C. G. Kowalenko
Agriculture and Agri-Food Canada, Pacific Agri-Food Research Centre, Box 1000, Agassiz, British Columbia, Canada V0M 1A0
Can. J. Plant Sci. 80: 1–10
A significant amount of research on nitrogen (N) dynamics has been conducted within the past 20 yr in south coastal British Columbia. This succinct set of data has practical and environmental information on N cycling particularly focusing on gains to and losses from agricultural fields, and transformations of soil N pools. Coastal British Columbia fields have received large annual additions by application of fertilizer and manure. Some of the manure N from animals using locally grown forages is recycled within the farm operation, but a large amount of N is imported as feed especially for intensive animal production. Budget calculations estimated that there may be substantial losses of N through volatilization from manure, particularly from housing and storage areas, and during application to fields. Some of the volatilized ammonia in holding areas may be recycled to fields via precipitation. Direct measurements of these losses and returns of N have not been made. Studies have shown that there is limited risk of leaching of nitrate beyond the root zone during the growing season because most of the annual rainfall occurs over the winter and because nitrate can be adsorbed to soil particles. However, any extractable inorganic N (nitrate directly and ammonium after nitrification) in the profile at the end of the growing season will be lost over the winter. Most of that loss is due to nitrate leaching, but conditions are also favorable for denitrification. There is considerable (>200 mg N k–1 in some soils) ammonium-N fixed in Fraser Valley soils, but the impact of this phenomenon to crop growth is still poorly understood. Wetting and drying cycles have a great influence on the dynamics of this pool of soil N. The response of spring growth of grass to the time of N application was influenced by the relative competitiveness of microorganisms and plants for available soil N. A study comparing short-season (broccoli) and long-season (sweet corn) crop responses to N applications showed that the rate at which the plants require N influences their response to N amendments. Raspberries were found to require relatively small quantities of N on a land area basis because of the wide inter-row distances. An autumn soil nitrate test has been proposed for making fertilizer N recommendations for raspberries. Although knowledge gained from this research has provided a basis for interpreting studies for the development of N management practicesand for making interim recommendations, a method to predict the amount of N mineralized from soil organic matter is key to the development of soil-analysis-based N rate recommendations.
Key words: N cycling, nitrate, ammonium, fixed ammonium, soil organic N, mineralization
Nitrogen utilization by forage grasses
G. Bélanger1 and F. Gastal2
1Soils and Crops Research and Development Centre, Agriculture and Agri-Food Canada, 2560 Hochelaga Boulevard, Sainte-Foy, Québec G1V 2J3, Canada; 2Station d’écophysiologie des plantes fourragères, Institut National de la Recherche Agronomique, 86600, Lusignan, France
Can. J. Plant Sci. 80: 11–20
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
Nitrogen cycling in silvopastoral systems in the Pacific Northwest: A review
D. J. Thompson1, R. F. Newman2, G. Hope2, K. Broersma1, and D. A. Quinton1
1Agriculture and Agri-Food Canada, Kamloops, British Columbia, Canada V2B 8A9; and 2British Columbia Ministry of Forests, Kamloops, British Columbia, Canada V2B 8A9
Can. J. Plant Sci. 80: 21–28
Clearcuts in interior British Columbia are often aerially seeded with domestic forages such as orchardgrass and alsike clover to prevent erosion and help control understorey vegetation during establishment of lodgepole pine plantations. These seeded clearcuts provide valuable mid-summer range for cattle and with careful management there is little damage to planted trees. There is growing concern about N losses due to clearcutting and site preparation and what effect these might have on long-term forest productivity. The literature indicates that without cattle or forage seeding natural N inputs from the atmosphere and N fixation are barely sufficient to provide adequate nutrition for a lodgepole pine stand. This literature review addresses what effect introducing domestic forages and cattle grazing can have on N cycling on clearcuts. Forage seeding alone may reduce N losses due to runoff and leaching and legumes can fix atmospheric N, but grazing by cattle can counteract some of these benefits. Estimates of N losses due to cattle grazing were calculated using summary data from a long-term grazing trial conducted in interior British Columbia where experimental pastures were either aerially seeded with clover-orchardgrass mixtures or left unseeded. Using forage yields, cattle gains, and a number of assumptions, N losses due to cattle grazing on the seeded pastures were calculated as 2.4 kg N ha–1 yr–1 compared with 0.8 kg N ha–1 yr–1 on native vegetation. Losses were from N in new cattle tissue and N volatilized from urine as ammonia. Increased losses due to grazing seeded forages were short-lived as the forage production of seeded pastures was equal to that of native vegetation by the seventh year. During this period, the losses due to grazing seeded forages may be balanced by increased capture of labile N by the forages.
Key words: N cycling, seeded clearcuts, cattle grazing.
Plant mineral accumulation, use and transport during the life cycle of plants: A review
A. Liptay and A.E. Arevalo
Agriculture and Agri-Food Canada. Greenhouse and Processing Crops Research Centre, 2585 Rd. 20, Harrow, Ontario, Canada N0R 1G0
Can. J. Plant Sci. 80: 29–38
Minerals accumulated during each stage of plant development are important, especially for the initial portion of subsequent stages of growth. For example, minerals acquired during seed ontogeny are largely responsible for the earliest stage of seedling growth. Without these minerals, seedling development would be arrested or impossible. Thus, even though the amount of minerals may be relatively small in the seed, their presence is absolutely essential. Similarly, although the mineral nutrient content of a seedling used as a transplant in establishing a crop in the field may seem rather minuscule, the importance to the initiation of development of the successive stage of growth is critical. Moreover, seedling-mineral content, plant performance and seed production can be improved by the selection of optimal cultural practices. This review examines acquisition, content and use of minerals in the various stages of plant development and growth as well as agricultural approaches to enhance mineral accumulation.
