bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of soil compaction, soil moisture and soil type on growth and nodulation of soybean and common bean
Authors: Buttery B. R. , Tan C. S. , Drury C. F. , Park S. J. , Armstrong R. J. , Park K. Y
Published: April 2011

In field tests we have observed year-to-year differences in the severity of the effects of soil compaction on nodulation and growth of common bean; these differences appeared to be related to the amount of rainfall during the growing season. We decided to use better controlled conditions in the greenhouse, and extend the scope of the study to another legume crop and a different soil type, in order to investigate the hypothesis that copious water supply alleviates the adverse effects of soil compaction on nodulation and plant growth.The effects of two levels of soil compaction and of high and low water supply on the growth and nodulation of common bean and soybean were investigated in separate pot tests using a Fox sandy loam and a Brookston clay loam soil.Root growth of both species was severely restricted by dry compacted conditions. Plant growth as a whole was clearly reduced by both increased compaction and by reduced water supply, presumably mediated by the effects on root growth. The effect of reduced water supply was more severe in the highly compacted pots, and more severe in the clay loam than in the sandy loam.In the sandy loam, low moisture reduced nodule numbers and weights in both species, while increased bulk density reduced the numbers of nodules but not the dry weights. In the clay loam, nodule weights and numbers were very low, presumably, owing to high levels of nitrate, which may have resulted from mineralization of soil organic matter during storage.A generous supply of water obviously alleviated some of the adverse effects of soil compaction on plant growth. This is in general agreement with results of earlier field trials, where severity of the effects of soil compaction varied with the quantity of rainfall. Key words: Soybean, common bean, soil compaction, soil moisture, nodulation, bulk density
Experiences with the utilization of wastes in nursery potting mixes and as field soil amendments
Authors: Chong Calvin
Published: April 2011

The nursery/landscape industry has been one of the fastest growing agricultural sectors in Canada. Since 1980s, the Ornamental Nursery Research Program at the Horticultural Research Institute of Ontario (HRIO) has been conducting research which focuses on environmentally friendly production practices. Emphasis is on the use of composted or uncomposted organic wastes as amendments in container potting mixes. Various projects have evaluated mixes derived from wastes such as spent mushroom compost, paper mill sludge, apple pomace, and various types of barks. In the late 1980s and early 1990s, the scope of the research expanded to include composting and a wider assortment of wastes such as waxed corrugated cardboard, municipal solid waste compost, wood chips from pallets and furniture and demolition wastes, food wastes, and organic fertilizers manufactured from meat by-products, and selected industrial wastes. Presently, paper mill sludge is being evaluated as field soil amendment for growing nursery shade trees and also for use in rehabilitating marginal, non-agricultural land. Key words: Waste recycling, land rehabilitation, composts, organic wastes, container culture, shade tree culture, ornamentals, nutrition
Weather conditions associated with apple production in the Okanagan Valley of British Columbia
Authors: Caprio J. M. , Quamme H. A.
Published: April 2011

An analytical method that generates χ2 indices of association was used to determine the "critical" levels of daily weather occurrences associated with annual variations in apple production (Malus domestica Borkh.) in the Okanagan Valley of British Columbia over a 72-yr period, 1920–1991. The weather was recorded in the centre of the region (the Pacific Agri-Food Research Centre, Summerland). High temperatures during flower bud initiation in June (≥30 °C) and during flower bud development in August (≥26 °C) were associated with poor production the following year. Low temperature during November, December and February (critical value range, ≤ −7 °C to ≤ −29 °C) was the main climatic factor limiting apple production. These time periods correspond to the occurence of historical winter injury events. Daytime temperatures ≥5 °C at times during January also affects apple production adversely, probably because warm weather leads to tree deacclimation. Daily precipitation in March (≥1.0 mm) was associated with good production years which may indicate a requirement for early irrigation. Production was favoured by mild temperatures during bloom (≥21 °C daytime, ≥11 °C nighttime) and adversely affected by both very low temperatures (≤10 °C nighttime) and unseasonably high temperatures (≥28 °C daytime) coinciding with the temperature requirements of pollination and pollen tube growth. Good production years were also associated with a lack of low nighttime temperature (≤5 °C) in spring, probably associated with frost in low lying areas. Hot, dry weather during August of the harvest year (≥33 °C daytime, ≤2 mm) had a negative impact on apple production possibly because of loss in net photosynthesis, lower fruit size or apple sunburn. Warm weather during harvest (≥17 °C daytime) favoured production, probably because of improved conditions for harvest operations and low fruit losses from autumn frosts. Key words: Malus domestica Borkh., tree fruit, climate, heat stress, spring frost, winter injury
Dynamics of nitrogen and dry-matter partitioning and accumulation in broccoli (Brassica oleracea var. italica) in relation to extractable soil inorganic nitrogen
Authors: Bowen P. A. , Zebarth B. J. , Toivonen P. M. A.
Published: April 2011

