Canola Genotypes Research Articles

Interrelationships between seed yield and 20 related traits of 49 canola (Brassica napus L.) genotypes in non-stressed and water-stressed environments

Development of new canola (Brassica napus L.) cultivars requires efficient tools to monitor trait association in a breeding program. The efficiency of a breeding program depends mainly on the direction of the correlation between yield and its components and the relative importance of each component involved in contributing to seed yield. This research uses sequential path analysis to determine the interrelationships among seed yield and 20 related traits. Forty nine canola genotypes were grown in two environments (non-stressed and water-stressed conditions) to determine the important components of seed yield. Observations were recorded on 20 other canola traits. Correlation coefficient analysis revealed seed yield was positively correlated with all the traits except stem diameter and days to flowering in the non-stressed environment. Seed yield was significantly positively correlated with all measured traits except first pod height, first lateral branch height, number of lateral branches pod-1, number of pods plant-1 and stem diameter in the water-stressed environment. Sequential path analysis identified the 1000-seed weight (TSW) and main stem length as important first order traits that influenced seed yield in the non-stressed environment. Plant height and the TSW were important first order traits that influenced seed yield in the water-stressed environment. All direct effects were significant, as indicated by bootstrap analysis. The results suggest that TSW could be used as a selection criterion in selecting for increased seed yield in canola in both non-stressed and water-stressed conditions.

Fertilizer response for hybrid and open-pollinated canola and economic optimal nutrient levels

Hybrid (HY) canola (Brassica napus L.) produces a higher seed yield than open-pollinated (OP) canola. While it is expected higher-yielding HY canola may require higher total available nutrients, especially nitrogen (N), the evidence is not conclusive. This study used canola yield data from several site-years and fertility experiments to determine whether HY and OP canola types require different rates of total available N (TAN) and total available phosphorus (TAP). The yield response of the two canola genotypes to TAP was the same, but for TAN the yield response was greater for HY canola. The quadratic yield response results were confirmed using three plateau equations. Optimal TAN for HY canola was higher than for OP canola. Soil test laboratories and producers growing HY canola need to modify N fertility for HY canola, compared with OP canola for which most of the current N fertilizer recommendations were developed. Key words: Economics, fertilizer, yield response, canola, hybrid, open-pollinated

Nucleic Acid Metabolism, Proline Concentration and Antioxidants Enzyme Activity in Canola ( Brassica nupus L.) Under Salinity Stress

Seedling of five canola genotypes, Hyola 308, Hyola 401, Hyola 60, Optlon 50 and RGS003, were grown in Hoagland nutrient solution containing S 1 = 0, S 2 = 100, S 3 = 200 and S 4 = 300 mmol L −1 NaCl in controlled environment. Proline, antioxidant activities like catalase (CAT), ascobrate peroxidase (APX) and guaiacol peroxidase (GPX) and some enzyme activities of nucleic acid metabolism were determined in shoot and root 20 days after induction of salinity stress. Results showed application of stress significantly affected plant growth components such as fresh (FW) and dry weight (DW) of canola genotypes. Among the genotypes, RGS003 had the highest reduction of FW and DW in S 3 treatment. By increasing NaCl levels from 0 to 300 mmol L −1, the activity of two antioxidant enzymes (APX and CAT) in shoot and root increased but GPX in all of genotypes decreased. The increase in salinity stress, increased proline concentration in both root and shoot tissues of canola genotypes. Hyola 401 genotype had the maximum concentration of proline in root and shoot in S 3 treatment. Along with increased salinity stress in all of the studied plants, salinity significantly increased the level of the total nucleic acid and the activity of DNase I in all of salinity treatments and at the S 3 level, RGS003 had the maximum concentration of nucleolytic enzyme.

Fatty acid composition of canola ( Brassica napus L.), as affected by agronomical, genotypic and environmental parameters

Vegetable oils with a high relative amount of unsaturated fatty acids are of great significance for human health. There is not any data on the effects of tillage practices on fatty acid composition of canola ( Brassica napus L.). Hence, in a 2-year split plot experiment, the effects of different tillage systems (no (NT), minimum (MT) and conventional tillage (CT)), canola genotypes (Hyola 401 (V1) and PF (V2)) and sowing dates (including Sep. 8, 23 and Oct. 7) on the fatty acid composition of canola were evaluated. Tillage practices and the combination of canola genotypes and sowing dates were randomized to the main and sub-plots, respectively. The highest oleic acid content was the result of combining NT, V1 and Sep. 23, and the lowest was related to the combination of CT, V2 and Oct. 7. While the combination of NT, V1 and D1 resulted in the highest amount of unsaturated fatty acids, this amount was the lowest for the combination of CT, V2 and Sep. 23. For the selection of an appropriate canola producing strategy, all these parameters must be taken into account. The combination of NT, V1 and Sep. 23 may be the most favorable cropping strategy for canola production under a Mediterranean climate.

