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Article

Effects of Fertilization Patterns on the Growth of Rapeseed Seedlings and Rhizosphere Microorganisms under Flooding Stress

by
Xuepeng Wu
1,2,
Junjie Wu
1,2,
Bingqian Zhou
1,2,
Bo Hong
1,2,
Dongfang Zhao
1,2 and
Mei Guan
1,2,3,*
1
College of Agriculture, Hunan Agricultural University, Changsha 410128, China
2
Hunan Branch of National Oilseed Crops Improvement Center, Changsha 410128, China
3
Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, Changsha 410128, China
*
Author to whom correspondence should be addressed.
Agronomy 2024, 14(3), 525; https://doi.org/10.3390/agronomy14030525
Submission received: 22 January 2024 / Revised: 7 February 2024 / Accepted: 1 March 2024 / Published: 3 March 2024
(This article belongs to the Section Soil and Plant Nutrition)
Browse Figures
Versions Notes

Abstract

:
In order to explore the effect of fertilization patterns on the growth of rapeseed seedlings under waterlogging stress, three fertilization patterns (conventional fertilization, supplemental organic fertilization, and supplemental microbial fertilization) were set up using the variety Xiangyou 708 as the material, and waterlogging treatment was carried out during the seedling stage of rapeseed. The effects of fertilization patterns on the growth of rapeseed seedlings and rhizosphere microorganisms under waterlogging stress were investigated. The results showed that all three fertilization patterns exhibited that waterlogging stress inhibited the growth of rapeseed seedlings, inhibited root activity, and changed the structure of rhizosphere bacterial community structure. However, supplemental organic and microbial fertilization better promoted the growth of rapeseed seedlings, reduced the impact of waterlogging stress on the growth of rapeseed seedlings, and accelerated the recovery of rapeseed seedlings after waterlogging stress. Under normal water supply, supplemental organic fertilization enriched P_Bacteroidota, P_Actinobacteriota, P_Chloroflexi, and G_Flavisolibacter in the rhizosphere soil of rapeseed, while supplemental microbial fertilization enriched P_Bacteroidota and G_Flavisolibacter in the rhizosphere soil of rapeseed. After 7 days of waterlogging treatment, supplemental organic fertilization enriched P_Verrucomicrobiota in the rhizosphere soil of rapeseed, while supplemental microbial fertilization enriched P_Actinobacteriota, G_SC-I-84, and G_Ellin6067 in the rhizosphere soil of rapeseed. The enrichment of these bacteria may be related to the growth promotion and waterlogging tolerance of rapeseed. This study provides evidence that microbial and organic fertilizer can promote the growth of rapeseed and enhance its waterlogging tolerance, as well as evidence that some rhizosphere microorganisms have a potential role in promoting the growth and waterlogging tolerance of rapeseed.

