bluuebunny/crossref_metadata_2025 huggingface dataset:
Nitrogen contribution of field pea in annual cropping systems. 1. Nitrogen residual effect
Authors: Beckie H. J. , Brandt S. A.
Published: April 2011

The nitrogen (N) residual effect of field pea (Pisum sativum L.) to a succeeding non-legume crop was determined in a small plot experiment at Scott, Saskatchewan in the moist Dark Brown soil climatic zone, and in a small plot and landscape experiment near Melfort, Saskatchewan in the moist Black soil climatic zone from 1993 to 1995. The N residual effect, defined as the amount of fertilizer N required for a non-legume crop grown on non-legume stubble to produce the same yield as that of the non-legume grown on field pea stubble, averaged 27 and 12 kg N ha−1 at Melfort and Scott, respectively, in the small plot experiment, and 28 kg N ha−1 in the landscape experiment. Landscape slope position and preseeding tillage did not have a significant or consistent effect on the magnitude of the N residual effect of field pea to the succeeding non-legume crop. The N residual effect, calculated using the difference (economic N rate) method, was presumably due solely to the N benefit, with no non-N benefit contribution. The non-N benefit was effectively marginalized when the crop sequence that included field pea was compared with a reference rotation that included a cereal and an oilseed crop. Based on field pea seed yields and the calculated N residual effect, the N credit (N fertilizer replacement value) of field pea to a succeeding non-legume crop in the moist Black soil climatic zone was 15 kg N ha−1 for every 1000 kg of seed. This is slightly higher than the current recommendation of 5 to 10 kg N ha−1 1000 kg−1 seed. Results from the small plot experiment at Scott indicate that current N credit recommendations for field pea are appropriate for the moist Dark Brown soil climatic zone. Key words: Pisum sativum, Triticum aestivum, Hordeum vulgare, Brassica rapa, Linum usitatissimum, nitrogen residual effect
Wheat straw placement effects on total phenolic compounds in soil and corn seedling growth
Authors: Opoku G. , Vyn T. J. , Voroney R. P.
Published: April 2011

The effects of placement of wheat (Triticum aestivum L.) straw on the release of phenolic compounds potentially phytotoxic to corn (Zea mays L.) seedling growth were examined in plastic pots under controlled conditions in growth cabinets. The treatments were soil only (control), soil with straw only in the top 2.5 cm, and soil with mixed straw. Each of these treatments was either sown or not sown with corn. Corn radicle length and seedling biomass were significantly reduced, relative to other treatments, when wheat straw was present only in the top layer of soil. Water extracts from soil with surface straw had higher amounts of total phenolic compounds than the other treatments at each of the sampling times. The concentration of phenolic compounds increased with time, with average amounts at 14 and 28 d being 53 and 77%, respectively, of the concentration at 42 d. The presence of corn reduced the amount of phenolic compounds at 14 and 42 d compared with when corn was absent (P = 0.01). Water extracts prepared from soil after 42 d from all the treatments were used to investigate germination of corn seeds. Germination of corn seeds and radicle extension were inhibited by water extracts from all the above soils at 42 d compared with the control (deionized water). Coleoptile length was inhibited when concentration of phenolic compounds exceeded 10 ppm. Soil NO3-N differences among the treatments were insignificant at the various sampling times. This indicated that the observed corn growth differences were mainly due to the presence of phenolic compounds. Key words: Wheat (winter), straw replacement, phenolic acids, seedling, allelopathy
Hybrid necrosis as a barrier to gene transfer in hexaploid winter wheat × triticale crosses
Authors: Bizimungu B. , Collin J. , Comeau A. , St-Pierre C.-A.
Published: April 2011

An interspecific wheat × triticale hybridization program was initiated with the scope of widening and improving the winter wheat gene pool. However, progress was hampered by severe necrosis that caused the death of F1 hybrids from crosses between the most winterhardy wheat and triticale cultivars. This paper describes hybrid necrosis as the main barrier to gene transfer between winter wheat cultivars Borden, Augusta and Ruby, and hexaploid winter triticales OAC Wintri and K9-6. Crosses with tester lines revealed that the three winter wheats were carriers of the necrotic Ne2 allele. High temperature (30 °C) treatment until heading stage permitted to only partially circumvent the problem. A study of cross direction effects at the backcross level showed that the conventional method (F1 × wheat) was more efficient for plant recovery, but plants produced by the alternative backcross system (wheat × F1) were more self-fertile. Within the most winterhardy germplasm, hybrid necrosis is a major problem for transferring genes between winter wheat and triticale. The use of non-necrotic winter wheat lines such as MC11N, a local winter wheat selection, may have a special value as a bridge to circumvent the necrosis problem. Key words: Hybrid necrosis, Ne genes, wheat × triticale hybrids, cross direction
Inoculation of seeds with Bipolaris sorokiniana and soil fumigation methods to determine wheat and barley tolerance and yield losses caused by common root rot
Authors: Bailey K. L. , Duczek L. J. , Potts D. A.
Published: April 2011