Evaluation of Environmental and Genetic Variability and Heritability in Roselle (H. Sabadell L.) and Canola (Brassica napas L.) Population

The main genetic parameters were determined on the main traits of different populations from canola and roselle crops. Two field experiments were planted in randomized complete block design, where 7 canola genotypes, randomly chosen were planted, and 6 roselle genotypes were chosen were used in the study. Genetic variances in canola populations were 120.585, 110492.36 and 31.85 for flowering date, seed yield/ha and oil content, respectively. The heritability values were 0.85, 0.55 and 0.71 for the previous canola traits, respectively. Seed yield/ha of the seven canola populations ranged from 953.43 kg/ha of Sero-6 to 1528.08 kg/ha of Wichita. As for roselle populations, the genetic variances were 135.11, 7511.80 and 60.58 for flowering date, dry calyces yield/ha and vitamin C concentration, respectively. The values of heritability were 0.58, 0.55 and 0.77 for the previous traits. Dry calyces yield/ha of the 6 roselle genotypes ranged from 248.29 kg/ha of Sudan-1 to 495.18 kg/ha of IND-6.

Nitrogen efficiency of canola genotypes varies between vegetative stage and grain maturity

There is no information on whether N efficiency in canola at maturity can be reliably determined by screening germplasm in the vegetative stage. Twelve canola genotypes identified in preliminary screening study as having either high or low N efficiency indices were tested for consistency in N efficiency between the vegetative stage and maturity. Plants were grown in a glasshouse under low or adequate N supply and N efficiency was assessed using the following criteria: dry weight at deficient N supply, relative yield at low vs. adequate N supply, and N utilisation efficiency. None of the 12 tested genotypes was classified as efficient or inefficient under all three criteria. One genotype (46C74) was classified as efficient under two criteria, and one genotype (Surpass 300 TT) was inefficient under two criteria. At maturity, three additional efficiency criteria were used: harvest index, N harvest index, and oil and protein concentration in seed. Two genotypes (Wesway and 46C74) (ranked as efficient at vegetative stage) remained efficient at maturity under most of the efficiency criteria used. On the other hand, genotype Surpass 603 CL ranked inefficient during the vegetative stage was ranked as efficient at maturity under two criteria. Overall, there was little consistency in the N efficiency ranking between vegetative stage and maturity in 12 tested genotypes. Screening canola germplasm for N efficiency for breeding purposes would therefore require an assessment at maturity.

Australian canola germplasm differs in nitrogen and sulfur efficiency

Eighty-four canola genotypes, including current commercial Australian genotypes, some older Australian genotypes, new breeding lines, and several genotypes from China, were screened for nitrogen and sulfur efficiency in the early growth stage. Plants were grown in a glasshouse using virgin brown Lancelin soil (Uc4.22) supplied with basal nutrients. The treatments were: (i) adequate nitrogen and sulfur, (ii) low nitrogen, and (iii) low sulfur. Canola shoots were harvested at 38 days after sowing when growth reduction and the nitrogen and sulfur deficiency symptoms were evident in most genotypes. The nitrogen or sulfur efficiency in canola genotypes was evaluated on the basis of: (1) growth at low nitrogen or sulfur supply, (2) growth at low relative to adequate nitrogen and sulfur supply, and (3) nitrogen or sulfur utilisation efficiency expressed as shoot dry weight per unit of nitrogen or sulfur content in shoots. Genotypic variation in growth and nitrogen or sulfur efficiency in canola germplasm was significant. Two genotypes (Chikuzen and 46C74) were ranked efficient and 2 inefficient (CBWA-005 and Beacon) in uptake and utilisation of nitrogen under all 3 criteria. In terms of sulfur efficiency, genotype Argentina was ranked efficient, whereas CBWA-003 and IB 1363 were classified inefficient under all 3 criteria. Two canola genotypes (Surpass 600 and 46C74) were both nitrogen- and sulfur-efficient in terms of relative growth at low v. adequate nutrition; their use in the breeding programs could be considered.

