Wild pollinators enhance oilseed rape yield in small-holder farming systems in China

Glasshouse bioassays were conducted to assess the impact of different inputs of oilseed rape plant material on soil and rhizosphere microbial diversity associated with subsequently grown oilseed rape (Brassica napus) plants. The first bioassay focussed on the effect of oilseed rape rhizodeposits and fresh detached root material on microbial communities, in a rapid-cycling experiment in which oilseed rape plants were grown successively in pots of field soil for 4 weeks at a time, with six cycles of repeated vegetative planting in the same pot. Molecular analyses of the microbial communities after each cycle showed that the obligate parasite Olpidium brassicae infected the roots of oilseed rape within 4 weeks after the first planting (irrespective of the influence of rhizodeposits alone or in the presence of fresh detached root material), and consistently dominated the rhizosphere fungal community, ranging in relative abundance from 43 to 88 % when oilseed rape was grown more than once in the same soil. Fresh detached root material also led to a reduction in diversity within the soil fungal community, due to the increased relative abundance of O. brassicae. In addition, rhizosphere bacterial communities were found to have a reduced diversity over time when fresh root material was retained in the soil. In the second glasshouse experiment, the effect of incorporating mature, field-derived oilseed rape crop residues (shoots and root material) on microbial communities associated with subsequently grown oilseed rape was investigated. As before, molecular analyses revealed that O. brassicae dominated the rhizosphere fungal community, despite not being prevalent in either the residue material or soil fungal communities.

Remote prediction of yield based on LAI estimation in oilseed rape under different planting methods and nitrogen fertilizer applications

Promoting sustainable smallholder farming systems in China

Pollination is one of the most important processes in terrestrial ecosystems. This free nature service depends on a homogeneous distribution and sufficient density of flower-visiting insects, mainly wild bees and managed honey bees. Habitat destruction and habitat fragmentation and intensive land-use led to species loss on multiple trophic levels.The aim of this work was to answer the question whether pollination is still sufficiently ensured by wild bees and honey bees in intensively managed agricultural landscapes. For this, it was necessary to quantify local honey bee abundance and wild bee species composition and density in relation to landscape structure at different spatial scales. Thus it was tested, how solitary wild bees, social bumble bees and honey bees interact with the surrounding landscape (chapter 4). Furthermore, the influence of possible pollination limitation due to low densities of flower-visiting bees on yield of oilseed rape was studied in dependence of the surrounding landscape (chapter 5). Finally, the effect of different pollination vectors on oilseed rape was measured to quantify the relative importance of bee pollination and wind pollination for fruit set. The spatial distribution and density of managed honey bees was measured using Geographical Information Systems, for the district of Göttingen (Germany). In Germany, in a period of twelve years (1989 2000), the total number of managed honey bees decreased by 26% representing a loss of about 260.000 honey bee locations. Bee diseases and the high percentage of old beekeepers led to this situation. In conclusion, the current situation of beekeeping in the district of Göttingen has reached a critical level. The conservation of wild pollinator and the support of beekeeping must be a central topic to ensure pollination services for agricultural crops. If not, a full-coverage pollination by honey bees cannot be guaranteed.An aim of this study was the analysis of the effects of landscape context and the influence of the percentage of semi-natural habitats on species composition of trap-nesting wild bee communities a gradient of structurally poor to structurally rich landscapes. An increasing proportion of the semi-natural habitats in the surrounding landscape had no positive effect on species diversity at any spatial scale. In contrast, an increasing proportion of rapecrop fields influenced the number of brood cells per nest and the total nest number of Osmia rufa (Hymenoptera: Apidae) at small spatial scales. In conclusion, all studied agricultural landscapes only supported relatively low numbers of solitary bees and wasps.Bee visitation is necessary for pollination. To analyse the value of the degree of flower-visiting bees we analysed, if an increasing diversity and density of flower-visiting bees may have positive effects on the yield of oilseed rape (Brassica napus L. ssp. oleifera (Metzg.), Brassicaceae). Flower visitor observations indicated significantly increased seed set per flower with increasing honey bee densities, whereas the abundance of flower-visiting wild bees had no measurable effect on yields of oilseed rape. Bee visitation had no effect on real yield (g/m²), probably as a result of the high compensatory-growth ability of oilseed rape and variation in cultivation methods or local soil conditions between the landscapes. In contrast, rape yield was positively related to a higher percentage of rape crop fields in the surrounding landscape, possibly due to higher pollen densities in the air and enhanced wind pollination.Summarizing this study, species richness and abundance of solitary wild bees depends on landscape context and habitat composition. Species diversity and abundance of flower-visiting bees increase with higher percentage of semi-natural habitats in the surrounding landscape. Generally, habitat fragmentation and destruction of ecologically valuable habitats can cause decreasing bee diversity (solitary wild bees, social bumble bees and honey bees). Pollination as a free nature service depends on a high pollinator density and may result in a higher fruit set and yield thus confirming the economical importance of pollination. In conclusion, a further loss of pollinators must be avoided to protect most wild plant species and to ensure high yields of insect-pollinated cultivated plants.