Key words: Nutrient uptake, field crop establishment, seed mineral content, seed yield, crop growth
Recirculation of nutrients in container nursery production
Peter Purvis2, Calvin Chong2, and Glen P. Lumis3
Department of Plant Agriculture, University of Guelph Division: 2Horticultural Research Institute of Ontario, Vineland Station, Ontario, Canada L0R 2E0 and 3Horticultural Science, Guelph, Ontario, Canada N1G 2W1
Can. J. Plant Sci. 80: 39–45
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
Arbuscular mycorrhizae and the phosphorus nutrition of maize: A review of Guelph studies
Murray H. Miller
Department of Land Resource Science, University of Guelph, Guelph, Ontario, Canada N1G 2W1
Can. J. Plant Sci. 80: 47–52
The role of mycorrhizae in phosphorus nutrition of maize (Zea mays L.) is related to the fact that the P concentration in maize shoots at the four- to five-leaf stage affects final grain yield.
In the early 1980s we observed greater early-season shoot-P concentration (mg g–1) and P absorption (mg plant–1) from a no-till compared to a conventional tillage system. Further studies established that the greater P absorption is due to a more effective arbuscular mycorrhizal (AM) symbiosis when the soil is not disturbed. The greater P absorption is largely a result of the undisrupted mycelium present in an undisturbed soil, rather than to increased colonization. This mycelium retains viability through extended periods in frozen soil. In the spring this mycelia network is able to acquire P from the soil and deliver it to the plant immediately upon becoming connected to a newly developing root system. Increased P absorption has not resulted in increased grain yield in field trials. Some additional factor limits yield with no-till maize preventing the advantage of early P absorption from being realized as yield. When maize follows a non-mycorrhizal crop such as canola (Brassica napus L.), mycorrhizal colonization is delayed, reducing early-season P absorption. Yield reductions may occur.
In summary, AM mycorrhizae are involved in P nutrition of maize and an understanding of their functioning will assist us in modifying management practices to maximize economic returns through increased fertilizer efficiency.
Key words: Maize, arbuscular mycorrhizae, phosphorus nutrition, tillage, canola
The inheritance of stem rust resistance in Thatcher wheat
D. R. Knott
Department of Plant Sciences, University of Saskatchewan, Saskatoon Saskatchewan, Canada S7N 5A8
Can. J. Plant Sci. 80: 53–63
Thatcher was the predominant wheat (Triticum aestivum L.) cultivar on the Canadian prairies in the 1950s. Until race 15B (TMH) of stem rust (Puccinia graminis pers. f. sp. tritici Eriks. & Henn.) became widespread, Thatcher had good resistance to stem rust, but was susceptible to leaf rust (P. recondita f. sp. tritici Rob. ex Desm.). Although genes for stem rust resistance have been identified in Thatcher, the inheritance of its resistance has never been fully understood. The objective of this research was to attempt to elucidate the inheritance of the resistance of Thatcher and to determine why it had a reputation as a poor parent for rust resistance. Over a period of 40 yr, crosses and backcrosses to a susceptible genotype and two sets of single seed descent (SSD) lines were studied. The second set of SSD lines was tested with isolates of six races of stem rust to which Thatcher is resistant. The data showed that Thatcher is a very heterogenous cultivar with individual plants differing widely in the genes for stem rust resistance that they carry. The inheritance of rust resistance varied greatly from race to race and was often quite complex. Either complementary genes or a gene plus a suppressor appeared to condition resistance to one race. Most genes gave resistance to only one race. The presence of Sr5, which Thatcher is known to have obtained from Kanred, was confirmed. Most of its many additional genes probably came from Iumillo durum wheat.
Key words: Stem rust, Thatcher wheat, single seed descent
Farm-level profitability analysis of alternative tillage systems on clay soils
Emmanuel K. Yiridoe1, Tony J. Vyn2, Alfons Weersink3, David C. Hooker4, and Clarence Swanton5
1Department of Economics and Business Management, Nova Scotia Agricultural College, P.O. Box 550, Truro, Nova Scotia, Canada B2N 5E3 (e-mail e.yiridoe@nsac.ns.ca); 2Department of Agronomy, Purdue University, West Lafayette, IN, 47907-1150, USA; 3Department of Agricultural Economics and Business, University of Guelph, Guelph, Ontario, Canada N1G 2W1; 4Ridgetown College Campus, University of Guelph, Ridgetown, Ontario, Canada N0P 2C0; and 5Department of Plant Agriculture, University of Guelph, Guelph, Ontario, Canada N1G 2W1
Can. J. Plant Sci. 80: 65–73
Crop yields, production costs, and net returns for seven alternative conservation tillage (including five reduced tillage and two no-till) treatments were compared with a conventional tillage (CT) treatment for a corn (Zea mays L.) – soybean (Glycine max L. Merr) rotation for two clay soils in southwestern Ontario. There was no significant difference in corn and soybean yields between the CT and the conservation tillage systems at either location, although actual yields tended to be highest for CT management. Tillage treatments that used a common set of machinery for corn and soybean production generated savings in annual machinery costs. Variable costs were lowest for the reduced-tillage treatments and highest for the two no-till treatments due to higher equipment expenditures and additional herbicide requirements. For a given location, there was often no significant difference in net returns between CT and the conservation tillage treatments, although average net returns for the corn–soybean cropping systems tended to be highest for CT and lowest for no-till.
