Canola Varieties Research Articles

New resistances offer opportunity for effective management of the downy mildew (Hyaloperonospora parasitica) threat to canola

Downy mildew (Hyaloperonospora parasitica) is a problem for canola production worldwide, including in Australia where it has remained a persistent threat since 1998. Testing of 131 Brassicaceae varieties, including 109 Australian canola varieties (Brassica napus and B. juncea) and 22 diverse Brassicaceae (including B. napus, B. carinata, B. juncea, B. nigra, B. rapa, Crambe abyssinica and Raphanus sativus) highlighted excellent resistance to downy mildew. Using a mixture of 10 H. parasitica isolates, R. sativus Colonel and Boss showed highest resistance to H. parasitica, with per cent disease index (%DI) values of 3.7% and 10.2%, respectively. These were followed by (%DI values): B. carinata ATC 94011 (11.1%), B. napus CB™ Tanami (14.1%) and Komet-741 A (14.3%), B. juncea 397.23.2.3.3 (14.8%), B. napus ATR-Banjo (16.9%), Hyola 575 CL (16.9%), Komet-744 A (18.1%), Cresor-770 B (18.5%), Wamus (18.5%), Surpass 400 (19.2%), Hyola 432 (19.4%) and Hyola 76 (19.4%), and C. abyssinica (19.9%). These varieties were also considered highly resistant. Another five B. juncea genotypes and B. nigra P.23845 were considered highly resistant with %DI of 22.2%. Those considered resistant (but not highly resistant) included hybrid B. napus Hyola 444 TT, Hyola 500 RR, Hyola 504 RR, Pioneer 46Y78, Pioneer 45Y77 and Hyola 650 TT, and the non-hybrid variety ATR-Eyre, all with %DI values 23.1–28.2%. By contrast, B. napus Thunder TT, Hyola 450 TT and ATR-Grace were highly susceptible with %DI values of 90.3%, 88.2% and 81.7%, respectively. Cluster analysis revealed six distinct clusters (highly resistant, resistant, moderately resistant, moderately susceptible, susceptible, very susceptible) for the tested Brassicaceae genotypes that, on average, showed similar responses within each cluster against H. parasitica based on their %DI values. From 2000 onwards (with the exception of Surpass 400), 10 B. napus varieties and one B. juncea released were classified as highly resistant; however, there was no overall correlation between year of variety release and level of resistance expressed against H. parasitica. This is the first study to demonstrate the existence of very high levels of pathotype-independent resistance in Australian canola varieties to H. parasitica. The most resistant varieties identified can be used in canola breeding programs and also directly deployed into regions where downy mildew is prevalent, providing the canola industry with an immediate and effective option for management of this important disease.

Determining Thermal Properties of Canola Pods as Function of Variety and Times of Harvest = تحديد الخصائص الحرارية لقرون نبات الكانولا لتوظيفه تحديد الأصناف وأوقات الحصاد