Effects of selenium content in green parts of plants on the amount of ATP and ascorbate–glutathione cycle enzyme activity at various growth stages of wheat and oilseed rape

Detecting farmland parcels in high-resolution remote sensing images is challenging in smallholder farming systems in China, characterized by fragmented plots, irregular shapes, and varying scales. To improve detection accuracy in these contexts, this study proposes AAMS-YOLO, a YOLO-based farmland parcel detection model. In the feature extraction stage, the model incorporates an Adaptive Mix Attention (AMA) Block, balancing robust feature extraction with low computational overhead through spatial mixing and Efficient Multi-Scale Attention (EMA). During feature enhancement, to effectively detect targets of different scales, the Attentional Scale Sequence Fusion with P2 network (ASFP2Net) integrates the Triple Feature Encoder (TFE) module and Scale Sequence Feature Fusion (SSFF) module. In the prediction stage, a Multi-Scale Attention Head (MSAHead) enhances adaptability through multi-scale attention mechanisms. Extensive experiments on a custom-built dataset validate AAMS-YOLO's effectiveness, demonstrating notable enhancements over the baseline in mAP0.5 (2.6%) and mAP0.5:0.95 (2.2%) and surpassing other state-of-the-art algorithms. The proposed model excels in detecting small and densely overlapping objects through advanced feature fusion and multi-scale processing strategies.

In two experiments, in the growing season March–May, freshly harvested double‐low oilseed rape (Brassica napus) plants were fed ad libitum to penned roe deer (Capreolus capreolus) and red deer (Cervus elaphus). In Experiment 1, oilseed rape was fed to five roe and 12 red deer as 60% of their daily dry matter (DM) intake for four weeks, after a two‐week dietary change‐over period. The rest of the diet comprised cattle‐rearing pellets (33%) and freshly cut heather (Calluna vulgaris) plants (7%). In Experiment 2, oilseed rape was fed to seven roe and eight red deer as 100% of the diet for up to six weeks, after a two‐week change‐over period.In both experiments, Heinz bodies were found in roe deer blood 2–3 weeks after the start of the change‐over period, with a fall in mean packed cell volume (PCV) and blood glutathione (GSH) concentration. In Experiment 2, after 5–8 days of feeding on 100% oilseed rape, four roe deer showed signs of inappetance and were changed to a diet of 80% oilseed rape. At the same time, the other three roe deer had very low PCV (< 60% of normal values) and oilseed rape feeding was discontinued for those animals. The red deer showed no symptoms of haemolytic damage nor any change in blood GSH concentration in either experiment, but showed a gradual fall in PCV in Experiment 2. No other ill‐effects were observed in any of the animals.Intakes of oilseed rape (gDM/kg0–75/day) were lower for the roe deer than the red deer in both experiments. The severity of haemolytic anaemia in the roe deer was related to the proportion of oilseed rape in the diet, rather than the amount ingested. It was concluded that the health of roe deer ingesting oilseed rape may be affected if other foods are not available.