Potencial alelopático de extratos aquosos de genótipos de canola sobre Bidens pilosa

O objetivo deste trabalho foi avaliar o efeito de extratos aquosos de plantas de genótipos de canola na germinação e comprimento da radícula de picão-preto (Bidens pilosa). Os tratamentos estudados foram constituídos dos genótipos de canola Hyola 420, Hyola 401, Hyola 43, Hyola 60, Hyola 61, Y 3000, H 1432, Dln 03-02, Dln 03-04, Sdh 03-01, Sdh 03-07, Sw-2797 e Sw-Eclipse, nas concentrações de extrato aquoso a 100, 75, 50, 25 e 0%. O delineamento experimental foi inteiramente casualizado, em esquema fatorial com dois fatores 12 x 4 (genótipos e concentração do extrato), com quatro repetições. O experimento foi conduzido em caixas gerbox com papel de germinação embebido nos extratos das plantas de canola, sobre os quais foram dispostos aquênios de picão-preto. Sete dias após a semeadura, avaliou-se o número de aquênios germinados e o comprimento das radículas. Os resultados revelaram que os extratos de canola influenciam negativamente a germinação de aquênios e o comprimento da radícula de Bidens pilosa. Para alguns genótipos, as baixas concentrações de extratos estimularam tanto o crescimento da radícula quanto a porcentagem de germinação dos aquênios; em altas concentrações, os genótipos não diferiram na germinação dos aquênios e no comprimento da radícula.

Proteome-level changes in the roots of Brassica napus as a result of Plasmodiophora brassicae infection

Clubroot, caused by the obligate parasite Plasmodiophora brassicae, has emerged as an important new disease of canola ( Brassica napus) in Alberta, Canada. Changes in the root protein profile were examined by two-dimensional gel electrophoresis at 12, 24, 48 and 72 h after inoculation of a susceptible canola genotype with the pathogen. A total of 20 protein spots were identified as either increasing (13 spots) or decreasing (7 spots) in intensity relative to water-treated controls. The identities of these proteins were established by MS/MS, and included proteins involved in lignin biosynthesis, cytokinin metabolism, glycolysis, intracellular calcium homeostasis, and the detoxification of ROS. Decreased abundance of adenosine kinase, which is involved in cytokinin homeostasis, supported previous reports indicating a key role for cytokinin in the early phases of clubroot infection. An approximately sixfold reduction in caffeoyl-CoA O-methyltransferase abundance suggested a reduction in host lignin biosynthesis after pathogen challenge, and is consistent with the compatible nature of the interaction examined. Interestingly, levels of enzymes involved in ROS metabolism declined sharply at 12 h after inoculation, but increased at 24–72 h. Collectively, these data suggest major changes in canola metabolism shortly after challenge by the pathogen, which may result in the susceptibility of the host.

Growth, P uptake and rhizosphere properties of wheat and canola genotypes in an alkaline soil with low P availability

The aim of the present study was to assess the role of soil type on growth, P uptake and rhizosphere properties of wheat and canola genotypes in an alkaline soil with low P availability. Two wheat (Goldmark and Janz) and two canola genotypes (Drum and Outback) were grown in a calcareous soil (pH 8.5) at two P levels [no P addition (0P) or addition of 200 mg kg−1 P as Ca3(PO4)2 (200P)] and harvested at flowering or maturity. Shoot and root dry weight, root length and shoot P content were greater in the two canola genotypes than in wheat. There were no consistent differences in available P, microbial P and phosphatase activity in the rhizosphere of the different genotypes. Shoot P content was significantly positively correlated with root length, pH and phosphatase activity in the rhizosphere. The microbial community composition, assessed by fatty acid methylester analysis, of the canola genotypes differed strongly from that of the wheat genotypes. The weight percentage bacterial fatty acids, the bacteria/fungi (b/f) ratio and the diversity of fatty acids were greater in the rhizosphere of the canolas than in the rhizosphere of the wheat genotypes. In contrast to the earlier studies in an acidic soil, only small differences in growth and P uptake between the genotypes of one crop were detected in the alkaline soil used here. The results confirmed the importance of root length for P uptake in soils with low P availability and suggest that the rhizosphere microbial community composition may play a role in the better growth of the canola compared to the wheat genotypes.

