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Callus was induced from pieces of immature inflorescence of a sterile F1 hybrid (2n = 4x = 28) between Elymus canadensis and E. trachycaulus on MS medium supplemented with 2 mg/L of 2,4-D. Calli were of two types: compact or soft. Regeneration occurred predominantly from the compact callus. Although some plantlets were obtained on the callus initiation medium, the frequency of regeneration increased considerably when the callus was transferred to an auxin-free MS medium. Deliberate aging of callus induced cytological instability and variation in chromosome number of the regenerants. Five of the 43 regenerated plants had deviant chromosome numbers, including an octoploid (2n = 8x = 56). Chromosome pairing in the octoploid plant suggests that it originated through chromosome doubling.Key words: callus culture, variation, chromosome number.

In spite of regular chromosome pairing, hybrids between Elymus canadensis (Linnaeus) and E. trachycaulus (Link) Gould ex Shinners at the tetraploid level are sterile owing to structural differences between the donor genomes. However, the hybrids between these species at the octaploid level (obtained through chromosome doubling of the tetraploid hybrid and also from a cross between the octaploids of E. canadensis and E. trachycaulus) exhibited a predominance of bivalents in meiosis in spite of the autotetraploid nature of their constituent S and H genomes. The colchicine-induced amphiploids showed varying degrees of fertility. Comparison of chromosome pairing in the hybrid octaploids with that in the parental octaploids and hexaploids revealed that random bivalent formation is promoted when the S and (or) H genomes are at the tetraploid level, but not when they are in the triploid state. A bivalentizing mechanism under polygenic control is suggested to explain the predominance of bivalents in the tetraploid S and H genomes.Key words: Elymus, S genome, H genome, octaploids, bivalents, bivalentization.

A tissue culture induced octoploid of Elymus canadensis was crossed with two accessions ("Canada" and "Montana") of the same tetraploid species to produce hexaploids. Hexaploid (2n = 42) and near-hexaploid progeny (2n = 43 or 40) obtained from the crosses were morphologically vigorous but either partially or completely sterile. Mean frequencies of univalents and trivalents in the hexaploid pollen mother cells at metaphase I were 3 or 4 and 2 to 4 per cell, respectively. In view of the genomic constitution of the parents, the hexaploids were expected to be genomically double triploids. Nevertheless, bivalents, averaging 14–17 per cell, predominated. This might be due to the failure of chiasma formation and chiasma terminalization. One hexaploid plant was backcrossed to the tetraploid. The progeny consisted of one pentaploid and five aneuploids including one tetrasomic and two trisomics. All of the progeny from the backcrosses were less vigorous than aneuploids at the near-hexaploid level. Tetrasomics and trisomics had stainable pollen and a 17–19% seed set. Two trisomic plants were morphologically indistinguishable from each other and predominantly showed chromosome pairing of 14 II + 1 I. This indicates failure of chiasma formation and chiasma terminalization between homologous chromosomes.Key words: Elymus canadensis, hexaploids, tetrasomics, trisomics, meiosis.

Karyotype of Canada wildrye (Elymus canadenisis L.) was described using giemsa C-banding techniques. Most of the chromosomes showed dome banding pattern polymorphism. Small to large terminal and centormere bands were observed in most of the chromosomes. A faint satellite was observed in one chromosome. Tow chromosomes had a large interstitial band near the centromeres in the long arms. The Giemsa C-banding pattern of E. Canadensis is compared to that of Pseudoroegneria spicata and Critesion boddanii to illustrate species relationship.

Callus was induced from segments of immature inflorescences of Elymus canadensis×Psathyrostachys juncea and Elymus canadensis×Secale cereale F1 hybrids on MS medium supplemented with 2 mg/l of 2,4-D and plants were regenerated from the calluses on a hormone free MS medium. The plants regenerated from both the hybrids exhibited a high degree of stability in morphology, chromosome number and chromosome pairing. The reasons for this are discussed.

Eleven C2 and two C3 0pen-pollinated plains from Elymus canadensis × Secale cereale amphiploid plants (2n = 6x = 42, SSHHRR) were examined for chromosome constitution and meiosis. Chromosome numbers of the progeny varied: 2n = 26, 27, 28, 36, 37, 39, 40, and 41. Elimination of portions of genome constituents were made at random and were irregular in all o the progeny. Monosomic (2n = 41) and nullisomic (2n = 40) plants lost one to two E. canadensis or S. cereale chromosomes and showed average of 17 to 18 bivalents and 4 to 5 univalents per cell at Ml. The C2, aneuploid plants with 36 to 41 chromosomes seemed to result from selfing or intercrossing among; the C1 amphiploid plants, while the plants of 2n = 26 to 2S (6–9 II + 10–141) might originate from outcrosses of the Cl amphiploid to S. cereale. Bivalent pairing might be preferentially intragenomic (S-S, H-H, or R-R). The occurrence of multivalents indicates a low potential of both intragenomic and intragenomic pairing; Pollen of the lour plants showed poor stainability (1 to 13 %) and no seed set in any of the progeny.

