Spring Canola Research Articles

Selenium accumulation in durum wheat and spring canola as a function of amending soils with selenite, selenate and or sulphate

Aims A comparison was performed between plant species to determine if extractable, rather than total soil Se, is more effective at predicting plant Se accumulation over a full growing season.

Review: Breeding spring canola (Brassica napusL.) by the use of exotic germplasm

Rahman, H. 2013. Review: Breeding spring canola ( Brassica napus L.) by the use of exotic germplasm. Can. J. Plant Sci. 93: 363–373. The need of broadening genetic diversity in spring canola (Brassica napus) breeding programs seems to be the general consensus among canola breeders and researchers. Diversity analysis by the use of molecular markers has identified several B. napus gene pools as well as allied Brassica species that are genetically distinct from spring canola B. napus; and these gene pools can be used for the improvement of this crop. Use of genetically diverse and un-adapted B. napus germplasm in the breeding of spring canola can be challenging, as introduction of several unwanted traits/alleles from exotic germplasm into spring canola occurs, and this would require repeated cycles of breeding for improvement. Similarly, use of allied species can be even more challenging due to the difficulties associated with interspecific hybrid production, sterility of hybrids, linkage drag, and the introduction of unwanted alleles. However, this can be compensated in the long-term perspective for the improvement of this crop. Some research efforts have been made in recent years to broaden allelic diversity in spring canola for the improvement of seed yield and other traits in open-pollinated and hybrid cultivars with promising results. Seed yield is a complex trait which is controlled by several gene loci with multiple alleles at these loci as well as interactions between loci and different alleles. This makes the identification of right allelic combinations an extremely challenging task. However, canola breeders have been able to make steady improvements in this crop in past decades based on the amount of allelic diversity present in existing breeding material. Introduction of favourable new alleles in breeding programs would allow breeders to create superior allelic combinations, enhancing the diversity in current breeding materials to further improve the crop. With the availability of the Brassica genome sequence, knowledge of sequence variation in specific genes and cost-effective high-throughput genotyping, it is expected that molecular plant breeding will play an important role in the breeding of canola cultivars. Discovery of favourable allele combinations in a short span of time is likely to be facilitated through the application of modern breeding tools.

Replacing Fallow with Continuous Cropping Reduces Crop Water Productivity of Semiarid Wheat

Water supply frequently limits crop yield in semiarid cropping systems; water deficits can restrict yields in drought‐affected subhumid regions. In semiarid wheat (Triticum aestivum L.)‐based cropping systems, replacing an uncropped fallow period with a crop can increase precipitation use efficiency but reduce wheat productivity. Our objective was to analyze crop sequence and environmental effects on water use, components of water productivity, and net returns of winter wheat (WW) in a semiarid region. A field study was established to evaluate eight 3‐yr crop sequences, including a wheat phase followed by a feed grain phase (corn [Zea mays L.] or grain sorghum [Sorghum bicolor (L.) Moench]) and an oilseed phase (OS; spring canola [Brassica napus L.], soybean [Glycine max (L.) Merr.], sunflower [Helianthus annuus L.], or none [fallow]). Standard measurements included crop water use (WU), canopy leaf area index at anthesis, biomass, grain yield, and yield components. Net return (NR) was calculated as the difference between crop revenue and total operating costs. Replacing an uncropped fallow period with an OS crop reduced water productivity responses of WW (biomass, grain yield, and NR) by 18, 31, and 56%, respectively, relative to that of WW grown after fallow. These responses to continuous cropping corresponded to reductions in all components of a water‐limiting yield production function. The modest water productivity observed (0.28–0.62 kg m−3), relative to a reported global range of 0.6 to 1.7 kg m−3, indicates opportunity to improve wheat water productivity through management and genetic gain.

Investigation of correlation yield and yield components of 12 spring canola Hybrids in Iranshahr climatic region