The effects of six rates of N fertilization (0, 125, 250, 375, 500 and 625 kg N ha−1) on the dynamics of N utilization relative to extractable inorganic N in the soil profile were determined for broccoli in three growing seasons. The amount of pre-existing extractable inorganic N in the soil was lowest for the spring planting, followed by the early-summer then late-summer plantings. During the first 2 wk after transplanting, plant dry-matter (DM) and N accumulation rates were low, and because of the mineralization of soil organic N the extractable soil inorganic N increased over that added as fertilizer, especially in the top 30 cm. From 4 wk after transplanting until harvest, DM and N accumulation in the plants was rapid and corresponded to a rapid depletion of extractable inorganic N from the soil. At high N-fertilization rates, leaf and stem DM and N accumulations at harvest were similar among the three plantings. However, the rates of accumulation in the two summer plantings were higher before and lower after inflorescence initiation than those in the spring planting. Under N treatments of 0 and 125 kg ha−1, total N in leaf tissue and the rate of leaf DM accumulation decreased while inflorescences developed. There was little extractable inorganic soil-N during inflorescence development in plots receiving no N fertilizer, yet inflorescence dry weights and N contents were ≥50 and ≥30%, respectively, of the maxima achieved with N fertilization. These results indicate that substantial N is translocated from leaves to support broccoli inflorescence growth under conditions of low soil-N availability. Key words: N translocation, N fertilizer
Effects of growth-stage-based alfalfa harvest on weed encroachment and resultant quality
Authors: Moyer J. R. , Fraser J. , Rode L. M. , Topinka A. K.
Published: April 2011

Growth-stage-based alfalfa harvest treatments were imposed on a 2-yr-old Beaver alfalfa stand in 1992 to determine the effect of harvest treatments on yield and quality. By 1993, alfalfa cut at the vegetative stage or prebud stage contained 25% dandelions by weight. At these stages weeds lowered crude protein content in the total forage relative to pure alfalfa. Weed contents were similar and less than 1% by weight in forage cut at prebloom and later stages. Crude protein and fibre contents were similar in total forage and pure alfalfa at prebloom and later stages. Key words: Acid detergent fibre, crude protein, cutting management, dandelion, growth stage, neutral detergent fibre
Nitrogen fertilization and orchard-floor vegetation management affect growth, nutrition and fruit quality of Gala apple
Authors: Neilsen G. H. , Hogue E. J. , Meheriuk M.
Published: April 2011

Gala apple (Malus × domestica Borkh) trees on M.26 rootstock planted in 1989, were subjected to a factorial combination of treatments involving two N fertilizations (N1 and N2) and two orchard-floor vegetation-management treatments (V1 and V2), 1990–1995. Single annual, spring-broadcast application of N at 80 kg ha−1 were made at N1, while N2-treatments involved split N applications of either 2 × 100 kg ha−1 (1990–1993) or 3 × 80 kg ha−1 (1994–1995). Herbicide strips (1.5-m width) were maintained free of orchard-floor vegetation year-round (V1) or annually until mid-July (V2). The high N regime (N2) increased leaf and fruit N concentration and decreased fruit P and leaf and fruit K concentrations but had few negative effects on fruit quality, decreasing harvest fruit ground red color in 2 yr and firmness in a single year and titratable acidity of stored fruit in 2 yr. Increased tree yield was measured at N2 only in 1995. Greater vegetation competition in the V2 treatment decreased yield in 1991–1992 and cumulative yield for 1991–1995 but had few effects on leaf and fruit N concentrations. Leaf and fruit K concentrations were generally increased at V2 as was titratable acidity of stored fruit. Fruit from V2 treatments had increased red ground color (2 yr) and increased firmness at harvest (3 yr) or after storage (2 yr) but decreased soluble solids at harvest (2 yr). Fruit was free of disorders and had a high Ca concentration regardless of treatment or year implying Gala apple is a good Ca accumulator. Key words: Malus × domestica, leaf and fruit N, P and K, fruit Ca, yield, fruit firmness
The effect of preharvest foliar sprays of calcium on quality and shelf life of two cultivars of sweet bell peppers (Capsicum annuum L.) grown in plasticulture
Authors: Toivonen Peter M.A. , Bowen P.A.
Published: April 2011

The effect of preharvest calcium sprays on postharvest quality of sweet bell peppers grown in plasticulture was studied. Calcium was applied as three sprays of 0.4% (wt/vol) CaCl2 in water to plots of Oriole and Bell Boy peppers in each of 2 yr. Fruit weight, water loss, firmness, decay and the composition of the pectic fractions were determined at harvest and during storage. Preharvest sprays of CaCl2 increased the weight of fruit for Oriole, improved firmness retention in storage, decreased decay, increased pericarp wall thickness and the insoluble pectic fractions of both cultivars but had no effect on water loss in storage. The results suggest that Ca improves firmness retention through enhancing the pectic composition of cell walls and pericarp wall thickness. Effects of Ca sprays on reducing decay could not be attributed to factors measured in this work. Preharvest foliar sprays of CaCl2 show promise in reducing postharvest decay and improving firmness retention in sweet bell peppers grown under plasticulture. Key words: Capsicum annuum L., calcium, pectin, shelf life, postharvest decay
The effect of temperature, seed colour and linolenic acid concentration on germination and seed vigour in flax
Authors: Saeidi G. , Rowland G. G.
Published: April 2011

