bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of HPS supplemental lighting and soil water levels on growth, essential oil content and composition of two thyme (Thymus vulgaris L.) clonal selections
Authors: Letchamo W. , Gosselin A.
Published: April 2011

The growth, esssential oil content and composition of two clonally selected Thymus vulgaris plants were each significantly affected by two light regimes (LR) and three different soil water levels (SWL). The highest dry matter accumulation was achieved from plants grown under supplemental light (SL) at 90% SWL. The leaf area increased linearly from 959 cm2 to 1635 cm2 for Selection 1 and from 543 cm2 to 1322 cm2 for Selection 2 under natural light and from 1180 cm2 to 3512 cm2 for Selection 1 and from 958 to 2821 cm2 for Selection 2 under supplemental light, respectively, for plants grown under 50 to 90% SWL. The coefficient of correlation between shoot yield and leaf area was highly significant (r2 = 0.96). However, maximum essential oil content and yield per plant were recorded at 70% SWL for Selection 1 grown under SL. There were significant shifts in the content of phenols, particularly in monoterpene hydrocarbons in the essential oil, due to the differences in LR and SWL. The major constituent of the essential oil, thymol, accounted for the shift from about 48.6% to 85.5% for Selection 1 and the shift from 47.2% to 68.9% for Selection 2, depending on the treatment levels. Our data showed a maximum level of 85.5% thymol accumulation in the essential oil of Selection 1 grown at 70% SWL under SL. We established that both selections under investigation belonged to the thymol chemotype. Key words:Thymus vulgaris L., Lamiaceae, essential oil, thymol
Pathogenicity and mycotoxin production of Fusarium species causing head blight in wheat cultivars varying in resistance
Authors: Wong L. S. L. , Abramson D. , Tekauz A. , Leisle D. , McKenzie R. I. H.
Published: April 2011

Fusarium head blight (FHB) of wheat has recently become more prevalent in Manitoba, Canada. The objectives of this study were to assess the pathogenicity of Fusarium species isolated from infected wheat spikes, determine their potential to produce trichothecene mycotoxins and evaluate wheat cultivars for resistance to these Fusarium species. This information is a prerequisite to the development of cultivars with effective resistance to FHB in Manitoba. Eight Chinese and three Canadian wheat cultivars were evaluated against individual strains of seven Fusarium species singly in the field. Severity of FHB was measured as percentage of discolored peduncles and percentage of tombstone kernels. On this basis, Fusarium culmorum and F. graminearum were highly pathogenic, F. sporotrichioides had intermediate pathogenicity, and the other species were weakly pathogenic. For F. culmorum and F. graminearum, FHB severity correlated positively with kernel weight reduction and recovery of Fusarium species from the seed and correlated negatively with seed germination. Fusarium species varied in their ability to produce trichothecenes in infected wheat spikes. Wheat inoculated with F. poae contained both type A and B trichothecenes, while that inoculated with F. culmorum and F. graminearum produced type B only. Wheat inoculated with F. sporotrichioides contained type A trichothecenes, while that inoculated with F. avenaceum contained no detectable trichothecenes. Concentration of DON correlated positively with percentage of tombstone kernels in F. culmorum and F. graminearum, and that of HT-2 toxin correlated positively with percentage tombstone kernels in F. sporotrichioides. Biggar, Katepwa and Sceptre wheats were susceptible to F. culmorum and F. graminearum. High levels of resistance, expressed as low FHB severity combined with low trichothecene production, were found in several Chinese cultivars. These traits could be incorporated in adapted cultivars and be monitored by use of artificial inoculation. Key words:Fusarium culmorum, Fusarium graminearum, fusarium head blight, mycotoxins, resistance, wheat
Effects of environment and cultivar on total mixed-linkage β-glucan content in eastern and western Canadian barleys (Hordeum vulgare L.)
Authors: Narasimhalu P. , Kong D. , Choo T. M. , Ho K. M. , Ferguson T. , Therrien M. C. , May K. W. , Jui P.
Published: April 2011

Two-row and six-row barley (Hordeum vulgare L.) cultivars, originating from eastern and western Canada were grown in six environments across Canada. The grain was studied for the effects of environment and cultivar on the total mixed-linkage β-glucan content (TBG, g hg−1 DM). Environment significantly affected TBG content in barley. TBG content differed among the 32 eastern or 43 western Canadian cultivars but the mean TBG for the eastern cultivars was not different from the mean of western cultivars. All eastern cultivars were hulled-feed types, and their TBG ranged from 3.31 in Micmac to 4.09 in Birka for two-row barleys, and from 3.78 in OAC Kippen to 4.41 in Maskot for six-row barleys. Western hulled cultivars which included feed and malt types, contained TBG ranging from 3.37 in Manley to 4.14 in Betzes for two-row barleys, and from 3.71 in Heartland to 4.42 in Tankard for six-row barleys. The two-row hulless cultivar, Condor, contained more TBG (4.69) than the other two hulless cultivars, CDC Richard (3.91) and Scout (3.85). The six-row hulless cultivars, CDC Buck and Tupper, were equal in TBG (4.35). The mean TBG was lower for the two- than six-row barleys (3.7 vs. 4.0), and a broader range for TBG in the two- (3.31–4.55) than six-row barleys (3.71–4.42) suggesed the greater possibility of producing low and high TBG barleys from the two-row cultivars. Canadian cultivars contained between 3.31 and 4.55 g TBG hg−1 DM, and there is a need to develop feed-type barleys containing a third less than the minimum TBG, and food-type barleys containing a third more than the maximum TBG. Key words: Barley, Hordeum vulgare cultivars, β-glucan
Effect of nitrogen fertilizer residues on the response of irrigated bromegrass to fertilizer nitrogen
Authors: Leyshon A. J. , Campbell C. A.
Published: April 2011