Canola pod thermal properties including thermal conductivity, specific heat, and thermal diffusivity in three common canola varieties (Hyola 420, Hyola 401, and Hyola 50) cultivated in the North of Iran at before-harvest, harvest, and post-harvest stages were measured. Thermal conductivity coefficient determined by line heat source, specific heat was determined through mixture method and thermal diffusivity was determined by calculation. The results showed that there was significant difference of thermal conductivity and specific heat between the three varieties, however, there was no significant difference of thermal diffusivity between these verities. Also, there was significant difference of thermal conductivity and specific heat between the three sampling time, however, there was no significant difference of thermal diffusivity between these sampling time. The results showed that there was significant difference of thermal conductivity, specific heat and thermal diffusivity between the interaction effects of variety and time. The thermal conductivity of Hyola 420 was significantly higher than that of Hyola 50 and Hyola 401 at pre-harvest and stage. However, the difference was not significant between the three varieties at both harvest and post-harvest stages. Thermal conductivity was significantly higher for pre-harvest stage than harvest and post-harvest stages for Hyola 50 and Hyola 420. However it was significantly higher for pre-harvest stage than harvest stage which in turn was significantly higher than post-harvest stage. Specific heat was significantly higher for Hyola 420 than Hyola 401 which in turn was significantly higher than Hyola 50 at pre-harvest and stage. The difference of specific heat was not significant between Hyola 420 and Hyola 401, however, Hyola 50 was significantly lower than that of Hyola 420 and Hyola 401 at harvest and stage. The difference was not significant between the three varieties at post-harvest stages. The difference was not significant between the three stages for Hyola 50. The difference of specific heat was not significant between pre-harvest and harvest for Hyola 401, however, post- harvest was significantly lower than that of pre-harvest and harvest stage. Specific heat was significantly higher for pre-harvest stage than harvest stage which in turn was significantly higher than post-harvest stage for Hyola 420. Thermal diffusivity was significantly higher for Hyola 420 than Hyola 50 which in turn was significantly higher than Hyola 401 at pre-harvest stage. The difference was not significant between the three varieties at harvest and post-harvest stages. Thermal diffusivity was significantly higher at harvest stage than post-harvest stage which in turn was significantly higher than pre-harvest stage for Hyola 50. And, it was significantly higher at post-harvest stage than harvest stage which in turn was significantly higher than pre-harvest stage for Hyola 401. The difference was not significant between the three stages for Hyola 420. The results are usable in thermal properties modeling and also prediction of the value of the properties. Also the results are relevant and applicable for drying before threshing used in farm dryer unit and reducing seed losses at canola harvest.

Row Spacing and Seeding Rate Effects on Canola Population, Weed Competition, and Yield in Winter Organic Canola Production

Increasing seeding rate and widening row spacing to allow for between row cultivation may reduce weed competition in organic canola (Brassica napus L.) production. Research was conducted to evaluate the effects of row spacing and seeding rate on canola population, weed competition, and yield in organic canola production. Canola variety Hornet was planted at five seeding rates (3.4, 6.7, 10.1, 13.4, and 16.8 kg ha−1) at three row spacings (17, 34, 68 cm) in Goldsboro, Kinston, and Salisbury, NC, in 2011 and 2012. Between row cultivation was performed in the 68‐cm row spacing as weather permitted. Canola population increased with increasing seeding rate across all row spacings, and canola populations were highest with the 17‐cm row spacing, followed by the 34‐ then 68‐cm row spacings. Yield was similar across row spacings at the lower seeding rates in five of the six environments. At these environments, yield tended to increase in the 17‐cm row spacing as seeding rate increased but declined in the 68‐cm row spacing with increasing seeding rate. In one environment with a unique weed community, weed suppression and yield were higher with the 68‐cm row spacing. It was concluded that the yield plasticity of canola will provide producers flexibility in selecting row spacing, and seeding rate selections should be based on desired row spacing.Core Ideas Increasing canola seeding rate and widening row spacing to allow for between row cultivation may serve as mechanisms to reduce weed competition in canola production, but have rarely been evaluated in organic production. This study was conducted to evaluate seeding rate and row spacing effects on weed competition and yield in organic canola production. Despite different canola populations across canola row spacings, yield tended to be similar at low seeding rates across the row spacings indicating canola has the ability to compensate for low population. Depending on the weed species at your environment, widening row spacing to allow for between row cultivation may prove critical for reducing weed competition and increasing canola yield. Yield tended to increase with increases in seeding rate at the 17‐cm row spacing, however yield declines were observed with higher seeding rates in the 68‐cm row spacing, which is likely attributed to intraspecific competition. Organic canola producers have flexibility when selecting row spacing and seeding rates due to the great plasticity of canola.