Wheat and barley plants that are severely infected with common root rot yield less than uninfected ones. Resistant cultivars usually have fewer diseased plants but some cultivars show tolerance as no yield loss occurs even though many plants display disease symptoms. This study assessed disease severity and yield loss due to common root rot in cultivars of wheat and barley by two techniques: i) sowing infested seed in soils with low inoculum levels of Bipolaris sorokiniana (Sacc. in Sorok.) Shoem., and ii) planting healthy seed in soil treated with the fumigants, metam and basamid. Infested seed exhibited reduced emergence, increased disease severity, but plot yield was not significantly affected compared with uninfested seed. The average yield loss or gain from seed treatment amongst all selections of wheat and barley was not significantly different. Losses were of the same magnitude (11.1% in barley, 6.2% in wheat) as reported in other studies. Soil fumigation reduced levels of B. sorokiniana in soil and disease severity. It also led to increased nutrient levels in soil and plant tissues, plant height, and plot yields by 16–29% compared with untreated areas. Tolerance to common root rot was exhibited by BW632, Virden, and Melvin. These losses are higher than reported in other studies which suggests yield loss may be underestimated or that common root rot is only one component of a root problem complex being affected by fumigants. Key words: Common root rot, loss, tolerance, seed inoculation, fumigation
Genetics of resistance to alfalfa mosaic virus in red clover
Authors: Martin P. H. , Coulman B. E. , Peterson J. F.
Published: April 2011

Virus diseases are known to reduce the yield and persistence of stands of red clover (Trifolium pratense L.). Alfalfa mosaic virus (AMV) is one of the causes of mosaic in red clover and may also cause mottling and leaf distortion. The goals of this study were to identify genotypes resistant to AMV within commercial red clover cultivars and to determine the inheritance of this resistance. Cultivars and progenies were screened for resistance by means of mechanical inoculations. Plants showing no symptoms after three successive inoculations were assayed for the presence of the virus using ELISA (enzyme-linked immunosorbent assay). Resistant plants were detected at a frequency of just over 1% in the five cultivars screened. Crosses among and between resistant (R) and susceptible (S) plants were carried out over two successive cycles of selection. In cycle 1, R × R crosses produced a higher frequency of resistant plants (19.8%) in the progenies than R × S crosses (10.9%). S × S crosses produced no resistant progeny. For crosses of resistant plants from cycle 1 progeny, (R × R) × (R × R) produced 47.8%, (R × R) × (R × S) produced 31.4% and (R × S) × (R × S) produced 29.3% resistant cycle 2 progeny. Crosses of resistant and susceptible cycle 1 plants resulted in resistance frequencies in cycle 2 which were not significantly (P < 0.05) greater than cycle 1. When only resistant plants were selected for further crossing, the percentage of resistant plants increased from 1.3 to 47.8 over the two cycles of selection. It was concluded that resistance to AMV in red clover is under polygenic control and that it should be relatively simple to select a highly resistant population through recurrent selection. Key words: Red clover, Trifolium pratense L., virus disease, alfalfa mosaic virus, recurrent selection
Boron-isotope fractionation in plants
Authors: Marentes E. , Vanderpool R. A. , Shelp B. J.
Published: April 2011

Naturally-occurring variations in the abundance of stable isotopes of carbon, nitrogen, oxygen, and other elements in plants have been reported and are now used to understand various physiological processes in plants. Boron (B) isotopic variation in several plant species has been documented, but no determination as to whether plants fractionate the stable isotopes of boron, 11B and 10B, has been made. Here, we report that plants with differing B requirements (wheat, corn and broccoli) fractionated boron. The whole plant was enriched in 11B relative to the nutrient solution, and the leaves were enriched in 10B and the stem in 11B relative to the xylem sap. Although at present, a mechanistic role for boron in plants is uncertain, potential fractionating mechanisms are discussed. Key words: Brassica oleracea var. italica Plenck (broccoli), Triticum aestivum L. (wheat), Zea mays L. (corn), boron, isotope fractionation
Molecular and embryonic evidence of apomixis in cassava interspecific hybrids (Manihot spp.)
Authors: Nassar Nagib M. A. , Vieira Marco Andre , Vieira Clibas , Grattapaglia Dario
Published: April 2011

In cassava, apomixis could fix hetereozygosity and prevent the transmission of systemic pathogens which complicate vegetative propagation of the crop. Evidence from maternal inheritance of RAPD markers and the structure of the embryonic sac in large progeny sets of two distinct genotypes have further confirmed that apomixis occurs in cassava. Here, we have built on an earlier report of apomixis in cassava in four ways (1) we estimated the rate of faculative apomixis in the range of 2% (2) we detected the occurrence of apomixis in a second genotype, derived form a different interspecific cross; (3) apomictic behavior was demonstrated in an F1 individual and (4) embryonic evidence showed that the mode of apomixis is aposporic. Since apomixis was detected in an F1 interspecific hybrid it is possible that genes for apomixis could be transferred directly to cultivated cassava from a wild relative. Key words: Cassava, interspecific hybrid
Harvest management and N-fertilization effects on protein yield, protein content and nitrogen use efficiency of smooth bromegrass, crested wheatgrass and meadow bromegrass
Authors: McCaughey W. P. , Simons R. G.
Published: April 2011