In Canada, the edible-oil type of flax (Linum usitatissimum) known as solin must have a linolenic acid concentration of less than 5% and a yellow seed colour. The yellow seed distinguishes solin from regular, high-linolenic acid linseed flax. Both altered fatty acid ratios and seed colour can have a negative impact on seed germination. The effects of temperature, seed colour and seed linolenic acid concentration on germination and seed vigour were studied in four populations that were near-isogenic for seed colour and linolenic acid level. For all populations, a germination temperature of 5 °C resulted in a significantly lower germination than at 10 or 15 °C. With one exception at 5 °C, where yellow seed had a greater germination than brown seed, there was no difference in germination frequency between brown and yellow seed. Also, there was no difference in germination between low and high linolenic acid seed with the exception of one population where low linolenic acid seeds had lower germination at 5 °C. In vigour tests however, yellow seed had lower seed vigour than brown seed in all populations. Low linolenic acid seeds had lower seed vigour than high linolenic acid seed in one population. Selection for seed vigour is essential in the breeding of solin varieties. Key words: Seed colour, linolenic acid, germination, seed vigour, flax
Crop density and seed production of tall fescue (Festuca arundinacea Schreber). 2. Reproductive components and seed characteristics
Authors: Fairey N. A. , Lefkovitch L. P.
Published: April 2011

The population density and spatial arrangement of plants may influence the productive life and performance characteristics of a perennial grass-seed crop. A study was conducted to determine the effects of the initial density (1.6, 3.1, 6.3, 12.5, 25, 50 and 100 plants m−2) and row spacing (20, 40, and 80 cm) of plants on reproductive yield components and seed characteristics of tall fescue (Festuca arundinacea Schreber), over 3 consecutive production years (1991–1993) in the Peace region of Canada. The weight proportion of cleaned-to-uncleaned seed was 85–86% for the three lowest plant densities and then decreased, as density increased, to 82% at 12.5 plants m−2 and 66% at 100 plants m−2. The 1000-seed weight decreased as density increased and ranged from 1.68 to 2.22 g (i.e., 595 000 to 450 000 seeds kg−1). The specific seed weight ranged from 18 to 31 kg hL−1; it differed among years, but the effect of plant density was inconsistent. The germination capacity of the seed was unaffected by plant density, but differed among years; it averaged 87%, 88% and 59% in 1991, 1992 and 1993, respectively. The seed yield/plant, the number of panicles/plant, and the number of seeds/plant decreased exponentially as plant density increased. The number of clean seeds/panicle decreased, as plant density increased, in the first year but was less affected subsequently, particularly with the 20-cm row spacing. The seed yield was correlated closely with the number of panicles m−2 (r = 0.659***). An initial density no greater than 25 plants m−2 in rows spaced 20–40 cm apart enhanced seed quality by producing a greater proportion of clean seed which had a higher 1000-seed weight. Such a plant density, however, is at the low end of the optimum range for maximizing seed yield per unit land area. Key words: Tall fescue, Festuca arundinacea Schreber, population density, plant and row spacing, yield components, seed quality
Seed yield of three Bromus species native to western Canada
Authors: May K. W. , Willms W. D. , Stout D. G. , Coulman B. , Fairey N. A. , Hall J. W.
Published: April 2011

There is an increasing demand to use native grass species for revegetating disturbed sites such as logged clearcuts. The value of such species is closely linked with their ability to produce seed. We compared seed yield of three native Bromus species (Bromus carinatus Hook. & Arn., B. ciliatus L., and B. anomalus Rupr. Ex Fourn.) and three domestic forage species (B. riparius Rehm., B. inermis Leyss., and Dactylis glomerata L.) and tested the hypothesis that native species divert fewer resources to reproductive growth than do domestic grasses. Six experiments were conducted at five locations in western Canada to evaluate the potential for seed yield from native brome. Bromus carinatus seeds ripened, on average, the first week of August, similar to B. riparius and D. glomerata, while seed of B. anomalus and B. ciliatus ripened about the third week of August, similar to B. inermis. Seed yields were highly variable among sites and between years. Over all sites, yields among species were not significantly different (P = 0.05). Mean second-year yield was less than half of that of the first harvest year. Yields of 2–3 t ha−1 were found for B. anomalus, B. ciliatus and B. inermis at certain sites. Seed yields were positively correlated to inflorescence number m−2 in both harvest years and to harvest index in the first harvest year. Based on seed yields that were similar to B. inermis in this study, it should be possible to produce sufficient quantities of reasonably priced seed of native Bromus species for the revegetation industry. Key words: Smooth bromegrass, meadow bromegrass, orchard grass, Bromus sp., Dactylis glomerata
Climate change in the semiarid prairie of southwestern Saskatchewan: Late winter–early spring
Authors: Cutforth H. W. , McConkey B. G. , Woodvine R. J. , Smith D. G. , Jefferson P. G. , Akinremi O. O.
Published: April 2011