Insect pollination, despite its potential to contribute substantially to crop production, is not an integrated part of agronomic planning. A major reason for this are knowledge gaps in the contribution of pollinators to yield, which partly result from difficulties in determining area-based estimates of yield effects from insect pollination under field conditions. We have experimentally manipulated honey bee Apis mellifera densities at 43 oilseed rape Brassica napus fields over 2 years in Scandinavia. Honey bee hives were placed in 22 fields; an additional 21 fields without large apiaries in the surrounding landscape were selected as controls. Depending on the pollination system in the parental generation, the B. napus cultivars in the crop fields are classified as either open-pollinated or first-generation hybrids, with both types being open-pollinated in the generation of plants cultivated in the fields. Three cultivars of each type were grown. We measured the activity of flower-visiting insects during flowering and estimated yields by harvesting with small combine harvesters. The addition of honey bee hives to the fields dramatically increased abundance of flower-visiting honey bees in those fields. Honey bees affected yield, but the effect depended on cultivar type (p=0.04). Post-hoc analysis revealed that open-pollinated cultivars, but not hybrid cultivars, had 11% higher yields in fields with added honey bees than those grown in the control fields (p=0.07). To our knowledge, this is the first whole-field study in replicated landscapes to assess the benefit of insect pollination in oilseed rape. Our results demonstrate that honey bees have the potential to increase oilseed rape yields, thereby emphasizing the importance of pollinator management for optimal cultivation of oilseed rape.

Background: Temperate agroforestry is regarded as a sustainable alternative to monoculture agriculture due to enhanced provisioning of ecosystem services. Plant health and food safety are crucial requirements for sustainable agriculture; however, studies of fungal diseases and mycotoxin contamination of crops grown under temperate agroforestry are lacking. This study therefore aimed to compare fungal colonization and mycotoxin contamination of crops grown in temperate agroforestry against conventional monoculture. Methods: The biomass of plant pathogenic fungi in oilseed rape plants and barley and wheat grain harvested in 2016 to 2018 at four paired agroforestry and monoculture sites was quantified using species-specific real-time PCR. Mycotoxin content of barley and wheat grain was determined by HPLC-MS/MS. Results: The colonization of oilseed rape plants with the vascular pathogen Verticillium longisporum and wheat grain with the head blight pathogen Fusarium tricinctum was lower in agroforestry than in conventional monoculture. Mycotoxin content of barley and wheat grain did not differ between agroforestry and monoculture systems and did not exceed the legal limits of the EU. Remarkably, fumonisin B1 was detected in wheat grains at two sites in two years, yet the low levels found do not raise food safety concerns. No differences were found between the two production systems with regard to infection of wheat and barley grain with five Fusarium species (F. avenaceum, F. culmorum, F. graminearum, F. poae, and F. proliferatum) and oilseed rape with fungal pathogens Leptosphaeria biglobosa, Leptosphaeria maculans, and Sclerotinia sclerotiorum. Conclusions: Temperate agroforestry does not negatively affect the infection of wheat, barley and oilseed rape with major fungal pathogens though it may suppress the infection of oilseed rape with V. longisporum and wheat grain with F. tricinctum. Furthermore, temperate agroforestry does not increase mycotoxin contamination of barley and wheat. Therefore, temperate agroforestry does not negatively affect food safety.