There is a lack of information on the interaction of harvest management, grass species and N-fertilizer interaction on forage quality and nitrogen use efficiency of dryland grasses. In a 3-yr field trial, harvest management (2 cut, hay management vs. a 3–4 cut simulated pasture management system) and nitrogen fertilizer (0, 40, 80, 120, 160 kg N ha−1) were examined for their effects on protein yield (PY), protein content (PC), nitrogen use efficiency (NUE), nitrogen recovery (NR) and soil test nitrate-nitrogen (STN) under crested wheatgrass (Agropyron cristatum [L.] Gaertn.; CWG), meadow bromegrass (Bromus biebersteinii Roem & Schult.; MBR) and smooth bromegrass (Bromus inermis L.; SBR) swards. Generally, grasses managed under a two-cut hay system had lower (P < 0.05) PC than grasses managed under a 3–4 cut simulated pasture system (and occasionally higher NR and NUE) but harvest management did not consistently affect PY. There were few consistent differences between grass species for PY, PC, NUE and NR with relative ranking and significance changing between site-years. Generally, MBR responded to N-fertilizer in a similar manner to previously studied dryland grasses such as CWG or SBR. N-fertilization increased PY and PC but did not consistently affect NUE, NR and STN. Key words: Protein yield, protein, nitrogen recovery, nitrogen use efficiency, hay, pasture
Isogenic analysis of glufosinate-ammonium tolerant and susceptible summer rape lines
Authors: Kumar A. , Rakow G. , Downey R. K.
Published: April 2011

The development of transgenic Brassica napus L., tolerant to non-selective broad-spectrum herbicides, such as glyphosate and glufosinate-ammonium, could provide canola growers with an efficient method of weed control. The objective of this study was to determine whether the phosphinothricin-acetyl transferase (pat) gene which imparts tolerance to glufosinate-ammonium, affects the growth, development, productivity, and seed quality of B. napus canola. Nineteen glufosinate-ammonium tolerant and susceptible isogenic pairs of the B. napus cv. Westar, derived from independent transformation events, were evaluated in two field trials in each of 2 yr in Saskatchewan. Tolerant lines of six isogenic pairs were similar in their agronomic performance and seed quality to their susceptible counterparts indicating that glufosinate-ammonium tolerant B. napus can be developed that is not negatively affected in yield and quality by the presence of the pat gene. Several tolerant lines exhibited delayed flowering and maturity, lower biomass and seed yields, and lower oil and protein contents indicating positional effects of the pat gene on performance. Tolerant lines carrying two inserts of the pat gene were more negatively affected in their growth and development than single insert tolerant lines. The results of this study indicate that it would be beneficial to generate a number of different transformants and select elite transgenic lines which are not affected in their performance by the presence of the pat gene for use in cultivar development. Key words: Brassica napus, glufosinate-ammonium tolerance, isogenic analysis
Medallion soybean
Authors: Voldeng H. D. , Guillemette R. J. D. , Leonard D. A. , Cober E. R.
Published: April 2011

Medallion is a 2500 crop heat unit soybean (Glycine max [L.] Merr. cultivar with good yield potential. Key words: Soybean, cultivar description
Optimum planting density and harvest stage for little-leaf and normal-leaf cucumbers for once-over harvest
Authors: Schultheis Jonathan R. , Wehner Todd C. , Walters S. Alan
Published: April 2011

Optimum planting density and harvest stage were determined for once-over harvest of little-leaf and normal-leaf cucumbers. Three harvest stages (10, 25, and 50% oversize fruit) and four plant densities (37,000, 75,000, 150,000, and 300,000 plants/ha) were evaluated on little-leaf cucumber (H-19) and normal-leaf cucumber (Sumter and Regal). Plant density did not affect skin color, seedcell size, and seed size in the cultivars evaluated. However, lighter skin color, larger seedcell, and larger seed size were detected at the later harvest stages in H-19. Harvest stage did not influence fruit skin color in Regal and Sumter, but seedcell size and seed size increased quadratically with harvest stage. H-19 produced the highest yield (tonne/ha) and dollar value ($/ha) followed by Regal and Sumter. Considering fruit quality and dollar value, the 10% harvest stage at 330 000 plants ha−1 was the optimum stage and density for once-over harvest of H-19 under North Carolina growing conditions. Higher yield occurred at the later harvest stages, but poorer fruit quality (increased seed and seedcell size, and a lighter skin color) was associated with those stages. Fruit quality and dollar value of Regal was best at the 10% harvest stage at approximately 240 000 plants ha−1, while 200 000 plants ha−1 was best for Sumter. Key words: Cucumis sativus, cucumber, plant type, spacing, crop ideotype, vegetable production
The inheritance of leaf and stem rust resistance in Triticum monococcum L.
Authors: Bai D. , Knott D. R. , Zale J. M.
Published: April 2011

Resistance to leaf rust (Puccinia recondita f. sp. tritici Rob. ex Desm.) is common in Triticum monococcum L. For example, the 49 accessions in the University of Saskatchewan collection all gave a fleck reaction to leaf rust race CBB. To obtain some indication of whether they all carried the same gene, a set of diallel crosses was made among five of the accessions and three extra crosses were made between two additional accessions and two in the diallel set. The 13 F2 populations involving a total of seven accessions were tested with LR CBB and no segregation for susceptible seedlings occurred. Thus, the seven T. monococcum accessions all carried at least one gene in common. To determine the number of genes involved in leaf rust resistance, four crosses were made between a highly resistant accession, TM157 (IT 0;), and four moderately resistant ones (IT 2−). The F2 populations segregated for two independent dominant genes, one conditioning a fleck reaction and one a type 2 reaction. All seven highly resistant accessions must carry the first gene. Two of the T. monococcum accessions were resistant to stem rust (P. graminisf. sp. tritici Eriks. & Henn.) SR TMH. They proved to carry single genes for resistance, Sr22 in TM65 and Sr35 in TM157. Key words: Wheat, leaf rust, stem rust, inheritance
Physiological attributes associated with early-season drought resistance in spring durum wheat cultivars
Authors: Hafid R. El , Smith Dan H. , Karrou M. , Samir K.
Published: April 2011