Key words: Net returns analysis, conservation tillage systems, clay soils, corn, soybeans
Utilization of doubled haploid technique in Brassica rapa population improvement
H. Friesen and R. Scarth
Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2
Can. J. Plant Sci. 80: 75–82
The utilization of doubled haploid (DH) plants in population improvement of Brassica rapa was studied by randomly intercrossing 4, 8, 12 and 22 DH lines developed from the B. rapa cultivar Reward and the B. rapa breeding line DSC-3 for two generations to constitute synthetic populations. The synthetic populations and the DH plants used in their formation were evaluated for agronomic performance at two locations in the field in 1996 and for genetic variation using random amplified polymorphic DNA (RAPD) analysis. Intercrossing as few as four DH lines from the breeding line DSC-3 produced a synthetic population with improved performance over that of the contributing DH lines. The synthetic population produced from the interpollination of eight DH lines showed an agronomic performance over that of the contributing DH lines to a level similar to the Reward donor population. RAPD analysis efficiently characterized the genotypic variation present in DH lines and synthetic populations, detecting 22–72% polymorphism between DH lines, 17–53% and 27–47% polymorphism in the first and second synthetic populations, respectively. This characterization may be useful as a tool in the reestablishment of heterogeneity and recovery of agronomic performance in B. rapa synthetic populations derived from DH lines by determining the level of genetic variability among DH lines and therefore optimal population size.
Key words: Brassica rapa, synthetic population, doubled haploids, RAPD, agronomic performance
Effect of varying seeding date on crop development, yield and yield components in canaryseed
Perry R. Miller1
1Department of Land Resources and Environmental Sciences, Montana State University, P.O. Box 173120, Bozeman, MT 59717-3120
Can. J. Plant Sci. 80: 83–86
The effects of varying seeding date on crop development, yield and yield components in canaryseed (Phalaris canariensis L.) have not been previously reported. In 1996 and 1997, a seeding date study was conducted at Swift Current, SK, which included barley (Hordeum vulgare L.), canaryseed and wheat (Triticum aestivum L.) sown at three dates in separate tilled fallow and untilled wheat stubble sites. Terminal summer drought occurred in both years of this experiment. Cumulative degree days (DD0) to reach maturity did not differ significantly among seeding dates for barley, or for wheat in 1997, while cumulative degree days to reach maturity decreased by 60 DD0 with delayed seeding for wheat in 1996. In contrast, cumulative degree days to reach maturity in canaryseed increased by 70 DD0 in 1996 and by 90 DD0 in 1997 with delayed seeding. Delaying seeding from the early to the late date decreased canaryseed yield by 29%, while barley and wheat yields decreased only 14 and 11%, respectively. Panicle density in canaryseed was reduced 24% between the early and late seeding dates, while barley and wheat spike densities were reduced only 2 and 6%, respectively. The large yield reduction in canaryseed was likely due to slowed crop development with delayed seeding, which intensified late-season drought stress. The slowed crop development with delay in seeding date in canaryseed may be due to vernalization requirement in this crop. In the semiarid prairie region, canaryseed should be seeded early to maintain a rapid crop development rate to minimize yield loss due to drought stress.
Key words: Canaryseed, Phalaris canariensis L., seeding date, drought stress
Distribution of carbohydrate during grainfill in Leafy and normal maize hybrids
C. J. Andrews1, L. M. Dwyer1, D. W. Stewart1, J.-A. Dugas2, and P. Bonn1
1Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, Central Experimental Farm, Ottawa Ontario K1A 0C6; and 2Glenn Seed Ltd., Blenheim Ontario N0P 1A0, Canada
Can. J. Plant Sci. 80: 87–95
The Leafy (Lfy) genotype in corn has extra leaves above the ear in comparison to normal non-leafy genotypes and has been shown to increase yields in some geographical areas. In this study, carbohydrate distribution in three Lfy hybrids (two of which were "staygreen") and a normal check (Pioneer 3790) were analyzed in a short-season area (2800 Crop Heat Units, suitable for 85 day Relative Maturity hybrids). Total sugar and starch were determined at all aboveground levels of leaf and stem on 1 August 1990 and this distribution was used to calculate total canopy carbohydrates in two subsequent years from samplings of leaf and stem at only three or four canopy levels bracketing the ear level. Husk, cob and kernel components were also analyzed at three sampling times during grainfill. Major differences in the 2 yr were observed, but in general there was approximately twice the carbohydrate in the canopy at and above the ear in the Lfy genotypes compared to the check. There was also more carbohydrate in the husk and cob in the Lfy lines, but substantially less carbohydrate below the ear in these lines. Rates of grainfill were generally higher in the Lfy hybrids, but the rate of Lfy hybrid A, the early senescent hybrid, was slower in the cooler growing season. Despite the greater amount of carbohydrate in the Lfy hybrids in comparison to the traditional check, their grain yields were not greatly increased, indicating that the kernel component provided a weak sink. This characteristic is probably associated with the long season and tropical origin of the Lfy germplasm.