Effect of foliar application of nano iron and manganese chelated on yield and yield component of canola (Brassica napus L.) under waterdeficit stress at different plant growth stages

In order to study the effect of nano- iron and manganese fertilizer, a field experiment was conducted at 2013-2014 growing season at the Research Farm in Faculty of Agriculture, Tarbiat Modarres University, Tehran, Iran. Experiment was conducted as a randomized complete block design arrangement in split plot with three replications. Three irrigation regimes (without water deficit stress, water deficit stress at vegetative stage and water deficit stress at reproductive stage) were randomized to the main plots and combinations of foliar nano-iron and nano-manganese application as were randomized to the sub plots. Statistical analysis showed that irrigation and spraying regimes and their interactions had significant effect on most of the measured traits. Water deficit stress significantly reduced yield and yield components of RGS canola variety. The most reduction was observed in plants under water deficit condition at reproductive stage. Use of micronutrients increased canola grain yield. The maximum grain yield was observed in plants that treated with iron sulfate 1 per thousand + manganese sulfate 1.5 per thousand. In general, low concentration levels of iron and manganese foliar application was more effective on plants for reduction harmful effect of water deficit levels than high micronutrient concentrations.

Floral Initiation in Response to Planting Date Reveals the Key Role of Floral Meristem Differentiation Prior to Budding in Canola (Brassica napus L.)

In Brassica napus, floral development is a decisive factor in silique formation, and it is influenced by many cultivation practices including planting date. However, the effect of planting date on floral initiation in canola is poorly understood at present. A field experiment was conducted using a split plot design, in which three planting dates (early, 15 September, middle, 1 October, and late, 15 October) served as main plot and five varieties differing in maturity (1358, J22, Zhongshuang 11, Zheshuang 8, and Zheyou 50) employed as subplot. The purpose of this study was to shed light on the process of floral meristem (FM) differentiation, the influence of planting date on growth period (GP) and floral initiation, and silique formation. The main stages of FM developments can be divided into four stages: first, the transition from shoot apical meristem to FM; second, flower initiation; third, gynoecium and androecium differentiation; and fourth, bud formation. Our results showed that all genotypes had increased GPs from sowing to FM differentiation as planting date was delayed while the GPs from FM differentiation to budding varied year by year except the very early variety, 1358. Based on the number of flowers present at the different reproductive stages, the flowers produced from FM differentiation to budding closely approximated the final silique even though the FM differentiated continuously after budding and peaked generally at the middle flowering stage. The ratio of siliques to maximum flower number ranged from 48 to 80%. These results suggest that (1) the period from FM differentiation to budding is vital for effective flower and silique formation although there was no significant correlation between the length of the period and effective flowers and siliques, and (2) the increased number of flowers from budding were generally ineffective. Therefore, maximizing flower numbers prior to budding will improve silique numbers, and reducing FM degeneration should also increase final silique formation. From the results of our study, we offer guidelines for planting canola varieties that differ in maturity in order to maximize effective flower numbers.

Effects of NaCl and KCl on Physiological Aspects of Two Canola Varieties = تأثير كلوريد الصوديوم والبوتاسيوم على الجوانب الفسيولوجية للنوعين من زيت الكانولا

In order to investigation reaction of physiologic morphological traits in canola in early growth stages an experiment was conducted at the green house conditions. Treatments consist of NaCl in four levels, two levels of KCl and two varieties of canola. Results showed that amount of photosynthesis in RGs003 in compare of Licord and control treatment increased 67 and 14 percent respectively in T5 treatment. The stomata conductivity was greater from applied T5 treatment than other treatments except of control. The maximum biomass was observed in Licord which increased 34 percent in compared of other variety in T5 treatment. Dry root weight in RGs003 was greater than Licord variety. Results of coefficient regressions were showed positive relation between morphological traits in any level of salinity stress that is a necessity to do more investigation in range of these compositions biomass and leaf area (R2=0.86) than biomass and relative water content (R2=0.66)

Fine mapping of a dominant gene conferring chlorophyll-deficiency in Brassica napus.