One of the common features of the Mediterranean climate in North Africa is the uncertainty of rainfall immediately after wheat (Triticum durum Desf) emerges. Relatively little work has been done to compare the drought resistance of spring durum wheat cultivars under early-season drought stress. There is a limited insight into the physiological basis of spring durum wheat drought resistance in rainfed Mediterranean regions. Field experiments were conducted in 1995 and 1996 growing seasons, and a greenhouse experiment was conducted in 1996 to examine differences in some physiological characters among six spring durum wheat cultivars in response to different durations of early-season drought, and rewatering; and to determine the relationships of these characters to drought resistance. Six spring durum wheat cultivars were evaluated under four water regimes. Water regime treatments were: a well-irrigated treatment; and three water deficit treatments imposed during the period from emergence through either the onset of tillering, mid-tillering or the end of tillering. Cultivars differed widely in their response to early season water stress. Under drought stress conditions, grain yield, aboveground dry matter yield, water use efficiency for the grain (WUEg) and for the total dry matter (WUEdm) were strongly positively associated with net CO2 uptake:transpiration ratio (A/E), and osmoregulation capacity. It is concluded that drought-induced changes in A, A/E, stomatal resistance, and osmotic adjustment are possible key control points in determining the drought-resistance of a cultivar. Furthermore, there is a substantial degree of intraspecific variation for the above mentioned physiological attributes to explore as a selection tool. Selection for high osmoregulation capacity and high A/E ratio would seem to be a justifiable means of improving total dry matter and grain yield under conditions of early-season water stress. Key words: Wheat, Triticum durum Desf., physiological attributes, early-season drought
Effects of crop rotations and fertilizer management on leaf spotting diseases of spring wheat in southwestern Saskatchewan
Authors: Fernandez M. R. , Zentner R. P. , McConkey B. G. , Campbell C. A.
Published: April 2011

The objective of this study was to determine the effect of crop sequence, summerfallow frequency, and fertilizer application, on the severity of leaf spotting diseases of spring wheat (Triticum aestivum L.). In the field experiment examined, Pyrenophora tritici-repentis (Died.) Drechs. was the pathogen most commonly isolated from lesioned leaf tissue, followed by stagonospora blotch (Phaeosphaeria nodorum [E. Müller] Hedjaroude). The severity of leaf spots in wheat after fallow was greater than in monoculture continuous wheat, or in wheat after a noncereal crop. Percent area with leaf spots in wheat grown after wheat was higher than in wheat grown after flax (Linum usitatissimum L.) or lentil (Lens culinaris Medikus) in years with high disease pressure (1995 and 1996), but not in 1993 or 1994 when overall disease levels were low. Under soil N-deficient conditions, leaf spot levels increased in years with dry summers (1994 and 1996), whereas a P deficiency decreased leaf spot severity in years that had cool and wet springs (1995 and 1996). A survey of producers' fields confirmed the observations made in the research plots, in particular, wheat after wheat was not more severely diseased than wheat grown in rotation with a noncereal crop. We concluded that the use of fallow, or 1 yr of rotation with a noncereal crop, will not reduce leaf spotting diseases of spring wheat in southwestern Saskatchewan. The best rotation aimed at reducing the levels of disease appeared to be 2 consecutive years of spring wheat, followed by at least 2 yr of a noncereal crop, or by a noncereal crop and summerfallow. Key words: Leaf spot, tan spot, Pyrenophora tritici-repentis, stagonospora blotch, Phaeosphaeria nodorum, septoria blotch, Mycosphaerella graminicola, crop rotation, tillage, fertility
Management practices for black lentil green manure for the semi-arid Canadian prairies
Authors: Brandt S. A.
Published: April 2011

Previous research with lentil (Lens culinaris Medic.) green manure in the semiarid prairies of western Canada has indicated that water use by the green manure crop often reduces grain yield of the succeeding cereal crop compared to those obtained after conventional summerfallow. In this study, we evaluated several green manure management practices that have potential to trap snow and enhance overwinter soil water recharge. These practices included: using herbicides to halt the growth of the green manure crop thus eliminating the need for soil incorporation, planting mustard (Sinapis alba L.) strips after incorporation, and leaving standing strips of non-incorporated lentil. Our results showed that none of the green manure management strategies increased wheat (Triticum aestivum L.) yield or grain protein concentration compared to wheat grown on conventional summerfallow. Leaving strips of standing lentil during bud stage incorporation provided barriers for wind erosion protection, while not decreasing wheat yield or protein content. Glyphosate or 2,4-D amine applied at bud stage of the lentil, and without soil incorporation, reduced available soil N. However, 2,4-D did not halt plant growth and water use quickly enough to avoid reducing yield of the succeeding wheat crop, while glyphosate generally halted water use more rapidly. The inability of the green manure management strategies to increase wheat yields over that obtained from conventional summerfallow was because the soil rooting zone is typically filled to capacity with water by this latter practice under the prevailing soil and climatic conditions. If green manuring is practised, early incorporation with lentil leave strips is the most promising management system. However, even with improved water management practices, green manuring did not demonstrate a consistent advantage over summerfallow, which may be required to offset the added economic costs required to enact this practice. Key words: Lens culinaris, legumes, summerfallow, soil nitrogen, soil water, wheat
OAC Bayfield soybean
Authors: Tanner J. W. , Luzzi B. M. , Gostovic P. , Montminy W. , Hume D. J.
Published: April 2011

