Including perennial forages in cropping systems is recognized as one of the best ways to enhance agricultural sustainability. While rotational benefits of forages have been established in small plot research trials, there is no documentation of whether these benefits are being observed on commercial farms, or whether producers manage forage stands to maximize rotational benefits. A survey of 253 Manitoba and Saskatchewan producers known to include forages in their crop rotations was conducted in 1992. The survey area was divided into six agroclimatic zones and correspondence analysis was used to test whether responses differed across the survey area. Sixty‐seven percent of respondents indicated a yield benefit from including forages in the crop rotation, with the greatest yield benefit observed in wetter zones of the survey area. Eighty‐three percent of the respondents observe weed control benefits for one (11% of respondents), two (50% of respondents), or more (33% of respondents) years after forages. The majority of respondents indicated that their forage acreage would not increase in the future. Average forage stand duration varied significantly (P < 0.10) with agroclimatic zone, ranging from 3 to 5 yr in wetter areas (south‐central Manitoba) to 6 to 9 yr in the driest areas (south Saskatchewan). The two most common reasons cited for forage stand termination were reduced forage yield and damage by pocket gophers (presumably Thomomys talpoides and Geomys bursarius). Less than 12% of respondents cited rotational considerations as their primary reason for terminating forage stands, indicating that producers are not managing their forage crops to maximize rotational benefits. Producers relied heavily on tillage in both forage crop establishment and forage stand termination phases of the production system. It was suggested that decreasing the amount of tillage and fallow associated with forage‐based cropping systems would not only facilitate increased cycling of forages in rotations, but also increase agricultural sustainability. Research Question Perennial forage crops are known to enhance sustainability of dryland cropping systems, hence, there is considerable interest in exploiting this traditional practice in modern agriculture. While there is considerable information on rotational benefits of forages from small plot research trials, there is no documentation of whether these rotational benefits are observed on commercial farms. Hence, the first objective was to determine whether producers perceive weed control and yield benefits from inclusion of perennial forages in their rotations, and to determine whether rotational benefits differ in the different agroclimatic zones of western Canada. The second objective was to determine whether producers' management practices are aimed at maximizing cycling of forage crops to capture rotational benefits, or whether they strive to maximize forage stand duration. Literature Summary There is a great deal of information about the benefits of including forage crops, especiall...

Brassica juncea var. juncea canola is a new oilseed species that is developed from B juncea (L.) Czern. mustard with its oil and meal quality equivalent to conventional canola species. Understanding of the phenological characteristics and yield responses to diverse environments will allow the crop to be better adapted to target production areas. This study determined the responses of the juncea canola to various soil‐climatic conditions and was compared with B napus L. canola, B rapa L. canola, juncea mustard, and Sinapis alba L. mustard. The five oilseed species/cultivars were grown under various N fertilizer rates (0, 25, 50, 100, 150, 200, and 250 kg N ha−1), at four Saskatchewan locations from 2003 to 2005. On average, flowering began 40 d after seeding (DAS) for alba mustard and rapa canola (earliest), 49 DAS for napus canola (latest), and 44 DAS for juncea canola (intermediate). Flowering duration was longest for juncea canola (30 d) and shortest for napus canola (22 d). The napus canola and juncea mustard produced higher (1684 kg ha−1) seed yields than the three other oilseeds (1303 kg ha−1 on average). For all oilseed species, the seed yield was highly responsive to N fertilizer rates from zero to about 100 kg N ha−1, and thereafter, the rate of yield responses declined. The amount of N fertilizer required to achieve the maximum seed yield was 106 kg N ha−1 for rapa canola, 135 kg N ha−1 for alba mustard and napus canola, and 162 kg N ha−1 for the two juncea spp. Overall, juncea canola had lower seed yield than more popular hybrid napus canola, and the yield stability of juncea canola was lowest among the five oilseed species when examined across diverse environments. Earlier flowering, longer flowering duration, and greater tolerance to drought stress exhibited by juncea canola make the crop best adapted to the drier areas of the northern Great Plains. The improvement of seed yield and yield stability is the key to potentially adapt this new oilseed species to a wider range of environmental conditions.

