivity.     

Heritability of, and genetic correlations among, forage and seed yield traits in Ladino white clover

Sixteen white clover genotypes and their half-sib progenies were grown in pure stand. Each clover progeny was also grown in a mixed stand that also included three grass varieties of different species. Dry matter (DM) yield was measured over 2 years and seed yield at the second year. Competitive ability of clover families was defined as the ratio between mixed stand and pure stand for clover DM yield. Narrow-sense heritability from parent-offspring regression of pure stand data was high to moderate (h²0.50) for DM yield, seed yield and most of their components. Persistence as predicted by stolon density showed negative genetic correlations with seed yield (r_g= -0.70) and DM yield (r₂= -0.60), whereas seed yield and DM yield tended towards a negative correlation (r₂=0.45). Sizes of different vegetative or reproductive organs were generally correlated positively. Evidence was provided that the set of parent genotypes represents well the genetic variation available within the Ladino gene pool. The results highlighted the difficulty of combining relatively short-term DM yield, persistence and seed yield into a unique plant type. Differences in competitive ability emerged only in the second year, better ability being related mainly to petiole length among the traits assessed in pure stand.     

Recurrent selection for yield in Glycine max using genetic male-sterility

Summary Recurrent selection, using genetic male sterility to facilitate intermating in Glycine max, was evaluated when selecting among individual space-planted S₀ soybean plants for three yield-related traits: 1) seed yield per se (YLD), 2) apparent harvest index (AHI), and 3) a selection index in which seed yield was regressed on maturity (REG). The original intermating population was a combination of the cultivar Century and two F₂ populations segregating for male sterility. The selection intensity through three cycles of selection was 20%. The YLD population increased in mean yield by 2.8±2.2 g plant^-1 cycle^-1 buf shifted significantly toward late maturity by 3.9±0.6 days cycle^-1. The AHI population decreased in yield by 4.4±2.6 g cycle^-1 while maturity shifted slightly earlier; there was very little change in AHI. The REG population increased in yield by 5.7±2.4 g plant^-1 cycle^-1 while shifting toward later maturity by only 0.8±0.5 day cycle^-1. We concluded that selection among S₀ plants in these populations, using the selection index of yield regressed on maturity, was affective in increasing single plant yields without causing a significant shift in maturity. Selecting for yield per se caused an unacceptable shift toward late maturity and selection for AHI was ineffective for increasing yield or AHI.     

Development of breeding populations from interspecific hybrids between Trifolium repens L. and T. occidentale Coombe

Trifolium occidentale is a diploid wild relative of T. repens (white clover) with adaptation to dry, saline coastal habitats. Transfer of drought and salt‐tolerant adaptive traits to white clover could be potentially valuable if interspecific hybridization can be achieved efficiently and leads to fertile hybrid populations. To achieve hybridization, 4x plants of T. occidentale were generated. Efficient techniques for generation of 4x plants and their identification using dry pollen shape are described. Interspecific 4x F₁ plants were achieved without embryo rescue. F₂ populations and first backcross hybrids to white clover were also efficiently achieved. Although male and female fertility were lower than in white clover, they were adequate to produce large amounts of seed from small numbers of inflorescences. Thus, early generation interspecific hybrid prebreeding populations can be readily developed, opening the way for transfer of traits from T. occidentale to white clover.     

Genetic combining ability estimates in the F<Subscript>1</Subscript> and F<Subscript>2</Subscript> generations for yield,its component traits and alkaloid content in opium poppy (<Emphasis Type="Italic">Papaver somniferum</Emphasis> L.)

The F ₁ and F ₂ generations of a twenty parent fractional diallel cross of opium poppy (P. somniferum L.) were analyzed for combining ability for ten quantitative and five quality (alkaloids) traits. The results indicated significant differences among the parents for combining ability for all the traits. The GCA and SCA components of variances were significant for all the characters. However, the SCA component of variance (δ ²s) was predominant indicating the preponderance of non-additive gene effect for all the traits except for leaves/plant and papaverine in F₁ hybrids. The average degree of dominance (δ ²s/δ ²g) was more than unity indicating over dominance and also confirming non-additive mode of gene action. Among the parents IS-16, IS-13 and NBRI-1 for early flowering, BR226 and BR241 for branches/plant, capsule weight/plant, seed yield/plant and husk yield/plant, BR227 for leaves/plant, UO1285 for capsule size and opium yield/plant, NBRI-5 for husk yield/plant, morphine, codeine, and thebaine and ‘Papline’ for plant height and papaverine content were found good general combiners. Parent ND1001 was good combiner for codeine and narcotine content. Inclusion of good general combiners in a multiple crossing program or an intermating population involving all the possible crosses among them subjected to bi-parental mating may be expected to offer maximum promise in breeding for higher opium, seed yield and alkaloid contents.     

Genetic variation in a Norwegian germplasm collection of white clover (Trifolium repens L.)

Phenotypic (r_p), genotypic (r_g), genotype × location (r_gl) and error (r_e)correlations for important agronomic characters were estimated for eleven Norwegian populations of white clover (Trifolium repens L.), originating from between 58^°52′N and 69^°30′N latitude, and from altitudes of 10 to 450 m a.s.l. The populations were evaluated in monoculture clonal field plots for two years at two locations in Norway. All pairwise correlations between foliage height, leaflet length, dry matter yield (DMY) and general performance were positive and significant. Winter survival was positively correlated with general performance, spring growth and DMY, but negatively associated with internode length, while seed yield showed a small positive genotypic correlation with foliage height. Considerable differences were, however, revealed among populations with regard to sign and magnitude of the estimated correlations. Within-population estimates of r_g were consistently positive between DMY, general performance and most other characters; between foliage height on the one hand and leaflet length, winter survival and seed yield on the other hand, and between internode length and leaflet length, indicating pleiotropy. Correlations involving other character-combinations varied substantially among populations, and imply presence of linkage and/or coadaptation. Path coefficient analysis was used to partition the genotypic correlations between some of the characters into direct and indirect effects. Path coefficients revealed that foliage height had the highest positive direct effect on DMY, followed by winter survival and internode length. Leaflet length, which showed a positive, significant simple correlation with DMY, exhibited a negligible direct influence, counterbalanced nearly completely by the positive indirect effect on DMY via foliage height. Positive indirect effects on DMY via foliage height were also found for winter survival and internode length. The coastal populations from North and Middle Norway, and a southern highland population showed the largest expected responses to phenotypic selection for most of the characters. The results demonstrate that there is enough genetic variation in adapted local populations to develop new improved cultivars adapted to high-latitude environments that combine upright growth habit with sufficient winter-hardiness and persistency. This revised version was published online in July 2006 with corrections to the Cover Date.