Two nitrogen (N) fertilizer response trials were superimposed, in 2 consecutive years, on a set of large plots of irrigated bromegrass (Bromus inermis Leyss.) that had been fertilized with different rates of fertilizer N up to 200 kg ha−1 for the previous 9 and 10 yr, respectively. During those years, forage dry matter responded in direct proportion to fertilizer N rate. In the subsequent two trials we determined the residual effects of the prior fertilizer treatments on the response of bromegrass to new applications of N fertilizer, and the N rate required to achieve maximum yields. The yield response of the bromegrass to the applied N was a function of prior fertilizer history and the moisture conditions. In the first trial, under good moisture conditions, the previously unfertilized plots had maximum yields at a N rate of 382 kg N ha−1; yields declined at higher rates. Responses of previously fertilized plots to additional N were linear. The y-intercepts (where no N was applied) were higher for plots that had been fertilized at higher N rates in the initial 9-yr study while the slopes of the yield responses were less steep. In contrast, in the second trial, conducted in a year when irrigation water was restricted, all forage yield responses to N fertilizer were curvilinear, Y-intercepts were again higher on plots that had been fertilized at higher N rates in previous years. In this case, however, the slopes of the N responses became progressively steeper with increasing N rate while increasingly larger quadratic coefficients resulted in maximum yields being attained at progressively lower N rates. Nevertheless, maximum yields were higher than those of the previously unfertilized plots. Changes in the response curves were attributed to alterations in the soil organic N and to a lesser extent, to changes in the capability of the bromegrass to respond to fertilizer N. Soil tests found no carry-over of fertilizer N as residual inorganic N but the initial potential rate of mineralization (N0k) reflected changes in the quality of soil organic matter influencing the response to N fertilizer applications. The results suggest the need for soil testing laboratories to take into account the prior fertilizer history of the grass stand when developing recommended N fertilizer rates for irrigated bromegrass. Key words: Bromegrass, N fertilization, residual N, mineralizable N
Response of eight Canadian spring wheat (Triticum aestivum L.) cultivars to copper: Copper content in the leaves and grain
Authors: Owuoche J. O. , Briggs K. G. , Taylor G. J. , Penney D. C.
Published: April 2011

Concentrations of copper (Cu) in the youngest fully emerged leaves (YFEL) and grain of eight widely grown Canadian spring wheat (Triticum aestivum L.) cultivars, Biggar, Columbus, Conway, Katepwa, Laura, Oslo, Park and Roblin, were determined. Leaves were sampled at five growth stages from field plots grown in 1990 and 1991 on Cu-deficient soil or soil treated with 12.2 kg Cu ha−1 as Cu sulphate. Symptoms of Cu deficiency, mainly rolling and wilting of young leaves and twisting and terminal dieback, were noted on Katepwa, Park and Roblin at Zadok growth stage 24. Significant (P ≤ 0.01) effects on Cu concentration in the YFEL were found due to cultivar, copper treatment, year and growth stage. The Cu concentrations in Katepwa, Park and Roblin not treated with Cu ranged between 4.6 and 5.7 μg g−1 in 1990 and between 2.8 and 3.5 μg g−1 in 1991 at Zadok growth stage 22. Cultivars Biggar, Columbus, Conway, Laura and Oslo did not show symptoms of Cu deficiency and had Cu concentrations in the range of 4.6–5.4 μg g−1 in 1990 and 2.3–3.1 μg g−1 in 1991. Deficiency symptoms were observed on Katepwa and Park supplied with Cu, although concentrations of Cu in the YFEL were relatively high. Grains sampled from the tillers generally had lower Cu concentrations than those from main stems, but the magnitude of this difference varied with the year. Significant correlations were found between Cu concentrations in the YFEL and grain yield (r = 0.90* in 1990 and 0.89* in 1991) and with floret fertility (r = 0.74* in 1990 and 0.94** in 1991). These large and significant correlations confirm the important role of Cu nutritional status in influencing floret fertility and grain yield. Critical levels of Cu in the leaves needed for unlimited growth could not be defined because of year-to-year variability. In this study, Cu concentration in the YFEL was not a useful indicator of potential Cu use efficiency in different wheat cultivars. However, for individual plants under Cu-deficiency stress, Cu concentration in the YFEL was a good indicator of the grain yield potential of different cultivars. Key words:Triticum aestivum, copper, youngest fully emerged leaves, tissue analysis
Effect of Zn on the concentration of Cd and Zn in plant tissue of two durum wheat lines
Authors: Choudhary M. , Bailey L. D. , Grant C. A. , Leisle D.
Published: April 2011

Irrespective of fertilizer treatments, durum wheat (Triticum turgidum L. var durum) Cd concentration was lowest in the grain and highest in the roots and was in the order: root > leaf > stem > grain. Soil-applied Zn decreased the Cd concentrations in durum wheat grain, leaf, stem, and root. But, foliar application of Zn resulted in Zn loading of the leaf and stem and had little effect on plant Cd concentration. Application of P and N plus P fertilizer increased tissue Cd concentration and decreased stem and leaf Zn concentration to near insufficiency, while application of Zn to soil with N plus P fertilizers increased tissue Zn concentration to sufficiency level and decreased plant Cd concentration of the two durum wheat lines. Key words: Cd, durum wheat, Zn, dry matter, plant tissue
Influence of nitrogen fertilization on broccoli yield, nitrogen accumulation and apparent fertilizer-nitrogen recovery
Authors: Zebarth B. J. , Bowen P. A. , Toivonen P. M. A.
Published: April 2011

