bluuebunny/crossref_metadata_2025 huggingface dataset:
Mobilization of stored nitrate in broccoli (Brassica oleracea var. italica)
Authors: Liu Liangxue , Shelp Barry J.
Published: April 2011

The study tested the hypothesis that substitution of nitrate supply with other anions induces the mobilization of stored nitrate in broccoli (Brassica oleracea var. italica) plants. Broccoli plants, grown under greenhouse conditions in soilless culture, were provided with either a continuous supply of nitrate in the nutrient solution until commercial maturity, or with a nitrate supply only up to inflorescence emergence. At inflorescence emergence, nitrate was also substituted with various chloride or sulphate salts of sodium, potassium and ammonium (15 and 5 mmol L−1). During the period of inflorescence development studied, plant size increased by two- to threefold. Nitrate removal or its substitution with chloride or sulphate salts of sodium and potassium (15 mmol L−1) resulted in 13% less dry-matter accumulation and 63–97% less xylem-sap nitrate than continuous nitrate supply, and 57–62% decline in the plant-nitrate content found at inflorescence emergence. In contrast, chloride or sulphate salts of ammonium (5 mmol L−1) sustained plant growth, while also decreasing xylem-sap nitrate by 83–90% and plant-nitrate content by 58–62%. Phloem-exudate nitrate of plants receiving nitrate continuously was only 7% of that of xylem sap, and was decreased by 63% by an interrupted nitrate supply. Therefore, the removal of nitrate and substitution with a low supply of ammonium, rather than other anions, is recommended for decreasing plant-nitrate content. Key words: Broccoli, chloride, mobilization, nitrate, sulphate
Losses of canola seeds from feeding by Lygus species [Heteroptera: Miridae] in Manitoba
Authors: Turnock W. J. , Gerber G. H. , Timlick B. H. , Lamb R. J.
Published: April 2011

Pods of canola plants (Brassica napus L., mostly cv. Westar) were sampled annually from 11–40 canola fields in Manitoba in 1985–1991. The effects of temperature, precipitation, and lygus bug density (in 1989 and 1990) on seed classes (normal, aborted, and collapsed) were determined. In 1991, all pods from 10 racemes sampled from each of 11 canola fields in Manitoba were examined, and the collapsed seeds were classified as injured by lygus bugs or not. The proportion of aborted seeds was not related to lygus bug densities or to weather conditions. The proportion of collapsed seeds varied from 2 to 53% among fields and was related to the number of lygus bugs in the field at the time the pods were collected. Collapsed seeds increased by 1.5% for each lygus bug per sweep. In 2 yr, the proportion of collapsed seeds increased with the mean monthly temperature and decreased with the total precipitation in July, but these weather factors accounted for little of the variation in the proportion of collapsed seed in most years. Collapsed seeds occurred at low frequency in many pods at all canopy levels, but they were most common in small pods in the upper part of the canopy. The proportion of seeds injured by lygus bugs was estimated to be 3–5%, on average, and in some fields, 20%. In addition, lygus bug feeding on other parts of the host plant may induce seed collapse. Key words: Insecta, Lygus, Brassica napus, seed damage, canola
Resistance to stem rust in barley and inheritance of resistance to race QCC
Authors: Fox S. L. , Harder D. E.
Published: April 2011

Twenty-two barley (Hordeum vulgare L.) cultivars and lines were evaluated for resistance to stem rust (Puccinia graminis Pers. f. sp. tritici Eriks. & Henn.) race QCC in field trials over a 3-yr period, and the inheritance of resistance of several genotypes to race QCC was investigated using replicated F3 lines. Rust severities ranged from 17 to 58% between 14 different cultivars and lines which carried the stem rust resistance gene Rpg1, indicating that factors other than Rpg1 conferred resistance. Hietpas-5 (Rpg2) had moderate resistance while PI 382313 (Rpg3) had good resistance to race QCC. In the cross Hiproly-15/Peatland-9, F2 adult plants segregated 3R: 1S to race MCC, confirming the presence of gene Rpg1 in Peatland-9. Some F3 lines derived from F2 plants with Rpg1 were susceptible to race QCC, however, indicating that Rpg1 was ineffective against race QCC. A second gene in Peatland-9, designated for the interim as RpgU and independent of Rpg1, was shown to confer a moderate level of resistance to race QCC. Similar segregation patterns in the presence of race QCC and pedigree analysis suggested that the cultivars Husky and Diamond contain this gene. This gene is likely present in other related cultivars such as Vantage and Bonanza. Segregation in progeny of the cross Hiproly-15/Q21861 indicated that resistance to race QCC was controlled by two recessive genes in Q21861. Gene Rpg2, tested in F3 lines, was found to provide a moderate level of resistance to race QCC, similar to RpgU, but was less effective in the heterozygous condition. The phenotypic expression of RpgU differed from Rpg1, Rpg2, and Rpg3, suggesting that RpgU is a previously unreported gene for stem rust resistance in cultivated barley. Key words: Barley, Hordeum vulgare, stem rust, Puccinia graminis, resistance
Success of a selection program for increasing grain yield of two-row barley lines and evaluation of the modified augmented design (type 2)
Authors: May K. W. , Kozub G. C.
Published: April 2011