In order to survey investigation of correlation yield and yield components of 12 spring canola hybrids in Iranshahr climatic region, an experiment was conducted in Agricultural and Natural Resources of Balouchestan Research Center, during 2009-2010 based on, randomized complete block design (RCBD) with 4 replications. The experiment of 12 spring canola hybrids provided by Karaj Research Institute of improvement and Provision of Saplings and Seeds includes; Hyola 43, Hyola 60, Hyola308, Hyola 308.3, Hyola 308.8, Hyola 330, Hyola401, Hyola 401.15E, Hyola 420,19-H,Syn-2, Syn-3.The characteristics considered in the present study are as follow; grain yield, oil yield, oil percent, 1000 seeds weight, number of: pods per plant, seeds per pod, days to flowering, days to harvest and the length of ripening period were seen among genotypes. The results of variant analyses showed that their characteristics in all of them had meaningful differences. Comparing average grain yield revealed that Hyola 401 had the most grain yield (4755 kg /h) and Hyola 308.3 had the least grain yield (1547 kg /h) in Iranshahr climatic region. Considering number of pods per plant Hyola 308.3, Hyola 420 with 104.3 and 87 pods respectively have the highest amount, but Hyola 330 , H_19 with 43 and 43.25 average number of pods per plant have the lowest amount. Considering number of seed per pod Hyola 308 , syn-3 with 34.25 and 33.75 have the highest number ,but Hyola 308.3 , Hyola 401.15E with 25 and 19.75 average number of seed per pod have the lowest one. Considering the number of seed per pod Analyses of simple correlation between characteristics confirmed that the average of 1000 seeds weight and the length of ripening have a positive and meaningful correlation with the grain and oil yield, However growth period has a negative and meaningful correlation with oil and grain yield. Key words: Canola (Brassica napus L.), cultivar, correlation, yield, yield components.

First Report of Root Rot Caused by Rhizoctonia solani AG-10 on Canola in Washington State.

Canola (Brassica napus L) production has gained renewed interest in Washington State over the past few years, primarily for the purpose of producing biofuel. Plants were observed to be showing symptoms of Rhizoctonia root rot and postemergence damping-off. In many cases, this was due to Rhizoctonia solani AG-2-1, which was previously documented (4). However, additional plants were occasionally observed that were stunted and had reduced vigor, but lacked the distinctive severe stem damage and postemergence damping-off, which are both symptoms of infection with R. solani AG-2-1. Isolates of R. solani AG-10 were collected from symptomatic plants or baited from root zone soil at various dryland production locations in eastern Washington, including sites near Colfax, Pullman, and Walla Walla. Initial identification was determined by quantitative (Q)-PCR using R. solani AG-10 specific primers (3). The identity was verified by sequencing random isolates identified by Q-PCR (GenBank Accessions Nos. JQ068147, JQ068148 and JQ068149). All sequenced isolates had 99% identity to previously reported isolates of R. solani AG-10. Six isolates were chosen to test pathogenicity on canola plants in the greenhouse. Sterilized oats were inoculated with each of six isolates of R. solani AG-10 and grown for 4 weeks. The soil was infested with ground oat inoculum (1% wt/wt) and spring canola cv. Sunrise was seeded into 3.8 × 21-cm containers. After 3 weeks of incubation at 15°C, plants were harvested and assessed. Emergence was reduced in the infested soil with 73 to 93% (average 81%) emergence compared with 100% emergence in the noninfested soil. There was no evidence of postemergence damping-off. However, all six isolates of R. solani AG-10 significantly reduced the plant height and top dry weights compared with the noninfested controls. The plant height in infested soil was 28 to 42% (average 34%) shorter and top dry weights were 37 to 70% (average 54%) lower than in noninfested soil. Roots of infected plants had a light brown discoloration along with reduced length and fewer lateral roots. Additional host plants were tested, including wheat (Triticum aestivum L.), barley (Hordeum vulgare L.), pea (Pisum sativum L.), chickpea (Cicer arietinum L.), and lentil (Lens culinaris Medik.). There was no significant reduction in plant height or plant dry weight for any of these hosts. R. solani AG-10 was previously found to be weakly virulent on canola and other cruciferous hosts in Australia (1,2). To our knowledge, this is the first report of R. solani AG-10 causing disease on canola in Washington State. Reference: (1) R. K. Khangura et al. Plant Dis. 83:714, 1999. (2) G. C. MacNish et al. Australas. Plant Pathol. 24:252, 1995. (3) P. A. Okubara et al. Phytopathology 98:837, 2008. (4) T. C. Paulitz et al. Plant Dis. 90:829, 2006.