Fifty four hybrid plants between Elymus canadensis and Psathyrostachys juncea were obtained by handpollination and embryo culture. The average cross compatibility between both species was 31.2 percent. One amphiploid plant was induced by colchicine treatment. The hybrid and amphiploid plants resembled P. juncea in appearance but showed a higher plant height and dry matter yield than the parents. The hybrids showed extremely low pollen stainability and were completely sterile. With the exception of one plant (2n=3x+1=22), all hybrid plants were allotriploids (SHN, 2n=3x=21). The amphiploid plant (SSHHNN, 2n=6x=42) showed 58.9% pollen stainability and 11.6% seed fertility.

Reciprocal hybrids between Elymus trachycaulus (2n = 4x = 28) and Elymus canadensis (2n = 4x = 28) were generated through emasculation and hand-pollination. All the F1 hybrid plants were tetraploids (2n = 28). The F1 hybrids were readily produced (9 plants from 150 pollinated florets; 6% success) in crosses where E. canadensis was used as the pistillate parent and the hybrid plants were produced directly from the apparently normal hybrid seeds. The percentage of hybrid plants produced was lower (7 plants from 400 pollinated florets; 1.7% success) in crosses where E. trachycaulus was used as the pistillate parent, and embryo culture procedures were necessary to recover plants from the shriveled seeds produced. Distinct morphological as well as cytological differences between the reciprocal hybrids were observed. All the F1 plants from each reciprocal cross more closely resembled their pistillate parent, indicating a strong maternal influence. Chromosome pairing at metaphase I showed a very high frequency of cells with a hexavalent configuration (69–81%) and a low frequency of cells with univalents (15–23%) in hybrids produced from crosses with E. canadensis as the pistillate parent. In all hybrids produced from crosses with E. trachycaulus as the pistillate parent, chromosome pairing showed a relatively low frequency of cells with a hexavalent (12–22%), while the frequency of cells with univalents was high (78–81%). Cytology of these hybrids indicates substantial control by cytoplasmic genes on chromosome pairing behavior. Reciprocal hybridization betwen octaploid E. trachycaulus (8x) and tetraploid E. canadensis (4x) plants yielded three 2n = 42, one 2n = 41, and one 2n = 39 hybrid plants. All plants were weak and sterile and more closely resembled the octaploid parent, although some intermediate characters were apparent.Key words: Elymus, reciprocal hybrids, maternal influence, cytoplasmic genes, chromosome pairing.

Partially fertile synthetic amphiploids (2n = 8x = 56) of Canada wildrye × slender wheatgrass F1 hybrid were crossed to slender wheatgrass and tetraploid lines resembling slender wheatgrass were recovered after four backcrosses. The BC1 progeny was hexaploid, while the BC2 and BC3 progenies were aneuploids with chromosome numbers ranging from 31 to 38. Tetraploid lines were recovered in the BC4 generation along with 29- and 30-chromosome types. Multivalents (mostly trivalents) resulting from intergenomic pairing were fequently encountered in BC1 and BC2 plants. The multivalent frequencies declined with each succeeding backcross. Pairing in the 28-chromosome BC4 plants was completely regular with 14 bivalents. Intergenomic pairing in the backcross progeny promoted introgression from Canada wildrye to slender wheatgrass.Key words: Elymus, intergenomic pairing, trivalents, recombination.

During the past several decades, research in both cognitive psychology and neuropsychology has become increasingly concerned with the processes that monitor and control human cognition. In the area of cognitive psychology, this research has focused on metacognition or metacognitive processes, and in the area of neuropsychology, it has focused on frontal lobe processes. It is evident that both areas have been referring to very similar concepts, with some variations, but with notably little acknowledgement of each other. The principal purpose of this study was to conduct an analysis of the main research within each of these areas and to examine the continuities and discontinuities in the theoretical premises and empirical results between the two areas. Results indicated that the two areas are remarkably similar in both theoretical premises and empirical results, but that cognitive psychology emphasizes monitoring and control, whereas neuropsychology tends to emphasize control only. A synthesis that unites the work in cognitive psychology and neuropsychology would supply many new directions for research.

