Rapeseed Plants Research Articles

Phytoremediation potential of rapeseed in phenanthrene‐contaminated soils under different irrigation regimes and pumice levels

AbstractTo evaluate the effects of irrigation regimes and pumice levels on the physiological parameters of rapeseed (Brassica napus) and phenanthrene phytoremediation efficiency, a 15‐week pot experiment was conducted in the open environment of the College of Agriculture at Fasa University. Three irrigation levels, 75%, 100% and 125% of the field capacity, I1, I2 and I3, respectively, and three pumice levels, 0%, 5% and 10% w/w soil, P0, P1 and P2, respectively, were considered. The results showed that the shoot fresh weight, shoot dry weight, shoot‐root ratio, root fresh weight, root dry weight, root volume, root length, root surface area and root length density in the I3P2 treatment increased by 25%, 35%, 22%, 35%, 19%, 24%, 19%, 21% and 19%, respectively, compared to the corresponding control (I2P0). A significant increase in the number of soil microorganisms (32%) and removal of phenanthrene (74%) were achieved in I3P2 compared to I2P0. According to the Pearson correlation coefficient, all physiological parameters of rapeseed had a high negative correlation with the residual phenanthrene in the soil and consequently increased its dissipation. Therefore, the rapeseed plant can be used as a practical and effective species for the phytoremediation of phenanthrene‐contaminated sites.

Genome-Wide Identification and Functional Characterization Reveals the Pivotal Roles of BnaA8.ATG8F in Salt Stress Tolerance and Nitrogen Limitation Adaptation in Allotetraploid Rapeseed.

Autophagy is a common physiological process in organisms, including higher plants. The ATG8 subfamily, the core member of the autophagy-related gene (ATG) family, plays a key role in plant growth and development and nutrient stress responses. However, the core ATG8 homologs and their roles in stress resistance remain elusive in allotetraploid rapeseed (AACC, Brassica napus L.). In this study, we identified 29 ATG8 subgroup members, consisting of three phylogenetic clades, based on the analysis of genomic annotation and conserved motifs. Differential transcriptional responses of BnaATG8s to salt stress, nitrogen limitation, and other nutrient stresses were investigated, and we identified BnaA8.ATG8F as the core ATG8 member through gene co-expression network analysis. Decreased BnaA8.ATG8F expression repressed the salt tolerance of transgenic rapeseed plants by significantly reducing the root Na+ retention under salt stress. Moreover, downregulation of BnaA8.ATG8F increased nitrogen (N) limitation sensitivity of transgenic rapeseed plants through decreasing N uptake, translocation, and enhancing N remobilization under nitrogen starvation. In summary, we identified the core ATG8 homologs and characterized their physiological and molecular mechanisms underlying salt stress tolerance and nitrogen limitation adaptation. Our results may provide elite genetic resources for the genetic improvement of nutrient stress tolerance in rapeseed.

High Sclerotinia sclerotiorum resistance in rapeseed plant has been achieved by OsPGIP6.

Sclerotinia sclerotiorum, a worldwide distributed fungal pathogen, causes serious adverse effects on the yield and seed quality of rapeseed. Polygalacturonase-inhibiting proteins (PGIPs) can protect the cell wall from degradation by pathogen-secreted polygalacturonases (PGs). The present study found several PGIPs from Oryza sativa, especially OsPGIP6 and 3 have much higher inhibitory activities to SsPGs than BnPGIP2 from Brassica napus. Among them, OsPGIP1, 4, 6 can significantly elevate the resistance of transgenic Arabidopsis to S. sclerotiorum. Subsequently, OsPGIP1, 3, 4, 6 were subjected to SSR resistance assay in transgenic rapeseed plants. Among which, OsPGIP6 showed the highest resistance to S. sclerotiorum. At 48 h after detached leaves inoculation, the lesion area of OE-OsPGIP6 rapeseed plants is only 17.93% of the non-transgenic line, and 22.17, 21.32, 52.78, 56.47%, compared to OE-BnPGIP2, OE-OsPGIP1, OE-OsPGIP2, OE-OsPGIP4, respectively. Furthermore, the lesion area of OE-OsPGIP6 reached 10.11% compared to WT at 72 hpi. Also, the lesion length on the stem of OE-OsPGIP6 plants was reduced by 36.83% compared to WT. These results reveal that OsPGIP family, especially OsPGIP6, has a great potential in rapeseed S. sclerotiorum-resistance breeding.