Long-term weather and hydrological data were analyzed to study climate change during late winter–early spring within an approximately 15 000 km2 area in the semiarid prairie near Swift Current, Saskatchewan. The climate has changed over the past 50 yr. Winter and spring maximum and minimum temperatures have warmed, snowfall amounts have decreased, and spring runoff has started earlier now than during past years. The percentage of precipitation as snow has decreased as temperatures have warmed. As well, even though temperatures have warmed, the date of the last spring frost has not gotten earlier with time. Key words: Climate change, semiarid prairie, winter and spring, temperature, snow, spring runoff
Annual forage production from spring-planted winter cereal monocrops and mixtures with spring barley
Authors: Juskiw P. E. , Salmon D. F. , Helm J. H.
Published: April 2011

Spring-planted winter cereals grown as monocrops or in mixture with spring cereals maintain yield and quality into late summer and fall, and can be used to replace or complement perennial pasture. Our objectives were to determine the response to clipping of spring-planted winter cereals, and to determine the effects of seeding rates and ratios of spring to winter cereals on this response. Monocrops of winter triticale (X Triticosecale Wittmack) cv. Pika and winter rye (Secale cereale L.) cv. Musketeer and mixtures of these cereals with the spring barley (Hordeum vulgare L.) cv. Noble were evaluated. Tests were conducted from 1991 to 1993 at Botha and Lacombe, AB. Mixtures of spring:winter cereals were 0:100, 25:25, 25:75, 50:50, 75:25, 75:75 and 100:100 (Lacombe only), where the ratio of components represented the percentage of the base seeding rate of 250 seeds m−2. Biomass yields for triticale treatments (5.5 t ha−1 at Botha and 6.3 t ha−1 at Lacombe for the May to October growing season) were generally as high as for the rye treatments (5.9 t ha−1 at Botha and Lacombe); however, at Lacombe, spring regrowth after overwintering for triticale treatments was only 0.6 t ha−1 compared with 1.0 t ha−1 for rye treatments (LSD0.05 = 0.17). As little as 25% spring barley in a mixture ensured good early-season biomass yields, but more than 50% reduced late-season biomass yields. All treatments produced good-quality forage with protein >20%, neutral detergent fibre (NDF) <45% and acid detergent fibre (ADF) <30%. Nitrate contents were frequently >0.5% at both sites in 1991 and 1992, especially for those treatments with spring barley. Key words: Winter triticale, winter rye, annual forage, biomass, forage quality
Recirculation of nutrients in container nursery production
Authors: Purvis Peter , Chong Calvin , Lumis Glen P.
Published: April 2011

This study evaluated (a) the capacity of a computerized injector to deliver and recirculate nutrients in a container nursery, and (b) plant growth and nutrient status under this regime compared with non-recirculated methods of fertilization, using Dart's Gold ninebark (Physocarpus opulifolius L. 'Dart's Gold') potted in 6-L containers filled with a medium of pine bark, peat, and soil (75, 15, and 10%, by volume). The injector was programmed to deliver NH4-N (24 mg L−1), NO3-N (196 mg L−1), P (54 mg L−1), and K (235 mg L−1) and other nutrients, with or without recirculation. Plants grown with recirculated nutrients were placed on aluminium troughs to collect the leachate, which was pumped back to the injector, recharged [based on a target electrical conductivity (EC) value of 1.85 dS m−1], and returned to the crop. Additional plants were grown on a crushed stone base and fertilized (a) by the computerized injector without recirculation, (b) with water soluble Plant-Prod 20-8-20 (200 mg L−1 N; non-recirculated) delivered through a Dosatron proportioner, or (c) with incorporated, controlled release Nutricote 18-6-8, Type 140 (6.5 kg m−3). NH4-N, NO3-N, P, and K concentrations delivered by the computerized injector (recirculated and non-recirculated; mean over six dates, 3 July to 28 August 1997) were 50, 22, 41, and 39%, respectively, lower than targeted values. Electrical conductivity values were not significantly different from targeted. The pH values (6.2 – 6.4) were higher than targeted (6.0). The amounts of N, P, and K used were reduced by between 57 and 77% with recirculation compared to without. Notwithstanding reduced N, P, and K values, plants grew best with recirculated nutrients and least with non-recirculated liquid 20-8-20. Key words: Fertigation, Harrow Fertigation Manager, recycling, woody ornamentals
Spread of Sclerotinia stem rot of soybean from area and point sources of apothecial inoculum
Authors: Wegulo S. N. , Sun P. , Martinson C. A. , Yang X. B.
Published: April 2011

Field experiments were conducted from 1995 to 1998 to quantify the spread of ascospores of Sclerotinia sclerotiorum, the causal agent of Sclerotinia stem rot of soybean. Incidence of Sclerotinia stem rot measured in a soybean field adjacent to a corn field naturally infested with S. sclerotiorum (area source) was highest close to the area source and decreased with distance from the area source. Disease gradients in the soybean field were described nearly equally well by the exponential model, power law model, and logit-log model. Disease incidence in transects in non-infested areas of a soybean field increased with distance from the edges of soybean and corn area sources of inoculum, reached a maximum at 10–12 and 18–20 m, respectively, from the edges of the inoculum area sources, then decreased in a manner characteristic of the disease gradient curve between 10–12 and 32 m, and 18–20 and 44 m from the edges of the area sources. In soybean plots, disease incidence decreased with distance from point sources of apothecial inoculum. The results from these studies suggest 1) the potential for field to field dispersal of S. sclerotiorum, and 2) that the majority of ascospores of S. sclerotiorum are deposited close to the source (apothecia). Where a concentrated area or point source of S. sclerotiorum inoculum exists, the general exponential model may provide good fits to Sclerotinia stem rot gradient data. Key words: Apothecial inoculum, disease gradients, logit-log model, power law model, simple exponential model
Nitrogen utilization by forage grasses
Authors: Bélanger G. , Gastal F.
Published: April 2011