The three cereal crops oats (Avena sativa L.), barley (Hordeum vulgare L.) and wheat (Triticum aestivum L.) were tested for forage yields alone and in combinations with each other as well as in combinations with peas (Pisum sativum L.), soybeans (Glycine max. L.) and rape (Brassica napus L.) at three sites and in 3 yr. A range of seeding rates and crop combinations was used. While high yields of forage were obtained from these annual crops, the most favorable yields would not justify the additional expense of cultivation and establishment when compared with perennial forage yields over the same 3-yr period. Oats gave the best yields where seasons were longer and rainfall higher whereas barley gave the highest yields in areas with a drier, shorter season. Higher seeding rates improved yields and reduced fibre contents for all crops over the range tested. This increase was not, however, substantial and with the possible exception of oats, high seed rates would not be economical. The presence of a non-cereal in the mixture always reduced yield, but peas in a mixture with oats gave an increased yield of crude protein per hectare. Where a mixture of a cereal with a non-cereal was used, peas with oats yielded more than rape with oats, while rape with barley yielded more than peas with barley. Seeding the cereal and the non-cereal in alternate rows reduced yields for all the crop combinations tested. Yields were increased by delaying the harvest date beyond the time when the grain was in the dough stage.

The parents and progenies of a 7 × 7 diallel cross of smooth bromegrass (Bromus inermis Leyss.) were evaluated for the genetic variability of some morphological characters and their associations with yield, at four locations in Alberta in 1976 and 1977. Locations, years and their interactions were highly significant for all characters and were subsequently treated as eight environments. The partition of the genotypic variance into general combining ability (GCA) and specific combining ability (SCA) showed that for all morphological characters, GCA was more important than SCA, indicating the importance of additive genetic effects. The genotype × environment (GE) interactions were highly significant. Variation accounted for by GCA was generally higher than the interaction effects of GCA and SCA with environments. Phenotypic and genotypic correlation coefficients revealed that both tiller density and height were significantly correlated with yields. Path coefficient analysis also showed that tiller density, followed by leaf area and tiller dry weight, exerted the greatest direct influence on yield. Selection for large leaf area and more and heavier tillers per unit area would simultaneously increase bromegrass productivity. Furthermore, selection should be based on multi-year and multi-location tests.

Thirty five octoploids (2n = 56). two aneuploids (2n = 54), and one hexaploid (2n = 42) were obtained from the self-fertilized octoploid which was regenerated from the immature inflorescence culture of Elymus canadensis. The octoploid regenerant showed gigas leaves and stems but reduced tillering and fertility. The selfed octoploid progeny varied from genotype to genotype for all of the characters investigated. Hexaploid was morphologically superior to other ploidy levels. Its dry matter yield was 34 % to 40 % higher than the octoploids and the tetraploids but fertility markedly decreased to 7.4 %. Chromosome pairing at metaphase 1 in the octoploid regenerant and its selfed progeny — octoploid, aneupioid. and hexaploid — were 2.57IV +0.83III + 21.23II + 0.971; 3.06IV + 1.06III + 19.66II + 1.251; 2.23IV + 0.85III + 16.54II + 4.69I; and 0.41IV + 8.34III + 8.25II − 3.141 per microsporocyte, respectively. High frequency of trivalents in hexaploid indicated that it is a doubled triploid. Unequal chromosome disjunction, laggards, and chromatid bridges were commonly observed at the anaphase stage in the first and second meiotic division.

SummaryThe effects of e-aminocaproic acid (EACA) on self-incompatibility was tested in a Phaseolus coccineus line which failed to form pods in controlled pollinations. Scanning electron microscope (SEM) and fluorescence miscroscopy confirmed problems in pollen-germination and pollen-tube growth but EACA-treated self- pollinations resulted in fairly normal pollen germination and pollen tube growth. In a few cases, pollen tubes were seen entering the embryo sac and occasionally pods were formed. Incongruity barriers also exist in crosses of P. coccineus × P. vulgaris, P. acutifolius × P. coccineus and their reciprocals. Effects of EACA on flower abscission, pod development and pod abscission were studied. Increased pod formation was observed in EACA treated materials, except in P. acutifolius × P. coccineus and P. coccineus × P. vulgaris cv. Jacobs Cattle. EACA seems to act at the stigmatic and stylar levels, thereby enhancing pollen germination and pollen tube growth and delaying flower abscission. The net...

