Clubroot is a worldwide soil-borne disease caused by Plasmodiophora brassicae, under the division of protist with certain similarity to flagellates. In recent years, the incidence of clubroot disease in the main rapeseed cultivation regions in China has increased significantly, posing a serious threat to rapseseed production. Breeding and cultivation of clubroot resistant varieties is the key to solving this problem. In this paper, we briefed the infection process of clubroot pathogen, described the current status on the clubroot resistance (CR) genes mapping and the breeding of Brassica napus CR varieties in China, and how these varieties have been utilized. We also discussed the main problems to be solved in the future in clubroot-resistance breeding and provide possible solutions. These gene resources and genetic materials were expected to be useful references for future breeding work and for supporting rapeseed industry.
Oilseed rape straw contains rich nutrition and has high value of fertilizer. A systematic review is necessary on current status and research progress of fertilizer utilization of oilseed rape straw in China. In this paper, we synthesized straw resource ledger data from the Ministry of Agriculture and Rural Affairs and literatures, thus to systematically analyze the nutrient foundation, utilization status, research progress, and problems of oilseed rape straw fertilizer utilization in China. We proposed countermeasures and suggestions afterwards. Results showed that contents of phosphorus, potassium and other elements in rapeseed straw were relatively high. In 2022, the fertilizer utilization of oilseed rape straw in China was 15.91 million tons (excluding Hong Kong, Macao, and Taiwan), mainly for directly returning to the field. The production of organic fertilizer from rapeseed straw and its combination with feed and base materials were also important parts. The fertilizer utilization of oilseed rape straw promotes soil nutrient supplementation, soil texture improvement, heavy metal adsorption, leading to crop yield increase. In the future, it is necessary to strengthen researches on rapid decomposition technology of oilseed rape straw, integration of returning technology models, and development of efficient equipment.
Guangxi is an emerging production area of three-cropping oilseed rape in the south of the Yangtze River in China. Its rape planting area is increasing year by year, and the development potential is huge. This paper reviewed the current situation of rape industry in Guangxi from aspects of planting area and yield, regional distribution, cultivars and technology. Problems of rape industry in Guangxi were analyzed, including low yield per unit area, lack of excellent varieties, cultivation techniques to be improved, insufficient industrial support and multi-functional utilization. Suggestions included diversified development of the industry from strengthening the breeding and popularization of rapeseed varieties with short growth period in Guangxi and increasing policy support.
In order to investigate the impact of agricultural mechanization on rapeseed yield, we empirically analyzes the impact, mechanism and heterogeneity of agricultural mechanization operations on the expanding area and increasing production of rape based on panel data of 16 regions in Hubei Province from 2010 to 2022. We find that agricultural mechanization operations could significantly increase rape yield. Moreover, this conclusion still holds after using instrumental variable method and a series of robustness tests. Mechanism analysis shows that agricultural mechanization operations mainly increase rape production by expanding rape planting area. The improvement effect gradually increases as planting area expands, although the path is not obvious through which agricultural mechanization operations improve rape production by increasing rape yield per unit area. Moreover, the yield increasing effect is diverse in different agricultural mechanization operation links. The effects are specifically manifested as machine tillage service > machine harvesting service > machine sowing service. We recommend that policy should include vigorously promotion on mechanization level of rape production, increasing support for key processes such as machine sowing, machine harvesting, and field management (fertilization, pesticide application, irrigation and drainage), help on reducing costs and increasing efficiency. Other policy recommendations include developing various forms of moderate-scale operations as family farms, farmer cooperatives, leading agricultural enterprises, and socialized agricultural services.
To characterize BnaGA1 genefunctionin Brassica napus, which is homologous to Arabidopsis thaliana GA1 gene, phylogenetic and expression pattern analysis of BnaGA1 were conducted. CRISPR/Cas9 technology was employed to generate BnaGA1 knockout mutants. Results showed 3 GA1 homologs in B. napus var. Westar. Among them, BnaA09.GA1 and BnaC09.GA1 exhibited similar gene structures and expression patterns, with noticeable expression levels in all tissues other than roots. Conversely, BnaA03.GA1 was nearly not expressed in the tissues detected. Phenotypic analysis on single-mutants bnaga1a09 and bnaga1c09, and double-mutant bnaga1 revealed that phenotype of bnaga1c09 was not obviously different from wild type, whereas plant height of bnaga1a09 was significantly reduced, accompanied with symptoms of gibberellin deficiency such as darker leaf color and delayed flowering. In double-mutant bnaga1, active gibberellins contents of GA3 and GA4 were significantly lower than that of wild type, and its phenotype was more obvious than bnaga1a09. Additionally, the elongation of its hypocotyl was inhibited, but this inhibition could be recovered by application of exogenous GA3. RNA-Seq results indicated that the differentially expressed genes between double-mutant bnaga1 and Westar were significantly enriched in metabolic pathways including cutin, suberin and wax biosynthesis, as well as plant-pathogen interaction. This research was expected to provide more support for elucidating crucial role of gibberellin biosynthetic gene BnaGA1 in B. napus development.