The modified augmented design (MAD) (type 2), which adjusts for environmental heterogeneity when large numbers of test lines are being evaluated in non-replicated plots, has been used in the barley (Hordeum vulgare L.) breeding program at the Lethbridge Research Centre. The superiority of test lines selected from two series of F7 test lines selected using the MAD were evaluated in replicated MAD tests (F8) and superior selections were further evaluated in standard replicated designs (F9). When adjustment was indicated for individual MAD tests, the generally high relative efficiencies (RE) confirmed the effectiveness of adjustment in reducing the error variation for yield. The need for adjustment and the adjustment method differed among replicates of the MAD conducted on adjacent blocks of land. The RE from replicated MAD tests indicated the effectiveness of the MAD for reducing the variability in the tests of F8 material. Correlations of the ranks of test lines in different replicates of MAD indicated that more of the same lines in each replicate would be designated as superior with adjustment for heterogenity. The lack of significant positive rank correlations among environments and clearly identifiable improvement in the mean yield was probably the result of the narrowing range in grain yield of the test lines as well as a genotype × environment interaction. Key words: Modified augmented design, Hordeum vulgare, barley, screening
Effect of heat stress during seed development and maturation on wheat (Triticum durum) seed quality. I. Seed germination and seedling vigor
Authors: Grass L. , Burris J. S.
Published: April 2011

Two wheat cultivars, Marzak and Oum-rabia, were subjected to three temperature regimes (20/15, 28/21, 36/29 °C) beginning 10 d after anthesis to maturity. As expected, high temperature resulted in low values of both seed yield and physical traits of seed quality. The effect of temperature on seed germination was not consistent among the two cultivars. High temperature during seed development and maturity had no effect on seed germination of Oum-rabia, whereas it decreased seed germination of Marzak. In contrast to seed germination, seed vigor was adversely affected by heat stress. This decline in seed vigor was reflected in reduced shoot and root dry weight, increased shoot/root ratio, reduced root length, low root number per seedling, and high seed conductivity. Excised embryo culture showed marked differences in the embryo growth potential. Although embryos from all treatments had germinated, a delay of 24–48 h was observed in the germination of embryos excised from seeds grown under high temperature conditions. Also, their shoot and radicle development over time lagged behind that of embryos isolated from seeds grown under cool temperature conditions. Exposing seeds to high temperature during development and maturity also resulted in low embryo oxygen uptake. Results presented in this study show that the growing conditions, in this instance temperature, of the parent plant affect the quality of its seed. Key words: Embryo, germination, oxygen uptake, vigor, wheat, high temperature
Hydroxamic acid content and plant development of maize (Zea mays L.) in relation to damage by the western corn rootworm, Diabrotica virgifera virgifera LeConte
Authors: Assabgui Rafik A. , Arnason J. Thor , Hamilton Robert I.
Published: April 2011

Recently identified resistance factors in two inbreds of maize (Zea mays L.) were investigated in relation to their concentrations over the course of maize root development. The purpose of this study was to determine the time of peak expression in relation to field resistance to larvae of the western corn rootworm (Diabrotica virgifera virgifera LeConte). Bi-weekly variation in root hydroxamic acid content, as determined by high-pressure liquid chromatography, was compared with field resistance of 4- to 16-wk-old maize plants. The phytochemical analysis showed that the major hydroxamic acids in corn roots were 2,4-dihydroxy-7-methoxy-(2H)-1,4-benzoxazin-3(4H)-one (DIMBOA), and its main degradation product was 6-methoxy-benzoxazoline (MBOA). The highest concentrations of DIMBOA equivalents, 2-hydroxy-7-methoxy-1,4(2H)-benzoxazin-3-one (HMBOA) and total hydroxamic acids were found in 6-wk-old root extracts for the inbred with low susceptibility, and 10-wk-old root extracts for the inbred with high susceptibility. In field trials, the inbred with low susceptibility suffered maximal root damage 8 wk post-infestation, followed by a rapid and pronounced recovery. Damage to the root system of the inbred with high susceptibility rose rapidly throughout the growing season, reaching a maximum 12 wk post-infestation, followed by minimal recovery. Plant morphological factors were unaffected and are insensitive as measurements of plant damage. Based on the observations of this study, it would appear that the concentration of hydroxamic acids in the root systems of maize plants plays a role in resistance to western corn rootworm larvae under field conditions. Key words: 2,4-dehydroxy-7-methoxy-1,4-benzoxazin-3-one, Diabrotica virgifera virgifera, western corn rootworm, antibiosis, hydroxamic acids, biochemical resistance
Nearest-neighbor-adjusted means as a selection criterion within two soybean populations
Authors: Helms T. C. , Orf J. H. , Scott R. A.
Published: April 2011

When the nearest-neighbor adjustment (NNA) reduces the magnitude of the residual mean square, plant breeders have the option of selecting genotypes on the basis of the NNA or unadjusted (UNADJ) means. The actual gain from selection for a specific set of experiments can be compared when selection is based on each criterion. Our objective was to compare the yields of lines selected with the NNA and UNADJ criteria. Three hundred soybean [Glycine max (L.) Merr.] experimental lines were evaluated in six environments. Each environment was considered a selection environment, and the actual yield advance was measured in the other five environments. In 11 out of 12 cases, the lines selected by the NNA and UNADJ criteria were equal in yield when compared in testing environments. Interlocation correlations were similar for both models. Predicted genetic gain was overestimated more often when using the NNA than the UNADJ model. Key words:Glycine max, heritability
Inheritance of the waxless character of Brassica napus Nilla glossy
Authors: Jianguo Mo , Wanqu Li , Qin Yu , Bodnaryk R. P.
Published: April 2011