Stomatal length and frequency were studied using a 7 × 7 diallel cross of smooth bromegrass (Bromus inermis Leyss.) clones and compared with data from an earlier study of the agronomic traits of the crosses. Silicon rubber impressions taken on different parts of a leaf, as well as on different leaves, showed that though variation was small for stomatal size, it was present for stomatal frequency. General combining ability was highly significant for both stomatal characters. Differences among the seven clones were marked. Both stepwise multiple regression and factor analysis were used to investigate the dependence structure that existed for stomatal and agronomic characters. Partial regression coefficients showed that stomatal frequency was related to yield. Factor analysis showed that the two stomatal characters accounted for 20% of the total variation in the dependence structure, whereas characters such as date of head emergence and plant height only accounted for 15%. These results reflect the importance of stomatal size and frequency in a breeding program in relation to agronomic practices.

Intergeneric hybrids recovered through plant regeneration from embryo callus culture and their colchicine-induced amphiploids were obtained from a cross of Elymus canadensis with Secale cereale (cv 'Gazeller'). The embryo-callus-regenerated F1 plants grew vigorously to maturity and regrew well after clipping, while the embryo-rescued F1 died of hybrid necrosis before maturity. Most of the morphological characters of the sterile F1 hybrids were intermediate between the parents, but tiller number and dry matter yield were higher than the parents. Amphiploids from these F1 plants had improved fertility but were less vigorous than the F1 plants. The predominance of univalents in the F1 and bivalents in the amphiploids indicated that the genomes S, H, and R were distinct. However, the occasional occurrence of multivalents reflected a random, intergenomic or intragenomic pairing. The mean chromosome associations of the F1 (2n=21, SHR), the C0 amphiploids (2n=42, SSHHRR), and the C1 amphiploid (2n=40) at metaphase I (MI) were 16.51I+2.05II+0.06III+0.02IV+0.02V, 2.20I+19.87II +0.02IV, and 7.10I+16.37II+0.04III+0.02IV, respectively. These amphiploids could be exploited as new germplasm for forage crop improvement by controlled introgression and backcrosses to the parents.

An autoallooctaploid (2n = 56) form of Elymus trachycaulus (Link) Gould ex Shinners (previously Agropyron trachycaulum (Link) Malte ex H. F. Lewis) was induced by treating allotetraploid shoots with 0.2% colchicine. Successive backcrossing to tetraploid pollen parents was successful and yielded five hexaploid (2n = 42), one pentaploid (2n = 35), and three hyperploid (2n = 31, 32, 33) plants. Metaphase I of the tetraploids was normal and 14 II chromosomes were observed, almost all of which were ring bivalents. Chromosome pairing in one octaploid, four hexploids, and one pentaploid were 4.38 IV + 0.65 III + 17.84 II + 0.85 I, 13.16 III + 0.84 II + 0.84 I, and 5.82 III + 8.18 II + 1.18 I, respectively. Efficiency of chromsome pairing (chiasmata per chromsome) was highest in tetraploids (1.29), lowest in hexaploids (0.75), and intermediate in both octaploid (0.95) and pentaploid (0.93) plants. The octaploid produced longer and broader leaves than the tetraploid, although the total dry matter produced was 14.3% lower. Total dry matter yield of the hexaploid was on an average 30.04% higher than the tetraploid and the leaves were significantly larger. The hexaploid plants were taller than both the tetraploid and the octaploid plants. Metaphase I pairing in hyperploid 1 (2n = 33) was 4.34 III + 9.66 II + 0.66 I, hyperploid 2 (2n = 32) was 2.98 III 11.03 II + 1.00 I; hyperploid 3 (2n = 30 + 1 t) was 1.97 III + 12.05 II + 0.66 I + 0.33 t. The pattern of chromosome pairing in these hyperploids suggest that they are a quintupal trisomic, a quadrupal trisomic, and a triple trisomic respectively. Backcrossing these hyperploids to euploid pollen parents was successful. Backosses and their progeny should result in a series of primary trisomiclines and some monosomic plants, which would be useful for gene mapping. Key words: octaploid, hexaploid (double triploid), pentaploid, tetraploid, hyperploid, trisomic monosomic, Agropyron.

Six lucerne (Medicago sativa) genotypes (Beaver, Vernal and four other strains being developed at the University of Alberta) and five smooth bromegrass (Bromus inermis) genotypes (Carlton, Magna and three genotypes being developed) were examined in terms of forage dry matter (DM) yield and degradability, as determined by the rate and amount of material which disappeared from bags suspended in the rumen of cattle. Dry matter yield did not differ (p > 0·05) between lucerne genotypes at first cut. The smooth bromegrass strain 517 had a proportionately Oil higher (P < 0·05) DM yield than did the Magna strain. No differences (P < 0·05) were detected within either smooth bromegrass or lucerne genotypes for 48 or 60 h in situ DM degradability. The 416E smooth bromegrass genotype, however, had a significantly higher (P < 0·05) rate of DM degradation in the rumen than the other genotypes and also exhibited a longer (P < 0·05) lag period before a significant amount of DM degradability occurred. In the in situ technique, approximately eighteen bags would have been needed to obtain DM degradability measurements with a confidence interval of 0·04 for DM degradability of a probability of 0·95. Further in vivo studies with the bromegrass genotypes are warranted to ascertain if the differences in digestion rates and lag times are related to meaningful differences in animal intake and digestibility.