BackgroundSilique number is an important component of yield in oilseed rape, which is largely determined by the number of flowers. Although many QTL for silique number have been identified in oilseed rape, none of these has been fine-mapped and further cloned, largely limiting their application in genetic improvement. In our previous study, a few-silique mutant (No.7931) caused by determinate inflorescence has been mapped to three close regions on C02 chromosome by bulked segregant analysis by sequencing (BSA-seq) of two pools of F2 individuals derived from this mutant and more-silique accession No.73290.ResultsIn the current study, the hybrid F1 between No.7931 and an indeterminate inflorescence accession No.73290 showed nearly determinate inflorescence. This supported that the determinate inflorescence of No.7931 was nearly dominant to the indeterminate inflorescence of No.73290, suggesting the dosage effect of the causal gene. In the BC3F2 near-isogenic lines with No.73290 background, the numbers of plants with determinate and indeterminate inflorescence displayed a segregating ratio of 3:1, suggesting that it should be controlled by a single dominant locus (named as SNPI.C2 thereafter). The first BSA region close to the end of C02 chromosome was validated and fine-mapped to 172 Kb region containing only 23 annotated genes. The RNA-seq of shoot apical meristem (SAM) at the initial stage of floral bud differentiation identified a total of 3196 differentially expressed genes (DEGs) between No.73290 and NIL-SNPI.C2, which were significantly enriched into 22 pathways (e.g., fermentation, glycolysis, polyamine metabolism and nitrogen-metabolism) that are highly associated with floral bud differentiation and flower number regulation. The results of fine-mapping, re-sequencing and transcriptome analysis were integrated, which identified two candidate genes that are involved in regulating meristem identity and have sequence and/or expression variation.ConclusionsThese results provide further insights and candidate genes for silique number in oilseed rape, which represent a significant advancement toward the cloning of causal genes and understanding of genetic mechanism for silique number in oilseed rape.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12870-026-08126-4.

A Two-year field experiment was carried out in 2009 and 2010 to evaluate the effects of different densities of wild oat and nitrogen (N) rates on oilseed rape yield and yield components. Experimental design was split plot with three replications. Increased nitrogen rates up to 150 kg N/ha caused an increase in oilseed rape grain yield in weed-free plots (4.26 t/ha; 1t = 10 3 kg), while even at the lowest density of wild oat (15 plants/m 2 ), increasing N fertilizer only up to 50 kg/ha led to a significant increase in grain yield. Wild oat growth was favored by high levels of N. Intraspecific competition reduced biomass, 100-seed weight and number of tillers of wild oat. Both lower N rate and intraspecific competition had negative effect on wild oat growth but the weed was still able to produce a considerable number of tillers and vigorous seeds. It showed that wild oat possess a no table adaptive plasticity and can allocate a greater proportion of its resource toward re -productive organs even under resource shortage conditions and, thus, it may increase the competitive ability of the weed over the crop.Our results suggest that effective weed management should be done to prevent wild oat seed production in crops preceding oilseed rape as well as to control the weed at early season in oilseed rape fields.

SUMMARYThe effects of exchangeable sodium on emergence, growth, development and yield composition of oilseed rape were investigated at Buenos Aires, Argentina in 1992. A pot experiment was performed using five exchangeable sodium levels, expressed as Sodium Adsorption Ratio (SAR: 12, 20, 27, 34 and 44). Soil with nine different exchangeable sodium contents (SAR from 0·5 to 50) and seven different particle size distributions (from sandy loam to clay) were used in a parallel trial to study the effect of soil crusting on oilseed rape emergence. Soil crusts were made using a rainfall simulator after seeds were sown. Both experiments showed that the direct effect of sodium on emergence occurred with SAR values higher than those which caused clay dispersion (SAR > 20). Oilseed rape seedlings could penetrate crusts having a resistance of < 230 kPa. At SAR values > 20, main stem growth and yield decreased significantly (P< 0·05). These reductions were counterbalanced by an increase in the number of secondary stems. At SAR levels > 34, stem number, grain number per pod on the main stem, as well as pod number on both main stem and secondary stems, were reduced, leading to a marked reduction in total yield. The most important agronomic effect of soil sodium on oilseed rape would be at emergence stage, due to soil crusting.

