During the period from 2000 to 2013, average canola yields from Canadian farms increased from 1330 to 2025kgha-1, or 54kgha-1 year-1. The objective of this review was to propose likely reasons behind ...this increase by examining genotypic, environmental and agronomic factors. During this period, hybrid canola cultivars with herbicide tolerance (HY-HT) expanded from 80% to >95% of the area sown to canola. Genetic gain from switching from open-pollinated cultivars to HY-HT cultivars was estimated to account for 32kgha-1 year-1. When some key environmental factors were examined, there were no significant linear changes in growing season temperature, although the linear increase in April and May precipitation was significant and likely responsible for an increase of 12kgha-1 year-1. When coupled with the yield increase from changes in atmospheric CO2 (3kgha-1 year-1), the environment was estimated to account for
Background. A complete ban on alcohol advertisements has been proposed for South Africa (SA), but there has been limited local research on the association between exposure to alcohol advertisements ...and alcohol consumption. Objectives. To examine the role of demographic factors, exposure to alcohol marketing and liking of alcohol advertisements in predicting use of alcohol in the past 6 months among older adolescents in Tshwane, Gauteng Province, SA. Methods. Participants comprised the adolescent sub-sample (N=869) of the International Alcohol Control study survey that was conducted in SA. They consisted of 408 males and 461 females aged 16 and 17 years who took part in structured interviews on their alcohol consumption and various alcohol-related attitudes and behaviours. A multiple survey logistic regression analysis of the dependent variable alcohol use in the past 6 months on the independent variables age, gender, educational status, socioeconomic status, exposure to alcohol brand marketing and liking of alcohol advertisements was used. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated. Results. The prevalence of drinking in the past 6 months was 10.6% (95% CI 5.9 - 18.3). The number of modes of alcohol brand/product advertising to which the adolescents were exposed was positively associated with alcohol use in the past 6 months. An additional mode of alcohol brand/product advertising exposure led to a relative increase of 1.13 (95% CI 1.01 - 1.28) in the odds of alcohol use in the past 6 months (e.g. a participant who was exposed to advertisements via seven different channels was 2.08 times more likely to have used alcohol in the past 6 months than a participant with exposure via a single channel). Having a strong dislike of alcohol advertisements was associated negatively (protective) with alcohol use in the past 6 months, with the odds ratio being 0.35 (95% CI 0.19 - 0.64). Having only a moderate dislike or a liking of alcohol advertisements was positively associated with alcohol use in the past 6 months among the study participants (OR 2.90 and 2.84, respectively). Age, gender, educational status and socioeconomic status were not independently associated with alcohol consumption. Conclusions. Exposure to alcohol marketing and not being strongly averse to advertisements of alcohol brands and products were associated with alcohol use among adolescents. The results have implications for policies on alcohol marketing in SA.
The malting barley (Hordeum vulgare L.) industry is often challenged by the availability of sufficient volume and quality to meet demand. Our objective was to evaluate the effects of agronomic ...practices on grain uniformity, protein concentration, yield, and yield components. Field experiments were conducted from 2005 to 2008 at eight rain-fed locations in western Canada. The effects of two seeding rates (200 and 400 seeds m−2) and five N (0, 30, 60, 90, and 120 kg ha−1) rates on two two-row barley cultivars (‘AC Metcalfe’ and ‘CDC Copeland’) were determined. Each experiment was conducted for 3 yr at each location (24 environments). CDC Copeland displayed some advantages over AC Metcalfe including higher grain yield, lower protein and more uniform kernels. For both cultivars, kernel weight, and plumpness were lower at the higher seeding rate; protein was also lower, maturity was earlier and kernels were more uniform. With increasing N rate, barley yield, kernel weight, and tillers plant−1 increased, but days to seed maturity and protein concentration also increased, and kernel plumpness and seed uniformity decreased. The increase in protein was less pronounced with CDC Copeland suggesting that there may be less risk with this cultivar of unacceptable protein levels at relatively high N rates. At many environments barley plant stand decreased while lodging increased with increasing N rates. To improve the likelihood that barley will be acceptable for malting growers should select low-protein varieties, seed at relatively high rates and limit N application.