Reaction to Plasmodiophora brassicae Pathotype 6 in Lines of Brassica Vegetables, Wisconsin Fast Plants, and Canola

Field trials were conducted from 2008 to 2010 to assess the disease reaction to clubroot, caused by Plasmodiophora brassicae Woronin, in selected lines of Brassica spp., including short-season vegetable crops [Shanghai pak choy (B. rapa subsp. Chinensis var. communis)], Chinese flowering cabbage (B. rapa subsp. Chinensis var. utilis), and napa cabbage (B. rapa subsp. Pekinensis), the Rapid Cycling Brassica Collection (RCBC), also known as Wisconsin Fast Plants, and spring canola (B. napus). The trials were conducted on naturally infested soil with P. brassicae at the Muck Crops Research Station in Ontario, Canada, where pathotype 6 is predominant. Clubroot incidence and severity were higher in 2008 and 2010 compared with 2009. The lines of Shanghai pak choy and Chinese flowering cabbage were highly susceptible to clubroot, but each of the clubroot-resistant cultivars of napa cabbage, ‘Deneko’, ‘Bilko’, and ‘Yuki’, was highly resistant to pathotype 6. Among the RCBC lines, B. carinata and B. juncea were highly susceptible and could be used as susceptible models for further studies. Two RCBC lines, B. napus and R. sativus, were resistant to pathotype 6. Two of the canola cultivars, 46A76 and 46A65, were susceptible, but two others, ‘45H21’ and ‘Invigor 5020LL’, were highly resistant to pathotype 6. This difference in response can be exploited in future studies of clubroot reaction in canola.

Improvement of spring canola Brassica napus by use of winter canola

Further improving of seed yield, other agronomic and seed quality traits in spring canola Brassica napus requires broadening of genetic diversity in this crop. The European winter oilseed B. napus is known to be genetically diverse from spring oilseed B. napus. We hypothesized that elite spring canola B. napus lines with greater seed yield and genetic diversity can be achieved through the use of European winter B. napus. For this, a winter x spring B. napus breeding program was undertaken at the University of Alberta, and pedigree and doubled haploid breeding techniques were applied. Spring canola lines with significantly increased seed yield were obtained in one cycle of breeding. Estimates of genetic diversity based on SSR markers revealed that some of the spring canola lines derived from winter x spring crosses possess greater diversity compared to the spring parents. The major constraint of this winter x spring breeding is that lateness of flowering and maturity are generally introduced into the spring type lines which would require repeated cycle of breeding for improvement.

Refining crop and livestock management for dual-purpose spring canola (Brassica napus)

Dual-purpose canola (Brassica napus) describes the use of a canola crop for grazed winter forage before seed production, a practice that has only recently been developed in southern Australia. Long-season winter canola has been grazed without yield penalty in higher rainfall zones of Australia (>650 mm) and the USA, but the potential areas are small. The feasibility to graze spring canola varieties across wider areas of the medium-rainfall (450–650 mm), mixed-farming zone in Australia is therefore of interest. We conducted a series of six field experiments involving a range of canola cultivars and grazing management and agronomy systems from 2007 to 2009 at Young in southern New South Wales, Australia, to determine the feasibility of and refine the principles for grazing dual-purpose spring canola without significant yield penalty. Mid-season, Australian spring canola cultivars including conventional and hybrid varieties representing a range of herbicide tolerance (triazine-tolerant, Clearfield®, and Roundup Ready®) were sown from 16 April to 12 May and grazed with sheep at a range of growth stages from early vegetative (June) to mid-flowering (September). In general, early-sown crops (sown mid-April) provided significant grazing (~800 dry sheep equivalent grazing days/ha) in winter before bud elongation, and recovered with no impact on grain yield or oil content. As previously reported, yield was significantly reduced (by up to 1 t/ha) when grazing occurred after buds had elongated (late July), due to the delayed flowering associated with bud removal by sheep and insufficient time for biomass and yield recovery. However, yield was also reduced in crops grazed before bud elongation if insufficient residual biomass remained (<1.0 t/ha for late July lock-up) to facilitate crop recovery even when there was little delay in crop development. We suggest that refinements to the existing ‘phenology-based’ grazing recommendations would assist to avoid yield loss in grazed spring varieties, and propose three grazing stages (safe, sensitive, and unsafe) that integrate the impacts of time, crop growth stage, residual biomass, and seasonal conditions to avoid yield loss under different circumstances. Such refinements to reduce the likelihood of grazing-induced yield loss would provide more confidence for mixed farmers to maximise the benefits from dual-purpose canola in different environments. Based on the outcomes of these experiments, dual-purpose spring canola is likely to have significant potential for wider application in other mixed farming zones, with similar region-specific refinements based on the principles reported here.