The Application of Auxin-like Compounds Promotes Cold Acclimation in the Oilseed Rape Plant.

Cold is a major environmental key factor influencing plant growth, development, and productivity. Responses and adaption processes depend on plant physiological and biochemical modifications, first of all via the hormonal system. Indole-3-acetic acid (IAA) plays a critical role in the processes of plant functioning. To assess the influence of the auxin-like compounds 1-[2-chloroethoxycarbonylmethyl]-4-naphthalenesulfonic acid calcium salt (TA-12) and 1-[2-dimethylaminoethoxycarbonylmethyl]naphthalene chloromethylate (TA-14) in the process of cold acclimation, long-term field trials over four years were performed with two rapeseed (Brassica napus L.) plant cultivars with different wintering resistance in temperate-zone countries. In these two rapeseed cultivars, namely ‘Casino’ (less resistant) and ‘Valesca’ (more resistant), investigations were conducted in the terminal buds and root collars. The application of auxin-like compounds revealed a close interlinkage between the composition of dehydrins and the participation of the phytohormone IAA in the adaptation processes. By applying TA-12 and TA-14, the importance of the proteins, especially the composition of the dehydrins, the IAA amount, and the status of the oilseed rape cultivars at the end of the cold acclimation period were confirmed. Following on from this, when introducing oilseed rape cultivars from foreign countries, it may also be of value to assess their suitability for cultivation in temperate-zone countries.

Оценка эффективности применения ярового рапса в технологии индуцированной фитоэкстракции никеля в условиях загрязненной дерново-подзолистой почвы

A greenhouse experiment was conducted to study the effect of chelating agent disodium salt of ethylenediaminetetraacetic acid (EDTA) on nickel phytoextraction with rapeseed plants (Brassica napus (L.) subsp. oleifera Metzg.) as test crop in the contaminated with Ni (40 and 120 mg/kg) Albic Luvisol. The use of EDTA at a dose of 0.5 mmol/kg of soil increased the nickel uptake by plants by 1.9 - 2.4 times compared to EDTA unamended soil. Due to the absence of phytotoxic effect, values of uptake, bioaccumulation and translocation coefficients, the highest efficiency of nickel phytoextraction by rapeseed plants was achieved at doses of metal in the soil at the level of approximately permissible concentration (40 mg/kg). Keywords: PHYTOREMEDIATION, INDUCED PHYTOEXTRACTION, NICKEL, CHELATING AGENT, DISODIUM SALT OF ETHYLENEDIAMINETETRAACETIC ACID (EDTA), SPRING RAPESEED, POLLUTION, ALBIC LUVISOL

Genome-wide identification, phylogeny, and expression profiling analysis of shattering genes in rapeseed and mustard plants

BackgroundNon-synchronized pods shattering in the Brassicaceae family bring upon huge yield losses around the world. The shattering process was validated to be controlled by eight genes in Arabidopsis, including SHP1, SHP2, FUL, IND, ALC, NAC, RPL, and PG. We performed genome-wide identification, characterization, and expression analysis of shattering genes in B.napus and B. juncea to gain understanding into this gene family and to explain their expression patterns in fresh and mature siliques. ResultsA comprehensive genome investigation of B.napus and B.juncea revealed 32 shattering genes, which were identified and categorized using protein motif structure, exon-intron organization, and phylogeny. The phylogenetic study revealed that these shattering genes contain little duplications, determined with a distinct chromosome number. Motifs of 32 shattering proteins were observed where motifs1 and 2 were found to be more conserved. A single motif was observed for other genes like Br-nS7, Br-nS9, Br-nS10, Br-jS21, Br-jS23, Br-jS24, Br-jS25, and Br-jS26. Synteny analysis was performed that validated a conserved pattern of blocks among these cultivars. RT-PCR based expressions profiles showed higher expression of shattering genes in B. juncea as compared to B.napus. SHP1, SHP2, and FUL gene were expressed more in mature silique. ALC gene was upregulated in fresh silique of B. napus but downregulation of ALC were observed in fresh silique of B. juncea. ConclusionThis study authenticates the presence of shattering genes in the local cultivars of Brassica. It has been validated that the expression of shattering genes were more in B. juncea as compared to B.napus. The outcomes of this study contribute to the screening of more candidate genes for further investigation.