Canola genotypes differ in potassium efficiency during vegetative growth

There is no knowledge about the differential capacity of canola genotypes to take up potassium (K) and produce dry matter under conditions of low soil K availability. Hence, 84 canola genotypes were screened for K efficiency in the glasshouse. Plants were grown in sealed pots containing K-responsive, sandy soil without or with K added. Twelve genotypes were selected for advanced screening in the glasshouse in a different K-responsive soil. Genotypes with a mean K efficiency ratio (the ratio of shoot dry weight at deficient and adequate K supply) greater than one standard error above or below the median genotype value were classified as K-efficient or K-inefficient, respectively. There were significant differences between genotypes in the K efficiency ratio in both screening experiments, indicating that genotypes responded differently to K availability. In the initial screening experiment, 19 genotypes were rated as K-efficient and nine genotypes rated as K-inefficient based on the K efficiency ratio. In the advanced screening experiment with 12 genotypes, three genotypes were rated as K-efficient and two as K-inefficient. Genotypes Wesbarker and Rainbow were K-efficient and Genkai K-inefficient in both experiments. Correlation of the K efficiency ratio with (i) shoot K content in the initial and advanced screening and (ii) shoot K concentration in the advanced screening, indicates that the observed differences in K efficiency were due to genotypic differences in both the uptake and the utilization of K. K-efficient genotypes have a potential to improve canola yields on soils with low K availability.

Interrelationship between yield and yield related traits of spring canola (Brassica napus L.) genotypes

The research was conducted in order to determine yield related characters which are more effective as selection criteria than yield itself. Three spring canola (Brassica napus L.) genotypes have been investigated for plant height, number of primary branches (including the main raceme), number of pods per plant, pod length, number of seeds per pod, seed weight per pod and 1000 seed weight and their correlations with seed yield per plant. Seed yield had highest correlation with number of pods per plant (r= 0.935 and r= 0.973 in Skopje and Strumica, respectively), followed by seed weight per pod (r= 0.693 and r= 0.729) and 1000 seed weight (r= 0.627 and r= 0.680). Path coefficient analysis was used to identify the direct and indirect effect of studied characters on seed yield. Number of pods per plant (p=0.759 and p=0.877 for Skopje and Strumica, respectively) and seed weight per pod (p=0.216 and p=0.225) had the highest direct effect on seed yield in both locations followed by 1000 seed weight (p=0.056 and p=0.010). The coefficient of determination (R2) was 0.943.

Brassica genotypes differ in growth, phosphorus uptake and rhizosphere properties under P-limiting conditions

Compared to other crops, Brassicas are generally considered to grow well in soils with low P availability, however, little is known about genotypic differences within Brassicas in this respect. To assess the role of rhizosphere properties in growth and P uptake by Brassicas, three Brassica genotypes (mustard, Brassica juncea cv Chinese greens and canola, Brassica napus cvs Drum and Outback) were grown in an acidic soil with low P availability at two treatments of added P: 25 and 100 mg P kg −1 as FePO 4 (P25 and P100). The plants were harvested at the 6-leaf stage, at flowering and at maturity. Shoot and root dry weight (dry weight) and root length increased with time and were lower in P25 than in P100. In P25, shoot dry weight was lowest in Outback and highest in Chinese greens. In the P100 treatment, Chinese greens had a higher shoot dry weight than the two canola cultivars. Chinese greens had a lower root dry weight and root length at flowering and maturity than the canola genotypes in both P treatments. Irrespective of P treatment, shoot P concentration was lower in Chinese greens than in the two canola genotypes. Specific P uptake (μg P m −1 root length) decreased with time. In P25, Chinese greens had the lowest specific P uptake at the 6-leaf stage but it was higher than in the two canola genotypes at flowering and maturity. In P100, Outback had the lowest specific P uptake. Available P in the rhizosphere (resin P) decreased over time with the greatest decrease from the 6-leaf stage to flowering. In P25, resin P in the rhizosphere was greatest in Chinese greens at the 6-leaf stage and flowering and smallest in Outback at flowering. Microbial P and acid phosphatase activity changed little over time, were not affected by P treatment and there were only small differences between the genotypes. The rhizosphere microbial community composition [assessed by fatty acid methyl ester (FAME) analysis] of Outback and Chinese greens differed from that of the other two genotypes at the 6-leaf stage and flowering, respectively. At maturity, all three genotypes had distinct microbial communities. Plant traits such as production of high biomass at low shoot P concentrations as well as the capacity to maintain high P availability in the rhizosphere by P mobilisation can explain the observed differences in plant growth and P uptake among the Brassica genotypes.