A gronomy J our n al • Volume 10 0 , I s sue 2 • 2 0 0 8 285 ABSTRACT Nitrogen accounts for the largest energy input in oilseed production. Understanding N use characteristics of oilseed crops will help improve N use effi ciency and minimize production costs. Th is study determined nitrogen use effi ciency (NUE, defi ned as seed yield produced per unit of N supply), nitrogen fertilizer use effi ciency (NFUE, defi ned as seed yield produced per unit of fertilizer N), and crop N uptake for oilseed crops under diverse environments. Five oilseed crops, namely Brassica juncea, B. napus, and B. rapa canolas, and B. juncea and Sinapis alba mustards, were grown at seven rates of N fertilizer (0, 25, 50, 100, 150, 200, and 250 kg N ha -1 ), at 11 sites (year × location combinations) in Saskatchewan from 2003 to 2005. At sites with low soil N supply or low rainfall, alba mustard, juncea canola, and rapa canola had lower NUE and NFUE than juncea mustard and napus canola.At sites with high soil N supply or rainfall, napus canola had the greatest NUE and was the most sensitive to the gradient of productivity among the fi ve oilseeds. All oilseed species responded to N fertilizer rates in a similar manner; both NUE and NFUE decreased as N fertilizer rate increased. Th e minimum NUE and NFUE were obtained with N fertilizer rate greater than 150 kg N ha -1 . At sites with low soil N supply or rainfall, alba mustard had the least NUE or NFUE response to increasing N fertilizer rates and napus canola the greatest. At sites with high soil N supply or rainfall, juncea mustard had the least NUE and NFUE response to increasing N fertilizer rates and rapa canola the greatest. On average, seed N uptake was greatest for juncea canola and juncea mustard and least for alba and rapa canola. Th e fi ve oilseed species had similar response patterns of seed N uptake to N fertilizer rates, while the magnitude of response varied among species. Improving NUE in oilseed production systems requires optimizing rates of N fertilizer which vary depending on environmental conditions, and soil N supply and rainfall during the critical growth period of the oilseed crops play an important role in aff ecting NUE.

Defatted meals and protein concentrates from six accessions of Sinapis alba and one accession of Brassica juncea mustard seeds were analysed for their polypeptide profile and functional properties. Two types of protein concentrates were prepared using acid-induced and calcium-induced protein precipitations. Meals from the S alba seeds had similar polypeptide composition, which was different from that of the B juncea meal. Non-reducing sodium dodecyl sulfate polyacrylamide gel electrophoresis showed that two of the major polypeptides (50 and 55 kDa) in S alba seeds were susceptible to acid-induced precipitation but resistant to calcium-induced precipitation. The B juncea meal proteins were significantly (p ≤ 0.05) more susceptible to heat coagulation than the S alba meal proteins. Emulsifying activity index was significantly higher (p ≤ 0.05) in the B juncea meal and protein concentrates when compared with similar products from S alba. It was concluded that the presence of a high-molecular-weight (135 kDa) disulfide-bonded polypeptide could have contributed to the lower emulsifying power of the S alba products when compared with the B juncea proteins that do not have this polypeptide.

Purpose Best agricultural practices can be adopted to increase crop productivity and lower carbon footprint of grain products. The aims of this study were to provide a quantitative estimate of the carbon footprint of selected oilseed crops grown on the semiarid northern Great Plains and to determine the effects of N fertilization and environments on the carbon footprint.Materials and methods Five oilseed crops, Brassica napus canola, Brassica rapa canola, Brassica juncea canola, B. juncea mustard, and Sinapis alba mustard, were grown under the N rates of 0, 25, 50, 100, 150, 200, and 250 kg N ha −1 at eight environsites (location × year combinations) in Saskatchewan, Canada. Straw and root decomposition and various production inputs were used to calculate greenhouse gas emissions and carbon footprints. Results and discussion Emissions from the production, transportation, storage, and delivery of N fertilizer to farm gates accounted for 42% of the total greenhouse gas emissions, and the direct and indirect emission from the application of N fertilizer in oilseed production added another 31% to the total emission. Emissions from N fertilization were nine times the emission from the use of pesticides and 11 times that of farming operations. Straw and root decomposition emitted 120 kg CO 2 eq ha −1 , contributing 10% to the total emission. Carbon footprint increased slightly as N rates increased from 0 to 50 kg N ha −1 , but as N rates increased from 50 to 250 kg N ha −1 , carbon footprint increased substantially for all five oilseed crops evaluated. Oilseeds grown at the humid Melfort site emitted 1,355 kg CO 2 eq ha −1 , 30% greater than emissions at the drier sites of Scott and Swift Current. Oilseeds grown at Melfort had their carbon footprint of 0.52 kg CO 2 eq kg −1 of oilseed, 45% greater than that at Scott (0.45 kg CO 2 eq kg −1 of oilseed), and 25% greater than that at Swift Current (0.45 kg CO 2 eq kg −1 of oilseed). Conclusions Carbon footprint of oilseeds was a function of the rate of N fertilizer, and the intensity of the functionality varied between environments. Key to lower carbon footprint in oilseeds is to improve N management practices.