Nitrogen fertilizer is a major input cost in canola (Brassica napus L.) production and farmers are interested in improving N use efficiencies. A multi-site study in western Canada was conducted to ...determine the merits of polymer-coated urea (Environmentally Smart Nitrogen, ESN) compared with urea on weed management and yield of hybrid and open-pollinated (OP) canola. Treatments included a hybrid and OP canola cultivar, ESN and urea, 100 and 150% of soil test N fertilizer rates, and 50 and 100% of registered in-crop herbicide rates. Canola was grown in rotation with barley (Hordeum vulgare L.) in a no-till system and both crops of the rotation were present each year. Fertilizer and herbicide rate treatments were applied to the same plots in four consecutive years to determine annual and cumulative effects. Hybrid compared with OP canola reduced weed tissue N concentration in 40% of the cases and reduced weed biomass in 80% of the cases. Additionally, weed tissue N concentration was lower with ESN than with urea in 70% of the cases, indicating that crop-weed competition for soil N might be reduced if ESN were used. Canola yield was greater for the hybrid cultivar in 15 of 20 site-years. Both cultivars expressed a positive yield response to the 150% N fertilizer rate in 10 of 20 site-years. This yield response occurred in three additional site-years with hybrid canola, indicating that hybrid cultivars have a higher N demand under favorable growing conditions. Canola yield was similar with ESN and urea in 14 of 20 site-years. The ESN compared with urea increased canola yield in 4 site-years and in one additional site-year for hybrid canola, indicating that ESN may be advantageous in some situations. Canola seed oil concentration was similar with ESN and urea in 19 of 20 site-years. Information gained in this study will be used to develop improved fertilization strategies for canola production on the semiarid Canadian prairies.
Adoption of glyphosate-resistant canola (
Brassica napus L.) has increased glyphosate applications to this crop, and concerns have been raised about unintended consequences of these multiple ...applications. A field trial was conducted to evaluate the effects of pre-seed and in-crop glyphosate and alternative herbicides on soil microbial community functional structure, diversity and biomass. Pre-seed treatments were 2,4-
D, glyphosate and 2,4-
D
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glyphosate, and in-crop treatments were glyphosate applied once, glyphosate applied twice, ethalfluralin, ethalfluralin
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sethoxydim
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ethametsulfuron
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clopyralid, and sethoxydim
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ethametsulfuron. Rhizosphere and bulk soil was collected at flowering stage of canola and analyzed for bacterial community-level substrate utilization patterns and microbial biomass C (MBC). Where differences were significant, pre-seed application of both 2,4-D and glyphosate altered the functional structure and reduced the functional diversity of soil bacteria, but increased MBC. These effects were not necessarily concurrent. The reduction in functional diversity was due to reduction in evenness, which means that the soil where both pre-seed herbicides had been applied was dominated by only few functional groups. In 1 year, two in-crop applications of glyphosate also reduced the functional diversity of soil bacteria when applied after pre-seed 2,4-D, as did in-crop sethoxydim
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ethametsulfuron following pre-seed glyphosate. Even though significant differences between herbicides were fewer than non-significant differences, i.e., there were no changes in soil microbial community structure, diversity or biomass in response to glyphosate or alternative herbicides applied to glyphosate-resistant canola in most cases, the observed changes in soil microbial communities could affect soil food webs and biological processes.
As glyphosate-resistant (GR) crops are becoming common in agro-ecosystems, their effects on non-target soil organisms need to be monitored. We evaluated soil microbial biomass C (MBC), bacterial ...functional diversity and community structure, and dehydrogenase enzyme activity in a field experiment conducted at six sites on the Canadian prairies. Treatments consisted of a factorial arrangement of three GR wheat and GR canola crop frequencies and two tillage systems. GR crop frequencies were arranged in 4-yr wheat-canola-wheat-pea rotations, with GR wheat and GR canola in zero of four, two of four, or three of four possible GR crop frequencies. The two tillage systems were either low soil-disturbance direct-seeding (LDS) or conventional tillage (CT). MBC increased with increasing frequency of GR crops in two of 20 site-years in the rhizosphere, and had no effects in bulk soil. Depending on tillage, GR crop frequency also affected the functional diversity of rhizosphere soil bacteria in only two of 20 site-years, and had no effects in bulk soil. Shifts in the structures of bacterial communities related to GR crop frequency were detected, but they were few and inconsistent. In three of 22 cases (10 in rhizosphere+12 in bulk soil), the activity of dehydrogenase enzyme decreased with increasing frequency GR crops in both the rhizosphere and bulk soil. In five of 20 site-years, soil MBC in the rhizosphere was greater under CT than under LDS, regardless of GR crop frequency. In bulk soil, tillage affected soil MBC in five site-years, three of which had greater MBC under CT than LDS, and vice versa in the other two. Tillage affected the functional diversity of soil bacteria in the rhizosphere in three site-years, but the effects were not consistent. Similar inconsistent tillage-related patterns were observed in the community structures of bacteria. There were no tillage effects on bacterial diversity in bulk soil. Dehydrogenase enzyme activity was greater under LDS than under CT in three of four cases in which tillage had significant effects. Overall, GR crop frequency effects on soil microorganisms were minor and inconsistent over a wide range of growing conditions and crop management.
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