Effect of Planting Methods on Spring Canola (Brassica napus L.) Establishment and Yield in the Low-Rainfall Region of the Pacific Northwest

Growers are becoming interested in producing canola (Brassica napus or B. rapa) in the dryland, wheat-fallow region of the Pacific Northwest. Currently, agronomic research for spring canola in this region has not been initiated. This study evaluated the effect of no-till planting methods on stand establishment, crop yield, and seed oil quantity of spring canola in Washington and Oregon in 2009 and 2010. The treatments included: double disk opener; broadcast; broadcast plus rolled; Kile opener; Cross-Slot opener; and hoe opener (at Washington only). In this study, canola establishment was generally greatest with the double disk opener and least in the broadcast or broadcast plus rolled treatments at all four site-years. Yield was least in the broadcast treatment and rolling broadcast seed increased yield only 50% of the time. In three out of four site-years, canola planted with the various no-till openers yielded higher than broadcast seed. The adoption of spring canola in the wheat-fallow region of the Pacific Northwest would improve pest management strategies, diversify markets, and increase sustainability.

The effect of transpiration on selenium uptake and mobility in durum wheat and spring canola

Aims The objective of this study was to determine the relative importance of transpirational pull, Se speciation, sulfate and species on Se accumulation by plants, in order to determine which of these factors must be considered in the future development of models to predict Se accumulation by plants.

The effect of transpiration on thallium uptake and mobility in durum wheat and spring canola

The effect of transpiration on thallium uptake and mobility in durum wheat and spring canola

Physiological response of spring canola ( Brassica napus) to defoliation in diverse environments

Canola ( Brassica napus) has recently been developed for dual-purpose use where vegetative biomass is removed by grazing animals, after which the crop recovers and is harvested for grain. Maintaining seed yield depends upon the timing and extent of defoliation in relation to plant development and the seasonal conditions for recovery and regrowth. We sought insights into the physiological basis for crop recovery and seed yield following defoliation using detailed growth analysis of plants defoliated in the diverse environments of southern Australia (35°S) and eastern Canada (45°N). The crop was defoliated by grazing with sheep in Australia and cutting by hand in Canada. Although canola development progressed more rapidly in the warm, long-day summer growing season of eastern Canada, developmental stages and biomass accumulation progressed at similar rates on the basis of photothermal time using a base temperature of 0 °C. Hybrid, conventional, and triazine-tolerant canola cultivars, with inherently different growth rates but similar phenology, showed little difference in their response to defoliation at any site. At all sites, recovery after defoliation was characterised by a rapid recovery in the absolute growth of leaves, a sustained reduction in stem biomass, but little impact on pod biomass. Despite this rapid recovery in leaf growth rates, leaf area and biomass in defoliated treatments recovered to only 50% of un-defoliated treatments prior to leaf drop, and reduced stem growth was manifested in reduced plant height (20–30 cm) at all sites. Despite the lack of response to defoliation in pod growth rate across all sites, final seed yield was reduced by defoliation in both years at Ottawa (by 0.6 t ha −1 or 25%) but not at the two Australian sites (Young and Wagga Wagga), except when the crop was affected by severe post-flowering water stress. Overall, the results from the Australian sites support previous observations of complete seed yield recovery in crops defoliated in the vegetative stage, provided sufficient time and reasonable conditions allow sufficient biomass recovery to fulfil the water-limited seed yield potential. In contrast, the Canadian crops did not recover seed yield following defoliation despite similar peak LAIs and more favourable regrowth conditions. Later defoliation after bud elongation, combined with accelerated development prevented the recovery of leaf area and biomass and reduced assimilation during pod-fill in defoliated plants.

DISTRIBUTION OF SECONDARY METABOLITES IN BRASSICA NAPUS GENOTYPES

ABSTRACT Secondary metabolites (flavonoids and phenolics) in the methanolic extracts of Brassica napus genotypes, spring and winter canola were evaluated. Antioxidant activity of the extracts was evaluated by β-carotene linoleic acid model system, scavenging ability of hydrogen peroxide (H2O2) assay and cupric reducing antioxidant capacity (CUPRAC) assay. Also, total flavonoid contents of the extracts were determined by aluminum chelating method. Results showed that naringin and eriodictyol were found to be in both species. Data showed that winter canola exihibited high antioxidant capacity with 60.6 ± 0.4% in β-carotene linoleic acid model system and also CUPRAC value (4.18 ± 0.11 mM TEAC/g) and scavenging ability of H2O2 (57.12 ± 1.13%) was higher than spring canola. However, total flavonoid content of spring canola was higher than that of winter canola. Both canola species may be of importance in variety improvement, nutraceuticals, bio-pharmaceuticals and food additives as natural antioxidants. PRACTICAL APPLICATIONS This study reveals antioxidant activity of the methanolic extracts of Brassica napus genotypes, spring and winter canola seeds growing in Turkey, measured by various assays including by β-carotene linoleic acid model system, scavenging ability of hydrogen peroxide assay and cupric reducing antioxidant capacity (CUPRAC) assay. Total flavonoid contents of the extracts were also measured as quercetin equivalent by aluminum chelating method. Secondary metabolites of the extracts of Brassica napus genotypes were analyzed by high-performance liquid chromatography.