Leaf colour regulation is important in photosynthesis and dry material production. Most of the reported chlorophyll-deficient loci are recessive. The dominant locus is rarely reported, although it may be more important than the recessive locus in the regulation of photosynthesis efficiency. During the present study, we mapped a chlorophyll-deficient dominant locus (CDE1) from the ethyl methanesulfonate-mutagenized Brassica napus line NJ7982. Using an F2 population derived from the chlorophyll-deficient mutant (cde1) and the canola variety ‘zhongshuang11’, a high-density linkage map was constructed, consisting of 19 linkage groups with 2,878 bins containing 13,347 SNP markers, with a total linkage map length of 1,968.6 cM. Next, the CDE1 locus was mapped in a 0.9-cM interval of chromosome C08 of B. napus, co-segregating with nine SNP markers. In the following fine-mapping of the gene using the inherited F2:3 populations of 620 individuals, the locus was identified in an interval with a length of 311 kb. A bioinformatics analysis revealed that the mapping interval contained 22 genes. These results produced a good foundation for continued research on the dominant locus involved in chlorophyll content regulation.

Comparative environmental impact assessment of herbicides used on genetically modified and non-genetically modified herbicide-tolerant canola crops using two risk indicators

Canola (Brassica napus L.) is the third largest field crop in Australia by area sown. Genetically modified (GM) and non-GM canola varieties released or being developed in Australia include Clearfield® (imidazolinone tolerant), TT (triazine tolerant), InVigor® (glufosinate-ammonium tolerant), Roundup Ready® - RR® (glyphosate tolerant) and Hyola® RT® (tolerant to both glyphosate and triazine). We used two risk assessment approaches – the Environmental Impact Quotient (EIQ) and the Pesticide Impact Rating Index (PIRI) – to compare the environmental risks associated with herbicides used in the canola varieties (GM and non-GM) that are currently grown or may be grown in the future. Risk assessments found that from an environmental impact viewpoint a number of herbicides used in the production of TT canola showed high relative risk in terms of mobility and ecotoxicity of herbicides. The EIQ field use rating values for atrazine and simazine in particular were high compared with those for glyphosate and trifluralin. Imazapic and imazapyr, which are only used in Clearfield® canola, had extremely low EIQ field use rating values, likely reflecting the very low application rates used for these chemicals (0.02 to 0.04kg/ha) compared with those used for atrazine and simazine (1.2 to 1.5kg/ha). The PIRI assessment showed that irrespective of the canola variety grown, trifluralin posed a high toxicity risk to fish (Rainbow trout, Oncorhynchus mykiss), algae and Daphnia sp. While the replacement of trifluralin with propyzamide had little effect on the mobility score, it greatly decreased the ecotoxicity score to fish, algae and Daphnia sp. due to the lower LC50 values for propyzamide compared with trifluralin. This study has shown that based on likelihood of off-site transport of herbicides in surface water and potential toxicity to non-target organisms, the GM canola varieties have no advantage over non-herbicide tolerant (non HT) or Clearfield® canola.

Impact of Foliar Application with Salicylic Acid on Biochemical Characters of Canola Plants under Cold Stress Condition

In this study the effect of foliar application of salicylic acid on the chlorophyll content, antioxidant enzymes activity, and the content of solute protein and proline were investigated in two canola varieties (Brassica napus L., cv ‘RGS’ and ‘Licord’) leaves during 0, 24, and 48 hours after salicylic acid treatment. The results showed that the content of total chlorophyll was decreased in ‘RGS’ cultivar during the experiment and this process was related with increasing of salicylic acid concentration. The activity of superoxide dismutase, peroxidase, and also lipid peroxidation were increased significantly after 48 hours compared with the first day. The results of catalase activity showed that, this trait was decreased 24 hours after salicylic acid treatment and this decrease was related with salicylic concentration. The content of protein in both cultivars slightly changed and plants treated with salicylic acid had more protein content, by contrast proline was greatly affected by salicylic acid treatment and its content was the highest 24 hours after treatment. According to the present findings the application of salicylic acid has useful effects on the biochemical traits of Brassica napus cultivars. Therefore it may be effective for the improvement of plant growth in cold regions.

Molecular and systems approaches towards drought-tolerant canola crops.