Inheritance studies using two reciprocal and two backcross combinations made from a wax-less (Wl) line of oilseed rape, B. napus 'Nilla glossy' and two normal wax (Nwl) genotypes showed that the Wl character of Nilla glossy is recessive to the Nwl. Chi-square tests revealed that the segregation ratios of B1 and F2 plants fit 3:1 and 15:1 (Nwl:Wl) ratios, respectively, and these are consistent with the presence of two gene pairs. Key words:Brassica napus, epicuticular wax, genetic marker, cer mutant
Decision support systems and computer models, new tools for contemporary agriculture
Authors: Moulin A. P.
Published: April 2011

not available
RCAT Calico soybean
Authors: Ablett G. R. , Stirling B. T. , Fischer J. D.
Published: April 2011

RCAT Calico is a late Maturity Group II soybean [Glycine max (L.) Merr.] cultivar with excellent yield potential, and lodging resistance and high seed protein content. Key words: Soybean, cultivar description
AC Albatros soybean
Authors: Voldeng H. D. , Guillemette R. J. D. , Leonard D. A. , Cober E. R.
Published: April 2011

AC Albatros is a 2500 crop heat unit soybean [Glycine max (L.) Merr.] cultivar with good yield potential. Key words: Soybean, cultivar description
Morphogenetic and structural characteristics of field-grown timothy cultivars differing in maturity
Authors: Bélanger G.
Published: April 2011

The leaf area development of grasses and, subsequently, radiation interception depends on morphogenetic processes such as leaf extension and appearance. No detailed studies of leaf extension and appearance of field-grown timothy (Phleum pratense L.) cultivars differing in maturity have been reported in the literature. Leaf extension and appearance of field-grown timothy cultivars differing in maturity and their impact on sward structural characteristics such as leaf size per tiller and tiller density were studied during primary growth in the spring of 1991 and 1992. The leaf extension rate of early-maturing cultivars was greater than that of late-maturing cultivars during primary growth of timothy. There were no differences in leaf appearance rates among cultivars Hence, individual tillers of early-maturing cultivars developed a larger leaf size than late-maturing cultivars. In 1992, late-maturing cultivars had a greater tiller density than early-maturing cultivars which compensated for the smaller leaf size. Different tiller density-tiller size characteristics of early and late-maturing timothy cultivars resulted in a similar outcome in terms of LAI. Key words:Phleum pratense L., timothy, leaf extension, leaf appearance, tillering
Red smudge in durum wheat reduces seedling vigour
Authors: Fernandez M. R. , DePauw R. M. , Clarke J. M. , Lefkovitch L. P.
Published: April 2011

The effect of red smudge, caused by Pyrenophora tritici-repentis (Died.) Drechs, on germination and early seedling development of four durum wheat (Triticum turgidum L. var. durum Desf.) cultivars was examined using artificially and naturally infected seeds. Rate of germination was similar for red smudged and healthy seeds. Percent germination of naturally infected, but not of artificially infected seeds, was lower for the red smudge than for the control treatments. The number of seminal roots was also lower for the naturally infected than for the control seeds. Lengths of the longest seminal root and of the coleoptile at 12 d were greater in the control than in the disease treatments, regardless of whether the seeds were naturally or artificially infected. It was concluded that red smudge of durum wheat seed reduced seedling vigour. There was transmission of P. tritici-repentis to the coleoptile but not to the true leaves. Key words: Red smudge, tan spot transmission, seedling vigour, durum wheat
Indicators for desiccation timing in field pea
Authors: Warkentin T. D. , Sloan A. G.
Published: April 2011

Three visible indicators of seed water content were evaluated to determine the correct time to desiccate field pea. Assessment of the percentage of brown pods, using visual estimates or by counting, were equally effective indicators of seed water content. Counting "dry colored" seeds ("tan" for a yellow cotyledon cultivar; "blue-green" for a green cotyledon cultivar) was less effective. Key words: Field pea, Pisum sativum L., desiccation
Linola™ 989 low linolenic flax
Authors: Dribnenki J. C. P. , Green A. G. , Atlin G. N.
Published: April 2011

Linola™ 989 is the second low linolenic flax cultivar registered in Canada. In western Canada, Linola™ 989 is significantly earlier maturing than Linola™ 947 and Flanders, and has a significant yield advantage over Linola™ 947 in the Black and Brown soil zones. Linola™ 989 is significantly higher yielding than Flanders in the Black soil zone of Saskatchewan and Manitoba. Both Linola cultivars are yellow seeded. Key words: Flax, low linolenic acid, cultivar description, solin
AEC Blueridge Alpine bluegrass
Authors: Darroch B. A. , Acharya S. N.
Published: April 2011

AEC Blueridge alpine bluegrass (Poa alpina L.) is a reclamation variety developed for use in reclaiming and revegetating disturbed sites at high elevations. It is the first variety of alpine bluegrass released in Canada. Its primary advantage over varieties of other bluegrass species is its ability to thrive under the harsh environmental conditions found at high elevations. Key words: Cultivar description, AEC Blueridge Alpine bluegrass
Economics of monoculture cereal and mixed oilseed-cereal rotations in west-central Saskatchewan
Authors: Zentner R. P. , Campbell C. A. , Brandt S. A.
Published: April 2011