An understanding the relationships between N-fertilization rate, crop-N recovery, residual inorganic N in soil and crop yield can assist in making N fertilizer recommendations which balance crop value and environmental risk. Nitrogen was applied to three plantings of broccoli at 0, 125, 250, 375, 500 and 625 kg N ha−1 as a broadcast application of ammonium nitrate, 50% at transplanting and 50% 2 wk later. Crop-marketable yield, aboveground dry matter yield and N accumulation, and extractable-soil inorganic N to 75 cm depth were determined at harvest. Crop-marketable yield, measured as fresh weight of heads, increased with increasing N rate to a maximum between N rates of 435 and 560 kg N ha−1. Nitrogen accumulation in the aboveground portion of the plant increased with increasing N rate and reached a maximum of 345–465 kg N ha−1. Apparent fertilizer-N recovery in the aboveground portion of the plant decreased linearly from between 46 and 93% at a N rate of 125 kg N ha−1 to between 20 and 44% at a N rate of 625 kg N ha−1. Apparent fertilizer-N recovery in the harvested portion of the plant decreased linearly from between 14 and 25% at a N rate of 125 kg N ha−1 to between 8 and 14% at a N rate of 625 kg N ha−1. Soil profile nitrate-N to 75 cm depth at harvest increased with N application rate in a curvilinear fashion, and averaged 3 kg N ha−1 with no N applied to 420 kg N ha−1 at the maximum N rate. The potential to develop a soil nitrate test to predict the fertilizer-N requirement of broccoli is discussed. Key words: Plant-available N
Effects of time and rate of application of triazole fungicides on incidence and severity of blackleg and growth and yield of canola
Authors: Rempel C. B. , Hall R.
Published: April 2011

The ability of three triazole fungicides to reduce blackleg and to increase the yield of spring canola (Brassica napus) was tested at four locations in Ontario in 1990 and 1991 in fields containing stubble infested with Leptosphaeria maculons. In test 1, triadimefon (3.46 kg ha−1), diconazole (1.41 kg ha−1) and uniconazole (2.12 kg ha−1) were sprayed on foliage at the late rosette stage, or when flowers were opening on the main raceme, or at both growth stages at half rate (split). Split applications were most effective and reduced disease incidence and severity by 9.2 and 22.6%. Yields were not increased. In test 2, the fungicides were applied at the late rosette stage at four rates. The highest rates of triadimefon (9.24 kg ha−1), diconazole (3.76 kg ha−1) and uniconazole (5.64 kg ha−1) reduced disease incidence by 12.8, 10.6 and 6.4%, reduced disease severity by 25.7, 31.8 and 24.2%, and increased yield by 17, 33 and 30%, respectively. In both tests, most treatments increased seed weight, delayed crop flowering and maturity, reduced lodging and height, and increased vigor. Triazole fungicides applied as foliar sprays can reduce blackleg and improve yield of canola. Key words:Brassica napus, canola, triadimefon, diconazole, uniconazole, blackleg
Salt tolerance of Hordeum and Brassica species during germination and early seedling growth
Authors: Huang J. , Redmann R. E.
Published: April 2011

Germination response and early seedling growth of barley (Hordeum vulgare L. 'Franklin', 'Harrington' and 'Abee'), wild barley (H. jubatum L.), canola (Brassica napus L. 'Excel') and wild mustard (B. kaber L. C. Wheeler) were investigated in iso-osmotic solutions of salts (NaCl, Na2SO4 + MgSO4) and polyethylene glycol (PEG) with osmotic potentials close to −0.9 MPa. Germination of Harrington and wild barley was reduced most by the non-penetrating solute PEG, suggesting that ion penetration might have reduced osmotic stress in the salt treatments. Wild barley was more salt tolerant than Harrington based on seedling growth relative to control plants. Of the three barley cultivars, Franklin was similar in salt tolerance to Harrington, while Abee was the most sensitive to all osmotica tested. Barley varieties had the lowest germination rate and poorest seedling growth in the PEG treatment. Compared with canola, wild mustard showed consistently greater tolerance to all osmotica during germination and early seedling growth. Germination of the Brassica species was more sensitive to NaCl than to mixed sulphate salts. Additional calcium enhanced germination and improved seedling growth in Brassica species, especially in the PEG and NaCl treatments. Key words: Barley; calcium nutrition; canola; chloride salinity; sulphate salinity
The effect of quadrat shape and placement on the accuracy of yield and density estimates for crops seeded in narrow rows
Authors: Hume Larry , Shirriff Scott
Published: April 2011

Small quadrats (commonly 1-m2 or less) have been used extensively as the sampling unit in studies examining crops seeded in narrow rows. The effects of sampling unit shape and orientation on yield and plant density estimates was examined. When small quadrats are required for sampling crops seeded in narrow rows, sampling would best be done using rectangular quadrats with sides parallel to crop rows and having some multiple of row width. In seventy seven published papers from 1988 to 1994, the quadrat shape used in sampling plant populations was appropriate in only fourteen instances. Inappropriately shaped quadrats could result in errors of up to 25% in estimates of crop related variables, such as yield. Key words: sampling unit, quadrat shape, plot size, plot shape
AC Winsloe winter wheat
Authors: Nass H. G. , Johnston H. W. , Blatt C. R. , Atlin G. , Walton R. B.
Published: April 2011