To develop a system of clectrofusion for the genus Medicago, protoplast yields from 2 genotypes of M, sativa and 7 wild type1 accessions were determined. Protoplast extraction protocols from mesophyll cells, from suspension culture and from calls were evaluated. An alternating current of 10 volts an a frequency of 150 mhz was applied to tht1 protoplasts Ho align them in a pearl chain formation. A direct current pulse of 150 volts applied for 0.25 usec gave the highest number of protoplast fusions for material from mesophyll cells and suspension culture for both M. sativa and wild species. Over 20% of the protoplasts which occupied places in the “pearl chains” yielded fusion products. An average of 25% of the protoplasts treated with an electrical fusion pulse survived, started, to regenerate cell walls and to divide after a 12 days interval. This system can be used to produce new hybrids which, previously, could not be made in the genus Medicago.

Electrical and mechanical properties of the distal canine lower esophageal sphincter were studied in vitro to investigate possible means of inducing pacemaker activity. Both direct excitation and block of potassium conductance were investigated. The acetylcholine analog, carbachol, induced tissue depolarization and increase in tone but no electrical slow waves. Tetra-ethylammonium (TEA) chloride induced depolarization and evoked continuous spiking activity and increase in tone. BaCl did not depolarize the tissue but low amplitude spiking activity developed and increased tone. The putative potassium channel blocker, aminacrine at 2 × 10−4 M, induced electrical slow wave activity in the distal lower esophageal sphincter, with or without superimposed spikes, accompanied by phasic contractile activity. This activity closely resembled the spontaneous pacemaker activity observed previously in the proximal lower esophageal sphincter. The aminacrine-induced activity was abolished by calcium influx blockers. Aminacrine, but not TEA or BaCl, abolished the nonadrenergic nerve-mediated inhibitory junction potentials. In conclusion, block of inhibitory innervation, and induction of electrical slow waves as a control mechanism for phasic contractile activity, seems to require blockade of an aminacrine- but not TEA-sensitive potassium conductance.Key words: smooth muscle, potassium conductance, slow waves, aminacrine, lower esophageal sphincter.

Fifteen species from the genus Agropyron were crossed together. Fourteen of the crosses did not produce fruits. Twenty crosses produced varying numbers of caryopses. Of the fruits produced, 22% contained no embryos. For a variety of reasons it was possible to obtain only 2 plants from the remaining 140 embryos. The crosses which yielded viable plants were between A. trachycaulum cv. Primar (2n=28) and A. intermedium cv. Chief (2n=42) as well as between A. trachycaulum from Lethbridge (2n=28) and A. desertorum cv. Nordan (2n=28). The somatic chromosome numbers for the hybrids are 37 and 28. respectively. Studies of vegetative plant character are presented.

Tissue culture protocols were used to generate somaclonal variation in two synthetic populations of alfalfa. In both cases the somaclone populations give yields of dry matter about 29 % lower than the synthetic populations from which they were derived. Plant height and, for one population (LE-1), stem length, number of node per stem and internode length was also lower for the somaclones than for the original populations. The implications for plant breeding programs are considered and two hypotheses (one genetic and the other physiological), to account for the changes are presented.

The combining abilities for leaflet size and specific leaf weight (SLW) were determined at two different stages of growth in a 7 ✕ 7 diallel cross population of alfalfa (Medicago sativa L.). Both characters were heritable since the general combining ability was larger than either the specific combining ability or the reciprocal effects. Greater genetic variance was observed at an early bud stage than at a late bloom stage. Large differences in SLW were obtained only at an early bud stage. Leaflet size and SLW were not correlated. Genotypes that combined larger leaflet size and higher SLW were identified. Thus both traits would respond to selection in a plant breeding program. The correlation of these characters with forage yield was generally poor.