1169 I. 1170 II. 1170 III. 1172 IV. 1176 V. 1181 VI. 1182 1183 References 1183 SUMMARY: Modern agriculture is facing multiple challenges including the necessity for a substantial increase in production to meet the needs of a burgeoning human population. Water shortage is a deleterious consequence of both population growth and climate change and is one of the most severe factors limiting global crop productivity. Brassica species, particularly canola varieties, are cultivated worldwide for edible oil, animal feed, and biodiesel, and suffer dramatic yield loss upon drought stress. The recent release of the Brassica napus genome supplies essential genetic information to facilitate identification of drought-related genes and provides new information for agricultural improvement in this species. Here we summarize current knowledge regarding drought responses of canola, including physiological and -omics effects of drought. We further discuss knowledge gained through translational biology based on discoveries in the closely related reference species Arabidopsis thaliana and through genetic strategies such as genome-wide association studies and analysis of natural variation. Knowledge of drought tolerance/resistance responses in canola together with research outcomes arising from new technologies and methodologies will inform novel strategies for improvement of drought tolerance and yield in this and other important crop species.

Effects of Planting Date on Winter Canola Growth and Yield in the Southwestern U.S.

Canola (Brassica napus L.) has potential to become alternative cash crop (healthy oil for human and meals for animal uses) with tremendous rotational benefits in the Southwestern U.S., a region dominated by cereal-fallow cropping systems. However, information on optimum planting date for its successful production is limited. Field experiments were conducted in 2011-12 and 2012-13 seasons under irrigation condition to study the response of canola growth and yield to planting dates at Clovis, NM. Three planting dates (mid-September, late-September and early-October) and four canola varieties (early flowering: DKW41-10 and DKW46-15; medium flowering: Riley and Wichita) are studied. Fall plant stand density is significantly higher for early-October than mid- and late-September plantings. However, a ratio of fall to spring plant stand density indicates a greater reduction in spring plant stand density with early-October (25%) and mid-September (19%) than late-September (7%). Vegetative (by 13 days) and flowering (by 7 days) duration phases are significantly shortened with delay in planting. The decline in aboveground dry matter (DM) due to delayed planting resulted in significant seed yield reduction in both 2011-12 (26%) and in 2012-13 (8%) when early-October and mid-September plantings were compared. There was a positive relationship between final DM and canola seed yield, accounting for 84 and 34% variation for 2011-12 and 2012-13 seasons, respectively with the 2011-12 environmental conditions being conducive for genetically controlled variation in DM production to be more apparent and strong in explaining the variation in seed yield among varieties. Medium-flowering varieties produced higher DM (9741 vs. 8371 Kg•ha-1) and seed yield (2785 vs. 2035 Kg•ha-1) than early-flowering varieties. In addition to seed yield, DM can be used as an indirect selection criterion for seed yield in variety selection and appropriate planting dates including a guarantee for high crop residues (~75% of the total aboveground biomass) production to make canola a potential alternative cash and rotational break crop in the Southwestern U.S.

Relative yield and profit of Australian hybrid compared with open-pollinated canola is largely determined by growing-season rainfall

Australian canola growers have new technology options including hybrid and herbicide technologies, which have offered yield and profitability advantages in other canola-growing regions of the world. This study compared the yield and gross margins of hybrid and open-pollinated (OP) canola from different herbicide tolerance groups: triazine-tolerant, Roundup Ready, Clearfield and conventional across a wide range of environments in south-western Australia, and in the National Variety Trial network in southern Australia to investigate the relative advantages of these technologies. There were significant differences in yield responsiveness between hybrid and OP canola, the magnitude of which was determined by the growing-season rainfall/available water to the crop. Hybrid out-yielded OP canola in favourable environments where rainfall was high and the growing season was long. However, in areas of low rainfall where yield potential was low, hybrids showed little yield advantage over OP. In contrast, there were no differences in yield response between the four herbicide tolerance groups across the rainfall zones. The economic analysis showed that the break-even yield for hybrids versus OP canola was 1.25 t/ha for triazine-tolerant canola, 0.7 t/ha for Roundup Ready canola, and 1.7 t/ha for hybrid Clearfield canola. The gross margin analysis suggested that hybrid triazine-tolerant, Clearfield and Roundup Ready canola was more profitable than the OP system in the medium (growing-season rainfall of 265–330 mm) and high (330 mm) rainfall environments, but not profitable in the lower (<265 mm) rainfall area because the cost associated with hybrid seed outweighed the small yield benefit. The sensitivity analysis indicated that ± 10% changes in canola price and seed cost shifted the break-even yield by ± 0.1 t/ha. Our study makes a case for Australian canola breeders to maintain OP canola varieties, rather than shifting their focus entirely to hybrids, to underpin continued productivity and profitability in lower rainfall areas.