To provide technical support for development and protection of rapeseed varieties, a set of low-cost, efficient, and accurate KASP markers were established for Brassica napus variety identification. All 180 KASP markers were developed from 203 markedly polymorphic SNP loci from previous researches. 94 inbred lines and 181 accessions of national winter rapeseed trials in 2019-2020 were used for screening and verification of KASP markers. After filtering, 90 high-quality KASP markers were obtained for DNA fingerprinting of rapeseed accessions, with an average minor allele frequency, PIC (polymorphism information content), and heterozygosity of 0.20, 0.24, and 0.26, respectively. Phylogenetic and population structure analyses showed that the 181 accessions could be classified into 6 clusters, and each cluster contained accessions from distinct region trial groups. Based on high discrimination power, the combination of 25 KASP markers was enough to distinguish 174 accessions with more than 2 different loci. This study provided a precise, rapid and convenient KASP-based procedure with 90 SNP loci for rapeseed genetic diversity analysis and variety identification, which could have a broad application prospect in future molecular breeding and variety protection.
To better understand self-compatibility (SC) and self-incompatibility (SI), pollen germination medium and culture conditions of Arabidopsis and Chinese cabbage were improved.By improving in vitro pollen germination medium and culture conditions in Arabidopsis thaliana and Chinese cabbage, we developed a semi-in vitro pollination medium for Brassica napus and optimizing pollen germination conditions, and set up a semi-in vitro pollination method for B. napus. Results showed that at 22-23℃ and humidity of 48%-53%, bundles of pollen tubes could be observed 4 h after compatible pollination, while almost no pollen germinated at 4 h after incompatible pollination, indicating that the semi-in vitro pollination system could be used for B. napus self-compatibility (SC) and self-incompatibility (SI) research. Furthermore, by adding antisense oligonucleotides targeting self-(in)compatibility key recognition genes BnaSRK and BnaEXO70A1 to the culture medium, after 4 h of semi-in vitro pollination, 55.7% and 27.4% of rapeseed pollens adhered and germinated respectively. This indicated that inhibiting expression of these 2 key genes might affect self-(in)compatibility. After adding 10 mmol/L ethephon to the culture medium, the semi-in vitro pollination results showed approximately 77.4% of rapeseed pollen germinated, indicating that ethylene could disrupt self-incompatibility of rapeseed. In conclusion, genes and their physicochemical factors related to self-(in)compatibility B. napus might be rapidly unveiled and verified by using this semi-in vitro pollination method.
To improve yields of both vegetable stalk (stem) and rapeseeds, stalk-cut methods were studied on corresponding germplasm. Reasonable stalk-cut methods were chosed from 3 treatments: without pinching (CK); pinching when bolting stem reaches 20-30 cm, and cut stem by 10 cm (M1); pinching when bolting stem reaches 40-60 cm, and cut the stem by 20 cm (M2). 239 accessions were selected as materials, including 2 Brasscia napus parents with significant differences in vegetative parts, and their DH offsprings. Effects of treatments on related agronomic traits and comprehensive economic benefits were studied. Results showed that M2 stalk yield was the highest, with a 106.10% increase compared to M1. Compared with CK, M1 and M2 methods had different effects on materials with different genotypes. The average seed yield of both methods decreased by 12.07% and 14.80% respectively, although 87 accessions had increased yield by M1, and 59 accessions by M2, and 34 accessions increased by both. According to comprehensive economic benefits, both M1 and M2 could significantly improve the benefits, with group average benefits increased by 32.11% and 77.26% respectively, and the maximum benefit could be increased by 276.53%. The experiment showed that M1 and M2 methods had different effects on agronomic traits of plant height, branch height and effective branch number. Correlation analysis showed that stalk yield was significantly positively correlated with stem diameter, plant height, branch height and effective branch number, and negatively correlated with seed yield. Principal component analysis showed that stalk-cut changed the main component factors of DH population from yield factor to plant type factor. Generally, the comprehensive economic benefits of M2 were better. Aim to balance vegetable and oil, 2 accessions from the 239 germplasm were screened out according to their high comprehensive benefits, which had both high yield of stalks and seeds.