Seven clones of smooth bromegrass (Bromus inermis Leyss.), five of which were resistant to diseases caused by Pyrenophora bromi (Dred.) and Selenophoma bromigena (Sacc.), were crossed in all combinations forming a 7 × 7 diallel. Plants of both the F1 and its reciprocal cross, as well as the parents, were grown in the field at Edmonton and were measured for dry matter production, plant diameter, days to head emergence and plant height during their 2nd yr. Highly significant variation due to general and specific combining ability were recorded for all the traits. Four of the disease-resistant clones were low yielding and small in plant diameter. On the basis of general combining ability effects these same clones showed little promise as parents. However, one of the disease-resistant clones, B42, was found to perform relatively well and should be of value as a breeding stock.

Genotypes from twelve accessions of five wild species from the genusMedicago were screened for callus formation and somatic embryogenesis using two tissue culture protocols. These wild species were compared with two highly regenerable genotypes ofMedicago saliva. Embryogenesis for the wild types was very low. Wild species genotypes, which gave some callus production, were isolated.

Ten cultivars and breeding lines from two species of alfalfa (Medicago media and M. sativa) were screened for their ability to produce embryos and plantlets from the root and hypocotyl under three different tissue culture protocols. The three protocols differed in basal salt composition, vitamins, hormones and cytokinin additions. That protocol having a high 2-4,D low cytokinin induction step gave the highest percentage of embryogenic calli in some cultivars and lines. M. media cultivars and breeding lines had a high percentage of embryoid formation. M. sativa cultivars gave no embryoid formation. Two M. media breeding lines (Br1 and Le1), which were intermediate in the percentage of embryogenic calli formed from explants, had the highest number of regenerated plants established in soil. The creeping rooted M. media cultivar Heinrichs produced the highest percentage of embryogenic calli from explants but most of these embryoids were abnormal and failed to grow in soil or vermiculite. Accordingly, successful regeneration is directly related to the quality and quantity of the embryoids produced.

A diallel cross population was created from five clones that were randomly selected from five commercial ultivars of alfalfa (Medicago sativa L.). It was planted out at Edmonton and was studied for forage yield, vigor, growth habit, days to flower, plant height and frost tolerance in 1972 and 1973. Results showed that genetic difference between the five parents were large since the general combining ability (GCA) was more important than specific combining ability (SCA) and reciprocal effects (RE) for all the six characters. Greater genetic variance for forage yield, vigor, growth habit and plant height were observed in the second year of growth rather than in the year of establishment. Thus selection for these characters in the second year would be most effective. Genotype x environment interaction was significant for all characters and was relatively more important in the case of vigor and plant height. A study of the GCA effects showed that this source of variation was due to changes in the order of ranking for GCA effects over the environments. Genotypic correlation of the six characters revealed strong genetic association between forage yield, vigor, growth habit, plant height and frost tolerance in this population of alfalfa.

1. The electrical and mechanical activities of different regions of the canine lower oesophageal sphincter were measured using the single sucrose gap technique. 2. Spontaneous electrical activity was found in the region 0-6 mm oral to the squamocolumnar border. 3. The electrical activity consisted of bursts of spikes superimposed on slow waves. The slow-wave frequency ranged from 0.6 to 5 min-1 in different muscle strips. 4. The slow wave-spike complex and associated contraction were insensitive to tetrodotoxin and atropine. 5. In the pacemaker region, electrical stimulation of intrinsic nerves evoked excitatory junction potentials (atropine sensitive), inhibitory junction potentials (non-adrenergic) and post-stimulus excitation. 6. Increase in the frequency of the slow waves was obtained by muscarinic receptor stimulation (carbachol 10(-7) M) and 10 mM-KCl. 7. The distal lower oesophageal sphincter exhibited a high basal tension but did not show spontaneous electrical activity and stimulation of intrinsic nerves revealed only non-cholinergic, non-adrenergic inhibition. 8. The electrical slow-wave activity observed in the proximal sphincter may constitute the control mechanism for the phasic nature of the contractile activity seen during both the postprandial period and phase III of the interdigestive migrating myoelectric complex. 9. The neural cholinergic activity present in the proximal lower oesophageal sphincter suggests the possibility of neural modulation of the myogenic control activity.

Interspecific hybrids between Agropyron trachycaulum (Link) Malte (2n=28 and 56) as female and A. intermedium (Host) Beauv. (2n=42) were obtained by controlled pollination and embryo culture. Five pentaploid hybrids (2n=35 or aneuploid) were closest to A. intermedium in morphology, whereas a septaploid hybrid (2n=49), containing the tetraploid A. trachycaulum chromosome complement, was more like A. trachycaulum. Pentaploid hybrids showed achiasmatic and chiasmatic all types at meiosis, and in one of such hybrids the latter cells provided an average metaphase I configuration of 19.57I, 6.86II, 0.43II and 0.10IV. An aneuploid hybrid (2n=37) displayed extensive chromosome fragmentation at anaphase I, and other hybrids displayed absence of chiasmata in about half of meiotic cells. Pollen was usually shrivelled and non-staining. The septaploid hybrid had an average metaphase I configuration of 8.08I, 20.31II and 0.05III, and had 40% stainable pollen. Chromosome behaviour in parent genotypes was in accordance with genome formulae of SSHH for tetraploid A. trachycaulum and NNN1N1X4X4 for A. intermedium. Bivalent formation in the hybrids was attributed to pairing within H,S (septaploid hybrids) and N genomes and between H and S genomes (pentaploid hybrid). Multivalent formation was attributed to translocations and/or to segmental homologies within the N and X genomes.