AC Winsloe is a winter feed wheat (Triticum aestivum L. em. Thell.) with high grain yield, lodging resistance, and good winter survival. It is resistant to powdery mildew (caused by Erisyphe graminis D.C. ex Merat f. sp. tritici Marchal), moderately resistant to septoria leaf and glume blotch [caused by Septoria nodorum (Berk.) Berk.] and moderately resistant to fusarium head blight (caused by Fusarium graminearum Schwab and other Fusarium spp.). AC Winsloe is suitable for production in Eastern Canada, particularly in the Atlantic region. Key words:Triticum aestivum, wheat (winter), cultivar description
Hypericin content of Nova Scotia biotypes of Hypericum perforatum L.
Authors: Jensen K. I. N. , Gaul S. O. , Specht E. G. , Doohan D. J.
Published: April 2011

Photosensitization of livestock in Nova Scotia has often been attributed to St. John's wort (Hypericum perforatum L.), even though the weed generally occurs at low densities. This study's objective was to determine whether levels of hypericin, the photodynamic toxin causing photosensitization, were unusually high in Nova Scotia biotypes and whether levels increased in late spring, when photosensitization most commonly occurs. The mean hypericin content in vegetative growth of 11 Nova Scotia H. perforatum biotypes was 195 μg g−1 dry wt, whereas levels in biotypes from British Columbia and Australia were at least two- and threefold higher, respectively. Levels in field-collected plants were lowest in May (60 μg g−1 dry wt) and peaked in midsummer (160–280 μg g−1 dry wt). In a controlled-environment study, hypericin levels increased linearly with increasing temperatures. Furthermore, hypericin levels were not affected by infection by Colletotrichum gloeosporioides. Thus, the hypericin content of Nova Scotia biotypes is too low to be the cause of photosensitization in livestock. Key words:Hypericum perforatum, St. John's wort, hypericin, photosensitization
Fungicidal control of ascochyta blight of field pea
Authors: Warkentin T. D. , Rashid K. Y. , Xue A. G.
Published: April 2011

The use of fungicides for the control of ascochyta blight in field pea was investigated. Four fungicides were applied to the cultivars AC Tamor and Radley at two locations in Manitoba in 1993 and 1994. Fungicides were applied either once, twice, or three times at 10-d intervals, beginning at the initiation of flowering. Chlorothalonil and benomyl were effective m reducing the severity of ascochyta blight and increasing the yield and seed weight of field pea. The triple application of chlorothalonil resulted in a mean yield increase of 33% over that of the untreated control. Iprodione and propiconazole were relatively ineffective in controlling ascochyta blight. The percentage of seedborne ascochyta was not significantly affected by fungicide treatments. The severity of ascochyta blight was greater in 1993 that in 1994, resulting in greater benefits of chlorothalonil and benomyl applications in 1993. Key words: Field pea, Pisum sativum L., ascochyta blight, Mycosphaerella pinodes, fungicide
Genetic variability for leaf development in perennial ryegrass populations
Authors: Hazard L. , Ghesquière M. , Barraux C.
Published: April 2011

In perennial ryegrass (Lolium perenne, L.), leaf length is a highly heritable trait likely to respond to both natural and artificial selection. The genetic variability of components of leaf morphogenesis of perennial ryegrass was studied in 2 populations obtained from two cycles of divergent selection for lamina length, in 42 natural populations, and in forage and turf cultivars. The genetic progress in the two branches of the divergent selection was accompanied by a significant change in the leaf elongation rate, whereas the phyllochron and the leaf elongation duration remained relatively unchanged. The forage cultivars were not morphogenetically different from the natural populations, and hence progress for yield under infrequent cutting could be made by selection for long-leaf populations. Turf cultivars, however, were morphogenetically different from natural populations. Turf cultivars had small leaves with short sheaths and laminae. The population resulting from the selection for short leaf had laminae as long as those of turf cultivars but with longer sheaths.
AC Proteus soybean
Authors: Voldeng H. D. , Guillemette R. J. D. , Leonard D. A. , Cober E. R.
Published: April 2011

AC Proteus is a 2500 crop heat unit soybean [Glycine max (L.) Merr.] cultivar with seed protein levels about 6–9% higher than oilseed cultivars. AC Proteus is intended for whole-seed use in livestock rations. AC Proteus has field tolerance to phytophthora root rot and resistance to powdery mildew. Key words: Soybean, cultivar description, high protein cultivar
Seeding depth, rate and row spacing for winter wheat grown on stubble and chemical fallow in the semiarid prairies
Authors: McLeod J. G. , Campbell C. A. , Gan Y. , Dyck F. B. , Vera C. L.
Published: April 2011