OAC Bayfield is a 2725 CHU soybean (Glycine max [L.] Merr.) cultivar with excellent yield potential, broad adaptability in Ontario, adequate lodging resistance and above-average oil content. Key words: Soybean, cultivar description
OAC Brussels soybean
Authors: Tanner J. W. , Luzzi B. M. , Gostovic P. , Montminy W. , Hume D. J.
Published: April 2011

OAC Brussels is a 2700 CHU soybean (Glycine max [L.] Merr.) cultivar with very good yield potential and excellent lodging resistance. Key words: Soybean, cultivar description
Stevia rebaudiana: Its agricultural, biological, and chemical properties
Authors: Brandle J. E. , Starratt A. N. , Gijzen M.
Published: April 2011

Stevia rebaudiana is a member of the Compositae, native to Paraguay. It produces a number of high-potency low-calorie sweeteners in its leaf tissue. The sweeteners are diterpene glycosides and range between 30 and 320 times sweeter than sugar. Increasing consumer interest in natural food ingredients means that products like stevia sweeteners will be subject to increasing demand. Such demand will need to be supported by a modern mechanised production system. The purpose of this review is to summarize the existing agricultural, chemical and biochemical literature to provide a baseline for new research. Key words: Stevia, diterpene, steviol glycoside, sweeteners
Effect of moisture on quinclorac dissipation in Lethbridge soil
Authors: Hill B. D. , Moyer J. R. , Inaba D. J. , Doram R.
Published: April 2011

This study examined the dissipation and carry-over of quinclorac residues in a Lethbridge sandy clay loam with 2% organic matter. Experiments were conducted in covered outdoor lysimeters using different simulated rainfall regimes. Quinclorac residues were monitored in the top 10 cm of soil using chemical residue analysis and the activity of carried-over residues assessed by bioassay. Quinclorac dissipation was very slow although, in general, the amount of residue remaining decreased with increased moisture (117–447 mm) applied. Forty-eight weeks after quinclorac application, 85, 66, 52, 49, and 48% of initial residues remained in the very dry, dry, normal, wet and very wet moisture regimes, respectively. Residue persistence could be accurately predicted (r2 = 0.96) using a simple moisture model (% quinclorac remaining = 101% −0.18 × mm cumulative moisture) for up to 300 mm moisture. Quinclorac dissipation was attributed mostly to the residues leaching beyond the 0- to 10-cm soil layer. A separate laboratory experiment showed that 80% of applied quinclorac leached through 9.7-cm deep soil columns when 304 mm of water was applied. The quinclorac residues remaining after 48 wk were biologically available and caused injury to fababeans (Vicia faba L.) under all moisture regimes. Key words: Quinclorac, persistence, moisture effects, leaching, residue carry-over, recropping
Relationship between P and N concentrations in timothy
Authors: Bélanger G. , Richards J. E.
Published: April 2011

Tools quantifying the status of N and P in plants may help to achieve efficient management of these nutrients and to optimize crop growth and yield. The objective of this study was to establish the relationship between P and N concentrations during the regrowth of timothy (Phleum pratense L.) and, in particular, to estimate the critical P concentration required to diagnose P deficiency. The relationship between P and N concentrations was determined for timothy grown in two experiments conducted with early- and late-maturing cultivars under non-limiting N conditions in spring of 1991 and 1992, and in two experiments with four rates of N fertilization conducted in the spring of 1993 and the summer of 1994. Shoot biomass and P and N concentrations were determined weekly during each regrowth cycle. The P and N concentrations decreased with time in all four experiments. The decrease in P concentration with increasing shoot biomass was generally similar to the decrease in N concentration. The relationship between P concentration and shoot biomass was not different for early- and late-maturing timothy cultivars. This relationship, however, was affected by N fertilization. For a given shoot biomass, increasing N fertilization rates increased P concentration. The relationship between P and N concentrations under non-limiting N conditions is described by a linear relationship (P = 1.46 + 0.069N, R2 = 0.79, P < 0.001, n = 48) in which P concentration (P) and N concentration (N) are expressed in g kg−1 DM. The relationship between P and N concentrations was different under N limiting conditions. For a given N concentration, the P concentration was greater under limiting N conditions than under non-limiting N conditions. Our results show that the critical P concentration for shoot growth is a function of the N concentration in the shoot biomass and the level of N deficiency. The present study provides the relationship required to estimate the critical P concentration which is essential for quantifying levels of P deficiency in timothy, and in developing models to predict the quantity of fertilizer P needed to correct that deficiency. Key words: Phleum pratense L., timothy, nitrogen, phosphorus, grasses
Whole-season grass response to and recovery of nitrogen applied at various rates and distributions in a high rainfall environment
Authors: Bittman S. , Kowalenko C. G.
Published: April 2011