Quantitative genetic analysis of grain yield in an Australian Brassica napus doubled-haploid population

High yield is a major objective in canola-breeding programs. We analysed the genetic determinants controlling variation in grain yield in a doubled-haploid (DH) breeding population derived from a single BC1F1 plant from the cross Skipton/Ag-Spectrum//Skipton (designated as the SAgS population). DH lines were evaluated for flowering time and yield in two replicated trials and exhibited significant genetic variation for both traits. Yield showed negative correlation with flowering time; lines that flowered earlier had higher yield than late-flowering lines. A genetic linkage map comprising 7716 DArTseq markers was constructed for the SAgS population, and a ‘bin’ map based on 508 discrete single-position (non-co-segregating) marker loci was used for quantitative trait locus (QTL) analysis. We identified 20 QTLs (LOD ≥2) associated with variation in flowering time and grain yield. Two QTLs (Qy.wwai-A7/Qdtf.wwai-A7/Qfs.wwai-A7 and Qy.wwai-C3a/Qfs.wwai-C3a) appeared repeatedly across experiments, accounting for 4.9–19% of the genotypic variation in flowering time and yield and were located on chromosomes A07 and C03. We identified 22 putative candidate genes for flowering time as well as grain yield, and all were located in a range of 935 bp to 2.97 Mb from markers underlying QTLs. This research provides useful information to be used for breeding high-yielding canola varieties by combining favourable alleles for early flowering and higher grain yield at loci on chromosomes A07, C03 and possibly on A06.

Effect of phosphorus, potassium, and chloride nutrition on cold tolerance of winter canola (Brassica napus L.)

ABSTRACTWinter varieties of canola (Brassica napus L.) are susceptible to winterkill. Measurements of photosynthetic efficiency and survival of field-grown canola were used to evaluate the effect of chloride (Cl), potassium (K), and phosphorus (P) nutrition on winter field survival in northwestern USA. In a growth chamber experiment, effects of calcium chloride (CaCl2), potassium chloride (KCl), ammonium chloride (NH4Cl), or sodium chloride (NaCl) on the ability to tolerate subfreezing temperatures were evaluated. In the field, overwinter survival was higher, and greater photosynthetic activity continued later into the autumn in plants with increased sap Cl concentrations. In the greenhouse experiment, significantly greater survival occurred in plants with higher sap Cl concentrations, but only in plants that had not been cold acclimated. These results suggested that a greater concentration of chloride ion in the sap of canola plants is related to an increased ability to tolerate subfreezing temperatures, but other processes resulting from cold acclimation may largely obscure this effect.

Nutritional evaluation of canola meals produced from new varieties of canola seeds for poultry

This study evaluated the nutritional value of 14 canola meals from new varieties of canola and compared them to conventional canola meal samples and soybean meals in chickens. Five experiments that included different sources of canola meals or soybean meals were conducted. For each experiment, a precision-fed rooster assay with conventional or cecectomized roosters was conducted to determine TMEn or amino acid digestibility. Analyzed nutritional composition of the canola meal samples indicated increases in crude protein and amino acids for all test canola meals (49.41 to 50.58% crude protein on a dry matter basis) compared to conventional canola meals (40.73 to 43.01%). All test canola meals also contained lower amounts of neutral detergent fiber and acid detergent fiber. Most test canola meals had significantly higher TMEn values than the conventional canola meals (P < 0.05), but all were lower than the soybean meal (P < 0.05). The test canola meals had higher amino acid digestibility coefficients than conventional canola meals in Experiments 1, 2, and 4 (P < 0.05), and higher concentrations of digestible amino acids in all 5 experiments. The results of this study indicated that nutritional value of the canola meal from new varieties of canola was greater than conventional canola meal for poultry.