The effects of product price and input cost on the economic performance and riskiness of nine cropping systems were assessed over a 12-yr period on a Dark Brown Chernozemic loam to clay loam soil at Scott, Saskatchewan. The rotations included two 2-yr fallow (F)-crop systems with hard red spring wheat (W) (Triticum aestivum L.) and canola (C) (Brassica campestris L.), four 3-yr fallow-containing rotations with combinations of wheat, canola and barley (B) (Hordeum vulgare L.), a 4-yr and a 6-yr rotation that included alfalfa (Medicago sativa L.) hay, and continuous wheat. All crops were fertilized with rates of N and P based on general guidelines for the region, except for forage hay which was unfertilized. Four rotations (F-C, F-C-W, F-C-B, and F-W-W) showed good economic and risk performance under most price scenarios. The F-W and F-W-B rotations generally ranked intermediate, averaging about 11% lower in net return than the best systems at 1994 commodity price levels; however, at grain prices lower than 75% of these values, net returns were highest with F-W and F-C. It was profitable to substitute canola for wheat grown on fallow when the ratio of canola price to wheat price exceeded 1.8, and to substitute barley for wheat grown on stubble when the barley/wheat price ratio exceeded 0.75. Including alfalfa hay in the rotation was profitable only when the hay/wheat price ratio exceeded 0.8. The unit cost of producing wheat averaged $91 t−1 when grown on fallow, $106 t−1 when grown on canola stubble, $116 t−1 when grown on wheat stubble in fallow-containing rotations and $133 t−1 when grown on continuous wheat stubble. Similarly, the cost of producing barley averaged $74 t−1 when grown on canola stubble and $83 t−1 on wheat stubble. We concluded that producers in the Dark Brown soil zone of west-central Saskatchewan have a strong economic incentive to diversify crop rotations away from traditional monoculture cereal to mixed oilseed-cereal systems. Key words: Wheat, canola, barley, hay, production costs, net returns, riskiness
Indianhead black lentil as green manure for wheat rotations in the Brown soil zone
Authors: Zentner R. P. , Campbell C. A. , Biederbeck V. O. , Selles F.
Published: April 2011

Frequent use of summerfallow (F) to reduce the water deficit associated with cereal cropping in the Canadian prairies has resulted in severe erosion and a reduction in N-supplying power of the soils. It has been suggested that it may be feasible to use annual legumes as green manure (GM) to supply the N requirements and snow trapping to enhance soil water recharge for a subsequent cereal crop. Our objective was to test the feasibility of employing this management strategy for the Brown soil zone of southwestern Saskatchewan, by comparing yields and N uptake of hard red spring wheat (W) (Triticum aestivum L.) grown in a 3-yr rotation with Indianhead black lentil (Lens culinaris Medikus) (i.e., GM-W-W) with that obtained in a monoculture wheat system (i.e., F-W-W). Both cropping systems were operated for 6 yr, from 1988 to 1993, with all phases of the rotations present each year. The results showed that grain yields of wheat after GM were generally significantly (P < 0.05) lower than those after F, primarily because the GM reduced the reserves of available spring soil water. These results occurred despite the fact that five of the six growing seasons had above average precipitation. Yields of wheat grown on stubble were unaffected by rotation. Grain N concentration was greater for wheat grown on GM partial-fallow than for wheat grown on conventional-F in the final 3 yr of the study which was due mainly to the lower wheat yields in the GM system (i.e., yield dilution). Our results suggest that, for annual legume GM to be used successfully in the Brown soil zone, producers should seed it as early as possible (late April to early May) and terminate the growth of the legume by the first week of July, even if this means foregoing some N2 fixation. Key words: Summerfallow, soil water, grain protein, N content, soil nitrogen
The relationship between fall dormancy and germplasm source in North American alfalfa cultivars
Authors: Fairey D. T. , Fairey N. A. , Lefkovitch L. P.
Published: April 2011

Most of the genetic diversity of North American alfalfa cultivars has been accounted for by nine germplasm sources listed in descending order of winter hardiness as follows: Medicago sativa ssp. falcata, Ladak, M. sativa ssp. xvaria, Turkistan, Flemish, Chilean, Peruvian, Indian and African. In most instances, the breeder assigns a fall dormancy score and the relative proportions of each of the nine germplasm source for each cultivar at registration. The fall dormancy score (1 = dormant to 9 = non-dormant), determined by measuring plant height in October after harvest in early September, is used to indicate cultivar adaptation for different regions. This study examines the relationship between germplasm composition and plant height, the equivalence of fall dormancy. The signs on the partial regression coefficients of a multiple regression analysis of plant height on the proportional content of the nine sources of germplasm showed that the fall dormancy fell essentially into two classes, namely, a dormant category, comprising cultivars containing a large contribution of Falcata and Ladak, and a non-dormant category, in which Indian and African germplasm predominate. This does not necessarily preclude the influence of any of the other germplasm sources on fall dormancy, since they represent a rich source of diversity. However, nine distinct classes were not recognisable, perhaps because of the lack of an exact equivalence between fall dormancy class and plant height of the fall regrowth. Since these observations have not been derived in a common nursery, the latitude and latitude × cultivar effects have been disregarded. These limitations should be recognized when using the currently assigned fall dormancy ratings to predict cultivar adaptation. Key words: Alfalfa, fall dormancy, sources of germplasm
AC Bravor soybean
Authors: Voldeng H. D. , Guillemette R. J. D. , Leonard D. A. , Cober E. R.
Published: April 2011

AC Bravor is a 2750 heat unit soybean [Glycine max (L.) Merr.] cultivar with good yield potential. Key words: Soybean, cultivar description
Lentil (Lens culinaris) and fababean (Vicia faba) tolerance to post-emergence applications of imazethapyr
Authors: Wall D. A.
Published: April 2011