To understand the function of chitinase-like (CTL) genes on cold tolerance in winter oilseed rape Brassica rapa L., we cloned BraCTL1 gene promoter sequences from cultivar Tianyou 4 (poorly cold-resistant), and Longyou 7 (substantially cold-resistant). We instructed BraCTL1 gene promoter fusion GUS gene vectors, genetically transformed tobacco, and used PLACA online software to analyze BraCTL1 expression pattern and its cis-regulatory elements. Results showed that leaves of Longyou 7 became dark green and their petioles were obviously curved after low temperature treatments, while the leaves of Tianyou 4 were completely wrinkled, in which edges were obviously yellowed, and petioles were completely unsupported with obvious morphology of freezing damage. After low temperature stress, BraCTL1 expression in Longyou 7 leaves increased significantly and reached its peak value at -8℃, while that of Tianyou 4 with weak cold resistance reached the highest value at -4℃. The expression of BraCTL1 gene in leaves of both Longyou 7 and Tianyou 4 increased significantly after 2 h treatment at -4℃, and reached their highest values at 18 h and 24 h, respectively. The expression level of BraCTL1 gene was the highest in petioles, followed by leaves, and roots. Promoter structure analysis showed that BraCTL1 promoter region contains 7 different types of cis-acting elements, including cold stress response elements, light response elements, hormone response elements, drought response elements, anaerobic related elements and MeJA response elements. Full-length (2000 bp), W1 (1684 bp), W2 (1000 bp), and W3 (575 bp) deletion segments could all be expressed appropriately, according to GUS staining of BraCTL1 promoter fragments. The 5' end fragment at the -1684 bp to -575 bp sites also exhibited high transcriptional activity.
Oilseed rape seeds exhibit diverse variations in secondary seed dormancy (SSD), which led to subsequent occurrence of volunteer plants. To localize SSD loci, a natural population containing 106 rapeseed cultivars was used to map loci associated with SSD. Totally 29 968 high-quality single nucleotide polymorphism (SNP) markers were obtained by genotyping with the Brassica 90 K Illumina infinium™ array. Based on SSD phenotype in 3 years and their genotype information, 24 QTLs associated with SSD were identified by genome-wide association study (GWAS). Meanwhile, a high-throughput transcriptome sequencing assay was conducted using 2 cultivars with significantly different capacity of SSD to identify the differentially expressed genes by weighted gene co-expression network analysis (WGCNA). Eventually, 52 candidate genes for SSD were identified through conjoint analysis by GWAS with WGCNA, which were expected to provide important resources for SSD in rapeseed.
Potassium is a crucial element for crop yield and quality. Identifying members in cation/proton antiporter (CPA) gene family of Brassica napus, and exploring mechanisms of efficient potassium utilization in leaves with varying potassium fertilizer rates are of great significance. Through bioinformatics analysis, we identified 106 CPA family gene members in B. napus, which were classified into 3 subfamilies based on sequence alignment and phylogenetic tree analysis, as CHX family, NHX family, and KEA family. Evolutionary analysis revealed that whole genome triplication and segmental duplication played significant roles in the evolution ofCPAfamily genes. Field experiments with different potassium fertilizer rates combined with transcriptome analysis revealed that potassium deficiency stress significantly reduced dry weight and potassium content of leaves at various positions in B. napus. Compared to potassium-sufficient treatment, potassium deficiency stress significantly reduced dry weight and potassium content of B. napus leaves. Specifically, under potassium deficiency stress, dry weight and potassium content of the 3rd petioled leaf (upper leaf) decreased by 39.7% and 64.2%, respectively, while those of the 5th petioled leaf (lower leaf) decreased by 37.4% and 73.1%, respectively. There were significant differences in response of B. napus leaves to potassium deficiency stress, with more differentially expressed genes in lower leaves than in upper leaves. A total of 12 genes from the CPA family exhibited significant differences in expression, including 3 NHX family genes, 8 CHX genes, and 1 KEA family gene. The supply of potassium significantly influences the expression of genes belonging to the CPA family of monovalent cation/proton antiporters, and the CPA family genes in leaves at different positions of B. napus exhibit different responses to potassium.
To better understand the function of Bna.BON1 gene in Brassica napus on response to abiotic stress, 4 novel Bna.BON1 genes were isolated from B. napus, named as BnaA06.BON1, BnaC03.BON1, BnaA02.BON1 and BnaC02.BON1, respectively. Each of the Bna.BON1 contains typic C2 domain and vWA domain, all of them were localized in plasma membrane. Multiple sequence alignment and phylogenetic analysis showed that the Bna.BON1 proteins were highly homologous to BON1 proteins from Arabidopsis, B. rapa and B. oleracea. PlantCARE analysis showed that promoter regions of Bna.BON1 contained multiple cis-acting elements, involved in light responses, phytohormone response and stress response. qRT-PCR results showed that Bna.BON1 genes were highly expressed in leaves and juvenile stems. The expression levels of BnaA06.BON1 and BnaC03.BON1 were significantly induced by both low (4℃) temperature and high (40℃) temperature, respectively. The expression levels of BnaA02.BON1 and BnaC02.BON1 were significantly induced by both low and high temperatures, as well as drought and NaCl. These results indicated that Bna.BON1 plays an important role in response to abiotic stress in B. napus.