Twenty-one progenies and the parents of a 7 × 7 half diallel cross of smooth bromegrass (Bromus inermis Leyss.) were evaluated at four locations in Alberta in each of two years, for genetic variation and genetic by environment interactions in the expression of their yield potentials. Years, locations and their interactions were highly significant in the combined analysis of variance. Combining ability analysis revealed that general combining ability (GCA) and specific combining ability (SCA) were both important in the expression of yield, including spring, fall and annual yield, whereas GCA was more important than SCA for yield per area. Although the genotype × environment interactions were all highly significant, variation accounted for by combining ability effects was generally higher than the interaction effects of GCA and SCA respectively, with environments. High average GCA effects for spring, fall and annual yield were demonstrated for the clones UA5, UA9 and B42. These together with the high average SCA effects suggested that the three clones could be included in a synthetic to develop high yielding cultivars. The results suggested that recurrent selections involving multi-location and multi-year testing seems necessary in breeding for high yielding bromegrass cultivars in Alberta.

Emasculated clones of tetraploid and octaploid Elymus trachycaulus crossed with Pseudoroegneria spicata yielded 69 triploids and 13 pentaploid hybrids. The triploid hybrids were morphologically intermediate between the parental species but the pentaploid hybrids resembled E. trachycaulus more closely than P. spicata. A very high degree of plant size variability (very weak to very vigorous) was observed among the 50 triploids that survived to maturity. The variability among the pentaploids, though apparent, was not high. Mean chromosome associations among the selected eight triploids varied from low multivalent formation at meiosis (7.60 I + 6.18 II + 0.24 III + 0.08 IV) to high multivalent-forming meiosis (7.28 I + 5.66 II + 0.32 III + 0.36 IV). The bivalent configurations in these triploids were attributed to homoeologous pairing between the S1 genome of P. spicata and S genomes of E. trachycaulus and the multivalents indicated intergenomal and intragenomal pairings. Mean chromosome associations of 5.22 I + 11.94 II + 1.97 III in 78.7% and 7 I + 14 II in 21.3% of the 150 cells were distributed among the three pentaploid hybrids. The low frequency of trivalents and the absence of multivalents higher than trivalent configurations suggest that homoeologous pairing was substantially reduced and there was no intergenomal and intragenomal pairing in these 2n = 35 x hybrids. Fourteen triploids and three pentaploid hybrids were produced from 4x and 8x forms of E. trachycaulus and P. spicata spp. inermis crosses. The triploids were intermediate between the parents but the pentaploids were more similar to E. trachycaulus. Mean chromosome associations in the triploids (6.020 I + 5.315 II + 0.554 III + 0.235 IV + 0.250 V + 0.048 VI + 0.03 VII) and in the pentaploids (3.50 I + 10.18 II + 3.54 III + 0.13 IV) indicated a very high degree of intergenomal and intragenomal pairing in the triploids; nevertheless, it was greatly reduced in the pentaploids. The Pseudoroegneria spicata ssp. inermis genome may have gene(s) that affect a high degree of intergenomal and intragenomal pairing in triploid hybrids with E. trachycaulus. However, in pentaploid hybrids (SS HH S2) the S and H genomes of E. trachycaulus in double dose seem to have restored its regular meiotic bahaviour, at least partially, and reduced homoeologous pairing as well as intergenomal and intragenomal pairing. Key words: Elymus trachycaulus, Pseudoroegneria spicata, regular meiotic behaviour, double dose, intergenomal pairing, intragenomal pairing.

This study relates the yield of two harvests of Bromus inermis Leyss. to tiller type and morphology. Tillers were classified as being nonelongated, elongated and headed. At four times during the growing season, observations were made of tiller density; individual tiller weight; leaf number, area and weight; stem length, area and weight; leaf to stem ratio; specific leaf weight; head area and weight.