Dose response studies were conducted under field conditions from 1993 to 1995 to investigate the tolerance of lentil and fababean to post-emergence applications of imazethapyr (2-[4,5-dihydro-4-methyl-4(1-methylethyl)-5-oxo-1H-imidazol-2-yl]-5-ethyl-3-pyridinecarboxylic acid). Imazethapyr was foliar applied at dosages of 5 to 100 g a.i. ha−1. Lentils were injured by imazethapyr in all 3 yr. The minimum imazethapyr dosages that reduced lentil yields were 20, 10, and 50 g a i ha−1 in 1993 1994 and 1995, respectively; at these dosages yield losses were 31, 21 and 29% in the 3 yr, respectively. This study shows that imazethapyr should not be applied to lentil crops since yields are severely reduced at or below current dosages recommended (50 g a.i. ha−1) for use in western Canada. Fababean tolerance to imazethapyr was examined in 2 yr only. In both years, crop tolerance was excellent and fababean yield was unaffected by imazethapyr at dosages up to 100 g a.i. ha−1. Key words: Crop injury, leaf area index, yield
The structure and function of agricultural research
Authors: Clark E. Ann , Christie B. R. , Weise S. F.
Published: April 2011

Contemporary agricultural research is founded upon short-term controlled studies to examine, screen, and rank performance of genetic improvements or managerial processes. This approach has performed admirably in support of the resource-intensive, high-yield paradigm which has guided agricultural development since the second World War. Changes to this paradigm, which may occur in response to economic, societal, or environmental issues, may require increased emphasis on farm-based, system-oriented research to complement the experiment-station-based research which has proven so successful to date. Corresponding changes to the form, structure, intent, and ultimately, the beneficiaries of agricultural research are discussed. Key words: Long-term research, perennial forages, high-yield agriculture, on-farm research, fanning systems research, profitability, genotype × environment interactions, stability, adaptability
Sustainability, conservation tillage and weeds in Canada
Authors: Derksen D. A. , Blackshaw R. E. , Boyetchko S. M.
Published: April 2011

The sustainability of conservation tillage is dependent on the extent of changes in weed community composition, the usage of herbicides, and the development of integrated weed management (IWM) strategies, including biological weed control. The objective of this paper is to review research on conservation tillage and weed management in light of these factors. Recent Canadian research has found that changes in weed communities due to the adoption of conservation tillage are not necessarily those expected and were not consistant by species, location, or year. Changes reflected the use of different selection pressures, such as different crop rotations and herbicides, within the studies to a greater extent than weed life cycle groupings. Therefore, research that determines the reasons for change or the lack of change in weed communities is required to provide the scientific basis for the development of IWM strategies. Documented herbicide usage in conservation tillage varies from less than to more than conventional-tillage systems. Potential to reduce herbicide usage in conservation-tillage systems exists. Furthermore, the herbicides used in western Canada are different from those causing ground water contamination in the United States, are less volatile, and are used at lower rates. The presence of surface crop residues in conservation tillage may provide a unique environment for classical and inundative biological control agents. Some insects, fungi, and bacteria have the potential to survive to a greater extent in undisturbed plant residues. Residue management and conservation tillage systems are evolving in Canada. Research must keep pace by providing weed management strategies that enchance the sustainability of these systems. Key words: Biological control, zero tillage, integrated weed management, residues, herbicides, rhizobacteria.
Dwarfing genes, water-use efficiency and agronomic performance of spring wheat
Authors: Ehdaie B. , Waines J. G.
Published: April 2011

The Rht1 and Rht2 dwarfing genes have been used extensively to reduce height in wheat (Triticum aestivum L.). The Rht3 gene is also a potent dwarfing gene. Information in the literature is limited or conflicting as to the comparative effects of these genes on water-use efficiency (WUE) and agronomic performance under different environments. Four near-isogenic lines, rhtrht, Rht1Rht1, Rht2Rht2, and Rht3Rht3 in Maringa and three, rhtrht, Rht2Rht2, and Rht3Rht3 in Nainan 60 bread wheat backgrounds were used to determine the effects of dwarfing genes on plant height, total dry matter (TDM) and its components, evapotranspiration efficiency (ETE, TDM/water evapotranspired), WUE (grain yield/water evapotranspired), and carbon isotope discrimination (Δ) in well-watered and droughted pot experiments in the glasshouse. The near-isogenic lines were also grown in well-watered and droughted field experiments. The dwarfing genes consistently reduced plant height and kernel weight in Maringa and Nainari 60 backgrounds under all environmental conditions. The dwarfing genes significantly increased number of spikes per plant in Nainari 60 background in the glasshouse and number of grains per plant in Maringa background under field conditions. In most cases, TDM or shoot dry matter (SDM) in short isogenic lines was significantly reduced. The reduction in grain yield was less than that of TDM or SDM. Therefore, harvest index was greater in short isogenic lines than their respective tall standard counterparts. The effects of the dwarfing genes on root dry matter were relatively small. The dwarfing genes, on average, depressed ETE by 21% and WUE by 15% only in Maringa background. Plant height was positively correlated with TDM and ETE but negatively so with Δ in glasshouse experiments. Grain yield and TDM were positively correlated with ETE. Δ was negatively associated with ETE, TDM, SDM, and grain yield under glasshouse conditions. Key words: Spring wheat, dwarfing genes, near-isogenic lines, water-use efficiency, carbon isotope discrimination
The nitrogen and non-nitrogen rotation benefits of pea to succeeding crops
Authors: Stevenson F. C. , Kessel C. van
Published: April 2011

