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Gibberellic acid (GA) and ethephon (ETH) can stimulate seed germination and seedling growth. However, uncertainties persist concerning the efficacy of GA or ETH priming in mitigating drought stress effects. This study aims to elucidate the underlying mechanisms of drought tolerance in rice seedlings induced by GA or ETH priming. Rice seeds were primed by water, GA, and ETH and sown under polyethylene glycol (PEG-6000)-induced stress. We set non-primed seeds under normal conditions as a control to investigate the effects of GA or ETH on seed germination and seedling growth under drought stress. Drought resistance mechanisms were characterized by osmoregulation, homeostasis of reactive oxygen species (ROS), antioxidants and transmission electron microscopy analysis. Drought significantly inhibited germination and seedling development. Nevertheless, GA or ETH priming enhanced rice emergence and establishment under water-deficient condition. Furthermore, hormonal priming enhanced chlorophyll content and osmolyte accumulation, ROS detoxification and antioxidant enzyme activity in rice seedlings (shoots and roots) during drought stress. Ultrastructural observations revealed GA or ETH priming’s protective role in leaf mesophyll integrity, chloroplast preservation, and mitigation of drought-induced damage in root tip cells. Nonetheless, distinct defense responses and mitigation mechanisms emerged post-GA or ETH priming. While ETH treatment affected shoot fresh weight and root volume, GA priming excelled in germination attributes, seedling length, soluble sugar, H2O2reduction, electrolyte leakage, and ascorbate peroxidase activity under drought. GA and ETH priming promoted rice seed germination and seedling establishment under drought conditions by maintaining root conformation, attenuating oxidative stress, and maintaining cellular ultrastructure.

We produced a new biochar composite from waste bamboo powder and used it as a carrier for N,N-dimethylacetamide (DMAC) biodegradation. Characterization results highlighted the biochar composite's macroporous structure, comprising 72.14% of its total pore volume, facilitating bacterial colonization and growth. In comparison to traditional biocarriers and bamboo charcoal-loaded polyurethane (BC-PU), the biochar composite exhibited faster biofilm formation and achieved stability by the 5th day. Due to the increased biomass on the biochar composite, the DMAC degradation rate reached 80.44%, which was 1.5 times greater than that of BC-PU, indicating its potential for treating DMAC in biofilters. The Fourier transform infrared spectroscopy revealed the presence of abundant oxygen-containing functional groups in the biochar composite, which strongly interacted with bacterial adhesion. Selective passivation of oxygen-containing functional groups extended the biofilm formation time from 5 to 10 days, while the introduction of carboxyl groups expedited it by 1 day. Kinetic studies and the Derjaguin–Landau–Verwey–Overbeek theory demonstrated that the oxygen-containing functional groups reduced the total interaction energy and improved the mass transfer capacity of the biochar surface, thereby promoting biofilm formation. This study introduces a macroporous biochar composite with enhanced biodegradation capabilities, outperforming traditional biocarriers in VOCs degradation in bioreactors. The process provides a new direction for future biocarrier preparation.

Low temperature is a main adverse factor affecting successful seedling establishment in the Yangtze River basin, and thus low‐temperature stress tolerance at the germination and seedling emergence stages is an important attribute for rapeseed (Brassica napusL.) production. The present study was conducted to evaluate the low‐temperature stress tolerance indices (STIs) of a large conventional rapeseed genotype population at the germination and seedling emergence stages. Twelve seed germination‐ and seedling emergence‐related indices were investigated under normal and low‐temperature conditions, and the broad‐sense heritability of these indices ranged from 25.4 to 57.6%. Therefore, the selection of genotypes with strong low temperature tolerance is a feasible way to guarantee seedling establishment. Using principal component analysis, the STIs during the seed germination and seedling emergence stages have been divided into three main categories: dry matter weight, germination speed and final germination percentage, and root length with a seedling vigor index. The top three genotypes ranked by comprehensive STI score were Huayou No. 2, SWU44, and 2012‐K8053; the bottom three genotypes ranked by comprehensive STI score were Chuanyou18, wx1025, and 97096. The results of the present study could provide valuable information for breeders to utilize the rapeseed germplasm resources in the Yangtze River basin to achieve the goal of low‐temperature resistance breeding.