Key words: Maize, grainfill, leafy, carbohydrate distribution, phenology, sink size
A method to characterize root morphology traits in alfalfa
J. F. S. Lamb1, L. D. Johnson2, D. K. Barnes1, and J. J. Marquez-Ortiz3
1USDA-ARS in Department of Agronomy and Plant Genetics, University of Minnesota, 411 Borlaug Hall, 1991 Upper Buford Circle, St. Paul, MN 55108, USA; 2Cal/West Seeds, P.O. Box 1428, Woodland, CA 95776, USA; and 37206 Couser, Overland Park, KS 66204, USA
Can. J. Plant Sci. 80: 97–104
Productivity in alfalfa (Medicago sativa L.) has been shown to be influenced by root morphology. Our objectives were to identify the optimum age, cultural practices, and environmental conditions to characterize taproot diameter (TD), lateral root number (LRN), fibrous root mass (FRM), and determinate taproot percentage (DTP) in alfalfa. No correlations were found between greenhouse-cultured plants and 21-wk-old field-grown plants for LRN or FRM, while TD showed low to moderate correlations between greenhouse and field environments. Fourfold more plants with determinate taproots were identified in transplanted plots compared to seeded plots. All root traits were affected by plant spacing but, no germplasm × plant spacing interactions were found. Solid seeded plants needed more time to show maximum expression of root traits and scored lower for LRN and FRM and had smaller TD than spaced plants. Only TD had a significant germplasm × location interaction. Both TD and LRN increased with N fertilizer and between the seeding and first production years, but no germplasm × N rate or germplasm × year interactions were found. Rankings of alfalfa germplasms were the same at the end of the seeding year (22 wk after planting) and at the end of the first production year (74 wk after planting). Characterization of LRN and FRM in alfalfa should be conducted in seeded field plots with uniform plant spacing at one location, with or without N fertilizer at least 22 wk after planting. A similar protocol with evaluation at more than one location would be more appropriate for characterization of TD.
Key words: Medicago sativa L., root morphology, alfalfa
Effectiveness of elemental S fertilizers on forage grass
S. S. Malhi1, K. Heier1, and E. Solberg2
1Agriculture and Agri-Food Canada, Research Farm, P. O. Box 1240, Melfort, Saskatchewan, Canada SOE 1A0; and 2Agronomy Unit, Alberta Agriculture, Food and Rural Development, 6903 – 116 Street, Edmonton, Alberta, Canada T6H 4P2
Can. J. Plant Sci. 80: 105–112
Two field experiments were conducted from 1993 to 1995 to compare the effectiveness of various cumulative elemental S and sulphate-S fertilizer applications in increasing dry matter yield (DMY) and S uptake of forage grass. In exp. 1, one sulphate-S (Na2SO4) and two elemental S (Agric-Grade 0-0-0-95 and Tiger 90) fertilizers were applied annually to grass in mid- to late April at 10, 20, 30, 40 and 50 kg S ha–1 rates. The increase in DMY from S application was significantly lower with elemental S fertilizers than with Na2SO4 in the first and second years, but in the third year elemental S fertilizers had DMY increase similar to Na2SO4. In exp. 2, a number of elemental S and sulphate-S fertilizers were applied annually to grass in mid- to late April at 15 kg S ha–1 rate. There was a marked increase in DMY from S application in all the 3 yr with the three sulphate-containing S fertilizers (Na2SO4, K2SO4 and CaSO4). When elemental S fertilizers were used, only Turf-Grade 0-0-0-95 increased DMY in all the 3 yr and it produced DMY increase similar to the sulphate-S fertilizers in the third year. Elemental S Prills did not produce any significant increase in DMY in any of the 3 yr. Other elemental S fertilizers [e.g., Elemental S Powder, Agric-Grade 0-0-0-95 and Tiger 90] increased DMY in the third year only, but this increase was still less than the sulfate-S fertilizers. Turf-Grade 0-0-0-95 (with smaller granules) produced greater DMY increase than Agric-Grade 0-0-0-95 (with larger granules) in all the 3 yr (though significant in the third year only). The S fertilizers that contained small amounts of sulphate-S in addition to elemental S were generally more effective in increasing DMY than the similar fertilizers containing only elemental S. The increase in S uptake from applied S in grass showed usually similar trends as DMY increase. In conclusion, the results suggest that some elemental S fertilizers can be as effective in increasing forage DMY on perennial grass as sulfate-S fertilizers. However, depending upon soil type and climatic conditions two or more growing seasons may be needed for S in the elemental S fertilizers to become fully available to the plants.
Key words: Elemental S fertilizers, forage yield, grassland, sulphate-S fertilizers, sulphur uptake
K. M. Ho1, W. L. Seaman1, T. M. Choo1, R. A. Martin2, J. Rowsell3, L. Guillemette4, Y. Dion5, and S. Rioux5
1Eastern Cereal and Oilseed Research Centre, Research Branch, Agriculture and Agri-Food Canada, Ottawa, Ontario, Canada K1A 0C6; 2Crops and Livestock Research Centre, Agriculture and Agri-Food Canada, Charlottetown, Prince Edward Island, Canada C1A 7M8; 3New Liskeard Agricultural Research Station, New Liskeard, Ontario, Canada P0J 1P0; 4Kapuskasing Experimental Farm, Agriculture and Agri-Food Canada, Kapuskasing, Ontario, Canada P5N 2Y3; 5Centre de recherche sur les grains inc., Saint-Bruno-de Montarville, Quebec, Canada J3V 4P6
Can. J. Plant Sci. 80: 113–115
AC Legend is a six-rowed spring feed barley (Hordeum vulgare L.) cultivar bred at the Eastern Cereal and Oilseed Research Centre, Agriculture and Agri-Food Canada, and evaluated by the Easter Canada Barley Breeding Group. It was selected from a Chapais/CIMMYT-6 cross and is suitable for growing in eastern Canada, where it outyielded the check cultivars AC Stephen, Chapais, Myriam, ACCA and AC Westech. AC Legend is resistant to scald.