The efficient utilization of nitrogen (N) in grass production is essential to reduce the risks of water and air pollution, and the costs of production. Recent findings in grass physiology and agronomy should help in developing new tools to improve N utilization efficiency. A model of N dilution describing the decrease in plant N concentration with increasing shoot biomass under non-limiting N supply is used to define a critical N concentration in grasses required to reach maximum shoot growth and yield. The index of N nutrition (INN) is then calculated as the measured N concentration in a given situation divided by the critical N concentration. The INN is a diagnostic tool to quantify the level of N deficiency during growth cycles, and can also be used in crop modelling and in the interpretation of results from studies conducted over many sites and years. The "universality" of the model of N dilution is based on the increased proportion of structural to metabolic components during crop growth combined with the fact that the structural component has a lower N concentration. Inter- and intra-species differences in N concentration at a given shoot biomass can be related to differences in the proportion of leaves which are assumed to be equivalent to the metabolic component. Under N-deficient conditions, the reduction in grass growth is due to a reduction in the interception of solar radiation primarily through reduced leaf extension, and to a reduction in the conversion efficiency of intercepted radiation into shoot biomass primarily through an effect on biomass partitioning between roots and shoots. The concept of the critical N concentration based on the relationship between plant N concentration and shoot biomass is used to derive general and synthetic expressions of the effect of plant N nutrition on crop growth and crop growth processes. These recent findings on the relationship between N nutrition and the growth of forage grasses should result in the improvement of the efficiency of N utilization by a more precise fertilizer management and the development of more N efficient cultivars. Key words: Physiology, growth, photosynthesis, leaf, partitioning, model
Development and evaluation of grazing-tolerant alfalfa cultivars: A review
Authors: Smith Jr. S. R. , Bouton J. H. , Singh A. , McCaughey W. P.
Published: April 2011

Plant breeders have long sought to improve grazing tolerance of alfalfa without sacrificing the beneficial yield and quality attributes of this species. Most efforts have focussed on selecting for traits (e.g., creeping rootedness) related to grazing tolerance and/or simulated grazing, but these efforts failed to account for the multiple stresses caused by grazing animals. Trait selection often led to sacrifices in yield and other desirable characteristics resulting in cultivars that were not robust across grazing management systems and environments. An innovative selection procedure was recently developed at the University of Georgia which incorporated intensive grazing with continuous stocking by beef cattle. The development of "Alfagraze" using this procedure showed that grazing tolerance and high yields can be incorporated into the same cultivar, along with consistent performance across grazing management systems and environments. Subsequent research has shown that grazing tolerance can be improved within elite, high-yielding, multiple-pest-resistant cultivars and breeding populations. Selection using intensive grazing with continuous stocking has been summarised in a "Standard Test Protocol" that is now being successfully used by public and private alfalfa breeders and in cultivar evaluation programs in the USA, Canada, and other countries. Key words: Medicago sativa, Medicago sativa ssp. falcata, persistence, lucerne, grazing tolerance, Alfagraze
Variation amongst Canadian six-row spring barley cultivars for germination and emergence characteristics in controlled environments and in the field
Authors: Briggs K. G. , Dunn G. J.
Published: April 2011

Information is lacking concerning the extent of variability in Canadian six-row barley cultivars for differences in potential field germination vigour and other germination characteristics, and the extent to which these traits can be predicted from laboratory tests. This study was conducted to evaluate the extent to which a genetically diverse range of Western Canadian six-row barley cultivars differ in germination resistance and early seedling vigour or emergence rate under controlled environments and in the field, over a range of temperature stress conditions. Vigour was assessed by measuring germination rate, emergence rate, and dry weight accumulation in young seedlings, in the growth cabinet and in the field. Cultivars studied were selected to represent a wide range of genetic diversity typical of Canadian breeding programs of the early 1980s. Growth cabinet assays were conducted at six temperatures from 2.5 to 20 °C. Field trials were conducted using the same cultivars seeded at three dates per site in 2 yr, to assess cultivar emergence rates and seedling dry weight accumulation over a range of seedbed temperatures, using two seed sources from cultivar increases each grown in different years.Cultivars differed significantly for germination resistance in the growth cabinet, and the performance of cultivars was relatively consistent across assay temperatures and for the two different seed sources. Differences among cultivars in growth for seedling dry weight were also consistent across temperatures, but cultivar performance for seedling dry weight accumulation was not significantly correlated with germination resistance in the cabinet test. In field trials, days to emergence were highly and significantly correlated with germination resistance determined in the growth cabinet. Germination resistance was less strongly correlated with dry weight accumulation in the field at 5 wk. Across cultivars, seedling dry weight estimates in the field were significantly correlated with seedling dry weights assayed in the growth cabinet. Results from this study confirm that genetic variation in potential germination rate and seedling vigour in the field can be identified in six-row barley using the germination resistance assay in the growth cabinet. Germination resistance identified more cultivar differences than were found for the seedling dry weight accumulation tests, which were characterized by high coefficients of variation and low correlation between growth cabinet and field. Key words: Temperature, field seedling vigour, barley cultivars, prediction tests
Improvement of soybean somatic embryo development and maturation by abscisic acid treatment
Authors: Tian Lining , Brown Daniel C. W.
Published: April 2011