Recommendations regarding seeding depth, rate and row spacing for winter wheat (Triticum aestivum L.) production in the semiarid Canadian prairies have been extrapolated from those for the production of spring wheat in the region, or from information on winter wheat studies conducted in more humid areas of Saskatchewan. A factorial combination of two seeding depths (25- vs. 50-mm), two row spacing (18- vs. 36-cm) and two seeding rates (30 vs. 60 kg ha−1) was used to study plant establishment, grain yield and grain quality of winter wheat in the semiarid Brown soil zone. Three years of experiments were conducted on a Swinton silt loam near Swift Current, and on a Hatton fine sandy loam near Cantuar. Winter wheat was seeded directly into stubble at both sites and into chemically prepared fallow on the silt loam. On average, there was no significant difference (P < 0.05) due to planting depth. Deep planting reduced plant establishment and grain yield in only two of 11 site-years when humid conditions prevailed. Plant establishment and grain yield were superior for the 60 kg ha−1 seeding rate compared to the 30 kg ha−1 rate in the wet year (1986). In drier years (1987 and 1988) there was rarely any difference due to seeding rate. Narrow row spacing resulted in greater plant density than wide row spacing; however, row spacing had little effect on grain yield. In the semiarid prairie, where trash clearance for seeding implements is not usually a problem, and where many producers still swath the crop, it may be advantageous to use a narrow row spacing. However, if power requirements and trash clearance are important considerations, wide row spacing will be advantageous. Grain quality parameters (test weight, kernel weight and protein concentration) were not greatly affected by the factors studied. For winter wheat production in the semiarid prairie, we recommend that planting depth be shallow (about 25 mm), seeding rate be 60 kg ha−1, and row spacing be either narrow or wide depending on mode of harvesting. Key words: Semiarid prairie, winter wheat, grain yield, grain protein
Relationship of shoot morphology between seedlings and established turf in creeping bentgrass
Authors: Cattani D. J. , Smith Jr S. R. , Miller P. R.
Published: April 2011

Shoot morphological characteristics are important determinants of turf quality in creeping bentgrass. The objectives of this research were to determine differences for tiller and stolon characteristics among creeping bentgrass cultivars and germplasms and compare these characteristics between seedlings and established turf. Two experiments involving 10 and 15 entries were grown in controlled environment chambers and harvested as seedlings at 21, 35 and 49 d and 21, 28 and 35 d, respectively. Nine and fifteen creeping bentgrass entries were grown in separate field experiments on sand-based golf greens and core samples were taken for subsequent measurements at 3 yr and 1 yr, respectively. Tiller and stolon measurements included seedling tillers plant−1 in the controlled environment; tillers m−2 on established turf; and leaf number, leaf width, plant height/stolon length, internode length, internode number, and stolon diameter in all experiments. The correlation coefficient for seedling tillers plant−1 at 35 d between the two controlled environment experiments was r = 0.835 and for tiller density between the two field experiments was r = 0.930. There were differences among the creeping bentgrass entries for tiller number (9 7 to 20.2) and internode length (20 to 54 mm) when measured at 35 d and for tiller density (67 to 227 × 103 m−2) in established turf. Correlation coefficients between seedling tillers plant−1 at 35 d and tiller number m−2 in established turf ranged from r = 0 701 to r = 0 826. There was also a high correlation for stolon internode length between seedling and established turf, with r values ranging from r = 0 725 to r = 0.948. These results document differences for tiller and stolon characteristics between creeping bentgrass cultivars and germplasms and indicate the potential for plant improvement of these characteristics in creeping bentgrass using 35-d-old seedlings in a controlled environment. Key words: Creeping bentgrass, tiller number, tiller density, stolons, turf, seedling
Oslo and Biggar spring wheats respond differently to controlled temperature and moisture stress
Authors: Baker R. J.
Published: April 2011

In studying the inconsistent field performance of Oslo spring wheat, Oslo and Biggar were exposed to controlled levels of temperature and moisture stress in growth chamber experiments. Plants were started under low stress with day/night temperatures of 18/10 °C and watering to 90% of plant-available water. From 30 d after planting to maturity, temperature and/or moisture stress were applied to one-half of the material by raising day/night temperatures to 30/18 °C and watering to approximately 30% of plant available water every 3–4 d. Biggar produced greater root dry matter than Oslo under low temperatures but less under high temperature stress. Moisture stress caused a relatively greater decrease in kernel production in Biggar than in Oslo Although temperature stress reduced seed set relatively more in Oslo than in Biggar, Oslo was better able to compensate through the grain-filling period. The change in rank of grain yield per plant with increasing levels of stress indicates that Oslo was more tolerant to stress than Biggar. Key words: Temperature stress, moisture stress, spring wheat, Triticum aestivum.
Maple Glen soybean
Authors: Voldeng H. D. , Guillemette R. J. D. , Leonard D. A. , Cober E. R.
Published: April 2011

Maple Glen is a 2600 heat unit soybean [Glycine max (L.) Merr.] cultivar with good yield potential. Key words: Soybean, cultivar description
The Rothamsted long-term experiments: Are they still relevant?
Authors: Poulton P. R.
Published: April 2011

Maintaining soil fertility and sustaining or increasing crop yield is of worldwide importance. Many factors impact upon the complex biological, chemical and physical processes which govern soil fertility. Changes in fertility caused by acidification, declining levels of organic matter, or P and K status may take many years to appear. These properties can in turn be affected by external influences such as atmospheric pollution, global change, or changes in land management practice. Long-term experiments provide the best practical means of studying changes in soil properties and processes and providing information for farmers, scientists and policy makers. This paper shows how the experiments run at Rothamsted in southeast England continue to provide data which are highly relevant to today's agriculture and wider environmental concerns. Examples are given of how crop yield is affected by soil organic matter, by pests and disease and by P nutrition. The effect of atmospheric pollution on soil acidity and the mobilization of heavy metals are also examined. The need for making better use of existing long-term experiments is stressed. Key words: Soil fertility, sustainability, long-term experiments, global change
Summerfallow oilseed barrier strips for wind erosion control: Influences on the subsequent crop
Authors: McConkey B. G. , Dyck F. B.
Published: April 2011