PROTECTIONISM OR SUSTAINABILITY? QUESTIONING EUROPEAN INTENTION ON PALM OIL BAN USING TIME SERIES DATA

Palm oil is Indonesia’s competitive advantage in the international commodity market. Various derivative products are produced by palm oil. However, the European policy banning palm oil exports has become an obstacle to Indonesia’s palm oil export performance. Environmental issues are the reason for the ban on imports of Indonesian palm oil. However, in this research, we try to extend the view of sustainable issues. This study uses Indonesian palm oil exports and the European rapeseed oil trade to explain this issue. In this study, we try to explain a pure European policy of sustainability or protectionism. Based on the analysis results, it was found that this policy was strongly influenced by exports and production of European rapeseed oil. The effect of rapeseed oil production on palm oil imports proves that this policy has an element of protectionism to protect European rapeseed plants

Alleviation of salt stress in rapeseed (Brassica napus L.) plants by biochar-based rhizobacteria: new insights into the mechanisms regulating nutrient uptake, antioxidant activity, root growth and productivity

ABSTRACT Amendment of saline soils with biochar and rhizobacteria is a new technique to diminish the negative impacts of salt stress on plants. Hence, an original pot experiment was conducted in a glass greenhouse at the University of Tabriz to investigate the performance of salt-stressed (0, 6 and 12 dS m−1 NaCl) rapeseed (Brassica napus L.) plants in response to different biochar-related treatments (non-biochar, biochar, biochar-based Pseudomonas putida RS-198, biochar-based Azotobacter chroococcum RS-106 and both bacteria). The biochar-related treatments reduced sodium content, generation of reactive oxygen species, lipid peroxidation and enzymatic antioxidants in plant tissues while enhanced nutrient content, non-enzymatic antioxidants, main and lateral roots lengths and weights, main/lateral root length ratio, specific root length, root diameter, shoot length and weight, leaf area, chlorophyll content and seed and oil yields under saline conditions. The biochar-based Pseudomonas + Azotobacter was the superior treatment for reducing the harmful impacts of salt stress on rapeseed plants, which resulted in 83–109% and 69–115% improvements in seed and oil yields of this crop under moderate and high salinities, respectively. Therefore, inoculation of biochar with both rhizobacteria might be a novel approach for improving salt tolerance and productivity of rapeseed plants.

Nutrient balancing or spring flush – What determines spruce bark stripping level by red deer?

The distribution and population density of red deer (Cervus elaphus) are increasing in several regions of Europe. The deer may cause severe damage in commercial forestry and agriculture. Bark stripping is the main problem in forests, especially on Norway spruce (Picea abies), and is thought to mostly occur during winter when other forage is scarce. It has been suggested that an imbalance in the nutrient intake, and especially a diet including high amounts of easily-digestible macronutrients, such as agricultural crops, can lead to an increased urge to consume bark. Feeding on brassicas, for example rapeseed (Brassica napus) might have this effect. The aim with this study was to investigate the relationship between intake of rapeseed and bark stripping on Norway spruce by red deer during early spring. We did this by a controlled feeding experiment with four groups of captive red deer in southern Sweden. All groups were given spruce logs every week, while only two groups had access to freshly harvested rapeseed plants. In addition, influence of air temperature and forage nutritional composition was taken into account. Our results show that red deer bark stripping can be considerable not only during winter but also during spring green-up. We found no significant influence of rapeseed on bark stripping performed by the deer. However, at a threshold temperature, deer suddenly started to ingest large amounts of bark biomass, coinciding with a significant change in the bark’s concentration of starch. We suggest that the lack of effect of rapeseed feeding can partly be explained by overshadowing effects caused by such seasonal changes of bark characteristics, and partly by the fact that the rapeseed plants in our study contained lower than expected concentrations of easily-digestible macronutrients (apart from protein). We conclude that the risk of damage on spruce can be especially high during certain periods, something that is important to consider when mitigating bark stripping. However, several interactive effects are involved and must be considered in order to more efficiently mitigate damage.