In plant tissue culture, browning is one of the main restrictions for in vitro reproduction. To improve ability of callus differentiation for cabbage (Brassica rapa L.), effects of different anti-browning agents on browning of callus induction were studied. Cotyledon and hypocotyl of cabbage inoculum were used as explants, and silver nitrate, glutathione and activated carbon were used as anti-browning agents. Results showed that adding anti-browning agent in medium could significantly reduce callus browning and improve the differentiation and growth of callus. The anti-browning effect for both cotyledon and hypocotyl differentiation was the best when glutathione concentration was 30 mg/L and activated carbon concentration was 25 mg/L. Browning rate of cotyledon callus was higher than that of hypocotyl. Correlation analysis showed that browning rate of cotyledon callus was positively correlated with malondialdehyde content, and negatively correlated with superoxide dismutase activity. Browning rate of hypocotyl callus was positively correlated with soluble protein content, and negatively correlated with superoxide dismutase activity. In summary, browning degree of explants could be reduced by reducing the degree of cell membrane damage and increasing the activity of antioxidant enzymes by adding appropriate dosage of anti-browning agent and appropriate culture time.
To create new germplasm of Brassica napus, different doses of 60Co-γ-ray were used on parents of elite hybrids and lines. Effects of radiation on seedling rate, vegetative growth and variation rate of whole growth period were analyzed, and the optimal radiation dose was determined. Results showed that seedling rate, seedling fresh weight and leaf area decreased with the increase of radiation dose, with significant variation rates. The optimum dose of 60Co-γ radiation mutagenesis was ～1000 Gy for different materials. The sensitivity of the 4 materials to radiation was GRD328＞ YY300A＞ YY300R＞ GRI1626. GRD328 got the most cotyledon, stem, florescence and florescence mutants with the frequency of 0.07%, 1.18%, 1.87% and 0.37% respectively. YY300R got the most true leaf mutants with the frequency of 0.96%. YY300A obtained the most oil-content-variation, with the variation frequency 0.69%. By optimizing radiation mutagenesis method, a group of new germplasm materials with early maturity, multi-cotyledon, high oil content and multi-main stem were obtained.
To investigate the effect of magnesium （Mg） nutrition on photosynthetic carbon allocation in rapeseed leaves and its regulatory mechanism, we set Mg supply and light intensity treatments to analyze physiological and functional traits, leaf structural characteristics, leaf dry matter composition and quantification of leaf mass per area. The results showed that under the same conditions of magnesium supply, high light increased the thickness, density, specific leaf weight and photosynthetic capacity of oilseed rape leaves; low light decreased the unit area and carbohydrate content of oilseed rape leaves. Magnesium deficiency under high light significantly reduced oilseed rape biomass, root-crown ratio and photosynthetic capacity, and the trend of changes in the indicators of magnesium-deficient oilseed rape under low light was the same as that under high light, but the magnitude of changes was smaller, and the overall growth level of the plant was weaker and carbon accumulation was reduced. Quantitative analysis demonstrated that an increase in cell density played a key role in carbon investment per unit leaf area in Mg-deficient plants, followed by a decrease in the proportion of intercellular airspace. Additionally, the increase in cell density of Mg-deficient leaves was mainly influenced by nonstructural carbohydrates. Overall, magnesium deficiency significantly increases the allocation of photosynthetic carbon to non-structural carbohydrates, particularly under high light conditions, which reduced efficiency of photosynthetic carbon fixation.