Breeding for clubroot resistant spring canola (Brassica napusL.) for the Canadian prairies: Can the European winter canola cv. Mendel be used as a source of resistance?

Rahman, H., Shakir, A. and Hasan, M. J. 2011. Breeding for clubroot resistant spring canola (Brassica napus L.) for the Canadian prairies: Can the European winter canola cv. Mendel be used as a source of resistance? Can. J. Plant Sci. 91: 447–458. Canola (Brassica napus L.) cultivars resistant to clubroot disease, caused by Plasmodiophora brassicae, are desired by the Canadian canola growers. Different genotypes of its two parental species B.rapa and B. olaeacea carry resistance to this disease. Furthermore, the European winter canola cultivar Mendel, which was bred through introgression of resistance from its parental species, also carries resistance to P.brassicae pathotypes prevelent in Europe. The objective of this study was to investigate the usefulness of resistance of Mendel for the development of clubroot-resistant canola cultivars for the Canadian prairies. For this, crosses between Mendel and two Canadian spring canola lines were made and pedigree breeding was followed. Plants with spring growth...

72P01 CL Clearfield herbicide-tolerant spring canola

Rahman, H., Stringam, G. R. and Degenhardt, D. F. 2011. 72P01 CL Clearfield herbicide-tolerant spring canola. Can J. Plant Sci. 91: 527–528. 72P01 CL is a Clearfield herbicide-tolerant canola-quality Brassica napus L. cultivar registered in Canada in 2007. On average, 72P01 CL yielded 7% more seed and flowered 2 d earlier than the WCC/RRC check cultivars. Seed oil and meal protein content of 72P01 CL are similar to the WCC/RRC checks. Thus, 72P01 CL combines high seed yield with earliness of flowering, while retaining other desired traits at an acceptable level.

Usefulness of winter canola (Brassica napus) race-specific resistance genes against blackleg (causal agent Leptosphaeria maculans) in southern Australian growing conditions

Studies on the blackleg resistance of Brassica lines containing known race-specific, Rlm resistance genes can provide information on the potential use of these genes in the genetic improvement of Australian spring canola lines. Lines of four Brassica species (winter B. napus, B. nigra, B. juncea, B. rapa) containing one or more known specific Rlm genes were assessed for seedling and adult plant survival, on infected stubble derived from crops of both polygenic and B. rapa ssp. sylvestris resistance types, to determine their potential usefulness as sources of blackleg disease resistance in diverse environments in southern Australia. Seedling and adult plant resistance of lines differed depending on the stubble type used. The seedling and adult plant blackleg resistance of several lines containing the resistance genes Rlm1, Rlm1/Rlm3, Rlm7, and Rlm10 was consistently higher than the control line, AV-Sapphire, which carries polygenic resistance. The superior performance of these lines indicates that winter B. napus and B. nigra lines have outstanding potential for improving blackleg disease resistance under Australian conditions.

Adapting CROPGRO for Simulating Spring Canola Growth with Both RZWQM2 and DSSAT 4.0

Currently, canola (Brassica napus L.) is gaining importance as a potential feedstock in biodiesel production industries, increasing the demand for canola production acreage. Agricultural system models that simulate canola growth and yield will help to assess the feasibility of canola production under various agroclimatic conditions. In this study, we adapted the CROPGRO model for simulation of spring canola in both Root Zone Water Quality Model (RZWQM2) and Decision Support System for Agrotechnology Transfer (DSSAT 4.0). Soil water, phenology, leaf area index (LAI), biomass, plant height, and grain yield data from irrigation experiments conducted in 2005 on a Weld silt loam soil (fine, smectitic, mesic Aridic Argiustoll) in the semiarid climate at Akron, CO were used for model parameterization and calibration. Similar data from 1993, 1994, and 2006 were used for validation. Species and cultivar parameters for canola were developed using data from literature or by calibrating the existing CROPGRO‐faba bean (Vicia faba L.) parameters. Grain yields across various irrigation levels and seasons were simulated reasonably well by RZWQM2 with root mean square error (RMSE) of 215 kg ha−1 and index of agreement (d) of 0.98. Seasonal biomass development was simulated with RMSEs between 341 and 903 kg ha−1, d between 0.55 and 0.99, and R2 between 0.85 and 0.98. The CROPGRO‐canola parameters developed were also tested within the DSSAT 4.0 cropping systems model and found to produce results with similar accuracy.