High rates of nitrogen (N) fertilizer are often used on perennial grass in the coastal region of British Columbia and the Pacific Northwest, but there is little information on optimum rates for abundant high-quality yields and on their environmental implications. A field trial was conducted in each of 3 yr to determine the effect of rates and distributions of N on whole-season herbage yield and quality, and pre- and post-season extractable inorganic N in the soil. Yearly rates were 100, 200 and 400 kg N ha−1 applied to each of four cuts in the following distributions: 1.00/0/0/0, 0.50/0.25/0.25/0 and 0.25/0.25/0.25/0.25. Whole-season yield was increased by increasing rates of N in all three trials, but the increase varied from 17% (Trial 1) to 127% (Trial 3). Distributing the N uniformly through the season resulted in only a 5% increase in yield compared with applying all of the N at the beginning of the season. Rate of N had a substantial effect on average herbage crude protein and nitrate concentrations, but the distribution effect was greater on herbage N constituents than on yield. Increasing rates of N consistently increased average herbage nitrate concentrations, and crude protein in two of three trials. Applying all of the N at the beginning of the season increased average herbage crude protein and nitrate concentrations more than distributing it evenly through the season. Extractable inorganic N in the soil at the end of the season increased only at 400 kg N ha−1 rate and was not affected by distribution. Although distribution pattern influenced herbage yield and nitrogen concentrations, distribution did not influence total herbage N uptake or recovery in herbage plus soil. Rates and distributions of N on grass influenced herbage yield and quality, and soil extractable inorganic N in different ways; therefore, compromises in N management are required to optimize forage yield and quality, and soil nitrate concentrations. Autumn soil inorganic N testing may be useful as feedback information for fertilizer recommendations in the subsequent season. Spring soil inorganic N testing was a poor predictor of crop response to fertilizer in the high rainfall environment of the study. Key words: Nitrogen, plant crude protein, plant nitrate, forage yield, forage quality, apparent N recovery, residual soil N, soil N test
Sentry summer rape
Authors: Rimmer S. R. , Scarth R. , McVetty P. B. E.
Published: April 2011

Sentry is a summer rape (Brassica napus L.) cultivar with a high level of resistance to blackleg. Sentry is adapted to the long- and mid-season B. napus canola growing areas of western Canada. Key words: Rape (summer), blackleg resistance, cultivar description
The transfer of leaf rust resistance from Triticum timopheevii to durum and bread wheat and the location of one gene on chromosome 1A
Authors: Bai Dapeng , Knott D. R. , Zale Janice
Published: April 2011

Triticum timopheevii (Zhuk.) Zhuk. is noted for its resistance to diseases including leaf and stem rust of wheat. Only one gene (Lr18) for leaf rust resistance has been transferred from T. timopheevii to bread wheat. The objectives of this work were to study the inheritance of leaf rust resistance in five accessions of T. timopheevii and to transfer genes for resistance into durum and bread wheats. A diallel set of crosses was made among five T. timopheevii accessions that gave a fleck infection type with an isolate of leaf rust race CBB. None of the F2 populations of the 10 crosses segregated for resistance, indicating that the five accessions all had at least one gene for resistance in common. Several accessions were crossed and backcrossed twice to durum and to bread wheat. At least three genes for leaf rust resistance were transferred to durum wheat and one to bread wheat. The gene transferred to bread wheat and one of those transferred to durum wheat conditioned good resistance to a set of 10 diverse races of leaf rust. Resistance conditioned by all three genes was dominant in durum wheat but the one gene was recessive in bread wheat. Monosomic analysis of the bread wheat line showed that the gene is on chromosome 1A. It should be useful in breeding for leaf rust resistance in both durum and bread wheat. Key words: Triticum timopheevii, leaf rust resistance, durum wheat, bread wheat
Temperature response function for leaf appearance rate in wheat and corn
Authors: Jame Y. W. , Cutforth H. W. , Ritchie J. T.
Published: April 2011

The ability to predict leaf appearance would enhance our capability of modeling plant development and the rate of leaf area expansion. Many crop models use the constant thermal time for successive leaf tip appearance (which is often termed a phyllochron) as one model parameter to predict total number of leaves and date of anthesis. However, many researchers have found that phyllochron is not constant, but is dependent upon environment. The problem could be related to the simplified assumption that the daily leaf appearance rate is linearly related to temperature (and hence, phyllochron is constant, independent of temperature). In reality, the temperature response function for the development of a biological system is nonlinear. Thus, we fitted daily leaf appearance rate–temperature relationships obtained from growth room studies for both wheat (Triticum aestivum) and corn (Zea mays L.) to a nonlinear beta function with 0 °C as the base temperature and 42 °C as the upper critical temperature. The function described the relationships very well over the full range of temperatures for plant development. Other variables that are used to describe the duration and rate of leaf appearance, such as calendar days, phyllochron, and thermal rate of leaf appearance, are related to the daily leaf appearance rate, eliminating the need to develop various mathematical functions to independently describe the response of these variables to temperature. Because of the nonlinear nature of the temperature response function, we demonstrated that more accurate determinations of daily leaf appearance rates can be achieved by calculating rates over relatively short periods (i.e., hourly) and summing these to get the mean daily rate. Many environmental factors other than temperature also affect leaf appearance rate. However, once the proper temperature response function for leaf appearance rate is determined, it is much easier to determine when and how other factors are involved to modify the leaf appearance rate under a given environment.Key words: Temperature, leaf appearance rate, phyllochron, wheat, corn, beta function
Effects of method, rate and time of application of nitrogen fertilizer on seed production of tall fescue
Authors: Fairey N. A. , Lefkovitch L. P.
Published: April 2011