Three-row flax (Linum usitatissimum L.) and mustard (Brassica juncea L.) barrier strips were seeded 10.7 m apart on conventional-tillage summerfallow in mid- to late July for wind erosion control at Swift Current to determine their effects on soil water, soil fertility, weeds, and yield of the subsequent wheat (Triticum aestivum L.) crop. In 3 yr with average winter precipitation, snow trapped by the strips replenished soil water consumed by the oilseeds Over the relatively dry winter of 1991–1992, snow accumulation did not fully replenish water withdrawn by mustard barriers. The barrier strips did not affect soil water or subsequent spring wheat yields midway between the barriers. Wheat yields immediately on the previous oilseed strips averaged 6 and 17% less for flax and mustard, respectively. This yield depression was attributed to nitrogen deficiency However, over the entire field, estimated wheat yield loss from using oilseed barriers was less than 2%. N and F fertilizer, applied when seeding the oilseed strips, increased subsequent wheat yields. Weeds were not numerous in the study and so trifluralin applied when seeding the strips, had little effect on weeds and no effect on subsequent wheat yields. Although it caused slightly greater yield loss in the succeeding wheat crop, mustard has several advantages for summerfallow oilseed barrier strips compared with flax including a wider potential strip spacing, lower seeding rate, possible tolerance to grasshoppers, and potential for seeding later in the summerfallow period. Key words: Mustard, flax, wheat, fallow, erosion, nitrogen
Hill plots for yield evaluation in a doubled haploid recurrent selection program in barley (Hordeum vulgare L.)
Authors: Falk D. E. , Reinbergs E. , Chhina B. S. , Mather D. E.
Published: April 2011

Seven selected doubled haploid lines, from each of three cycles (C0, C1, C2) of a diallel recurrent selection program, the seven original parents and two check cultivars were evaluated in replicated hill and row plots at two locations in Ontario in 1988 and 1989. Comparison of hill and row plots using means ranges, coefficient of variation, repeatability and correlations among traits indicated that grain yield, days to heading plant height and powdery mildew resistance could be evaluated with similar accuracy and precision using either of the methods. Regression of row plot yield on hill plot yield was positive and highly significant showing a strong relationship between the two plot types for grain yield. Selection efficiency in hill plots was high for all the traits. The percentage of lines with similar performance for yield in both the plot types was high. The hill plot method appears to be a useful technique for evaluating homozygous lines for yield and other agronomic traits in a doubled haploid recurrent selection program in six-row barley. Key words:Hordeum vulgare L., barley, breeding methods, yield, powdery mildew, doubled haploid, recurrent selection
Harvest management and N-fertilization effects on yield and regrowth of smooth bromegrass, crested wheatgrass, and meadow bromegrass in the eastern prairies
Authors: McCaughey W. P. , Simons R. G.
Published: April 2011

Little information exists describing how pasture-type grasses such as meadow bromegrass (Bromus biebersteinii Roem & Schult.; MBR) may differ from hay-type grasses such as crested wheatgrass (Agropyron cristatum (L.) Gaertn.; CWG) and smooth bromegrass (Bromus inermis Leyss.; SBR) in terms of DMY response to harvest and fertilizer management. In a 3-yr field trial at Brandon, MB harvest management (two-cut hay management or three- to four-cut simulated pasture management) and nitrogen fertilizer (0, 40, 80, 120, 160 kg N ha−1) were examined for their interactive effects on DMY and percent regrowth of CWG, MBR, and SBR Grasses managed under a two-cut hay system generally had greater (P < 0.05) DMY and lower (P < 0.05) percent regrowth than grasses managed under a three- to four-cut simulated pasture system. There were few consistent differences in DMY between grass species with relative ranking and significance changing between site-years. However, percent regrowth of MBR was always greater (P < 0 05) than either CWG or SBR, indicating its value in rotational grazing systems. Generally, MBR responded to N-fertilizer in a similar manner to CWG and SBR. Nitrogen fertilization increased (P < 0.0001) total DMY linearly m all site-years with an apparent optimum of greater than 160 kg N ha−1 yr−1, but percent regrowth did not respond in a consistent manner. Environment, management, and grass species, respectively, accounted for 38.4, 33.2, and 0.6% of the total variation in DMY, emphasizing their relative impact on yield of dryland grasses. Key words: Grass, fertilization, hay, pasture, nitrogen
Corn yield after 10 years of different cropping sequences and weed management practices
Authors: Zhang Jianhua , Hamill Allan S. , Weaver Susan E.
Published: April 2011

In this study, corn yield was measured after 10 yr of various rotational sequences of corn, soybeans, and wheat or oats, and under three levels of weed management to determine the effects of land use history on crop yield. Corn yield varied significantly with both crop rotation and weed management. Com yields were lower after continuous corn or soybeans or immediately following corn, and higher after a cereal crop or a rotation including a cereal. Herbicide application alone maintained significantly higher corn yield than inter-row cultivation across cropping systems. Key words: Corn yield, crop rotation, Zea mays
Trifluralin and ethalfluralin granules in conservation-tillage soybeans (Glycine max)
Authors: Ahrens William H. , Endres Gregory J.
Published: April 2011