For each of the three spring wheat cultivars, Pembina, Thatcher, and Manitou, the weight of approximately 900 seeds from 30 randomly selected heads was recorded. These seeds were grown to maturity in the field and mature plant characters associated with yield were recorded. Simple and partial correlation coefficients as well as multiple regression formulae were calculated for all traits. The size of the individual seeds planted was shown to account for 2.5 to 4.5% of the observed variations in yield and other mature plant characters, including the number of heads produced per plant. Head number was the most important component of yield.

Two methods were used to analyse the relationship between 14 traits recorded from an 8×8 diallel cross between varieties of spring wheat. The stepwise regression analysis which introduces characters into a multiple regression equation in the order in which they contribute to yield, together with factor analysis was used to analyse the same dependence structure. The 14 causes were grouped into the basic factors which generate the dependence structure. The two methods were found to give complementary information. The way in which such knowledge would assist the plant breeders in making selections was demonstrated.

The literature provides three explanations of the way in which genetic homeostasis functions. An attempt was made to determine which of these was applicable to the changes which occurred when selection for geotaxis was relaxed in certain strains of Drosophila melonogaster. The strains, for which selection stopped, were divided into two parts and generations were advanced in two environments. One was the same as that in which selection had been made and the other was new. When selection was relaxed strains reverted to a mean geotactic score close to that of the populations from which they had been selected. This change was more rapid in the new environment. A series of diallel crosses compared strains for which selection was continued with those for which it was relaxed. An analysis of the components of genetic variation showed that the principle change that had taken place was in the additive component of genetic variation. It was concluded that genetic homeostasis resulted from the action of natural selection on additive genetic variance, a conclusion which is in agreement with one of the three current hypotheses.

A regression technique was used to analyze the behavior and adaptability of widely grown commercial strains of Canadian hard spring wheat. Yield advances achieved by plant breeding in the past 60 years were estimated. The analysis showed that the advantage derived from rust-resistant varieties has been to increase yields under high-productivity conditions. Manitou and Thatcher were shown to be the more widely adapted of the commercial strains considered. Park is adapted to high-productivity and Cypress to low-productivity conditions.The same method was used to analyze results from trials including strains from Mexico. Pitic 62 is a high-yielding variety shown to have low phenotypic stability. Of the strains tested, Carazinho is phenotypically the most stable but also has the lowest yield. This yield difference was particularly marked at the higher productivity levels.

Records from seven spring wheats in a diallel cross showed that flag-leaf lamina area, extrusion of the head from the leaf sheath, head length and yield were all controlled by minor genes. Additive gene action and general combining ability were shown to be important genetic factors for all characters studied. Partial dominance was present for yield, flag-leaf area and head length. There was evidence that over-dominance played a part in the inheritance of extrusion. The genetic factors which controlled the expression of small leaf size showed dominance over those for large leaves and appeared to be distributed over all chromosomes. Increased extrusion and large flag-leaf area were both shown to be associated with high yield.

Two methods of dividing the Prairie Provinces into regions, one based on soil type and the other on climate, were compared. Reasons were presented for grouping and considering trial sites by climatic regions rather than soil zones. A regression technique was used to study the yields of the more important commercial cultivars of wheat, durum, two- and six-row barley, oats, rape, and flax which have been tested in the Western Co-operative cultivar trials in the prairie provinces of Canada over the period 1953–68. The behavior of the commercial cultivars of the principle arable crops of the three provinces was considered and is discussed in relation to the main soil and climatic features of the area.

Inheritance of yield and its component (number of ears per plant, number of spikelets per ear, number of kernels per ear, 1000-kernel weight), together with the inheritance of morphological characters (flag leaf length, flag leaf breadth, peduncle length, extrusion length and leaf sheath length) and anthesis date was studied in a 5-parent diallel cross of spring wheat varieties. The diallel analysis of gene actions indicated that a large part of the total genetic variation observed for all the characters studied was in the form of additive genetic effects. The degree of dominance was also determined for each character. Number of ears per plant showed most overdominance, followed by leaf sheath length. Full or nearly full dominance was found for anthesis date, flag leaf length and yield per plant. Other characters showed partial dominance. Correlation coefficients showed that yield per plant, as well as being correlated with the yield components, was also assiciated with flag leaf breadth and leaf sheath length. There was no evidence of genetic barriers to the combining of ideal characters among the varieties of different origin.

A diallel cross among eight spring wheat cultivars examined the inheritance of yield, its components, certain developmental stages and morphological characters above the flag leaf node. Additive genetic variance was important for all the characters studied. For yield, kernels per ear, ear volume and for the developmental stages considered dominance was also present. Results presented here agreed with the main conclusions drawn in four other diallels crosses which were reported previously.