Forage canola (Brassica napus): spring-sown winter canola for biennial dual-purpose use in the high-rainfall zone of southern Australia

European winter canola (Brassica napus L.) varieties adapted to the long, cool seasons in high-rainfall areas of southern Australia have recently been adopted as autumn-sown, grain-only and dual-purpose crops. A spring-sown winter canola could be used as a biennial dual-purpose crop, to provide additional forage for summer and autumn grazing before recovery to produce an oilseed crop. We report a series of field experiments demonstrating that European winter canola types have suitable phenological characteristics to allow for their use as biennial, spring-sown crops, providing significant forage (2.5–4 t ha–1) for grazing while remaining vegetative through summer and autumn, and recovering following vernalisation in winter to produce high seed yield (2.5–5.0 t ha–1). Sowing too early (September) in colder inland areas risked exposure of the crop to vernalising temperatures, causing the crop to bolt to flower in summer, whereas all crops sown from mid-October remained vegetative through summer. Crop stands thinned by 20–30% during summer, and this was exacerbated by grazing, but surviving stands of ~30 plants m–2 were sufficient to support high yields. Grazing had no effect on grain yield at one site, but reduced yield by 0.5 t ha–1 at a second site, although this was more than offset by the value of the grazed forage. The spring-sowing approach has potential to replace the existing forage rape–spring cereal sequence, or to add a further option to the existing autumn-sown winter canola in areas such as southern Victoria, where early autumn establishment can be problematic and spring-sown crops can better withstand pests and winter waterlogging, which limit yield of autumn-sown crops. Because these are the first known studies in Australia to investigate the use of spring-sown winter canola, further work is warranted to refine further the crop and grazing strategies to maximise productivity and profitability from this option.

Integrating dual-purpose wheat and canola into high-rainfall livestock systems in south-eastern Australia. 1. Crop forage and grain yield

The development of guidelines for successful dual-purpose (graze and grain) use of wheat and canola in Australia’s high-rainfall zones (HRZ) has mostly emerged from separate wheat- and canola-focused research. Less attention has been placed on the benefits of integrating dual-purpose wheat and canola into pasture-based grazing enterprises. We conducted a farming systems experiment during 2010–11 to evaluate the benefits of integrating wheat and canola as dual-purpose crops into a pasture-based grazing system in Australia’s south-eastern tablelands. We compared forage production and grain yield in three separate crop–livestock systems in which the sheep grazed long-season wheat, winter canola or a combination of these. Initial growth rates were higher in early-autumn-sown canola than wheat in 2010, but were much lower although similar in both crops in 2011. Significant forage was available from both canola (3.1–3.4 t ha–1) and wheat (2.3–2.4 t ha–1) at the onset of grazing, but winter growth rates of wheat were higher than those of canola, leading to increased sheep grazing days (SGD). In the favourable 2010 season, dual-purpose wheat and canola separately provided 2393 and 2095 SGD ha–1, and yielded 5.0 and 1.9 t ha–1 grain, respectively, with an apparent nitrogen limitation in canola. In the drier season of 2011, grazing was reduced to 1455 and 735 SGD ha–1 in wheat and canola, respectively. Wheat yield was reduced from 5.9 to 5.4 t ha–1 grain by grazing, whereas canola yield was unaffected (3.6 t ha–1). In both years, grazing did not affect harvest index or oil content of canola, but harvest index was higher in grazed wheat crops. The yield of wheat and canola crops grazed in sequence did not differ from yield in treatments where animals grazed only a single crop, but the total overall grazing window when crops were grazed sequentially increased by 1054 and 618 SGD ha–1 in wheat, and by 1352 and 1338 SGD ha–1 in canola in 2010 and 2011, respectively. The major benefits of including crops that can be grazed sequentially were the widening of the grazing window and other operational windows (sowing, harvest), along with the rotational benefits for wheat by including canola in the system. Additional benefits to pastures may include eliminating the need to re-sow, because a more productive pasture composition is maintained under lower grazing pressure while stock are on crops, and reduced weed invasion. The commercial availability of new, herbicide-tolerant winter canola varieties provides significant opportunities to underpin the performance of dual-purpose crop sequences on mixed farms in the high-rainfall zone.