Field experiments were conducted on loam soils in North Dakota to evaluate green and yellow foxtail control and grain yield in soybeans after fall application of trifluralin or ethalfluralin granules in untilled wheat stubble. Herbicides applied in October or November were left unincorporated or were "incorporated" with conservation-tillage methods including an undercutter, rotary hoe, or undercutter followed by a rotary hoe. A conventionally tilled standard treatment was included where trifluralin or ethalfluralin were incorporated by a field cultivator. Levels of postplant residue were at least 52% cover and 3810 kg ha−1 of aboveground dry matter where herbicide granules were left unincorporated or were incorporated by conservation-tillage methods. Trifluralin and ethalfluralin at 1.12 kg ha−1 applied as granules in mid-October in untilled stubble and incorporated with conservation-tillage methods controlled foxtail 88–92% and 87–94%, respectively, as determined the following June. Control in conservation-tillage treatments was as effective as the conventional tillage standard of trifluralin or ethalfluralin at 1.12 kg ha−1. Soybean yield correlated reasonably well with foxtail control and appeared to be maximized where good weed control was achieved either in conventional tillage or in conservation tillage with use of the undercutter. Key words: Conservation tillage, no-tillage, trifluralin, ethalfluralin, rotary hoe, undercutter
Estimation of N2O emissions from agricultural soils in Canada. II. 1990–2005 inventory
Authors: Rochette P. , Worth D E , Huffman E C , Brierley J A , McConkey B G , Yang J. , Hutchinson J J , Desjardins R L , Lemke R. , Gameda S.
Published: April 2011

International initiatives such as the United Nations Framework Convention on Climate Change and the Kyoto Protocol require that countries conduct national inventories of their greenhouse gas emissions. The primary objective of the present study was to apply a country-specific (Tier II) methodology at the regional (≈150 000 ha) scale to estimate direct N2O emissions from agricultural soils in Canada for the period 1990–2005. Other N2O sources such as manure management and indirect emissions were estimated using the Tier I Intergovernmental Panel on Climate Change (IPCC) methodology and were included to provide a complete assessment of agricultural N2O emissions. Total N2O emissions from agricultural sources averaged 58.1 Gg N2O-N yr-1 between 1990 and 2005 (from 48.9 in 1990 to 71.6 Gg N2O-N yr-1 in 2004). Of these mean emissions, 39.3 Gg N2O-N yr-1 or 68% were direct emissions from soils, 8.7 Gg N2O-N yr-1 or 15% were direct emissions from animal waste management systems and 10.1 Gg N2O-N yr-1 or 17% were from indirect emissions. Application of synthetic N fertilizers was the largest direct source of soil N2O with average emissions during the inventory period of 13.7 Gg N2O-N yr-1 or 35% of direct emissions. Crop residues (9.3 Gg N2O-N yr-1; 24%), grazing animals (6.8 Gg N2O-N yr-1; 17%) and manure applied to soils (4.1 Gg N2O-N yr-1; 10%) were the other major direct soil N2O sources. New non-IPCC N2O sources/offsets included in the Tier II methodology accounted for 10% of total direct soil emissions. Emissions occurring during summerfallow (2.2 Gg N2O-N yr-1; 6%), in lower portions of the landscape (2.2 Gg N2O-N yr-1; 6%), and following irrigation (0.7 Gg N2O-N yr-1; 2%) were partially offset by changes in tillage practices (-1.2 Gg N2O-N yr-1; -3%) and in coarse-textured soils (-0.2 Gg N2O-N yr-1; -1%). Differences in N2O estimates between Tier I and Tier II approaches mainly arise from the use of lower fertilizer-induced emission factors in the dry Prairie region and the addition of several new N2O sources/offsets in the Tier II methodology. Key words: Nitrous oxide, soils, greenhouse gases, inventory
Net nitrogen mineralization in typical paddy soils of the Taihu Region of China under aerobic conditions: Dynamics and model fitting
Authors: Li H. , Han Y. , Roelcke M. , Cai Z.
Published: April 2011

An efficient nitrogen fertilizer recommendation for plant production depends on the amount of N supplied by the soils. A study to investigate the characteristics of net N mineralization in typical paddy soils in an important rice production area of China was conducted on aerobic soils for 147 d of incubation at 25°C. Results showed that the organic nitrogen mineralized ranged from 40 to 360 mg N kg-1 or from 2.92 to 14.17% of total N. In a partial correlation analysis, the N mineralized was only correlated with total N and alkaline hydrolyzable N. Principal component analysis indicated two types of soil physical and chemical properties, each with different influence on N mineralization. Four models: (1) an effective cumulated temperature model (Temperature model), (2) a one-component, first-order exponential model (One-pool model), (3) a two-component, first-order exponential model (Two-pool model), and (4) a two-component, mixed first- and zero-order exponential model (Special model) were fitted to the measured amounts of N mineralized over time using a non-linear regression procedure. All models gave good fits. Model parameters were compared and correlated with the soil basic properties and nitrogen availability indices. All results showed that the Special model performed a better prediction of net nitrogen mineralization in paddy soils under non-flooded conditions than the other models investigated. Key words: Seasonally flooded soil, aerobic net N mineralization, simulation modeling, nitrogen availability indices
Measurement and modeling of surface charge and cation binding in agricultural soil
Authors: Taillon K M , Hendershot W H
Published: April 2011