GENETIC AND PHYSIOLOGICAL ASPECTS OF SILIQUE SHATTERING IN RAPESEED AND MUSTARD

Rapeseed (Brassica napus L.) and mustard (Brassica juncea L.) are two important oilseed crops grown worldwide for edible oil and meal production, as well as, a source of renewable energy. Silique shattering at the maturity stage is the major cause of seed yield reduction in brassica. Losses in seed yield are more in developing countries due to poor management and the non-availability of combine harvesters. Silique shattering resistance is essential for achieving good seed yield especially in Brassica napus. The silique on plants of rapeseed and mustard mature in different phases due to indeterminate growth habit, which is also a reason for shattering losses. Silique shattering is linked with the creation of a dehiscence zone in a brassica pod. When the siliqua wall loses its hydration, along the length of the siliqua, a few cell layers separate the replum from the pericarp tip of the two silique valves. In the dehiscence zone, it involves the collapse of cell walls and cell separation, as well as, the destruction of the middle lamella and enhanced hydrolytic enzyme activity. To avoid seed yield losses, resistance against silique shattering is essential in rapeseed and mustard cultivars. There are multiple QTLs discovered that control variance in silique shattering. Previous studies validated the shattering process in the model plant Arabidopsis thaliana was controlled by eight different genes. However, their role in controlling silique shattering in rapeseed and mustard is unknown. Modern tools of mutation breeding and genetic engineering, especially CRISPR/Cas9 technology, can be utilized to identify the genetic source for shattering resistance in rapeseed and mustard, which will be helpful for the development of silique-shattering

The effect of humic acid on rapeseed (Brassica napus L.) plant growth, heavy metal uptake, phytoremediation parameters (BCF, TF and TI), and antioxidant activity in heavy metal polluted soil

The aim of this study was to investigate the effects of humic acid (HA) applications on rapeseed (Brassica napus L.) growth, heavy metal uptake, bioconcentration factor (BCF), translocation factor (TF), tolerance index (TI), catalase (CAT), ascorbate peroxidase (APX) enzyme activities and hydrogen peroxide (H2O2) content in polluted soil with lead (Pb), chromium (Cr), cadmium (Cd), and zinc (Zn). Three doses of HA (Control, HA1:500 mg kg-1, HA2:1000 mg kg-1, HA3:2000 mg kg-1) were applied in pots. HA1, HA2, and HA3 applications increased plant growth parameters compared to polluted soil. Compared to the control, HA applications in polluted soil increased the Pb, Cr, Cd, and Zn concentrations in the plant. However, HA applications in polluted soil significantly decreased the heavy metal content in roots and shoots of the plant compared to polluted soil. BCF in both roots and shoots of the plants were greater than 1 for Pb, Cr, Cd, and Zn. However, specifically HA2 application decreased the shoot and root BCF values in polluted soil. TF was smaller than 1 in Pb, Cr, Cd, and Zn in polluted soil. On the other hand, HA applications for Cd increased TF values. Shoot TI decreased 17.37 %, and root TI decreased 9.09% in polluted soil. CAT and APX enzyme activities and H2O2 increased significantly in polluted soil. However, HA applications decreased CAT and APX enzyme activities and H2O2 content in rapeseed. It is concluded that HA application in Pb, Cr, Cd, and Zn polluted soil has a remedial effect on the development of rapeseed by reducing heavy metal content and oxidative stress.

Genetic loci associated with freezing tolerance in a European rapeseed (Brassica napus L.) diversity panel identified by genome-wide association mapping.

Winter biotypes of rapeseed ( Brassica napus L.) require a vernalization treatment to enter the reproductive phase and generally produce greater yields than spring rapeseed. To find genetic loci associated with freezing tolerance in rapeseed, we first performed genotyping‐by‐sequencing (GBS) on a diversity panel consisting of 222 rapeseed accessions originating primarily from Europe, which identified 69,554 high‐quality single‐nucleotide polymorphisms (SNPs). Model‐based cluster analysis suggested that there were eight subgroups. The diversity panel was then phenotyped for freezing survival (visual damage and Fv/Fo and Fv/Fm) after 2 months of cold acclimation (5°C) and a freezing treatment (−15°C for 4 h). The genotypic and phenotypic data for each accession in the rapeseed diversity panel was then used to conduct a genome‐wide association study (GWAS). GWAS results showed that 14 significant markers were mapped to seven chromosomes for the phenotypes scored. Twenty‐four candidate genes located within the mapped loci were identified as previously associated with lipid, photosynthesis, flowering, ubiquitination, and cytochrome P450 in rapeseed or other plant species.