Recovery of tissue culture-derived plants through somatic embryogenesis is a useful system for genetic engineering of soybean. The effect of abscisic acid (ABA) on soybean somatic embryogenesis, development, and maturation was investigated. ABA at 1, 10, 50, 100, and 500 µM were applied at different stages of embryo development; namely, at the globular stage in suspension culture, at the development stage and at the maturation stage on solid media. ABA promoted embryo growth and development when applied at the globular stage. Embryo size, after 15 d and after 1 mo on development medium, was significantly greater than that without exposure to ABA. ABA promoted normal embryo morphogenesis and 62% more normal embryos developed when embryos were treated with ABA at the globular stage. ABA treated-embryos showed an increased tolerance to partial desiccation (from 24% to 78%) and exhibited an increased germination capability relative to non-ABA-treated controls (54% versus 8%). Somatic embryos appeared to undergo a decreasing sensitivity to ABA during maturation. ABA did not show an effect when applied during embryo development and maturation stages. A protocol for more normal embryo formation and improved embryo germination is reported. Key words: Glycine max, somatic embryogenesis, in vitro culture
Comparative performance of three test methods for determining chipping quality in tubers of potato (Solanum tuberosum L.)
Authors: Coleman Warren K. , Tai G. C. C.
Published: April 2011

The capacity of a colour chart and a reflectance photometer (Agtron) to accurately determine chipping quality of potato tubers was assessed using data sets taken over a 4-yr period for 17–32 cultivars. Both tests gave a high diagnostic accuracy for chipping quality regardless of sampling time from storage or the occurrence of high temperature reconditioning when evaluated by receiver operating characteristic (ROC) curve analysis. Receiver operating characteristic curve analysis showed that both tuber glucose content and chip colour provided good diagnostic performance in correctly separating processing from non-processing tubers over a range of growing and storage conditions. Identification of chipping from non-chipping tuber samples from a 13 °C storage across a range of cultivars and growing conditions occurred with a minimum chipping colour threshold range of 41–47 or a maximum glucose concentration range of 4.3–5.4 mmol L−1 of tuber cell sap. The practical value of a test can depend on such factors as prevalence of chippers in a tuber population as well as the cost of misclassifications, i.e., costs associated with false positive or false negative test results and expressed in relative terms as the unit cost ratio. An examination of Prevalence-Value-Accuracy (PVA) plots for one of the data sets indicated that total misclassification costs could increase rapidly, depending on the prevalence of chipping tubers and the relative amounts of false negative and false positive costs. Maximum costs were consistently associated with a prevalence of 50% chippers and a unit cost ratio of 0.5. In a tuber sample containing a high prevalence of chippers (50–70%) and a low unit cost ratio (<0.2), an acceptable colour threshold determined by PVA-Threshold (PVAT) plots would be approximately 40 to 50 from the Agriculture and Agri-Food Canada colour chart. However, if the colour chart was used for screening tuber samples with a low prevalence (20–40%) of chippers and a unit cost ratio >0.20, a threshold between 60 and 65 would be optimum. The latter range would be conservative and agrees with, and supports, current industry standards, which reside at 60 or better. Since a good diagnostic test should be repeatable and subject to minimal inter-observer variation, the more objective glucose or reflectance photometric tests may be preferable and provide acceptable diagnostic accuracy for processing quality. However, the present study indicates that all three test methods are acceptable for accurately separating chipping from non-chipping tubers regardless of sampling or storage protocols. Key words: Potato, colour chart, reflectance colorimetry, glucose content
Evaluation of disease forecasting variables for sclerotinia stem rot (Sclerotinia sclerotiorum) of canola
Authors: Bom M. , Boland G. J.
Published: April 2011

Selected environmental, crop and pathogen variables were sampled weekly from winter and spring canola crops before and during flowering and evaluated for the ability to predict sclerotinia stem rot, caused by Sclertinia sclerotirum. Linear and nonlinear relationships were examined among variables but, because no strong correlations were observed between final disease incidence and any of the variables tested, a categorical approach (e.g., disease severity) was used instead. Disease severity in individual crops was categorized as low (< 20% diseased plants) or high (> 20% disease), and differences in weekly rainfall, soil moisture, crop height, percentage of petal infestation, and number of apothecia m−2 and clumps of apothecia m−2 were significantly associated with differences in disease severity within or between years. Two disease prediction models were compared for the ability to predict low or high disease severities using petal infestation alone, or petal infestation in combination with soil moisture. The model that included petal infestation and soil moisture predicted more fields correctly than the model using petal infestation alone, but the accuracy of both was affected by the timing of soil moisture measurements in relation to petal infestation, and threshold values used in discriminating categories of soil moisture and petal infestation. Key words: Brassica rapa, Brassica napus, Sclerotinia sclerotiorum, disease prediction
Réponse du soya à la fertilisation minérale en éléments majeurs NPK sur des sols classés de riches à excessivement riches en phosphore ou en potassium des Basses Terres du Saint-Laurent
Authors: Tremblay G. , Beausoleil J.-M.
Published: April 2011