Early‐maturing rapeseed (Brassica napusL.) can alleviate the seasonal conflict between double‐season rice (Oryza sativaL.) and rapeseed in the Yangtze River basin. In this study, the early‐maturing rapeseed ‘Shengguang 127’ and intermediate‐maturing cultivar ‘Huayouza 9’ (control) were sown on 2 October under five different planting densities (150,000 [D1], 300,000 [D2], 450,000 [D3], 600,000 [D4], and 750,000 plants ha−1[D5]) during two growing seasons. The patterns of change in growth and development, yield, and yield components were investigated systematically to reveal the light energy and temperature production efficiencies and to quantify the ideal plant density for the early‐maturing cultivar. The results showed that the early‐maturing genotype advanced the whole growth period by 3 to 5 d under the same densities, compared with those of the intermediate‐maturing genotype. The yield and population dry matter weight of both cultivars decreased after an initial increase, with the density increased initially from the D1 to D3 treatment, where it reached a maximum, and then decreased to the D5 treatment. Similar trends were observed in the light and temperature production efficiencies. Under the same densities, the production efficiencies of light energy and temperature in Shengguang 127 were 14.7 to 24.2% higher than those of the control, respectively; the yield and harvest indices in Shengguang 127 were significantly higher than those in Huayouza 9, which was attributed to the significantly higher 1000‐seed weight. These results provide a theoretical basis for the agronomic management and breeding of high‐yielding traits of early‐maturing rapeseed in the Yangtze River basin.

The naturally drought-prone climate of the Tibetan Plateau has produced highly drought-resistant Brassica juncea. The objective of the present study was to examine improvement in drought resistance in B. napus by distant hybridisation between B. juncea and B. napus. Distant hybridisation was performed to generate F1 hybrids, which were open-pollinated by a set of breeding lines of B. napus. Continuous self-crossing was then performed to produce the F2–F6 generations, and 74 lines of new-type Brassica napus with stable fertility and morphological phenotypes were selected. The drought resistance of the 74 lines was evaluated during the germination stage by simulating drought stress at 15% PEG-6000, and a wide range of genetic variation in drought resistance was scored. Cytological identification of four lines chosen from strongly, intermediate and weakly drought-resistant clusters demonstrated that their chromosomes had gradually stabilised to B. napus (2n = 38) after advanced self-crossing. A drought-resistant line (line 290) and a drought-susceptible line (line 299) were selected to determine the physiological response to drought stress at the seedling stage. The results showed that proline, soluble protein and malondialdehyde contents of the drought-resistant line were always lower than those of the drought-susceptible line and other common rapeseed variety under drought stress and rewatering conditions. This indicates that the drought-resistant line may have a better reactive oxygen species scavenging system with a less extreme reaction to drought stress. Additionally, the results revealed that the genetic diversity of B. napus under drought resistance was broadened by distant hybridisation, which could encourage breeders to utilise the germplasm resources of B. juncea in the Tibetan Plateau to achieve the goal of drought resistance.

Soluble sugar content in silique wall and seeds of rapeseed (Brassica napus L.) has significant effects on seed oil formation and accumulation. We studied the relationship between soluble sugar content in B. napus seeds and silique wall and oil concentration under field conditions in two cropping seasons, and examined changes in soluble sugar content in seeds and silique wall under different nitrogen (N) levels. Two commercialised Chinese rapeseed varieties, HZ9 and HZ62, with high seed yield and different N responses were used. Our results indicated that carbon (C):N ratio and soluble sugar content in silique wall had the greater effect on seed oil concentration. When C:N ratio and soluble sugar content in silique wall were within 5–15% and 10–25%, respectively, plants had relatively well coordinated C and N metabolism, facilitating oil accumulation. During 25–35 days of silique development, when C:N ratio and soluble sugar content in silique wall were within 10–15 and 15–25%, respectively, oil synthesis was fastest; the highest accumulation rate was 3.8% per day. When they were each <5%, seeds tended to mature, and oil synthesis gradually decreased, ceased or degraded. During the early stage of silique development, if C:N ratio and soluble sugar content in silique wall were >15% and 30%, there was no apparent tendency for oil accumulation, probably because of adverse environmental conditions. When N application increased from 0 to 270kg ha-1, final oil concentration in seeds decreased by 0.024%. In summary, C:N ratio and soluble sugar content in silique wall are important in regulating seed oil concentration, whereas excessive N application significantly reduced seed oil concentration. Therefore, appropriate reduction of N application would save resources, provide environment benefits and increase rapeseed oil production with no substantial reduction in seed yield, through coordinated seed yield and oil concentration.