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alfalfa (Medicago spp.) under continuous and rotational stocking systems in pure stands and in mixture with meadow bromegrass (Bromus riparius Rehm. syn. B. biebersteinii Roem & Schult). Can. J. Plant Sci. 82: 337-347. The continuing development of adapted alfalfa (Medicago sativa L.) cultivars that combine high yield, disease resistance, winterhardiness, and grazing tolerance is of great value to the beef cattle industry in western Canada. This study evaluated alternative management strategies and plant measurements for assessing the grazing tolerance of alfalfa cultivars over 3 yr. Seven hay-type, four pasture-type, and one dual-purpose (hay or graze) cultivars were established in pure stands and in mixture with meadow bromegrass (Bromus riparius Rehm. syn. B. biebersteinii Roem & Schult). Stands were defoliated under continuous or rotational stocking with beef cattle (Bos taurus). Plants were assessed for winterhardiness, percent alfalfa within row, percent alfalfa cover, basal area and species composition. Continuous stocking resulted in consistent and significant differences between cultivars, whether persistence was measured as percent alfalfa within row, percent cover and basal area, in both pure and mixed stands (P < 0.05). High correlations between measurement techniques (r = 0.74 to 0.99; P < 0.05) confirmed the value of alfalfa within row and alfalfa cover as time and labour efficient methods to evaluate grazing persistence. Competition between alfalfa and meadow bromegrass resulted in a significant confounding effect under rotational stocking (P < 0.05). Winter injury was identified as an important criteria to evaluate for grazing persistence. The most grazing-tolerant genotypes were selected for subsequent breeding efforts to combine winterhardiness, grazing tolerance, and high productivity. This research showed that grazing method, grass competition, and severe winter conditions strongly influence differential survival of alfalfa cultivars under grazing in western Canada.Key words: Alfalfa, grazing tolerance, grazing systems, Medicago sativa L., Medicago falcata L. Arcang, persistence Katepa-Mupondwa, F., Singh, A., Smith, S. R., Jr. et McCaughey, W. P. 2002. Tolérance de la luzerne (Medicago sp.) à la paissance dans les régimes de paissance continue et en rotation sur peuplements purs ou mixtes avec le brome des prés (Bromus riparius Rehm. syn. B. biebersteinii Roem & Schult). Can. J. Plant Sci. 82: 337-347. La création continuelle de cultivars de luzerne (Medicago sativa L.) de mieux en mieux adaptés, se caractérisant par un rendement élevé, la résistance aux maladies, la rusticité et la tolérance à la paissance, apporte beaucoup à l'élevage des bovins de boucherie dans l'ouest du Canada. L'étude devait établir l'utilité de divers systèmes de gestion et paramètres végétaux dans l'évaluation de la tolérance des cultivars à la paissance sur une période de trois ans. Les auteurs ont cultivé sept variétés de type fourrager, quatre de type à pâturer et une de type double (foin ou pâturage) en peupleme...

Sinapis alba L. is a major specialty crop grown as a condiment in western Canada, but little is known about its genetic diversity. The objective of this study was to assess the level and pattern of genetic diversity in a collection of 127 S. alba accessions held at Plant Gene Resources of Canada using amplified fragment length polymorphism (AFLP) markers. Five AFLP primer pairs were applied, and 134 polymorphic bands were scored for each accession. These scored bands had frequencies of occurrence ranging from 0.02 to 0.99 with an average of 0.69. More AFLP variation was found within single (79.1%) than between (20.9%) S. alba accessions. A small degree of AFLP difference (1.7%) was observed among the accessions of various regions, while relatively large variation (9.2%) existed among the accessions of various countries. A large AFLP difference (15.6%) also existed between the yellow- and brown-seeded accessions, but only 6.2% difference was observed between the cultivar and landrace accessions. Two distinct groups of S. alba germplasm were identified on the basis of the seed colour (yellow or brown), although a few mixtures also existed. No apparent ‘duplicated’ accessions were observed. The most diverse accessions were from Italy, Spain, France and Greece. Among the most genetically distinct accessions were SA97 from Portugal, SA89 and SA88 from France, SA83 from Russia and SA57 from Italy. These findings are significant not only for managing S. alba germplasm, but also for identifying diverse germplasm that can be used by plant breeders to improve S. alba seed yield and quality parameters.