Biomechanical properties of ready-to-harvest rapeseed plants: Measurement and analysis

A large loss occurs in the combine harvesting of rapeseeds due to the fragility of rapeseed pods, and all the more so with the vibration of the combine header and the collision between the header and plants. Seed loss is greatly affected by the biomechanical properties of ready-to-harvest rapeseed plants. To understand the mechanism of pod cracking and seed loss and to propose measures for alleviating them, it is needed to study the biomechanical properties of ready-to-harvest rapeseed plants. To this end, “Huayouza 62”, a widely planted rapeseed variety in central China, was selected to study the biomechanical properties, including pod-cracking resistance, main stem-shearing resistance and resonant frequencies, of whole plants. The results showed that the distribution of pod-cracking resistance forces was 1.333–6.100 N in the mature stage, and the pod width and thickness had a significant influence on the cracking resistance. The main influencing factor of the main stem-shearing resistance was the stem diameter. A thicker main stem resulted in a larger shearing resistance force but a smaller shear stress. The moisture contents of the main stems varied from 47.71% to 76.13%. However, the varying moisture contents did not show a significant impact on the shearing resistance. The resonant frequencies of whole rapeseed plants ready for harvest ranged from 6.5 Hz to 7.5 Hz, which was close to the excitation frequency of the cutter bar on the 4LL-1.5Y harvester. This study lays a foundation for improving the design and construction of harvesting devices for rapeseed plants to reduce seed loss.

Influence of multicomponent fertilizers on spring rapeseed productivity

Field experiments were conducted on leached chernozem in conditions of forest-steppe of the Central Chernozem region in 2018-2020. Spring rapeseed cv. Rubezh was chosen as the object of the research. The processing of rapeseed plants was carried out twice: in the leaf rosette phase and growth of the central stem - according to the scheme: 1. Control (without treatment); 2. Ecolist Macro 12-4-7 (2L/ha); 3. BionexKemi (2L/ha); 4. Ecolist Macro 12-4-7+ Borogum (2L/ha + 1.0 l/ha); 5. Bionex-Kemi + Borogum (2L/ha + 1.0 L/ha). The studies conducted showed that the fertilizers used in the experiment contributed to a reduction in the growing season by 2-3 days. The treatment of spring rapeseed plants with agents positively affected both the indicators of the crop structure and, in general, the productivity of spring rapeseed. Foliar top dressing with the studied fertilizers contributed to greater fruit setting and preservation of the pods. In comparison with the control, the maximum increase - 1.80 c/ha and 1.62 c/ha - was obtained when using Ecolist Macro 12-4-7+ Borogum fertilizer complex and Bionex-Kemi + Borogum, respectively. The studied multicomponent fertilizers resulted in reducing of protein in spring rapeseed seeds, but significantly increased the oil content. The maximum oil yield was obtained from the use of a mixture of Ecolist Macro 12-4-7+ Borogum (769.4 kg/ha).

Effect of zeolite on the micro-morphological and biochemical features of the spring rapeseed (Brassica napus L.)

The study aimed to assess the effect of a natural mineral fertilizer – zeolite on the micro-morphological and biochemical characteristics of the spring rapeseed Brassica napus L. cv. ―Rif‖ ). Experiments were held at the Federal Research Center for Breeding, Agro-technics and Nursery Horticulture, Moscow, and Agro-industrial Institute, Bunin Yelets State University, Yelets, Russia from 2018 to 2020. The study scheme comprises four treatments as follows: a. control (no fertilizer), b. NPK @ 60-60-60 kg ha-1, c. Zeolite 5 t ha-1, and d. NPK @ 60-60-60 kg ha-1 + Zeolite 5 t ha-1. Results revealed that the maximum number of stomata was observed in the rapeseed crop treated with natural and mineral fertilizer – zeolite. On average, there were 537 pcs/mm2 on the adaxial surface, and 480 pcs/mm2 on the abaxial leaf surfaces. The mineral fertilizer application only, and in combination with a natural ameliorant, contributed an increase in photosynthetic pigments, which was about 22% more relative to the control. To determine the content of trace elements (Mn, Fe, Zn, and Ni) according to the phases of spring rapeseed development, the trace elements were decreased by the harvesting phase. The only exception was Co, where content was increased by the time of rapeseed ripening. The accumulation of the studied trace elements in spring rapeseed plants at maturity can be represented by the following decreasing series, Fe>Mn>Zn>Cu>Ni>Co. The correlation coefficients also revealed that there was a strong relationship among all the studied elements. A high correlation (r = 0.95) was found between the seed yield and the magnitude of the photosynthetic pigments.