The inclusion of a pulse crop in a rotation often leads to greater seed yields in the succeeding cereal crop. Two rotations were established at three sites in 1993 to examine the N and non-N rotation benefits of pea (Pisum sativum L.) to the subsequent wheat (Triticum aestivum L.) then oilseed crops. Wheat seed yield was 43% greater (rotation benefit) when preceded by pea rather than wheat, a consistent response among sites. Six to fourteen kg ha−1 of the extra 27 kg ha−1 of N accumulated by wheat in the pea–wheat rotation was derived from the additional N derived from pea residue. The additional soil N availability in the pea–wheat rotation, as indicated by the A-value, explained 8% of the rotation effect on seed yield (N benefit). The remaining 92% of the yield advantage in the pea–wheat rotation was attributed to non-N rotation benefit. The yield of the oilseed crop following the pea–wheat phase of the rotation did not differ from that following the wheat–wheat phase. The influence of growing conditions and cropping history on the magnitude of the N to non-N rotation benefits, and the contribution of different non-N effects, should be investigated further. Key words: Rotation benefit, pea, wheat, residue N, non-N benefit
Productivity, and composition of smooth and meadow bromegrass mixtures with alfalfa under frequent cutting management
Authors: Pearen J. R. , Baron V. S.
Published: April 2011

The value of smooth bromegrass (Bromus inermis Leyss.)–alfalfa (Medicago sativa L.) mixtures for pastures in central Alberta is limited by poor seasonal distribution of yield and low alfalfa persistence. Regrowth of meadow bromegrass (Bromus riparius Rehm.) exceeds that of smooth bromegrass. The effect of these grasses on yield, seasonal distribution and sward composition when grown in mixtures with alfalfa was evaluated. The DM yield of binary mixtures of Carlton or Manchar smooth bromegrass, or Regar meadow bromegrass with Peace or Beaver alfalfa was examined under a four-cut system at three sites in central Alberta for 3 yr. Annual yield was similar at all sites. Alfalfa cultivar did not consistently affect yield, but annual yield of meadow bromegrass-mixtures was 9 to 19% higher than mixture containing smooth bromegrass at Lacombe. Summer and fall production of meadow bromegrass mixtures was 18 to 53% and 40 to 69% greater (P ≤ 0.0001) than smooth bromegrass mixtures. Tiller weight of smooth bromegrass equalled or exceeded that of meadow bromegrass, so superior regrowth of meadow bromegrass mixtures was due to higher tiller density. Over 3 yr, annual yield of the alfalfa component was similar in smooth bromegrass- and meadow bromegrass mixtures, but alfalfa yield decreased (P ≤ 0.0001) 43 to 70% due to dramatic declines in alfalfa stem density. Competition from the associated grass and frequent defoliation reduced alfalfa longevity. Key words: Smooth bromegrass, Bromus inermis Leyss., alfalfa, Medicago sativa L., mixtures, pasture, sward structure
T2653 soybean
Authors: Voldeng H. D. , Frégeau-Reid J. A. , Guillemette R. J. D. , Leonard D. A. , Cober E. R.
Published: April 2011

T2653 is a 2600 heat unit soybean [Glycine max (L.) Merr.] cultivar developed for natto soyfood production. Key words: Soybean, cultivar description, natto
The effect of common root rot on the yield of resistant and susceptible wheat
Authors: Conner R. L. , Kozub G. C. , Bailey K. L.
Published: April 2011

The impact of common root rot, caused by Cochliobolus sativus, on the yield of mixtures of resistant and susceptible backcross-6 derivative lines of Neepawa and Chester wheat was examined in field tests at three locations between 1991 and 1994. Different blends consisting of all 25% incremental combinations of resistant and susceptible back-cross lines within each cultivar were evaluated for disease severity and yield at root rot nurseries and disease-free sites. Significant (P < 0.05) differences in yield were often detected among cultivars. However, within cultivars, no consistent yield differences were observed among blends of resistant and susceptible lines of the same cultivar regardless of root rot severity. Key words:Cochliobolus sativus, common root rot, yield, wheat
Dry bean (Phaseolus vulgaris) tolerance to imazethapyr
Authors: Blackshaw R. E. , Saindon G.
Published: April 2011

A field study was conducted during 3 yr to determine the growth and yield response of Pinto, Pink Red and Great Northern dry beans to various doses of imazethapyr. Imazethapyr was applied postemergence at 0, 25, 50 75 100, 150, and 200 g ha−1 to each class of dry bean. Results indicated that these four classes of dry beans responded similarly to imazethapyr. Dry bean injury increased and yields were reduced as dose of imazethapyr increased. At the proposed use dose of 50 g ha−1, imazethapyr reduced yield by 5 to 6%. Imazethapyr at 100 g ha−1 reduced dry bean yield by 10 to 12% and delayed maturity by 3 to 4 d. Benefits of superior weed control attained with imazethapyr should be weighed against potential crop injury when growers consider using imazethapyr in their dry bean weed management programs. Key words: Herbicide injury, maturity, seed yield, seed weight
Estimation of N2O emissions from agricultural soils in Canada. I. Development of a country-specific methodology
Authors: Rochette P. , Worth D E , Lemke R L , McConkey B G , Pennock D J , Wagner-Riddle C. , Desjardins R J
Published: April 2011