1. Introduction

Rapeseed is one of the most important oil crops in China, and the planting mode of rapeseed and rice rotation is mainly used. This planting mode accounts for more than 75% of China’s total rapeseed production. The rapeseed production areas in the Yangtze River Basin have more rainfall in spring and autumn, which often leads to higher soil viscosity and poor ventilation for rapeseed growth due to the previous crop of rice. Coupled with the high groundwater level caused by previous crops, waterlogging is extremely prone to occur [1,2,3,4].
When waterlogging occurs, due to the high water content in the soil, it has a significant impact on crop root respiration and normal metabolism, coupled with the accumulation of toxic substances in the roots, which can lead to slow growth or even death of crops. In addition, due to the impact of waterlogging on soil, the physicochemical properties of soil change, which also has an impact on plant rhizosphere soil microorganisms. Studies have shown that when crops are under stress, beneficial microorganisms can enhance the resistance of crops [5,6]. When adversity strikes, plant roots release signals to recruit microorganisms that have a positive effect on resisting adversity. This mechanism plays an important role in plants suffering from waterlogging stress [7,8,9]. After the end of waterlogging, plant roots are often damaged, and due to the slow recovery of roots, this leads to a significant lag effect of waterlogging [10].
In recent years, research on the tolerance of rapeseed to waterlogging has mainly focused on the genetic level, while there have been few reports studying the tolerance of rapeseed to waterlogging by adjusting the fertilization mode, e.g., studying the tolerance of rapeseed to waterlogging by supplementing organic or microbial fertilizers. Microbial fertilizer is made by mixing a variety of beneficial microorganisms, substrates, and some carriers that maintain microbial survival. The application of microbial fertilizer can improve the microbial environment in soil, increase the number of beneficial strains in soil, stimulate crop growth, and enhance stress resistance [11]. Organic fertilizer is made from animal waste and plant residues after fermentation and decomposition [12]. The most significant effect of applying organic fertilizer is to increase the content of organic matter in soil and regulate the balance of soil nutrients [13]. In addition, organic fertilizer can also improve soil texture, which indirectly promotes plant root absorption of nutrients in soil, promotes soil microbial activity, and increases biomass in soil [14]. These effects directly or indirectly promote crop growth and stress resistance. In recent years, with the use of microbial and organic fertilizers in agricultural production, the effects of these new fertilizers on crop yield increase and stress resistance enhancement have been increasingly recognized [13,15]. According to the research of Deng W et al., applying organic fertilizer can improve the stress resistance of rice [16]. According to the research of Xu H L et al., microbial fertilizer can enhance the water tolerance of sweet corn [17]. Therefore, it is very worthwhile to explore the application of organic and microbial fertilizers to study the tolerance of rapeseed to waterlogging. In this experiment, different fertilization modes and whether to carry out flooding treatment were used as variables to study the physiological indicators and rhizosphere soil bacterial species and community structure of rapeseed. The objective of this study was to explore the effects of organic and microbial fertilizers on the waterlogging tolerance of rapeseed. In addition, the bacterial community structure in the rhizosphere of rapeseed was studied by changing the fertilization mode and flooding. Further screening of bacterial communities with potential effects on enhancing the tolerance of rapeseed to waterlogging was conducted through intergroup differences. The above research provides a scientific basis for improving the waterlogging tolerance of rapeseed by changing the fertilization mode.

2. Materials and Methods

2.1. Overview of the Experiment Site

The experiment was conducted in 2022–2023 at the Hunan Agricultural University Internship Base in Liuyang City, Hunan Province (113°83′46′′ E, 28°30′93′′ N). The soil was red with pH of 6.2, organic matter, total nitrogen (N), and total phosphorus (P) of 23.37, 1.41, and 0.52 g·kg−1, respectively, and alkali-hydrolyzed N, available P and available K of 153.2, 36.98, and 109.7 mg·kg−1, respectively.

2.2. Experimental Materials

The test variety is Xiangyou 708, provided by the Hunan branch of the National Oil Crops Improvement Center. The test fertilizers are 45% potassium sulfate compound fertilizer (N:P2O2:K2O = 15:15:15), organic fertilizer (organic matter content ≥ 30%), and microbial bacterial fertilizer (multiresistant functional bacterial fertilizer, effective viable bacteria count ≥ 200 million/g). The compound fertilizer was developed by Wuhan Zhongnong International Trade Co., Ltd. (Wuhan, China), the organic fertilizer was developed by the Hunan Provincial Soil and Fertilizer Research Institute (Changsha, China), and the microbial fertilizer was developed by Disco Chemical Group Co., Ltd. (Shanghai, China).

2.3. Experiment Design

Three fertilization modes were used: 600 kg·ha−1 compound fertilizer (conventional fertilization); 600 kg·ha−1 compound fertilizer + 600 kg·ha−1 organic fertilizer (supplementary organic fertilizer); and 600 kg·ha−1 compound fertilizer + 600 kg·ha−1 microbial bacterial fertilizer (supplementary microbial fertilizer). The organic fertilizer used in this experiment was fermented from organic materials such as rapeseed meal, amino acids, and chicken manure. Microbial fertilizer was made from small-molecule organic carbon, mineral humic acid, and active functional bacteria. All three fertilizers were applied in a deep-tillage and mixing manner. All three fertilization patterns were applied as base fertilizer before sowing.
Two water treatment methods were used: natural precipitation, no irrigation; and after two months of normal growth of rapeseed from sowing, starting to flood the soil with irrigation water greater than the maximum field capacity. The irrigation water should flood the soil surface by 1–2 cm for seven days. After flooding, observe the water level in the field at a fixed time every day. If the water level is observed to decrease, replenish water in time to ensure stable water level in the field. Growth conditions should be observed and recorded daily.
The experiment began sowing on 23 September 2022, using a split-plot design with irrigation as the main area and fertilization as the secondary area. The split area was 8 m2 (two meters wide and four meters long), Each treatment was repeated in 3 plots, for a total of 18 plots. The plots for different fertilization treatments were spaced at 1 m, with a 1 m-wide protection row around them. The flooding treatment and no flooding treatment were carried out on different plots. The planting density was 30 cm for row spacing and 15 cm for plant spacing. Field sampling was conducted on 30 November 2022. After the first sampling, the flooding treatment was stopped and the natural precipitation state was restored. The second field sampling was conducted on 14 December 2022.