Key words: Hordeum vulgare L., six-rowed barley, feed barley, high yield, scald resistance
Tom Warkentin1, Allen Xue1, Al Sloan1, Khalid Rashid1, S.T. Ali-Khan2, Cecil Vera3, Denise Orr4, Kelly Turkington4, George Clayton4, and Gerald Loeppky5
1Agriculture and Agri-Food Canada, Morden Research Centre, Unit 100-101, Route 100, Morden, Manitoba, Canada R6M 1Y5; 2Agriculture and Agri-Food Canada, Fredericton Research Centre, Fredericton, New Brunswick, Canada E3B 4Z7; 3Agriculture and Agri-Food Canada, Melfort Research Farm, P.O. Box 1240, Melfort, Saskatchewan, Canada S0E 1A0; 4Agriculture and Agri-Food Canada, Lacombe Research Centre, Lacombe, Alberta, Canada T4L 1W1; 5Manitoba Crop Diversification Centre, 370 River Road, Portage la Prairie, Manitoba, Canada R1N 3V6
Can. J. Plant Sci. 80: 117–119
AC Melfort, a yellow cotyledon field pea (Pisum sativum L.) cultivar was released in 1998 by Agriculture and Agri-Food Canada, Morden Research Centre, Morden, Manitoba. AC Melfort has a semi-leafless leaf type, powdery mildew resistance, medium-large round seeds and good yielding ability, particularly in the warmer, drier zone of the prairies.
Key words: Field pea, Pisum sativum L., cultivar description, powdery mildew resistance
Hans-Henning Mündel1, Gilles Saindon2, Henry C. Huang1, and Ferdinand A. Kiehn3
1Agriculture and Agri-Food Canada, Lethbridge Research Centre, PO Box 3000, Lethbridge, Alberta, Canada, T1J 4B1 (e-mail: muendel@em.agr.ca); 2Agriculture and Agri-Food Canada, Potato Research Centre, PO Box 20280, Fredericton, New Brunswick, Canada, E3B 4Z7; 3Agriculture and Agri-Food Canada, Research Centre, Unit 100-101 Route 100, Morden, Manitoba, Canada R6M 1Y5
Can. J. Plant Sci. 80: 121–122
AC Redbond is a high-yielding, early-maturing, small red dry bean (Phaseolus vulgaris L.) cultivar with moderate resistance to white mold. It was developed from a series of crosses at the Agriculture and Agri-Food Canada Research Centre, Lethbridge, with cooperation from the Agriculture and Agri-Food Canada Research Centre Morden. AC Redbond, having an upright growth habit with moderate resistance to white mold, is particularly well adapted to the western Canadian prairies using the narrow-row production system, maturing on average 3 d before NW 63, with 10% higher seed yield.
Key words: Phaseolus vulgaris, small red bean, cultivar description, high yield, narrow row
AC Abbey hard red spring wheat
R. M. DePauw, J. M. Clarke, R. E. Knox, M. R. Fernandez, T. N. McCaig, and J. G. McLeod
Semiarid Prairie Agricultural Research Centre, Agriculture and Agri-Food Canada, P.O. Box 1030, Swift Current, Saskatchewan, Canada S9H 3X2
Can. J. Plant Sci. 80: 123–127
AC Abbey, hard red spring wheat (Triticum aestivum L.), is adapted to the Canadian prairies. It is significantly shorter than any of the check cultivars and has solid stems. AC Abbey expressed higher grain yield, earlier maturity, and heavier kernels than AC Eatonia, the solidstem check cultivar. It is resistant to the wheat stem sawfly (Cephus cinctus Nort.) and to prevalent races of common bunt and has moderate resistance to leaf rust and stem rust. AC Abbey is eligible for grades of Canada Western Red Spring wheat.
Key words: Triticum aestivum L., red spring wheat, yield, wheat stem sawfly, plant height, maturity
Analyse de l’étalement temporel de la floraison et influence sur la variabilité intra-arbre de la chute et de la croissance précoce des pêches
Françoise Lescourret, O. Inizan, and M. Génard
Unité de Recherches en Ecophysiologie et Horticulture, INRA, Domaine Saint Paul, site Agroparc, 84914 Avignon cedex 9, France
Can. J. Plant Sci. 80: 129–136
L’objectif de notre travail est d’expliquer la variabilité intra-arbre de la chute et de la croissance précoce des pêches. Nous avons supposé que l’étalement temporel de la floraison était un indicateur des compétitions pour les assimilats, présumés déterminants pour la tenue et la croissance, et que les fruits issus des fleurs précoces devaient être avantagés. C’est pourquoi nous avons effectué une description de l’étalement de la floraison chez le pêcher et répertorié les facteurs pouvant l’expliquer. Les principaux résultats indiquent que les fleurs du bas de l’arbre s’ouvrent avant celles des niveaux supérieurs, que les fleurs de l’extrémité du rameau sont plus précoces que celles de la base, et que les fleurs seules s’ouvrent 1 jour en moyenne avant les fleurs associées, ces dernières étant indépendantes pour l’anthèse. La variabilité de la chute et de la croissance précoce n’est pas expliquée par l’étalement de la floraison dans le sens prévu par notre hypothèse; en particulier, ce sont les fruits issus des fleurs les plus tardives qui sont avantagés pour leur tenue. Ceci nous a amenés à considérer l’effet des températures consécutives à la floraison. Nous suggérons qu’elles puissent être impliquées dans la tenue, voire dans la croissance précoce des fruits.