In the scientific literature there are numerous studies on soybean response to major mineral NPK elements. But there are few research data on this topic for the Lowland soils of the Saint-Lawrence Valley. A 3-yr study was conducted in 1994, 1995, and 1996 on three representative soil types of the lowland Saint-Lawrence Valley region: Dujour, Sainte-Rosalie and Saint-Urbain. These soils are classified from rich to excessively rich in available phosphorus and potassium as measured by the Mehlich 3 method. Results of this study indicate that yield is rarely significantly influenced by levels of nitrogen, phosphorus or potassium fertilization. Moreover, there are no significant interactions among those elements and soybean grain yield. Other observed variables (specific weight, grain visual quality, 100-seed weight, seed protein and oil contents) were generally not affected by the different levels of nitrogen, phosphorus or potassium fertilization. There were few significant interactions between major elements and those variables. Generally, soybeans did not respond to NPK mineral fertilization on representative soils of the Lowland Saint Lawrence Valley region classified from rich to excessively rich in available phosphorus and potassium. Key words: Soybean, fertilization, nitrogen, phosphorus, potassium, yield
Mixtures of paper mill sludge, wood chips, bark, and peat in substrates for pot-in-pot shade tree production
Authors: Chong Calvin , Lumis Glen P.
Published: April 2011

There is little scientific information on substrates for pot-in-pot shade tree production. The objective of this research was to examine various organic-waste-derived substrates for growing shade trees in pot-in-pot systems. Seedling whips of green ash (Fraxinus pennsylvanica Marsh.), Japanese birch [Betula platyphylla var. japonica (Miq.) Hara], and silver maple (Acer saccharinum L.) were grown for two seasons in 76-L containers. The containers were trickle irrigated and fertilized with controlled-release fertilizers. Treatments included a control nursery mix (50% by volume of pine bark:15% compost:35% topsoil) and nine other mixes classified into three groups: Group I (25, 50 or 75% bark mixed with 50, 25, or 0% wood chips, and 25% paper mill sludge); Group II (25, 50 or 75% bark; 50, 25 or 0% wood chips; and 25% peat); and Group III (25, 50 or 75% peat; 50, 25 or 0% wood chips; and 25% paper mill sludge). In both years, trunk diameters of the three species were greatest with Group III substrates, intermediate with Group II, and least with Group I. Trunk growth was positively correlated with water retention porosity, which ranged from 42 to 57%, 38 to 42%, and 20 to 27% for Groups III, II, and I, respectively. Trunk diameters of Group II and III trees were equal to, or slightly exceeded (10–12%), those of the nursery mix. The nursery mix had a water retention porosity of 49% and generally the highest content of soluble salts. The high-peat (50 and 75%) substrates marginally but consistently produced trees with the largest trunk diameters, although with birch (not the other species) shorter trees resulted as the peat content increased. Key words: In-ground containers, nursery, ornamentals, waste utilization, container culture
Uptake of foliar or soil application of 15N-labelled urea solution at anthesis and its affect on wheat grain yield and protein
Authors: Rawluk C. D. L. , Racz G. J. , Grant C. A.
Published: April 2011

Two growth chamber experiments were conducted to determine the effect of 15N-labelled urea solution foliar- or soil-applied at anthesis on recovery of fertilizer N in grain, grain protein and grain yield of Canadian Western Red Spring wheat (Triticum aestivum L.). Recovery of 15N-labelled urea-N in grain ranged from 4.5 to 26.7% with foliar application, and from 32.3 to 70.1% with soil application. Amending the urea solution with the urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) improved recovery of soil-applied N in exp. 1 only and did not increase N recovery from foliar applications. Nitrogen recovery of foliar-applied urea was increased on average from 10.6 to 25.0% by adding nonyl phenol ethoxylates (NPE), a non-ionic surfactant, to the urea solution. Grain protein was higher when urea was applied to the soil than when applied to the foliage. Addition of N at planting increased both grain protein and yield while only protein was enhanced with fertilizer N applied at anthesis. Although wheat cultivar, soil type and growing environment differed in the two experiments, protein content consistently increased with N application at anthesis, indicating the effect of N applied at anthesis is constant across a range of conditions. Key words: Triticum aestivum L., N-(n-butyl) thiophosphoric triamide, NBPT, non ionic surfactant, wetting agent, nitrogen recovery
Response of canola to simulated diamondback moth (Lepidoptera: Plutellidae) defoliation at different growth stages
Authors: Ramachandran Suresh , Buntin G. David , All John N.
Published: April 2011