The production of seed of tall fescue (Festuca arundinacea Schreber) provides an opportunity to diversify the agriculture of the Peace region with a new, un-subsidized, soil-conserving, cash-crop. Nitrogen fertility and nutrition are major components of the production of any grass-seed crop. A field study was conducted on the nitrogen (N) fertilizer requirements for optimizing seed yield and quality of tall fescue grown in the Peace region. Row-crop stands (30-cm spacing) were established at four sites in two consecutive seeding years (1993 and 1994), with two consecutive seed crops being harvested from each stand. A total of 18 N fertilizer treatments was applied to the first seed crop, a factorial combination of two methods (surface-broadcast, granular, ammonium nitrate 34–0–0, and soil-injected 28–0–0 solution), three times (early- to mid-September, early- to mid-October, and early- to mid-April prior to the first seed harvest), and three rates (50, 100, and 150 kg ha−1 N). The second seed crop received 68 kg ha−1 of surface-broadcast N applied in mid-September after removal of the harvest crop residue. Seed yield and quality were not affected by the time of N application. When compared with broadcast application, soil-injection of N fertilizer significantly reduced whole-plant dry matter (DM) yield and seed yield/seedhead by 7 and 9%, respectively, but the two methods of N application had no differential effect on clean seed yield ha−1, fertile tiller density, harvest index, thousand-seed weight, specific seed weight, germination, or on the proportion of clean seed. When compared with N at 50 kg ha−1, whole-plant DM yield was increased by 6 and 8%, and clean seed yield/seedhead by 15 and 14%, with the 100 and 150 kg ha−1 rates of N, respectively. The first- and second-year seed yields averaged 1319 and 952 kg ha−1, respectively, for the 1993 seeding year, and 1630 and 716 kg ha−1, respectively, for the 1994 seeding year. The cumulative seed productivity over the 2 production years was similar for the two seeding years, being 2271 kg ha−1 for 1993 and 2346 kg ha−1 for 1994. Each seed crop of tall fescue requires an available N supply from the soil in the range of 100 to 150 kg ha−1 N to maximize seed yield and quality. Key words: Tall fescue, Festuca arundinacea Schreber, nitrogen fertility, grass seed production, grass seed quality
Selection for resistance to Fusarium wilt in red clover
Authors: Venuto B. C. , Smith R. R. , Grau C. R.
Published: April 2011

In Wisconsin, Fusarium oxysporum, Schlect., a pathogen causing vascular wilt, is the most prevalent fungal pathogen recovered from diseased red clover (Trifolium pratense L.) plants. This study was conducted to determine the mode of inheritance for red clover resistance to this pathogen and to develop resistant germplasm. Virulent isolates of this pathogen, collected from red clover plants at the Ashland Research Station, Ashland, Wisconsin, were used to screen three populations, the red clover cultivars Arlington and Marathon and the C11 germplasm, for resistant plants. Plants were inoculated with the pathogen and evaluated for reaction, using a disease-severity index (DSI) score from 1 to 5 (1 = no reaction, 5 = plant dead). Selected plants from each cycle were intercrossed to produce subsequent generations. After two and three cycles of selection, the developed populations were simultaneously evaluated for gain from selection. The gain from selection for resistance in these populations (cycle 0 minus cycle 2) ranged from 0.31 to 0.48, 0.12 to 0.75, and 0.13 to 0.83 DSI units, respectively, for Arlington, Marathon, and C11. Estimated narrow-sense heritabilities, based on cycle-1 and cycle-2 progeny, were, respectively, 0.20 and 0.37 for Arlington, 0.15 and 0.13 for Marathon, and 0.06 and 0.17 for C11. These results indicate that resistance is a quantitative trait controlled by many loci, each contributing some portion to overall resistance in the host. Key words: Red clover, Trifolium pratense L., Fusarium oxysporum, vascular wilt, resistance
Growth and forage quality of three Bromus species native to western Canada
Authors: May K. W. , Stout D. G. , Willms W. D. , Mir Z. , Coulman B. , Fairey N. A. , Hall J. W.
Published: April 2011