H2O2-Responsive Hormonal Status Involves Oxidative Burst Signaling and Proline Metabolism in Rapeseed Leaves.

Drought alters the level of endogenous reactive oxygen species (ROS) and hormonal status, which are both involved in the regulation of stress responses. To investigate the interplay between ROS and hormones in proline metabolism, rapeseed (Brassica napus L.) plants were exposed to drought or exogenous H2O2 (Exo-H2O2) treatment for 10 days. During the first 5 days, the enhanced H2O2 concentrations in drought treatment were associated with the activation of superoxide dismutase (SOD) and NADPH oxidase, with enhanced ABA and SA levels, while that in Exo-H2O2 treatment was mainly associated with SA-responsive POX. During the latter 5 days, ABA-dependent ROS accumulation was predominant with an upregulated oxidative signal-inducible gene (OXI1) and MAPK6, leading to the activation of ABA synthesis and the signaling genes (NCED3 and MYC2). During the first 5 days, the enhanced levels of P5C and proline were concomitant with SA-dependent NDR1-mediated signaling in both drought and Exo-H2O2 treatments. In the latter 5 days of drought treatment, a distinct enhancement in P5CR and ProDH expression led to higher proline accumulation compared to Exo-H2O2 treatment. These results indicate that SA-mediated P5C synthesis is highly activated under lower endogenous H2O2 levels, and ABA-mediated OXI1-dependent proline accumulation mainly occurs with an increasing ROS level, leading to ProDH activation as a hypersensitive response to ROS and proline overproduction under severe stress.

Combined BSA-Seq Based Mapping and RNA-Seq Profiling Reveal Candidate Genes Associated with Plant Architecture in Brassica napus.

Plant architecture involves important agronomic traits affecting crop yield, resistance to lodging, and fitness for mechanical harvesting in Brassica napus. Breeding high-yield varieties with plant architecture suitable for mechanical harvesting is the main goal of rapeseed breeders. Here, we report an accession of B. napus (4942C-5), which has a dwarf and compact plant architecture in contrast to cultivated varieties. A BC8 population was constructed by crossing a normal plant architecture line, 8008, with the recurrent parent 4942C-5. To investigate the molecular mechanisms underlying plant architecture, we performed phytohormone profiling, bulk segregant analysis sequencing (BSA-Seq), and RNA sequencing (RNA-Seq) in BC8 plants with contrasting plant architecture. Genetic analysis indicated the plant architecture traits of 4942C-5 were recessive traits controlled by multiple genes. The content of auxin (IAA), gibberellin (GA), and abscisic acid (ABA) differed significantly between plants with contrasting plant architecture in the BC8 population. Based on BSA-Seq analysis, we identified five candidate intervals on chromosome A01, namely those of 0 to 6.33 Mb, 6.45 to 6.48 Mb, 6.51 to 6.53 Mb, 6.77 to 6.79 Mb, and 7 to 7.01 Mb regions. The RNA-Seq analysis revealed a total of 4378 differentially expressed genes (DEGs), of which 2801 were up-regulated and 1577 were down-regulated. There, further analysis showed that genes involved in plant hormone biosynthesis and signal transduction, cell structure, and the phenylpropanoid pathway might play a pivotal role in the morphogenesis of plant architecture. Association analysis of BSA-Seq and RNA-Seq suggested that seven DEGs involved in plant hormone signal transduction and a WUSCHEL-related homeobox (WOX) gene (BnaA01g01910D) might be candidate genes responsible for the dwarf and compact phenotype in 4942C-5. These findings provide a foundation for elucidating the mechanisms underlying rapeseed plant architecture and should contribute to breed new varieties suitable for mechanization.