Mots clés: Pêche, Prunus persica, floraison, chute des fruits, croissance des fruits, stade précoce du développement
Phenotypic diversity in four woody species on the Canadian prairies
M. A. Chowdhury1, S. Jana1, and W. R. Schroeder2
1Department of Plant Sciences, University of Saskatchewan, 51 Campus Drive, Saskatoon, Saskatchewan, Canada S7N 5A8; 2PFRA Shelterbelt Centre, P.O. Box. 946, Indian Head, Saskatchewan, Canada S0G 2K0
Can. J. Plant Sci. 80: 137–142
Genetic diversity is a prerequisite for plant adaptation and maintenance of a sustainable ecosystem. Not much information is available on the genetic diversity of woody species on the semi-arid Canadian prairies. We used RAPD fragments to assess the diversity of four woody species of the Elaeagnaceae family, sea buckthorn (Hippophae rhamnoides L.), Russian olive (Elaeagnus angustifolia L.), buffaloberry (Shepherdia argentea Nutt.) and silverberry (Elaeagnus commutata Bernh. Ex Rydb.) collected from several locations in southwestern Saskatchewan. The RAPD fragments were used to generate molecular data for this experiment. Of the total scorable RAPD fragments, 86, 80, 55.2, and 36.5% were polymorphic in sea buckthorn, buffaloberry, silverberry and Russian olive, respectively. Estimates of phenotypic diversity by AMOVA and Shanon’s information index revealed that buffaloberry and sea buckthorn had relatively high phenotypic diversity and Russian olive had low phenotypic diversity.
Key words: Sea buckthorn, silverberry, buffaloberry, Russian olive, RAPD, phenotypic diversity
Effects of day and night air temperature on growth, productivity and energy use of long English cucumber
Athanasios P. Papadopoulos and Xiuming Hao
Agriculture and Agri-Food Canada, Greenhouse and Processing Crops Research Centre, Harrow, Ontario, Canada N0R 1G0
Can. J. Plant Sci. 80: 143–150
To determine the optimum air temperature regime for greenhouse seedless cucumber production under North American conditions, the cvs. Corona (in the spring of 1990 and 1992) and Aramon (in the spring of 1992) were grown under nine day/night temperature regimes composed of a factorial combination of three day (18, 21 and 24ºC; DT) and three night (16, 18 and 20ºC; NT) heating temperatures, at a common 24ºC ventilation temperature. Plant development rates (leaf and flower number) were linearly increased with increasing daily average air temperature (MT), but not affected by day–night air temperature difference (DIF), indicating that plant development rates increased with increasing air temperature regardless of DT or NT. Specific leaf weight decreased with increasing DT or NT, and leaf photosynthesis rates decreased with increasing DT. Therefore, high DT or NT promoted the growth rates of young cucumber plants mainly through increasing leaf area ratios. Early and final yields of Corona were mainly affected by MT, not by DIF, while early and final yields of Aramon were mainly increased by DIF. Fruit size increased with increasing MT. Optimum MT for Corona fruit production was 19ºC heating temperature, at a 24ºC ventilation temperature. Optimum day/night air temperature regime for Aramon fruit production was at 21/16ºC day/night heating temperature, at a 24ºC ventilation temperature.
Key words: Cucumis sativus, growth, yield, fruit size, daily average air temperature, day-night air temperature difference
Physiological mechanism of tolerance of Lycopersicon spp. exposed to salt stress
Lada R. Rajasekaran1,2 D. Aspinall1, and L. G. Paleg1
1Department of Horticulture, Viticulture, Oenology, Waite Agricultural Research Inst., The University of Adelaide, Glen Osmond, South Australia 5064; 2Department of Plant Science, Nova Scotia Agricultural College, P.O. Box No. 550, Truro, Nova Scotia, Canada B2N 5E3
Can J. Plant Sci. 80: 151–157
The physiological mechanism of salt tolerance in Lycopersicon spp. was investigated. Ten Lycopersicon spp. were exposed to a gradual NaCl-induced decline in root zone water potential of –0.10 MPa d–1 for 10 d and maintained at –1.065MPa (221.4 mM NaCl) for a period of 20 d. Growth, water relations and accumulation of ions and compatible solutes, such as proline and the quaternary ammonium compound, trigonelline (methylated nicotinic acid), were studied and correlated. Salt tolerance, measured as growth, in selected Lycopersicon species of varying ecological habitats indicated that L. cheesmanii, native to a saline-coastal habitat, was the most tolerant and L. pennellii, the most sensitive. The commercial cultivar, L. esculentum ‘Duke’, ranked 7th in the order of relative tolerance to salt. All species accumulated proline in all organs in response to salinity; but there was no general relationship between the ability of these species to accumulate proline and their relative salt tolerance. Relative trigonelline accumulation in meristematic tissues of NaCl-stressed plants correlated with the salt tolerance of these species, however, as did their ability to (1) maintain turgor in the expanding leaves, (2) exclude Na+ from the expanded leaves and (3) exclude Cl– from the root tissues.