The adsorption performance of BC/PU-5 for n-hexane reached the maximum of 23.6 g g−1.Based on the kinetic calculation and DFT simulation, the adsorption mechanism of OSs on BC/PU-5 was discussed.The quantitative correlation between the structural parameters of OSs and the adsorption properties of BC/PU-5 was established.

A single functional leaf is usually sampled to evaluate the growth and photosynthetic assimilation of crops. However, there is large variation between leaves in winter oilseed rape (Brassica napus L.) at seedling stage. In this study, the morphological and physiological characteristics of various functional leaves were compared with characteristics of the whole plant at seedling stage for 2 years by using the oilseed rape cultivars Huaza 9 and Huaza 62 as plant material. The aim of this study was to identify a leaf that can represent the whole plant for assimilate accumulation characteristics at the seedling stage of the crop. The results showed that the photosynthetic rate and the contents of non-structural carbohydrates, nutrients and soluble proteins in fourth and fifth leaf of a plant were most closely related to those of the whole plant. The area and dry matter (DM) of all functional leaves were well correlated with those of whole plant, with the fifth leaf having the highest correlations. It is therefore recommended that the fifth leaf is most suitable to represent the whole plant for evaluation of growth and assimilate accumulation for winter oilseed rape at the seedling stage. The following regression equations for whole plant (y) and fifth leaf (x, dry matter or length×width) can be used to predict (1) DM accumulation (g) and (2) total leaf area (cm2) of the whole plant: (1) y=3.32x+1.51 (R2=0.88, P<0.001); (2) y=1.24x+222.69 (R2=0.67, P<0.001).

In this study, 137 canola (Brassica napus L.) accessions were evaluated for germination speed, which is a critical character in the plant life cycle. The accessions were grouped into three categories, fast (F), medium, and slow (S), with nine category F (7%) and 12 category S (9%) germination accessions identified and validated in repeated Petri dish and pot experiments. Although accessions in category F showed significantly faster germination and emergence than those in category S, seedling growth parameters did not differ greatly. Based on germination speed and seedling characteristics, four accessions with high early vigour and four with low early vigour were identified. Seed germination speed was not affected by seed weight and was not simply controlled by gibberellic acid and abscisic acid, but 10% smoke water significantly delayed seed germination. The identified accessions with contrasting early vigour can be used to study the genetic and molecular mechanism of seed germination and seedling development and to breed superior canola cultivars.

High light use efficiency is an important factor for yield improvement during the growing season for winter canola. This study explored the evaluation method of high light use efficiency during the whole growth period in order to screen high light use coefficient of crop genotypes in canola producing areas of Southwest China. The pot experiment was conducted with sixty canola cultivars which had already been planted in the crops planting areas of the middle and upper reaches of Yangtze River. The plant height, root neck diameter, number of pods per main inflorescence, pods per plant, dry weight of shoots, seed weight per plant, pericarp weight per plant, ratio of pericarps to seeds weight per plant, seeds number per pod and 1000-grain weight were investigated under the shading treatment of reducing the incoming solar light by 20%. The high light use coefficient of canola cultivars was evaluated comprehensively by principal component analysis, membership function, cluster analysis and stepwise regression analysis. With these analyses, the original twelve indices related to light use efficiency could be synthesized into the four independent indices which represented 86.4% of all the investigated information of canola with high photosynthetic efficiency. Sixty varieties were classified into three groups by cluster analysis, and ZS12, GYZ6, FY792, RHY6, CZY3 and ZYZ19 displayed higher light use efficiency; such 18 varieties as XDZY9, XY1, YY50 and so on, were medium light efficient ones; and the rest 36 varieties such as LY9, ZYZ781, SG127 and so on, fell to the relatively lower light use efficiency categories. The comprehensive evaluation in this study had screened such four indicators as the stem dry weight per plant, the pod number per plant, the seed number per pod and the 1000-seed weight, which could be regarded as identification indicators for high light use efficiency of canola.