For low cost and high efficiency of early-maturing rapeseed in triple-cropping systems, experiments on early-maturing rapeseed cultivar Yangguang 131 were conducted in 2022-2023. The experiment included 2 fertilizer types (A1: conventional fertilizer; A2: slow-released fertilizer), 3 fertilizer amounts (B1: effective content of nitrogen, phosphorus, and potassium at 300.00 kg/hm²; B2: 15% reduction from B1; B3: 30% reduction from B1), and 3 planting densities (C1: 3.75×105 plants/hm²; C2: 15% increase from C1; C3: 30% increase from C1), totally 18 treatments. Experiments were carried out in Changsha and Kunming to evaluate effects of fertilizer types, fertilizer amounts, and planting densities on growth, yield, and fertilizer use efficiency. Results showed that slow-released fertilizer (A2), compared to conventional fertilizer (A1), had significantly improved multiple growth indicators of Yangguang 131, plant height increased by 2.81%-9.09%, SPAD value by 4.85%-9.26%, individual plant dry matter by 4.82%-19.02%, individual plant yield by 8.28%-9.21%, and overall yield by 8.32%-9.19%. Additionally, nitrogen accumulation increased by 33.84%-46.09%, phosphorus accumulation by 14.71%-16.30%, potassium accumulation by 9.09%-14.01%, nitrogen agronomic efficiency by 11.87%-16.64%, nitrogen partial productivity by 8.25%-9.30%, and nitrogen recovery efficiency by 16.05-17.01 percentage points. Reducing fertilizer amounts significantly improved nitrogen agronomic efficiency (by 9.81%-30.83%) and nitrogen partial productivity (by 12.94%-34.27%), but had adverse effects on other indicators. Increasing planting density restricted the growth of individual plants but significantly improved overall yield (5.25%-10.68%), nitrogen accumulation (2.72%-15.59%), phosphorus accumulation (16.00%-39.30%), potassium accumulation (7.04%-21.87%), nitrogen agronomic efficiency (increased by 5.56%-11.75%), nitrogen partial productivity (increased by 5.41%-10.73%), nitrogen recovery efficiency (increased by 0.72-4.85 percentage points), and economic benefits (increased by 4.88%-10.02%).In both Changsha and Kunming, the highest yields were achieved under treatment A2B1C3, with 2685.00 kg/hm² and 2306.40 kg/hm², respectively. Additionally, the highest economic benefits in Changsha and Kunming were obtained under treatments A2B2C3 and A2B3C3, with 6882.75 CNY/hm² and 3404.55 CNY/hm², respectively. In summary, the application of slow-released fertilizer, combined with appropriate fertilizer reduction and increased planting density, minimizes the impact on individual plants and significantly enhances the overall yield and economic benefits of early-maturing rapeseed.
To improve yield, effect of transplanting period on rapeseed blanket seedlings growth was investigated by setting 4 transplanting periods on Nov. 1st, Nov. 16th, Dec. 1st, and Dec. 16th. Development of Brassica napus L. cv Ningza 158 was investigated on yield components, dry matter accumulation, light energy utilisation, leaf area index and angular pericarp area index. Results showed that delayed transplanting would result in lower seed yield of rapeseed, for example, in the 2021 trial, transplanting rapeseed after 1 November, one day later, would result in a yield decrease of 60.32 kg/hm2. Leaf area expansion and dry matter accumulation of transplanted rape before overwintering were significantly positively correlated with the accumulation of substances in the critical period of its yield formation. Delayed transplanting period would lead to a reduction in effective cumulative temperature gained by Ningza 158 before overwintering, with shortened nutritive growth stage, and reduced leaf area, resulting in a decrease in leaf area index and angular pericarp area index. The latter would lead to a decrease in the amount of dry matter accumulated. In 2021, Dec. 16th treatment led to a reduced aboveground dry matter weight by 93.54%, 84.42% and 58.10%, and underground dry matter weight by 82.87%, 78.16% and 55.05% at bud stage, flower stage and maturity stage respectively, compared with Nov. 1st treatment. It suggested that, an early transplanting period of rapeseed blanket seedlings might lead to rapid accumulation of dry matter and leaf area expansion after transplanting, and might have a promotional effect on rape development and yield formation.
Rape blanket seedling combined transplanter is driven by tractor PTO (power output). Due to the constant nature of PTO, the planting speed and working speed couldn't match in real time, which leads to instability of transplanting plant spacing, and thus affects planting quality. In order to improve plant spacing stability, an integrated electro-hydraulic proportional control hydraulic system is designed, based on RTK (real-time kinematic) satellite navigation and positioning differential technology to accurately measure working speed. Control parameters are obtained through system debugging: Kc= 15, Kp= 0.5, Ki= 0.15, Kd= 0.05. By optimizing the regression model, it is known that when plant spacing is 167.85 mm with working speed 3.21 km/h, the predicted value of plant spacing variation coefficient is 3.06%. On the surface of the verification test results, under the optimized parameters, average coefficient of variation of plant spacing is 3.21%, and error with the predicted value is only 4.7%. It shows that the established model is in good agreement with the actual situation, and the prediction of the coefficient of variation of plant spacing by CCD (central composite design) method is accurate and reliable.