Key words: Chloride accumulation index, Lycopersicon spp., proline accumulation index, salt tolerance index, sodium accumulation index, trigonelline accumulation index, water potential
Effect of subsoil tillage in the previous crop year on soil loosening and potato yield performance
D. A. Holmstrom and M. R. Carter
Agriculture and Agri- Food Canada, Research Branch, Crops and Livestock Research Centre, P.O. Box 1210, Charlottown, Prince Edward Island, Canada C1A 7M8
Can. J. Plant Sci. 80: 161–164
Soil compaction under potato rotations can be a common problem in Prince Edward Island. This can be further aggravated by naturally occurring compact subsoils. A study was conducted at eight sites on sandy loam soils in three regions of Prince Edward Island to determine whether the recommended practice of subsoiling the fall prior to the potato crop would improve the physical condition of the soil and result in improved yields. The study found that subsoiling provided only a marginal improvement in soil physical conditions. Soil loosening did not increase potato yield or quality.
Key words: Potato, subsoiling, yield response, potato quality
H. M. Haji, S. Mishra, and M. Devos
Canadian Tobacco Research Foundation, Box 186, Delhi, Ontario, Canada N4B 2W9
Can. J. Plant Sci. 80: 165–166
CT166 is a flue-cured tobacco (Nicotiana tabacum L.) cultivar with high yield, and matures earlier than the standard checks. Percent alkaloids in CT166 is significantly lower than the checks. Lower alkaloids is a desirable quality characteristic.
Key words: Nicotiana tabacum L., tobacco, cultivar description
H. M. Haji, S. Mishra, and M. Devos
Canadian Tobacco Research Foundation, Box 186, Delhi, Ontario, Canada N4B 2W9
Can. J. Plant Sci. 80: 167–168
CT681 is a flue-cured tobacco (Nicotiana tabacum L.) cultivar with high yield and grade index, and provides significantly higher economic returns to growers. Company evaluations are higher than the checks, and percent lamina is high. CT681 is resistant to black root rot [Thielaviopsis basicola (Berk. & Broome) Ferraris] disease.
Key words: Nicotiana tabacum L., tobacco, cultivar description
Managing crop losses from foliar diseases with fungicides, rotation, and tillage in the Saskatchewan Parkland
K. L. Bailey1, A. M. Johnston2, H. R. Kutcher2, B. D. Gossen1, and R. A. A. Morrall3
1Agriculture and Agri-Food Canada, 107 Science Place, Saskatoon, Saskatchewan, Canada S7N 0X2; 2Agriculture and Agri-Food Canada, P.O. Box 1240, Melfort, Saskatchewan, Canada S0E 1A0; 3Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, Saskatchewan, Canada S7N 5E2
Can. J. Plant Sci. 80: 169–175
The effects of three tillage systems, three crop rotations, and fungicide applications were evaluated on diseases of barley, wheat, canola and pea at Melfort, SK, from 1994 to 1998. During these years, reduced tillage did not increase crop losses due to diseases. Four-year rotations with higher proportions of broad-leaved crops and more crop diversity (i.e., canola, pea, flax, and barley) had higher yields than rotations with fewer broad-leaved crops and less crop diversity (i.e., canola, wheat, barley, and barley). However, these rotations did not influence the severity of septoria leaf blotch of wheat, net blotch of barley, the incidence of sclerotinia stem rot and blackleg of canola, or the severity of mycosphaerella blight of pea. Interplot interference may have been a factor influencing some diseases in plots, as the size was only 270 m2. Fungicide application of propiconazole on Harrington barley decreased foliar disease severity and increased yield by 23%, seed weight by 13%, and kernel plumpness by 25%. Application of azoxystrobin decreased foliar disease and increased pea yield 29% and seed weight by 7% for the pea cultivars Express and Highlight. Foliar disease severity on AC Taber wheat was reduced by application of propiconazole in 2 of 4 yr, but the yield response was very inconsistent. Similarly, AC Excel canola had inconsistent disease and yield response to applications of propiconazole and benomyl, but levels of sclerotinia stem rot and blackleg were very low in all years. These results indicate that reduced tillage will not result in significantly higher levels of disease that require fungicide inputs to maintain yield. Moving from cereal-based rotations to more diverse, broad-leaved based rotations improves the yield of cereals. However, regardless of tillage or rotation, higher yields may be obtained in barley and pea with fungicides for control of leaf spot disease in susceptible cultivars.
Key words: Plant disease, rotation, tillage, fungicides, yield loss
Weed communities associated with arable Saskatchewan farm management systems
J. Y. Leeson1, J. W. Sheard2, and A. G. Thomas1
1Agriculture and Agri-Food Canada, Saskatoon Research Centre, 107 Science Place, Saskatoon, Saskatchewan, Canada S7N 0X2; 2Department of Biology, University of Saskatchewan, 112 Science Place, Saskatoon, Saskatchewan, Canada S7N 5E2
Can. J. Plant Sci. 80: 177–185
The objective of this study was to determine the impact of a range of management systems on weed communities in cropped fields on farms in Saskatchewan. Farms (n = 28) with management systems defined by a combination of different cropping histories and chemical input levels were selected. Fields were surveyed on each farm in 1995, 1996, and 1997 after any post-emergent weed control to ensure that their weed communities reflected the impact of all agronomic management practices typical of the management system. Canonical correspondence analysis was used to determine whether weed communities were significantly correlated with management system after removal of variance due to ecoregion and year. The largest difference in weed communities attributable to farming system was between the systems with annual cropping histories and those that included perennials in the cropping history. Thus, the life history of the weeds reflected the life history of the crops. Herbicide use was correlated with the next largest difference between systems. A significant association between weed communities and different management systems indicates that weed species are being selected for by these systems. If such selection pressure continues, these species may become a threat to the system’s sustainability.