Effect of climate change and use of improved varieties on barley and canola yield in Manitoba

An, H. and Carew, R. 2015. Effect of climate change and use of improved varieties on barley and canola yield in Manitoba. Can. J. Plant Sci. 95: 127-139. A stochastic production function was estimated to investigate the effect of fertilizer inputs, changes in weather conditions and the use of improved varieties on barley and canola yields and its variability in Manitoba. Adoption of improved barley varieties did not have a significant effect on yield, while the adoption of herbicide-tolerant hybrid canola varieties was positively correlated with yield. An increasingly warmer climate in Manitoba is expected to have a slightly negative effect on mean barley yield and yield variance. In contrast, a warmer climate is expected to have a negligible effect on mean canola yield, but a positive effect on yield variability. Our results showed that a projected 50% increase in growing degree days would lead to a decrease of less than 1% in barley and canola yields.

Forage and grain yield of diverse canola (Brassica napus) maturity types in the high-rainfall zone of Australia

Cropping has recently expanded into arable areas of the high rainfall zone (HRZ) of Australia. We assessed the suitability of canola varieties of winter, winter × spring and spring-maturity at six sites across the south-eastern, northern and western HRZ of Australia for their suitability for dual-purpose production. Experiments measured potential forage production and the effect of defoliation or grazing on grain yield of crops sown from mid-March to mid-May. Overall, these experiments demonstrated the potential for dual-purpose canola across a wide area of the HRZ. In the south-eastern HRZ where winter conditions were sufficient for vernalisation and spring conditions were mild, winter and winter × spring types outperformed spring types as they provided an extended vegetative period for ‘safe’ grazing (prior to stem elongation), producing 3.0–6.8 t dry matter (DM) ha–1 of forage and recovered to produce 2.5–4.9 t ha–1 of grain yield. In the south-eastern region, early-sown winter types produced more forage than other canola types for grazing in late autumn and winter. In one experiment with four sowing times, consecutive delays in sowing of 2 weeks reduced forage available for grazing by 58%, 72% and 95% compared with the earliest sowing time of 10 March (6.1 t DM ha–1). Although spring types in this region provided some potential for grazing, the phenology was unsuitable for early sowing as the rapid onset of flowering reduced the period of safe grazing. Winter types were not suited to the western region, but the winter × spring and spring types produced &gt;1.0 t DM ha–1 of forage and grain yield of 2.3 t ha–1. In the northern region, spring types produced the highest grain yield (&gt;3.0 t ha–1) but suffered significant yield penalties associated with grazing. In other regions there was generally little or no effect of grazing on grain yield when crops were grazed or defoliated before stem elongation. These experimental studies confirm the potential for dual-purpose canola across all regions of the HRZ when suitable maturity types are sown, managed and grazed appropriately.

Effect of climate change and use of improved varieties on barley and canola yield in Manitoba

An, H. and Carew, R. 2015. Effect of climate change and use of improved varieties on barley and canola yield in Manitoba. Can. J. Plant Sci. 95: 127–139. A stochastic production function was estimated to investigate the effect of fertilizer inputs, changes in weather conditions and the use of improved varieties on barley and canola yields and its variability in Manitoba. Adoption of improved barley varieties did not have a significant effect on yield, while the adoption of herbicide-tolerant hybrid canola varieties was positively correlated with yield. An increasingly warmer climate in Manitoba is expected to have a slightly negative effect on mean barley yield and yield variance. In contrast, a warmer climate is expected to have a negligible effect on mean canola yield, but a positive effect on yield variability. Our results showed that a projected 50% increase in growing degree days would lead to a decrease of less than 1% in barley and canola yields.