Frost damage in rapeseed requires timely and effective recovery measures to restore growth. Given the variety of available recovery strategies, selecting the most appropriate one is critical. This study, conducted in the spring of 2024 in Shayang county and Dangyang couty, Hubei Province, aimed to systematically evaluate the effects of different recovery measures on the recovery of rapeseed following frost damage. The objective was to provide guidance for producers in choosing the most suitable recovery method. A split-plot experimental design was employed, with the main treatments being no stem removal and removal of frost-damaged stems (post-frost). The secondary treatments included various substances: a control, foliar sprays of Xinmeizhouxing, Bihu, Brassinolide, foliar fertilizer, quick-acting fertilizer with topdressing, and a combination of foliar fertilizer and quick-acting fertilizer with topdressing. Key parameters such as yield, yield components, and harvest index were analyzed. The results showed that all recovery measures significantly promoted the growth of rapeseed, leading to varying degrees of yield enhancement. Compared to the treatment where frost-damaged stems were removed, the no-stem-removal treatment resulted in average yield increases of 11.2% and 8.8% in Shayang and Dangyang, respectively. Under the no-stem-removal condition, application of various recovery materials significantly increased seed yield compared to the control, with yield increases ranging from 9.8% to 77.9% in Shayang and from 3.4% to 77.1% in Dangyang. The number of pods per plant showed the most notable increase, rising by an average of 47.5% and 32.6% in Shayang and Dangyang, respectively. The results suggest that, for direct-seeded rapeseed suffering from frost damage during the bolting stage, removing damaged stems is generally not recommended. Instead, a combination of foliar fertilizer and topdressing with quick-acting fertilizer, or the application of composite anti-frost agents such as Bihu spray.
Rapeseed in China might suffer from waterlogging stress throughout its entire growth, especially during seedling stage. To deeply understand the mechanism of alleviation by plant growth regulators, tolerance from strong waterlogging tolerant line YZ12, medium waterlogging tolerant line YZ45, and weak waterlogging tolerant line YZ59 were measured on their physiological traits. The varieties included. They were treated by CK (normal water supply), T1 (waterlogging treatment + spraying water), T2 (waterlogging treatment + spraying GA inhibitor uniconazole), and T3 (waterlogging treatment + spraying ABA inhibitor NDGA). Physiological traits were investigated, including antioxidant enzymes (SOD, POD, CAT), content of osmoregulatory substances (MDA, soluble protein, proline), endogenous hormones (GA, ABA), and photosynthetic physiology. Results showed that T1 treatment causing significant increases in SOD, POD, CAT activities, as well as MDA, soluble protein, proline GA and ABA contents, but decreased in net photosynthetic rate, stomatal conductance, and transpiration rate. It implied that although waterlogging led to a reduction in photosynthesis, rapeseed could possibly reduce the detrimental effects through physiological responses. T2 treatment could effectively alleviate waterlogging stress on seedling growth, but T3 treatment had no significant effects, which showed the differences on waterlogging tolerance responding to these 2 plant growth regulators. T2 treatment significantly reduced GA and osmoregulatory substances (MDA, soluble protein, proline) content, antioxidant enzyme (SOD, POD, CAT) activity, and intercellular CO2 concentration compared to T1. T3 treatment inhibited ABA synthesis, but its role on relieving waterlogging damage was relatively weak. Analysis found that inhibiting ABA synthesis significantly decreased GA content in the strong waterlogging tolerance lines, and reduced antioxidant enzyme (SOD, POD, CAT) activity, but had no significant effect on waterlogging tolerance. Therefore, Therefore, uniconazole could inhibit seedling growth during waterlogging by reducing GA levels. It could improve the antioxidant and osmotic regulation abilities of rapeseed via the ABA pathway. Uniconazole treatment also improved waterlogging tolerane of rapeseed seedlings by affecting photosynthesis and ventilation conditions.
Salt stress inhibits seed germination and seedling growth of Brassica napus. To investigate the promotive effect of seed priming on germination under salt stress, and also to improve salt tolerance of B. napus, two rape materials, as salt-tolerant SA102 and salt-sensitive WR011 were tested by utilizing NaCl, spermidine and melatonin for seed priming treatments at different concentrations and times. Germination and growth parameters under salt stress conditions investigation results showed that NaCl priming did not promote seed germination of the salt-tolerant SA102 under salt stress, and prolonged NaCl priming (24 h) inhibited germination, while salt-sensitive germplasm had the highest germination rate after 2 h of NaCl priming. Compared with NaCl priming, spermidine and melatonin priming were more effective for seed germination and seedling growth, but there were differences in the appropriate concentration and time of spermidine or melatonin priming for different B. napus materials. Salt-tolerant germplasm had the best salt tolerance at 2 mmol/L spermidine priming for 14 h, and salt-sensitive material had the best effect at 5 mmol/L spermidine priming for 3.5 h. Seed priming by melatonin significantly promoted germination and seedling growth under salt stress. The highest germination rates of both salt-tolerant and salt-sensitive materials were under 25 μmol/L (5 h) and 50 μmol/L (2 h) melatonin priming, respectively.