Genotype by environment interactions of Indian mustard ( Brassica juncea L.) and canola ( Brassica napus L.) in Mediterranean-type environments : II. Oil and protein concentrations in seed

The effects of genotype, environment and their interaction on oil and protein concentrations of seed in mustard and canola were investigated under field conditions in Mediterranean-type environments of south Western Australia over two seasons. Genotype, environment and their interactions showed large effects on oil and protein concentrations in both species. Oil and protein concentrations varied between crop species (mustard versus canola) and genotypes compared to those between environments. The effect of environment on protein concentrations was larger compared to that on oil concentration. The oil concentration ranged from 37.3 (Oscar) to 38 (887.1.6.1) and 40% (Monty). The protein concentration ranged from 22.9 (887.1.6.1) to 24.5 (Monty), 26 (Oscar) and 28.5% (Muscon). Variation in oil and protein concentrations between environments was largely accounted for by the interacting effects of total rainfall, post-anthesis rainfall, post-anthesis duration, average maximum post-anthesis and pre-anthesis temperatures and soil pH. Oil concentration of mustard and canola in Mediterranean-type environments was higher, but protein concentration was lower in environments where post-anthesis period was wetter and cooler. Seed oil concentration was inversely proportional to seed protein concentration in mustard and canola genotypes. Increase in seed yield increased the oil concentration, but decreased the protein concentration. Percentage increase in oil per unit increase in seed yield was higher in canola than in mustard genotypes, whilst percentage reduction in protein concentration per unit increase in seed yield was higher in mustard than in canola genotypes.

Agrobacterium-mediated transformation and generation of male sterile lines of Australian canola

An efficient protocol for Agrobacterium-mediated transformation of Australian commercial canola cultivars using seedling explants is described. Seedling explants provide flexibility and reduction in labour and maintenance costs of explant sources. Five commercial genotypes of canola were successfully transformed using the developed protocol. A transformation efficiency of 67% was obtained for genotypes Oscar and RK7 from cotyledon explants, which was higher than the rate for the most commonly used cultivar Westar (33%). Comparison of different seedling explants showed that although transgenic plants could be regenerated from all explant types (cotyledons, hypocotyls, and roots) used, the number of plants regenerated per explant type varied among the cultivars. Cotyledons produced the maximum number of transgenic shoots (RK7, RI25, Oscar, and Westar cultivars), whereas root explants produced the lowest numbers of shoots. Therefore, cotyledons and hypocotyls can be considered as ideal explants for the Agrobacterium-mediated transformation of these Australian canola cultivars. Integration and expression of the introduced transgene were analysed by DNA gel blot, leaf disc test, and GUS expression assays. Analysis of progeny showed that the transgene was stably inherited. The possibility of producing male sterile lines using an antisense approach was also explored. For this, Bcp1, a gene shown to be vital for viable pollen development, was targetted. Pollen ablation and lack of seed set were observed in the transgenic plants. Histochemical tests showed an intact tapetum layer and well developed pollen in control plants, whereas degraded tapetum and ablated pollen were noted in the transgenic plants. These results indicate that it is possible to generate stable transgenic male-sterile lines of canola using this strategy.

Análise de trilha dos componentes do rendimento de grãos em genótipos de canola

O caráter rendimento de grãos é uma variável de associação complexa, de importância econômica. Foi conduzido um ensaio no município de Lages-SC, no ano agrícola de 1996 no qual se utilizaram 12 genótipos de canola. O objetivo foi determinar a associação e os efeitos diretos e indiretos de alguns caracteres sobre a produção de grãos, através do estudo das correlações fenotípicas e pela análise de trilha. Utilizou-se o delineamento experimental em blocos casualizados, com quatro repetições. De acordo com os resultados obtidos, pode ser concluído que não há associação entre os caracteres estatura de planta com os caracteres massa de mil grãos e rendimento de grãos. A análise de trilha revelou que os componentes primários população de plantas por unidade de área e número de grãos por planta tem o maior efeito direto sobre a variável rendimento de grãos. Por outro lado, o caráter número de grãos por planta é o maior responsável pelo aumento massa de mil grãos. O coeficiente de trilha evidenciou que o componente secundário número de grãos por síliqua tem o maior efeito direto sobre o rendimento de grãos.