International initiatives such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol require that countries calculate national inventories of their greenhouse gas emissions. The objective of the present study was to develop a country-specific (Tier II) methodology to calculate the inventory of N2O emissions from agricultural soils in Canada. Regional fertilizer-induced emission factors (EFreg) were first determined using available field experimental data. Values for EFreg were 0.0016 kg N2O-N kg-1 N in the semi-arid Brown and 0.008 kg N2O-N kg N-1 in the sub-humid Black soil zones of the Prairie region, and 0.017 kg N2O-N kg-1 N in the humid provinces of Quebec and Ontario. A function relating EFreg to the "precipitation to potential evapotranspiration" ratio was determined to estimate annual emission factors (EFeco) at the ecodistrict scale (≈ 150 000 ha) in all agricultural regions of Canada. Country-specific coefficients were also developed to account for the effect of several additional factors on soil N2O emissions. Emissions from fine-textured soils were estimated as being 50% greater than from coarse- and medium-textured soils in eastern Canada; emissions during winter and spring thaw corresponded to 40% of emissions during the snow-free season in eastern Canada; increased emissions from lower (wetter) sections of the landscape and irrigated areas were accounted for; emissions from no-till soils were 10% greater in eastern, but 20% lower in western Canada than from those under conventional tillage practices; emissions under summerfallow were estimated as being equal to those from soils under annual cropping. This country-specific methodology therefore accounts for regional climatic and land use impacts on N2O emission factors, and includes several sources/offsets that are not included in the Intergovernmental Panel on Climate Change (IPCC) default approach. Key words: Nitrous oxide, soils, greenhouse gases, inventory
Shelterbelts and their effect on crop yield
Authors: Kowalchuk T. E. , Jong E. de
Published: April 2011

Shelterbelts planted to control wind erosion indirectly affect the adjacent crop. Yield data were collected during 3 yr from 15 fields cropped mainly to spring wheat seeded on fallow, to quantify the competition and sheltering effects of the shelterbelts (about 6 m high and 200 m apart) and to relate these to microclimate and plant-available soil N, P and water. In 1989 and 1990, when moisture conditions during the growing season were dry and close to average, respectively, competition by the trees and their approximately 5-m-wide grass edge reduced crop yield about 10 m into the field. Yields were slightly above the field mean about 10–20 m from the field edge. The competition effect was smaller and the zone of improved crop growth was absent in 1991 when water was abundant. Plant-available N and P were close to the field means at the edge of the cultivated fields and were highest about 10 m into the fields. Competition for water is believed to be the main reason for the reduced yields at the edge of the fields as most farmers seed-placed fertilizer P, and response to added fertilizer N appeared independent of distance from the shelterbelt. Competition for water occurs during the growing period of the crop, but also includes water taken up by the shelterbelt when the field is in fallow. The improved crop growth 10–20 m from the field edge appears related to the reduction in potential evaporation as distance to the shelterbelt decreases. Key words: Shelterbelts, crop, competition, shelter, evaporation, wind
Grazing impacts on bulk density and soil strength in the foothills fescue grasslands of Alberta, Canada
Authors: Chanasyk David S. , Naeth M. Anne
Published: April 2011

Alberta foothills fescue grasslands are very productive ecosystems but there is concern that the traditional season-long (continuous) grazing regimes may be leading to soil deterioration due to compaction and increased soil strength. The objectives of this study were to quantify grazing effects on soil bulk density and soil strength of sloped areas in the Alberta foothills fescue grasslands at the Agriculture Canada Stavely Range Substation. The effects of two grazing intensities (heavy and very heavy) for two treatments (short duration and continuous) on these two parameters were compared to an ungrazed control. Soil bulk density and soil water to a depth of 7.5 cm were measured with a surface water/density gauge. Soil strength was measured with a hand-pushed cone penetrometer to a depth of 45 cm. Cone index, the maximum penetration resistance in a given depth interval, was used as a measurement parameter for soil strength.Grazing affected both soil bulk density and penetration resistance. Even short-duration treatments affected these soil properties, although their effects were similar for both heavy and very heavy grazing intensities. Distinction between heavy and very heavy continuous grazing treatments was clear for both bulk density and penetration resistance, with the very heavy treatment having the greatest detrimental effect on these two soil parameters for all treatments. Bulk density and soil strength values were always lowest in the spring after snowmelt and highest late in the growing season, reflecting the water status of these ecosystems. Identical treatment rankings were obtained using bulk density and penetration resistance, but cone index was a more sensitive indicator of the effects of grazing than bulk density. Key words: Grazing, fescue grasslands, bulk density, soil strength
Relationship of physiological characters to yield parameters in oilseed rape (Brassica napus L.)
Authors: Chongo G. , McVetty P. B. E.
Published: April 2011

The physiological basis of seed yield in oilseed rape (Brassica napus L.) still remains unclear, and conclusions on the contribution of such traits to seed yield are difficult to make. Nine cultivars, classified into three yield groups (high, medium and low) based on significant differences in seed yield from previous trials, were tested over two locations and years. Leaf chlorophyll content, net photosynthetic rate per unit leaf area (PA), per unit leaf dry matter (PDM) and per unit leaf chlorophyll (PC), transpiration rate (TR) and water use efficiency (WUE) were investigated on fully expanded leaf numbers 4 (vegetative), 6 (early flowering) and 8 (early podding stage) on the main stem and related to seed yield, total dry matter (TDM) and harvest index (HI) of each yield group. Differences among yield groups for seed yield, TDM and HI were significant. Chlorophyll content was lowest on leaf 4, but increased with leaf age. Correlations between net photosynthetic rate and seed yield were not found. However, cultivars in the high yield group maximized their net photosynthetic rates (PA, PDM, and PC) on leaf 6 during early flowering at the time when TR was lowest and WUE at its highest. In the medium and low groups, photosynthetic rates were highest on leaf 4, but decreased to lowest values on leaf 8, together with the high yield group. In general, the results indicate that the largest contribution to net photosynthesis by oilseed rape leaves occurred during the vegetative and early flowering stages compared with the early pod-filling stage. Key words: Total dry matter, harvest index, photosynthesis, chlorophyll
CT157 flue-cured tobacco
Authors: Haji H. M. , Mishra S. , DeVos M.
Published: April 2011