To improve rapeseed yield red soil regions, effect of combined application ratio of biogas slurry and urea was investigated, as well as effect on nitrogen (N) distribution of soil aggregates in field experiment was conducted from 2022 to 2023. Treatments included N ratio of urea to biogas slurry of 85%∶15% (proportion of organic nitrogen is denoted as ON15, and so forth）, 55%∶45% (ON45), 40%∶60% (ON60), urea of 100% (ON0) and no urea (N0). The yield of rapeseed, soil aggregate composition and total nitrogen content were analyzed, their relationships between N content of different aggregates and relative yield of rapeseed were discussed. Results showed that the yield under biogas slurry combined with urea were significantly higher than that of N0 treatment by 16.53%-45.45% and 14.71%-50.98% in 2022 and 2023, respectively. Moreover, the higher the ratio of biogas slurry, the higher the yield. Compared with N0 treatment, the proportion of >2 mm aggregate components in ON15, ON30, ON45 and ON60 treatments were significantly increased by 48.83%-66.97% and 37.10%-61.09% in 2022 and 2023, respectively. Compared with the ON0 treatment, total N content at groups of >2 mm, 0.25-2 mm, 0.053-0.25 mm, and <0.053 mm aggregates in the ON60 and ON45 treatments were significantly increased in 2022 and 2023. In 2023, there was also a trend for the total N contents of the >2 mm and <0.053 mm aggregates in the ON30 treatment were significantly higher than those in ON0 treatment. Furthermore, the total N content of each aggregate component was significantly positively correlated with the relative yield. Parameters of fitting equation indicated that slope of the relationship between the total N content of the >2 mm aggregate component and the relative yield was significantly greater than those of other aggregate components, i.e., when total N content of the >2 mm aggregate component increased by 0.1 g/kg, the relative rapeseed yield could be increased by 5.08%-6.58%. Therefore, on red soil, application of biogas slurry with urea might be an important measure to improve rapeseed yield and promote N retention in aggregates. Among all aggregate components, the most effective way to achieve high rapeseed yield was to reasonably increase the total N content of the >2 mm aggregate component.
To investigate effect of crop rotation of rapeseed on structure and quality of calcareous soil under different planting patterns, a field experiment was conducted in Shanxi Taigu from 2020 to 2021 in maize continuous cropping fields with a randomized complete block design. Four planting patterns were set up: maize-wheat (MW), rapeseed-wheat (RW), rapeseed-maize (RM), and maize-maize (MM), MM as the control. Results indicated significant differences in soil organic carbon content, carbon pool management index, aggregate distribution, and aggregate organic carbon storage under different planting patterns. The stability of aggregates, soil carbon pool activity, and total organic carbon content were closely related to small size aggregates. Compared with MM, the traditional crop rotation pattern MW had better stability of aggregates and was more conducive to the storage of organic carbon in aggregates. The CMPI (carbon pool management index) of rapeseed rotation patterns RM and RW increased by 73.00% and 76.00%, the proportion of macro-aggregates was 14.90%-30.17% higher, and the organic carbon content of small aggregates was significantly higher by 9.44%-47.53%. The CL (carbon pool activity), CPI (carbon pool index), CMPI, and aggregate organic carbon storage of RM mode had significant advantages over RW. Based on these advantages, planting rapeseed might increase the organic carbon storage of aggregates by increasing the proportion of large aggregates and the organic carbon content of small aggregates, then improve soil structure and enhance soil carbon sequestration capacity.
Soil fertility in the Erhai Lake Basin is relatively high, however yield and nitrogen fertilizer utilization efficiency of rapeseed remain low. Therefore, it is urgent to develop new models of green, high-value rapeseed cultivation along with responding supporting fertilization technologies. This study seeks to examine impacts of various nitrogen fertilization strategies on rapeseed yield and quality, which serves a dual purpose as both vegetable and oil source. The objective is to identify the most effective fertilization practices to optimize rapeseed production in the Erhai Basin. Field experiment was conducted in Dali Bai Autonomous Prefecture from 2022 to 2023, implementing 2 base fertilizer treatments: green product model, where organic fertilizer replaces 50% of nitrogen typically supplied by chemical fertilizers, and green ecological model, which relies solely on chemical nitrogen fertilizers. Building on these treatments, 4 nitrogen application protocols were established: no topdressing control (CK), topdressing at the seedling stage (T1), topdressing at the five-leaf stage (T2), and topdressing at both the seedling and five-leaf stages (T3). This study compares the differences in rapeseed yield, flowering stalk yield, quality, and root morphology under the above fertilization regimes. Results are as follows. (1) In both green product and green ecological models, rapeseed yield increased by 98-283% and 164-244% respectively, while flowering stalk yield increased by 42-141% and 50-85%, compared to CK. (2) Nitrogen accumulation and nitrogen use efficiency of T3 treatment were significantly enhanced in both models when compared to other topdressing treatments. (3) Within the green product model, T3 treatment markedly improved both rapeseed quality and its flowering stalk, boosted seed oil yields and protein contents, reduced seed glucosinolate content, increased proportions of primary flowering stalkes, and decreased proportions of tertiary flowering stalks. (4) T3 treatment led to an increase in total root length, root surface area, root tip number, and root bifurcation number by 95% and 77%, 210% and 88%, 101% and 146%, 245% and 171% respectively, compared with CK in both models. (5) Under equivalent topdressing conditions, the green product model consistently outperformed the green ecological model in overall yield, quality, nitrogen accumulation, and root morphology of rapeseed and its flowering stalks. In conclusion, the green product model, in conjunction with segmented nitrogen fertilization at the seedling and five-leaf stages, significantly enhances root morphology in the early stages of rapeseed growth, resulting in improved yield and nitrogen use efficiency. This approach is recommended to be pivotal fertilization model for enhancing yield and quality of dual-use vegetable and oil rapeseed cultivation in the Erhai Basin.