2.4. Sample Collection and Determination

2.4.1. Harvesting of Rapeseed Seedlings

After the treatment, using a random sampling method, one rape plant from each experimental plot was taken. Three rape plants were taken from each treatment. The plants were taken out of the field, with the root system as intact as possible. The plants were cleaned and the surface moisture was wiped off with paper towels. The plants were divided into aboveground and underground groups. They were then placed in sealed bags and frozen for subsequent testing.

2.4.2. Collection of Rapeseed Rhizosphere Soil

The roots were dug out and gently shaken to disperse the loose soil attached to the plant roots. Sterile hairbrushes were used to collect soil that was tightly bound to the roots, and the soil was mixed evenly through a 1 mm sieve and then stored in sterile bags for refrigeration. It was sent to Allwegene, a company in Beijing, China, for soil microbial extraction and sequencing.

2.4.3. Determination of Plant Growth Indicators

A ruler was used to measure the stem diameter and plant height of rapeseed seedlings and an electronic balance to determine the fresh weight of the aboveground and underground parts of the plant. After measuring, the plant was blanched at 105 °C for 30 min, then dried at 80 °C until constant weight, and its dry weight recorded. The TTC colorimetric method was used to determine the root vigor of the plant [18].

2.4.4. Rhizosphere Microorganism Determination

An E.Z.N.A. Soil DNA Kit (Omega Bio-tek, Inc., Norcross, GA, USA) kit was used to extract genomic DNA from soil samples. Nanodrop 2000 (ThermoFisher Scientific, Inc., Waltham, MA, USA) was used to detect DNA quality and concentration. The V3–V4 region of the 16S rRNA gene of bacteria was amplified using universal primers 338F (5′-ACTCCTACGGGAGGCAGCAG-3′) and 806R (5′-GGACTACHVGGGT-WTCTAAT-3′). Add 8 bp barcode sequences at the 5′ ends of the primers upstream and downstream to distinguish different samples. Finally, universal primers with barcode sequences were synthesized and amplified on an ABI 9700 PCR instrument (Applied Biosystems, Inc., Foster City, CA, USA). Agarose gel electrophoresis (1%) was used to detect the size of the amplified target band—170 V for 30 min. The PCR products were automatically purified using the Agency AMPure XP (Beckman Coulter, Inc., Brea, CA, USA) nucleic acid purification kit. The concentration of the library was roughly determined using a Nanodrop 2000 (ThermoFisher Scientific, Inc., USA), and the size of the library fragments was detected using an Agilent 2100 Bioanalyzer (Agilent Technologies, Inc., Santa Clara, CA, USA). The concentration of the library was accurately quantified using the ABI StepOnePlus Real-Time PCR System (Applied Biosystems, Inc., USA). Finally, the library was sequenced on the Illumina Miseq/Nextseq 2000/Novaseq 6000 (Illumina, Inc., San Diego, CA, USA) platform using the PE250/PE300 sequencing strategy.

2.5. Statistical Analysis

The physiological experimental data were plotted using Excel 2013 software and analyzed using LSD and Duncan tests with SPSS 20.0. The statistical analysis was conducted at a significance level of p < 0.05, and the results are presented as means ± standard error.
The raw data were divided into different samples according to the barcode sequence. Pear (v0.9.6) software was used to filter and splice the sequencing data [19].
The sequences were removed from consideration if they contained ambiguous bases, and the parts with low-quality scores (≤20) were cut out in the sequences. During splicing, the minimum overlap setting was 10 bp, and the p-value setting was 0.0001. After splicing, Vsearch (v2.7.1) software was used to remove sequences with length less than 230 bp and the chimeric sequence removed by uchime method according to the Gold Database [20,21]. Qualified sequences were clustered into operational taxonomic units (OTUs) at a similarity threshold of 97% using the Uparse algorithm of Vsearch [20,22].
To minimize the effect from sequencing depth to the intersample variation, samples were subsampled (rarefied) to xxxx sequences per sample by random sampling. The BLAST tool was used to classify all OTU representative sequences into different taxonomic groups against the Silva138 Database, and the e-value threshold was set to1e-5 [23,24].
QIIME (v1.8.0) was used to generate rarefaction curves and to calculate the richness and diversity indices based on the OTU information and R (v3.6.0) software used to plot [20,25].
Based on the results of taxonomic annotation and relative abundance, R (v3.6.0) software was used for bar-plot diagram analysis. For describing the dissimilarity between multiple samples, PCA was analyzed by R (v3.6.0) based on the OTU information from each sample. Python (v2.7) software was used for LEfSe analysis [26].