CT157 is a flue-cured tobacco (Nicotiana tabacum L.) cultivar with superior quality. Grade index value and company evaluation are significantly higher than the checks. Key words: Nicotiana tabacum L., tobacco, cultivar description
Effect of herbicides on two species of clover underseeded into barley
Authors: Ivany J. A. , Holmstrom D. , Kunelius H. T.
Published: April 2011

Potato (Solanum tuberosum L.) producers on Prince Edward Island often underseed red clover (Trifolium pratense L.) into barley (Hordeum vulgare L.) crops so as to have a forage crop in the third year of the 3-yr rotation of potatoes-grain-forages. Some producers would like to plant an annual legume that could be underseeded in barley to improve soil organic matter levels in a 2-yr rotation of barley-potatoes. We examined, over 3 yr (1996–1998), the effect of herbicides commonly used in barley on perennial red clover and annual berseem clover (Trifolium alexandrinum L.) underseeded in barley. Based on clover plant stand after herbicide application, both red clover and berseem were killed by herbicide mixtures containing dicamba and were severely injured by bromoxynil. Red clover was severely injured by thifensulfuron/tribenuron mixture whereas berseem clover was only slightly injured. MCPA-Na generally caused little injury to either clover species whereas MCPB/MCPA caused less injury to red clover than to berseem clover. Clover yield in the fall reflected level of injury noted during the season. Key words: Red clover, berseem clover, underseeded clover, herbicide, dicamba, MCPA–Na
CG109 corn inbred line
Authors: Lee E. A. , Good B. , Chakravarty R. , Kannenberg L.
Published: April 2011

CG109 is a short seasoned corn (Zea mays L.) inbred line. CG109 exhibits excellent combining ability and stalk quality in hybrids. Key words: Corn, Zea mays L., cultivar description
Inheritance of resistance to a necrosis- and chlorosis-inducing isolate from Race 1 of Pyrenophora tritici-repentis in spring wheat
Authors: Duguid S. D. , Brûlé-Babel A. L.
Published: April 2011

Tan spot is a stubble-borne foliar disease of wheat (Triticum aestivum L.) caused by Pyrenophora tritici-repentis (Died.) Drechs. The potential for yield losses due to tan spot has increased with the adoption of conservation tillage practices. The main objective of this study was to determine the inheritance of resistance among seven wheat genotypes to the tan necrosis- and chlorosis-in ducing, race 1, isolate ASC1 (nec+ chl+), and the necrosis-inducing toxin, Ptr ToxA. Crosses were made between four resistant (Erik, ST6, 6B367, 6B1043) and three susceptible genotypes (Katepwa, BH1146, ST15). Parental, F1 and F2 populations were inoculated with ASC1 and infiltrated with Ptr ToxA under controlled environments. F2-derived F3 families were grown in the field and inoculated with ASC1. No reciprocal differences were observed. Resistance to the tan necrosis-inducing component of ASC1 and insensitivity to Ptr ToxA was controlled by a single recessive gene, whereas resistance to the chlorosis-inducing component of ASC1 was controlled by a single dominant gene. Genetic control of responses to each component (tan necrosis- or chlorosis-inducing) of ASC1 was independent. Lack of segregation among F2 progeny from crosses between resistant genotypes indicated that resistant genotypes carry at least one gene in common for resistance to ASC1. Key words: Triticum aestivum, Pyrenophora tritici-repentis, disease resistance, inheritance, Ptr ToxA, necrosis, chlorosis, toxin, tan spot, leaf spot
Field sampling strategies for studies of alfalfa forage quality
Authors: Grimsbo Jewett Jane , Sheaffer Craig C. , Moon Roger D. , S. Lamb JoAnn F.
Published: April 2011

Information is scarce on sampling techniques for field studies of alfalfa forage quality. Standard formulas are available for estimating the number of samples needed for reducing error in a study, but little is known about the impact of plot sampling on forage quality. Our objectives were to compare the strategy of manual harvesting from small areas within plots with that of grab sampling mechanically harvested forage, and to determine whether the within-plot location of sampling affected forage quality in any systematic way. Alfalfa forage was sampled from swaths of mechanically clipped forage (grab samples) and from hand-clipped areas within field plots (area samples). Systematic sample location within a plot had no discernable effect on forage quality. Calculations of predicted standard errors and required sample numbers indicated that one area or one grab sample per plot with three replicates would provide an acceptable standard error for comparison of alfalfa entries for protein and fiber concentration. Within-plot variability was greater at late-summer harvests than earlier harvests, but at all harvests one sample per plot with three replicates gave adequate precision for forage quality comparisons. Higher forage quality from grab samples than from area samples at spring harvests suggested the need for caution when comparing forage quality studies done with different harvest methods; however, there were few entry × sampling strategy interactions, which suggests that relative performance of entries would be similar regardless of the method of sampling. Key words: Alfalfa, forage quality, Medicago sativa L.; field sampling, bootstrap