EFFICIENCY OF USE OF MACRONUTRIENTS BY SPRING RAPESEED PLANTS

The relevance of this study is determined by the need to optimize the production process of agrocenoses of spring rapeseed and establish the regularities of the dynamics of macroelements in the soil under the influence of different rates of mineral fertilisers. In this regard, the purpose of this paper was to cover the regularities of changes in the content of macroelements in typical low-humus chernozems at different stages of spring rapeseed culture development in the conditions of the Right Bank Forest Steppe of Ukraine. Field, laboratory, analytical, and statistical research methods were used in the study. It was established that the highest content of macroelements in the soil at all levels of mineral fertiliser is in the phase of leaf rosette formation by spring rapeseed plants (BBCH 15-18). As plants grow through the phases, it decreases and reaches minimum values in the ripening phase (BBCH 85-88). The highest content of nitrogen mineral compounds was noted in BBCH 15-18: 52.0-60.2 mg/kg of soil depending on the fertiliser variant, the content in the variant without fertiliser application – 49.8 mg/kg of soil. It was found that the maximum content of mobile phosphorus compounds in the soil was recorded in the first half of the growing season. It was found that the content of mobile potassium in the soil is dictated by the amount of applied mineral fertilisers. The highest content was noted at the beginning of the vegetation of spring rapeseed, with a gradual decrease until the seed ripening phase (BBCH 85-88). A close correlation was established between the accumulation of dry matter in the BBCH 55-58 period and the yield level (r=0.91). The materials of this paper are of practical value for the improvement of processes related to the development of the productivity of spring rapeseed crops in the conditions of the Forest Steppe of Ukraine, as well as the rational use of mineral fertilisers on typical low-humus chernozems

Wax Extracted from Waste Cauliflower Leaves Shows Potential Antitranspirant Efficacy When Applied to Rapeseed Plants

The stress from excessive transpiration of water from plant leaves can damage crop growth during droughts. Specific commercial biostimulant products (antitranspirants) are available to reduce transpiration when applied to plants, but these products are expensive. Antitranspirants from waste would be cheaper, and the aim of this research was to extract leaf wax from a fresh produce processing waste and conduct a preliminary evaluation of its antitranspirant efficacy. Supercritical CO2 was used to extract wax from cauliflower leaves, and after formulating for spraying, the wax was applied to young rapeseed plants in three consecutive experiments. The wax was compared with a commercially-available terpene antitranspirant (di-1-p-menthene) for efficacy in reducing stomatal conductance and water use. In two of the three experiments, stomatal conductance was significantly reduced to similar extents by wax and by di-1-p-menthene, despite the wax being formulated and applied at a much lower concentration. Water use was reduced by wax in one experiment. Further research is needed on formulation, spraying conditions, and dose-response. These preliminary results demonstrate the potential for extracted leaf wax to act as a biostimulant and ameliorate plant drought stress.

BnA.JAZ5 Attenuates Drought Tolerance in Rapeseed through Mediation of ABA–JA Crosstalk

Drought stress reduces water availability in plant cells and influences rapeseed yield. Currently, key genetic regulators that contribute to rapeseed response to drought remain largely unexplored, which limits breeding of drought-resistant rapeseed. In this study, we found that Brassica napus JASMONATE ZIM-DOMAIN 5 (BnA.JAZ5), one of the transcriptional repressors functioning in the jasmonate (JA) signaling pathway, was triggered by drought treatment in rapeseed, and drought-susceptibility increased in BnA.JAZ5-overexpressing rapeseed plants as compared to wild-type plants, resulting in a lower survival rate after recovery from dehydration. After recovery for 3 days, 22–40% of p35S::BnA.JAZ5 transgenic plants survived, while approximately 61% of wild-type plants survived. Additionally, seed germination of BnA.JAZ5-overexpressing rapeseed was hyposensitive to abscisic acid (ABA). The germination rate of five transgenic lines was 32~42% under 9 µM ABA treatment, while the germination rate of wild-type plants was 14%. We also found that the average stomatal density of five overexpressing lines was 371~446/mm2, which is higher than that of wild-type (232/mm2) plants under normal conditions. These results indicate that BnA.JAZ5 regulated drought response in an ABA-dependent manner, possibly by affecting stomatal density. Interestingly, methyl jasmonate (MeJA) treatment rescued the ABA-hyposensitive seed germination, revealing crosstalk between JAZ5-meidated JA and the ABA signaling pathway. Taken together, our results suggest that BnA.JAZ5 attenuated drought resistance through the ABA-dependent pathway, which could represent important genetic loci for drought-resistant rapeseed breeding.