Key words: Weed communities, chemical input level, cropping history, canonical correspondence analysis, correspondence analysis, farming system
Influence of annual forages on weed dynamics in a cropping system
Allison Schoofs and Martin H. Entz
Department of Plant Science, University of Manitoba, Winnipeg, Manitoba, Canada, R3T 2N2
Can. J. Plant Sci. 80: 187–198
Alternatives to herbicides are needed for weed control. Field studies were conducted in 1994/1995 and 1995/1996 to investigate the nature of forage crop-weed dynamics and to test the effect of single year forage crops on the density and community composition of annual weeds in a following field pea (Pisium sativum L.) test crop. Five spring-seeded forage treatments were compared with wheat (Triticum aestivum L.) grain crops (with or without herbicides for grassy and broadleaved weeds): winter triticale (Triticosecale) (simulation grazed); spring triticale (silage); spring/winter triticale intercrop (silage, then simulation grazed); alfalfa (Medicago sativa L.) (hay); sorghum-sudangrass (Sorghum bicolor [L.] Moench × Sorghum sudanese [Piper]) (hay); and a weedy fallow (silage). A fall rye (Secale cereale L.) grain crop and a sweet clover (Melilotis officinalis L.)/winter triticale double crop (hay, then simulation grazing) were included in the 1995/1996 trial. All forage systems were at least as effective as the sprayed wheat control in suppressing wild oat (Avena fatua L.); however, effects on other weeds, especially broadleaved species, were variable. Biennial crops provided the best early season weed control, while long-season systems such winter triticale and the triticale intercrop provided the best late season weed control. Forages shifted the weed community composition away from wild oat and green foxtail (Setaria viridis L. Beauv.) to a similar or greater extent than herbicide-treated wheat. Forage systems that did not provide season-long crop competition tended to have more broadleaved weeds. Some forage systems increased pea grain yield the following year (relative to the sprayed wheat control); however, forages alone did not eliminate the need for herbicides in the pea crop. Annual forages may play an important role in integrated weed management, especially for wild oat, however further research to refine forage-based weed management systems is needed.
Key words: Integrated weed management, alfalfa, intercropping, double cropping, organic farming
Breeding summer turnip rape for resistance to brown girdling root rot
D. L.Woods1, T. K.Turkington2, D. McLaren3, and J. G. N.Davidson4
1Beaverlodge Research Farm, Box 29, Beaverlodge, Alberta, Canada T0H 0C0; 2Lacombe/Beaverlodge Research Centre, 6000 C&E Trail, Lacombe, Alberta, Canada T4L 1W1; 3Brandon Research Station, PO Box 1000A, RR#3, Brandon, Manitoba, Canada R7A 5Y3; 4Box 748, Beaverlodge, Alberta, Canada T0H 0C0
Can. J. Plant Sci. 80: 199–202
Screening of 260 Brassica rapa lines resulted in identification of five lines with partial resistance to brown girdling root rot (BGRR). A method for simultaneously selecting for canola quality traits and reduced disease susceptibility was developed and used to screen progeny of crosses to BGRR susceptible canola quality lines.
Key words: Turnip rape, Brassica rapa, brown girdling root rot, resistance
Six years of adaptive and on-farm spring cereal research in Newfoundland
D. Spaner1, D. B. McKenzie1, A. G. Todd1, A. Simms3, M. MacPherson2, and E. F. Woodrow1
1Atlantic Cool Climate Crop Research Centre, Agriculture and Agri-Food Canada, P.O. Box 39088 St. John’s, Newfoundland, Canada A1E 5Y7; 2Western Agriculture Centre, Government of Newfoundland and Labrador, Box 340, Pasadena, Newfoundland, Canada A0L 1K0; 3Geography Department, Memorial University of Newfoundland, St. John’s, Newfoundland A1B 3X9
Can. J. Plant Sci. 80: 205–216
Livestock farmers in Newfoundland use most available land for forages. The local production of feed grains is negligible and expensive imported feed accounts for almost one half of farm operating expenses. Here, our objectives were to develop basic agronomic principles of mechanized spring grain production and to demonstrate grain production techniques to the Newfoundland farming community. Barley seeding date trials were conducted at five environments in eastern and western Newfoundland between 1996 and 1998. The relationship between soil pH and barley grain yield was explored through grid soil and yield sampling in two large fields in both 1997 and 1998. Between 1993 and 1998 over 20 livestock farmers throughout Newfoundland cooperated with the Newfoundland Grain Project, growing and comparing varieties of barley (Hordeum vulgare L.), spring wheat (Triticum aestivum L.) and oats (Avena sativa L.) on their farms. Late seeding of barley in the spring/summer resulted in linear grain yield reductions. A levelling off of yield response did not occur at greater cumulated growing degree days, possibly because optimum accumulation for maximum barley yield potential does not occur in Newfoundland. Resistant regression lines, describing the relationship between soil pH and grain yield were developed for two barley varieties, indicated that Sterling reached a yield plateau around a soil pH 6 in 1998, while Chapais reached a yield plateau at soil pH 5.4 in 1997. Barley is well adapted to Newfoundland growing conditions, normally providing a high-yielding, mature grain of good feeding quality. Farmers collaborating with the project were generally impressed with the potential of growing barley for grain and some are now regularly doing so.
Key words: Seeding date; barley; wheat; oats; precision farming research