A field experiment was conducted to investigate oilseed rape influences with different sulfur content as green manure on soil nematode community of wolfberry orchard, which was included planting high sulfur content oilseed rape (Hg), low sulfur content oilseed rape (Lg) between wolfberry rows and clean tillage control (CK) 3 treatments. Results showed that, at May 15th, after 1.5 months of planting oilseed rape, compared with CK, soil nematode numbers of Hg and Lg treatment were significant increased by 103.45% and 53.64%. At June 30, after 3 months of planting oilseed rape, the soil nematode numbers of Hg and Lg treatment were significant increased by 72.90% and 51.34%; but at August 15, after turned oilseed rape for another 1.5 months, the soil nematode numbers of Hg and Lg treatment were significant decreased by 58.35% and 54.20%. At September 30, after turned oilseed rape for another 3 months, the soil nematode numbers of Hg and Lg treatment were increased by 5.10% and 0.14%, respectively. In the present study, soil nematode individuals and genus numbers of bacterivores were significant increased and of plant-parasites were significant decreased, especially in Heterodera genus of plant-parasites, respectively. Compared with CK, the nematode channel ratio was significant increased at the first 3 sampling, but was significant decreased at the 4th sampling by Hg and Lg treatment; richness index, the Shannon-Weiner index and the maturity index of free-living nematodes were significant increased and the maturity index of plant parasite index were significant decreased by Hg and Lg treatment, respectively. These results indicated that as green manure oilseed rape is benefit for increasing of nematode number, could increase the genu number and relative abundance of bacterivores, and decrease the genus number and relative abundance of plant-parasites, especially when high sulfur oilseed rape was used.
Vegetable bloting of rapeseed has high nutritional value. It can provide important data support for the popularization and application of vegetable bloting of rapeseed to clarify its edible quality as a vegetable and consumers' liking degree. In this study, the early-maturing Brassica napus L. variety WH14, medium-maturing Brassica napus L. cultivar Huayouza 62 (HZ62), Chinese flowering cabbage (Choi sum, or Guangdong-style flowering cabbage, GD) and purple cai-tai (Brassica rapa L. var. purpurea) (HS) were selected as the research objects, and the initial quality of WH14, GD, HZ62 and HS were compared respectively. The contents of soluble sugar, sucrose, starch, cellulose, pectin and lignin in cai-tai were determined, and the edible value was analyzed comprehensively based on the results of sensory evaluation after cooking. The results showed that the soluble sugar content of WH14 was 13.14% higher than that of GD, the lignin content was 22.71% higher and the cellulose content was 26.18% lower. The soluble sugar content of HZ62 was 55.16% higher than that of HS, the lignin content was 9.46% higher and the cellulose content was 4.21% lower. The results of sensory evaluation revealed that consumers showed a preference for all 3 kinds of cai-tai. It is concluded that WH14 is significantly better than GD in sweetness, overall quality and overall preference, while HZ62 has slightly higher sweetness, slightly worse texture and no significant difference in overall preference compared with HS. The above results demonstrate that the vegetable bolting of rapeseed is loved by consumers, has a good market prospect, and has a high promotion value.
Rapeseed is an important vegetable oil seed, which is prone to mildew and sourness when seed moisture is high after harvest. In this paper, a continuous tunnel microwave drying device was tested for processing newly harvested rapeseed. Seeds’ oil yield, peroxide value and acid value were analyzed by single factor experiment. Optimization of microwave drying process was tested through parameter investigation by response surface method and volatile compounds monitoring by GC-MS. Results showed that when the microwave power was 784 W, sample thickness was 8 mm and transfer speed was 0.70 cm/s, the oil yield of rapeseed could reach 39.19%, with peroxide value of 1.85 mmol/kg, and acid value of 0.46 mgKOH/g, sensory score of 93, and water content of 7.19%. Under this process condition, compared with hot air drying unfavorable hot and spicy substance is reduced.