Adaptability of irrigated spring canola oil production to the US High Plains

Canola oil is high in oleic acid which is commonly used for food and industrial purposes. To determine adaptability of spring canola (Brassica napus L.) to the High Plains for industrial oil production, 26 irrigated trials were conducted from 2005 to 2008. Trials were divided into five regions—1: 36–37°N 108°W; 2: 39–40°N 101–103°W; 3: 41–42°N 102–103°W; 4: 41–42°N 104°W; 5: 43–44°N 106–108°W. Cultural practices were based on site-specific protocols. Four cultivars, Hyola 401, Hyola 357 Magnum, SW Marksman, and SW Patriot, were planted in replicated plots in April or May under standard irrigation and harvested in July to October depending on region. Seed yield Hyola 401 and Hyola 357 Magnum were higher than SW Marksman and SW Patriot across the five regions and within Regions 1, 2, 3, and 5. Regions 1, 2 and 3 yielded significantly greater than did Regions 4 and 5. Samples from 18 trials were examined for their oil content and fatty acid distribution. The four cultivars had greater than 38% oil content; SW Marksman and SW Patriot had higher oil content than Hyola 401 and Hyola 357 Mag. Higher oil content was achieved in Regions 1, 4 and 5. Across and within regions, the percent of oleic acid did not differ for the four cultivars. The mean content of oleic acid decreased going north from Region 2 to Region 5, as did seed yield in the High Plains. Linoleic acid increased going north from Region 1. Linolenic acids showed little variation across regions. Considering yield and total oil content together, growing spring canola would be excellent in the High Plains.

Determining the fluxes of Tl+ and K+ at the root surface of wheat and canola using Tl(I) and K ion-selective microelectrodes

The objectives of this study were to develop and evaluate a Tl+ ion-selective microelectrode (ISME) and to determine the basis for observed differences in Tl accumulation by durum wheat (Triticum turgidum L. var ‘Kyle’) and spring canola (Brassica napus L. cv ‘Hyola 401’). Seedlings were grown hydroponically and fluxes of K+ and Tl+ were measured at the root surface in solutions containing 5 μM Tl+ or 3 mM K+. After testing two different Tl(I) ionophores, a functional Tl+ ISME was developed from calix[4]arene tetra-n-propyl ether which had a detection limit of 2.5 µM and a slope of 56.6 mV/dec. Measurements of Tl+ flux indicate that Tl+ efflux occurred within 300–500 µm of the root tip, and influx farther from the root tip. Compared with canola, wheat had a slightly larger region of efflux and a smaller region of maximal influx, resulting in flux per root branch that was 2.3 to 4 times greater in canola than in wheat. The magnitude and pattern of K+ fluxes by the two species were more similar. Our results indicate that observed differences in Tl accumulation by wheat and canola are due both to differences in the magnitude of Tl flux per root branch of these species, and to differences in root morphology resulting in more root tips in canola than in wheat roots.

STUDIES ON DIFFERENTIAL RESPONSE OF SPRING CANOLA CULTIVARS TO BORON TOXICITY

Although many states recommend boron (B) fertilizer for many field crops, information about B toxicity of canola is lacking. This experiment was carried out at Central Anatolia, Turkey from 2002 to 2003, to determine genotypic range in B efficiency of eight spring canola cultivars, to identify the B-inefficient cultivars and to identify specific responses. The cultivars were grown under B moderate deficiency (extractable B 0.56 mg kg−1) and toxic B applied (15 kg B ha−1) conditions. According to the results, seed yield varied significantly among the cultivars and B application decreased the seed yield by 31% on average. Also, toxic B application reduced protein and oil contents similar to seed yield, and increased leaf B concentration in all varieties. This study has shown that leaf B concentration has increased considerably when B is applied to Pactol and Star cultivars, but seed yield of +B and −B has not shown significantly a change. It is possible to say that Star and Pactol—which have not been affected by the toxic B application—are genotypes that are tolerant to B toxicity and may be cultivated at B toxic lands.