Models of metal adsorption have typically been developed and tested for soil components rather than whole soils and at cation concentrations higher than usual environmental conditions. This study investigates whether the non-ideal consistent competitive adsorption (NICA) model can be applied to ion binding in whole soils at low total metal concentrations. Surface charge was measured for 18 agricultural soils from southern Quebec over the pH range 3.5 to 8. The adsorption of Ca, Cd, Cu, Pb and Zn was also measured for three total metal concentrations of 2, 5 and 10 mg L-1 at pH 6 in a 0.005 M Ca(ClO4)2 solution. NICA model parameters were solved for each soil using the surface charge and adsorption data and a non-linear least squares fitting routine. Two types of binding sites were identified: the first type had a pKa near 4 while the second type had a pKa near 7.5. The first type of binding site contributed the greater proportion of the variable charge over most of the pH range, and the second site was unimportant at the lower pHs. The surface charge was accurately described by the NICA model with a mean R2 of 0.995. A mean of the surface charge parameters describing H+ binding accounted for more than 95% of the variable charge on the soils. For individual soils, the NICA model gave a fit to the experimental data with mean R2 values for Ca, Cd, Cu, Pb and Zn of 1.00, 0.906, 0.879 (two concentrations only), 0.825 and 0.918 respectively. When mean adsorption parameters, instead of values determined for each soil individually, are used, the model gave mean R2s for Ca, Cd, Cu, Pb and Zn of 0.938, 0.941, 0.998 (two concentrations only), 0.978 and 0.935. It seems that the NICA model can be used to describe the surface charge and adsorption of cations by whole soils. The mean adsorption parameters appear to describe the adsorption behavior of the soil nearly as well as the individually fitted parameters. This implies that mean parameters for these agricultural soils may provide satisfactory predictions for the adsorption behavior of similar soils. Key words: NICA model, NICCA, surface charge, cation binding, agricultural soil
Issues of sustainability and sustainable land management
Authors: Zinck J. A. , Farshad A.
Published: April 2011

The concept of sustainability shows many facets. Ecologists, environmentalists, agronomists, sociologists, economists and politicians use it with different connotations. In addition, the sustainability of land management systems varies in space, according to climate, soil, technology and societal conditions. Sustainable farming systems vary also in time, as they evolve and may collapse, frequently together with the corresponding sociosystems. Because of its complexity, sustainability is difficult to measure directly and requires the use of appropriate indicators for assessment. A good indicator is free of bias, sensitive to temporal changes and spatial variability, predictive and referenced to threshold values. Relevant data are often incomplete or inadequate for indicator implementation. To embrace the whole width of sustainability, several methods and techniques should be used concurrently, including land evaluation and coevolutionary, retrospective and knowledge-based approaches. It is, however, at the application level that major constraints arise. A sustainable land management system must satisfy a large variety of requirements, including technological feasibility, economic viability, political desirability, administrative manageability, social acceptability, and environmental soundness. Real world conditions at farm and policy-making levels need to be substantially improved to achieve sustainable land management. Key words: Definition, assessment and implementation issues of sustainable land management
Indicators and thresholds for the evaluation of sustainable land management
Authors: Syers J. K. , Pushparajah E. , Hamblin A.
Published: April 2011

Within the context of major land uses such as agriculture, the indicators of sustainability must be framed within the social and economic conditions of the society in question. Whereas an indicator is used to measure changes in key attributes, usually over time, a threshold provides a baseline against which sustainability can be assessed. A direct measure of sustainability using indicators is difficult, and indirect measures or surrogates may be easier to establish. There is some information on threshold values for indicators, particularly for indicators such as soil acidity and nutrient status, and for those relating to root physiology. Because some threshold values are soil specific, it seems likely that range of values will be required for a particular indicator. There have been few case studies involving indicators and thresholds for sustainable land management. Examples of soil and land suitability for the production of Hevea brasiliensis (rubber) in Malaysia and for the management of sloping lands for annual crops in the Philippines are discussed. Biophysical indicators and thresholds for sustainable rubber production appear to be reasonably well-understood, particularly those relating to climate and soil physical factors. For sloping lands in the Philippines, yield data and benefit: cost ratios give a clear picture of trends and sustainability. Key words: Sustainable land management, indicator
Long-term influence of cropping systems, tillage methods, and N sources on nitrate leaching
Authors: Izaurralde R. C. , Feng Y. , Robertson J. A. , McGill W. B. , Juma N. G. , Olson B. M.
Published: April 2011

The extent of nitrate leaching in cultivated soils of Alberta is unknown. We studied how long- and short-term agricultural practices influenced nitrate leaching in a cryoboreal subhumid soil-climate of north-central Alberta. The study used plots from three crop rotation-tillage studies at Breton on an Orthic Gray Luvisol, and from one at Ellerslie on an Orthic Black Chernozem. Soil samples were taken in the fall of 1993 from selected treatments as well as native forest sites in 0.3-m depth increments from 0 to 3.9 m and analyzed for NO3-N. No NO3− were found under native forest vegetation. NO3-N accumulated below 0.9-m depth of agricultural ecosystems cultivated for as long as 64 yr ranged from 0 to 67 kg N ha−1. At Breton, fallow-wheat rotation plots receiving fertilizer N and manure contained eight times more NO3-N below 0.9 m depth than non-fertilized plots. NO3-N levels in an 8-yr legume-based rotation and in continuous-barley plots were similar but greater than in continuous-forage plots. Eighty-seven percent of NO3− found under continuous barley occurred below the root zone compared with only 35% in the 8-yr rotation. At Ellerslie, NO3-N mass was related to fertilizer N and mineralization of soil organic matter. Increased efforts should be directed towards better synchronizing N release from or addition to soils with plant uptake. Evidence of greater nitrate leaching under zero tillage than under conventional warrants further confirmation. Key words: Nitrogen loss, fallow, Hordeum vulgare L., Triticum aestivum L., manure, legumes, synthetic fertilizer