The number of flowers and seed-bearing structures formed by the inflorescence meristem and the formation of ovules in the female reproductive part of the flowers are important yield-related traits of crop plants. It has been shown that cytokinin is a pivotal factor regulating these traits. Here, we explore the impact of mutation of CYTOKININ OXIDASE/DEHYDROGENASE (CKX) genes encoding cytokinin-degrading enzymes on these yield-related traits in oilseed rape (Brassica napus L.). We describe the identification of four BnCKX3 and two BnCKX5 genes as regulators of reproductive development in the allotetraploid B. napus. RNA-seq analysis and in situ hybridization showed expression of these genes in reproductive organs. Loss-of-function mutants for each of these CKX gene copies were identified by targeting induced local lesions in genomes (TILLING) and combined by crossing. Sextuple ckx3 ckx5 mutants showed an increased cytokinin concentration and larger and more active inflorescence meristems. They also produced up to 72% more flowers with gynoecia containing 32% more ovules and up to 54% more pods on the main stem. The weight of seeds harvested from the main stem of plants grown in the greenhouse or in the field was increased by 20-32%. Our results show that cytokinin regulates inflorescence meristem and placenta activity in oilseed rape. The work demonstrates the potential to achieve yield enhancement in a dicot crop plant by modulating the cytokinin status through mutagenesis of specific CKX genes.

Ovule number per ovary (ONPO) determines the maximum potential of seed number per fruit that is a direct component of seed yield in crops. This study aimed to dissect the genetic basis and molecular mechanism of ONPO using a newly developed doubled haploid (DH) population in oilseed rape. In all the four investigated environments, the ONPO of 201 DH lines exhibited normal distribution with a wide variation from 22.6 to 41.8, suggesting quantitative inheritance appropriate for mapping QTL. A skeleton genetic map of 2111 markers within 19 linkage groups was developed, with a total of 1715.71 cM in length and an average of 0.82 cM between markers. Linkage mapping identified ten QTLs that were distributed on eight chromosomes and explained 7.0-15.9% of the phenotypic variance. Among these, four were identical to the reported and two were repeatedly detected with relatively large effects, highlighting their potential for marker-assisted selection. Phytohormone quantification of ovaries (at the ovule initiation stage) from two pools of high and low ONPO lines showed significant differences in the levels of nine sub-types of phytohormones, suggesting their important roles in regulating ovule number. Transcriptomic analysis identified 7689 differentially expressed genes (DEGs) between the two pools, of which nearly half were enriched into functional categories of reported genes regulating ONPO, including protein, RNA, signalling, miscellaneous, development, hormone metabolism, and tetrapyrrole synthesis. Integration of linkage QTL mapping, transcriptome sequencing and BLAST analysis identified 15 homologues of reported ovule number genes and 327 DEGs in the QTL regions, which were considered as direct and potential candidate genes. These findings propose further insights into the genetic basis and molecular mechanisms of ONPO, which will facilitate future gene cloning and genetic improvement for enhancing seed yield in oilseed rape.

Salinity is one of the major constraints in oilseed rape (Brassica napus L.) production. One of the means to overcome this constraint is the use of plant growth regulators to induce plant tolerance. To study the plant response to salinity in combination with a growth regulator, 5-aminolevulinic acid (ALA), oilseed rape plants were grown hydroponically in greenhouse conditions under three levels of salinity (0, 100, and 200 mM NaCl) and foliar application of ALA (30 mg/l). Salinity depressed the growth of shoots and roots, and decreased leaf water potential and chlorophyll concentration. Addition of ALA partially improved the growth of shoots and roots, and increased the leaf chlorophyll concentrations of stressed plants. Foliar application of ALA also maintained leaf water potential of plants growing in 100 mM salinity at the same level as that of the control plants, and there was also an improvement in the water relations of ALA-treated plants growing in 200 mM. Net photosynthetic rate and gas exchange parameters were also reduced significantly with increasing salinity; these effects were partially reversed upon foliar application with ALA. Sodium accumulation increased with increasing NaCl concentration which induced a complex response in the macro-and micronutrients uptake and accumulation in both roots and leaves. Generally, analyses of macro- (N, P, K, S, Ca, and Mg) and micronutrients (Mn, Zn, Fe, and Cu) showed no increased accumulation of these ions in the leaves and roots (on dry weight basis) under increasing salinity except for zinc (Zn). Foliar application of ALA enhanced the concentrations of all nutrients other than Mn and Cu. These results suggest that under short-term salinity-induced stress (10 days), exogenous application of ALA helped the plants improve growth, photosynthetic gas exchange capacity, water potential, chlorophyll content, and mineral nutrition by manipulating the uptake of Na+.