In field trials conducted during 1995–1998, canola cultivar "Falcon" was subjected to different levels of simulated insect defoliation at four stages of crop growth. Plants were 0, 33, 67 and 100% defoliated at rosette and flowering stages during the 1995–1996 season as well as 2–4 leaf stage during the 1996–1997 and 1997–1998 seasons. Plants were 0, 50 and 100% defoliated at pod filling stage during all seasons. Over all seasons, defoliation did not consistently affect the number of plants per unit area, plant height, 1000 seed weight, and oil content of seeds for most of the defoliation treatments. However, defoliation at the 2–4 leaf and rosette stages made plants more susceptible to cold injury. Generally, canola could withstand a higher level of defoliation as crop development progressed. Maximum yield reductions occurred for defoliations at the 2–4 leaf stage followed by the rosette and flowering stages of the crop. No significant yield losses were recorded for defoliations at the pod filling stage. Results suggest that canola is most sensitive to defoliation in its early stages of growth. Greater amounts of defoliation can be tolerated as crop development progresses. The relationships between defoliation and yield loss were used to establish diamondback moth economic injury levels for canola at different crop growth stages. Key words: Canola, Brassica napus, oilseed rape, simulated defoliation, economic injury level
Test-weight and weathering of spring wheat
Authors: Gan Y. T. , McCaig T. N. , Clarke P. , DePauw R. M. , Clarke J. M. , McLeod J. G.
Published: April 2011

Wet weather often delays harvest and results in a grade reduction of wheat because of a decrease in test-weight, an important grading factor in Canada. The objectives of this study were to assess the effect of delayed harvest on test-weight loss of 14 Canadian wheat cultivars representing three different classes, and to develop a screening strategy for retention of test-weight for breeding programs. Non-weathered test-weight (NWTWt), weathered test-weight (WTWt), and test-weight loss (TWtLoss; i.e. NWTWt – WTWt) in the field, averaged over five field locations and 2 yr were similar within the CPS, CWAD and CWRS wheat classes, although there were genotypic differences for all three variables. Because test-weight requirements for the top grades are higher in the CWAD class than in other classes, durum cultivars would be more susceptible to downgrading during wet harvests. Historical data from the Durum Wheat Co-operative Test also suggests that, since 1950, the mean test-weight of the genetic lines has decreased by 3.7 kg hL−1, and is now close to the minimum for grade #1 in the CWAD class. Most of the decrease in test-weight observed over several weeks in the field could be simulated by a single 5 – 10 min soaking of non-weathered seed in the laboratory. Linear regression analyses of both field and laboratory samples indicated that 90% of the genotypic variation in weathered test-weight could be attributed to differences in the NWTWt. These results suggest that the screening strategy for retaining test-weight should focus on selection for increased NWTWt. This is much simpler than screening for high WTWt or low TWtLoss, which requires soaking of the seed or field weathering. Key words: Triticum aestivum, Triticum turgidum, quality
Poultry manure effects on soil nitrogen processes and nitrogen accumulation in red raspberry
Authors: Dean D. M. , Zebarth B. J. , Kowalenko C. G. , Paul J. W. , Chipperfield K.
Published: April 2011

This study examined the effects of solid poultry layer manure addition on soil N processes and on dry matter and N accumulation in red raspberry (Rubus idaeus L.). In trials conducted in two years, approximately 50% of the 400 kg total N ha−1 applied as manure was recovered as soil inorganic N 1 mo after manure application when manure was incorporated within 4 h of application. Three trials were conducted in two commercial raspberry fields: one with no history of manure use and one other with a history of heavy annual applications of poultry manure. Treatments included 55 kg N ha−1 as NH4NO3, 100 or 200 kg total N ha−1 as manure, and a control that received no manure or fertilizer N. Soil inorganic N to 60 cm depth was measured throughout the growing season. Berry yield was estimated, and dry matter and N accumulation was determined in floricanes at first berry ripening and in primocanes at the end of the growing season. Few significant effects of N fertilization were measured for any crop yield, growth or N accumulation parameter. This was attributed to the large (>150 kg N ha−1) supply of N to the crop in the unamended soil, primarily from soil N mineralization. Dry matter accumulation in the fruiting clusters was strongly correlated to estimated berry yield, and may provide a simple means for assessing relative yield within experiments. Soil nitrate measured in August after berry harvest may serve as a "report card" to assess N management in the current growing season, to refine fertilizer N management for subsequent growing seasons, and as an index of the risk of nitrate leaching over the following fall and winter in south coastal British Columbia. Key words: Nitrogen mineralization, nitrate leaching, manure N availability, Rubus idaeus
A two-year field study of a commercial biostimulant applied on maize as seed coating
Authors: Tweddell R. J. , Pelerin S. , Chabot R.
Published: April 2011

Under Québec agroenvironmental conditions, a 2 yr field study was conducted to evaluate the effect of the biostimulant Elorisan-MA on maize (Zea mays L.) plants subjected to different N-fertilization rates. The results show that, at any N-fertilization rate tested, the application of the Elorisan-MA seed coating did not significantly influence any maize yield parameters (grain yields, total shoot biomass and the N, P, K, Ca and Mg contents of the grains) relative to the non-treated seeds. In addition, laboratory tests show that the biostimulant did not significantly influence maize seedling growth. Key words: Biostimulants, Elorisan, maize, N-fertilization