There is growing interest in revegetating disturbed areas with native plant species; thus seed sources for appropriate native species need to be developed. In this study, we compared growth and forage quality of three native Bromus species (Bromus carinatus, B. ciliatus, and B. anomalus) collected in central Alberta with growth and forage quality of three domestic forage species (B. riparius Rehm., B. inermis Leyss., and Dactylis glomerata L.). Eight establishment year-locations were used for experiments conducted between 1993 and and 1996 at six locations in western Canada. Seedling establishment measured in 4 year-locations indicated that all native Bromus species established as well as the domestic bromegrasses, and that B. carinatus exceeded seedling establishment of the domestic bromegrasses. Bromus carinatus either yielded the same or less dry matter (DM) that the domestic bromegrasses, the same or more than D. glomerata, and more than B. ciliatus or B. anomalus. Bromus carinatus was either as tall as or shorter than the domestic bromegrasses, as tall as D. glomerata, and taller than Bromus ciliatus and B. anomalus. Bromus carinatus was more prone to lodging than B. ciliatus, B. anomalus, or the domestic species. These native Bromus species appear to have the required establishment potential and productivity to be suitable for reseeding disturbed areas and fill the niche where native species are required. Key words: Bromus, dry matter, crude protein, dry matter digestibility, acid detergent fibre, smooth bromegrass, meadow bromegrass
Effets d'un éclairage d'appoint sur la croissance et le métabolisme azoté primaire de la laitue mâche et de l'épinard cultivés en serre
Authors: Chadjaâ Hassan , Vézina Louis-Philippe , Gosselin André
Published: April 2011

Two cultivars of Lamb's lettuce (Valerianella sp. 'Valgros' et 'Vit') and one cultivar of spinach (Spinacea oleracea L. 'Martine RZ F1') were subjected to three light treatments. Two photoperiods, 12 h and 16 h were compared to natural light between January and April 1994. A photosynthetic flux of 50 µmol m–2 s–1 was provided as supplementary lighting using HPS lamps. The use of artificial lighting significantly increased biomass and nitrate reductase activity, while also reducing nitrate accumulation in leaves. The 16 h-photoperiod increased biomass and reduced nitrates content in leaves more than the 12 h photoperiod. In Lamb's lettuce, Valgos was more productive than Vit but accumulated more nitrates. The use of supplementary lighting gave high yields of lamb's lettuce and spinach in greenhouse under northern climatic conditions. Key words: Lamb's lettuce, spinach, nitrate reductase activity, nitrate, Valerianella sp., Spinacea oleracea L.
Phosphorus and nitrogen effects on the freezing tolerance of Norstar winter wheat
Authors: Gusta L. V. , O'Connor B. J. , Lafond G. L.
Published: April 2011

To increase the probability of winter survival, it is recommended that winter wheat (Triticum aestivum L.) be sown into standing stubble from a previous crop, which acts to trap an insulating layer of snow. Therefore, to replenish nutrients used by the previous crop and to obtain optimum yields of winter wheat, these soils have to be fertilized with N and P. The objective of this study was to determine the effect of N and P, alone and in combination, on the freezing tolerance of Norstar winter-wheat seedlings in the fall and in early spring and during storage at −4 °C throughout the winter months. None of the fertilizer treatments had an effect on the freezing tolerance of the seedlings in late fall, however, P in combination with N decreased freezing tolerance in March and April, with the effects being more pronounced at high rates of P. Seedlings sampled from the field in early May were similar in freezing tolerance, irrespective of the level of fall-applied N and P. Both shoot and root growth of seedlings collected in the spring were enhanced by P fertilization in combination with N. Fall-applied P increased the level of tissue N and P, while applications of N increased the level of tissue N of seedlings sampled in late fall. Key words: Winter wheat, nitrogen, phosphorous, freezing tolerance
Nodulation of beach pea (Lathyrus maritimus [L.] Bigel.) induced by different strains of rhizobia
Authors: Gurusamy C. , Bal A. K. , McKenzie D. B.
Published: April 2011

In an attempt to screen the most effective rhizobial strain for the potential cold-climate legume crop beach pea (Lathyrus maritimus L.), rhizobia from eight different species of Lathyrus were tested along with the native strain on a 9-wk-long pot culture. The native strain, ACCCRC, isolated from beach pea proved to be the most effective. The tropical legume grass pea (L. sativus L.) tested with the above strains failed to nodulate with ACCCRC, USDA 2422 and USDA 2446. Oleosome content of nodules assessed from histological sections reveals higher numbers in beach pea than in grass pea. Key words: Lathyrus maritimus L., Lathyrus sativus L., root nodules, oleosomes (lipid bodies)
AC Orford soybean
Authors: Voldeng H. D. , Turcotte P. , Guillemette R. J. D. , Cober E. R.
Published: April 2011

AC Orford is a 2500 crop heat unit soybean [Glycine max (L.) Merr.] cultivar with good yield potential. Key words: Soybean, cultivar description
Forage chicory persists in combination with cool season grasses and legumes
Authors: Kunelius H. T. , McRae K. B.
Published: April 2011

Forage chicory (Cichorium intybus L.) was grown alone and in combination with various grasses and legumes for three production years to determine growth, botanical composition, and persistence. Chicory mixed with grasses and legumes produced greater yields than chicory alone. Mixtures of orchardgrass (Dactylis glomerata L.) + white clover (Trifolium repens L.), timothy (Phleum pratense L.) + alfalfa (Medicago sativa L.), and timothy + red clover (Trifolium pratense L.) in combination with chicory produced the highest dry matter yields. Persistence of chicory was adequate; it survived for three production years in the cold-winter region of Atlantic Canada. Including chicory in grass/legume swards improved the seasonal distribution of herbage and increased late season production. Key words: Botanical composition, Cichorium intybus L., combinations, mixtures, persistence, seasonal yield distribution