Secondary dormancy, temperature, and burial depth regulate seedbank dynamics in canola

Abstract In western Canada, seasonal seedling recruitment has been reported in weedy canola populations, and seed persistence has been linked to the secondary seed dormancy potential of a genotype. Temperature influences secondary seed dormancy induction in this species. In these experiments we (1) investigated the influence of temperature and osmotic potential on secondary seed dormancy induction in canola, (2) related these to seedbank dynamics and seedling recruitment of two canola genotypes with different seed dormancy potentials in the field, and (3) investigated the influence of residue, burial depth, and soil type on seedbank dynamics and seedling recruitment in the field. In the laboratory, rates of seed dormancy induction were positively correlated to increasing temperatures and water stress. The role of temperature was approximately threefold more important to seed dormancy development than was osmotic potential within the tested ranges of these variables. In the field, seasonal seedbank dynamic...

Yield and Oil Content of Various Canola (Brassica napus L.) Genotypes under Rawalakot, Azad Jamu and Kashmir Conditions

Yield and Oil Content of Various Canola (Brassica napus L.) Genotypes under Rawalakot, Azad Jamu and Kashmir Conditions

In vitro shoot regeneration from commercial cultivars of Australian canola (Brassica napus L.)

Canola, (Brassica napus L.) is an important crop in Australia. Large genetic variability in the Australian canola cultivars is reflected by their diverse agronomic characteristics. Further improvement using modern breeding methods will lead to the generation of better canola varieties suited for Australian conditions. Genetic engineering relies on the development of efficient methods for regeneration of viable shoots from cultured tissues, and the successful application of transformation techniques. This study reports the in vitro shoot regeneration potential from seedling explants of 7 commercial genotypes (Dunkeld, Grouse, RK7, RI25, Oscar, Rainbow, and Monty) of Australian canola. Seedling explants of these genotypes were all responsive to shoot regeneration. Total number of shoots regenerated varied significantly among the 7 genotypes. Based on the number of shoots regenerated, Rainbow was found to be the most amenable to in vitro regeneration with 55% of cotyledon explants regenerating 2.47 shoots per explants on shoot initiation medium containing 6-benzylaminopurine (3 mg/L), 1-naphthylacetic acid (0.2 mg/L), and gibberellic acid (0.01 mg/L). Normal fertile canola plants from all the 7 genotypes were regenerated. The results obtained from this study will form the basis for genetic transformation studies.

Secondary seed dormancy prolongs persistence of volunteer canola in western Canada

In western Canada, little is known about the seedbank ecology of volunteer canola. Therefore, integrated recommendations for the management of this weed are limited. In this study, we investigated the seedbank persistence and seedling recruitment of two spring canola genotype groups with different secondary seed dormancy potentials under contrasting tillage systems. The study was conducted at two locations with different soils in the Mixed Moist Grassland ecoregion of Saskatchewan. A single cohort seedbank was established in 1999 and was followed for 3 yr in successive wheat crops. In a separate laboratory study, the six canola genotypes examined were classified as those with high and those with medium potentials for the development of secondary seed dormancy (HD and MD, respectively). After one, two, and three winters, maximum persistence of 44, 1.4, and 0.2% of the original seedbank was observed among the treatments, respectively. In 2001, HD canola genotypes tended to exhibit 6- to 12-fold greater persistence than MD canola genotypes, indicating lower seedbank mortality in HD canola. Seedling recruitment of HD canola also was higher than MD canola when differences were observed between these genotype groups. Therefore, long-term seedbank persistence of canola can be reduced by growing genotypes with low inherent potential for the development of secondary seed dormancy. The proportion of persisting seeds tended to be higher under conventional tillage than under zero tillage because of lower seedbank mortality, but no clear distinction in seedbank persistence in terms of absolute time could be made between these two tillage systems. Volunteer canola seedling recruitment followed the pattern of a typical summer-annual weed, where seedling emergence was observed only during May and June.