3. Results

3.1. Effects of Different Fertilization Patterns and Water Treatments on the Growth of Rapeseed during the Seedling Stage

As shown in Table 1 and Table 2, compared with the treatment without flooding for 7 days, the plant height, stem diameter, dry weight, and fresh weight of rapeseed seedlings subjected to flooding treatment were affected to varying degrees. After 7 days of flooding treatment, the stem diameter, aboveground fresh weight, aboveground dry weight, root fresh weight, total fresh weight, and total dry weight of rapeseed seedlings supplemented with organic and microbial fertilizer were significantly higher than those of the conventional fertilization group (p < 0.05). This indicates that the supplementary application of microbial fertilizers and organic fertilizers can improve the tolerance of rapeseed plants to waterlogging stress. After 14 days of recovery from flooding stress, the rapeseed seedlings supplemented with organic fertilizer and microbial fertilizer had significantly higher fresh and dry weight of the aboveground parts, fresh weight of roots, total fresh weight, and total dry weight than those of the rapeseed seedlings with conventional fertilization (p < 0.05). Under conventional fertilization conditions, compared with the 14-day recovery from flooding treatment, the rapeseed seedlings that were not subjected to flooding treatment and were further cultivated for 14 days showed a decrease in stem diameter, dry weight of aboveground parts, fresh weight of roots, dry weight of roots, and total dry weight of 31.6%, 40.9%, 28.9%, 34.5%, and 40.0%, respectively. This was the largest decrease compared to the other two fertilization modes. This indicates that the addition of microbial fertilizers and organic fertilizers accelerated the recovery of rapeseed after being subjected to flood stress.

3.2. Effect of Different Fertilization Patterns and Water Treatments on Root Vigor of Rapeseed during Seedling Stage

When plants are subjected to waterlogging stress, their root respiration is blocked, and the accumulation of toxic metabolites leads to a decrease in root vigor. As shown in Figure 1a, compared with no flooding treatment, the root vigor of rapeseed under different fertilization treatments significantly decreased after 7 days of flooding (p < 0.05). After 14 days of recovery from flooding, there were significant differences in root vigor between the conventional fertilization and the supplemented microbial fertilizer treatments for rapeseed seedlings (p < 0.05), while there were no significant differences in the other three treatments (p > 0.05). However, the application of organic fertilizer significantly increased root vigor under all water treatment conditions compared with the other two fertilization modes (p < 0.05).
As shown in Figure 1b, at the end of the flooding treatment, after 14 days of recovery, the rapeseed seedlings that had been subjected to flooding treatment began to resume normal growth, and root vitality also increased. After 14 days of recovery from flooding treatment, the root activity of rapeseed supplemented with microbial fertilizer, conventional fertilizer, and organic fertilizer increased by 83.7%, 49.3%, and 81.2%, respectively, compared to the previous conditions. This indicates that after the rape suffered from flooding stress, the recovery of the root activity of the rape plants supplemented with organic and microbial fertilizers was promoted.

3.3. Analysis of High-Throughput Sequencing Results and Relative Abundance and Diversity of Rhizosphere Bacteria

To investigate the differences in rhizosphere bacteria in rape at different stages under different fertilization and water treatment modes, the V3–V4 region of bacterial 16S rRNA was sequenced from rhizosphere soil samples of 12 treatment groups in Table 1. A total of 15,240 OTUs were generated through clustering, and 13,975 were retained after normalization (OTU clustering similarity level ≥ 97%). A total of 7287 OTUs were found in each treatment group supplemented with organic fertilizer, of which 2216 were common among the four groups (Figure 2a). A total of 8017 OTUs were found in the various treatment groups of conventional fertilization, of which 4076 were common to all four groups (Figure 2b). A total of 6488 OTUs were found in the various treatment groups supplemented with microbial fertilizer, of which 2347 were common to all four groups (Figure 2c). The Chao1 and Shannon indices of rhizosphere bacteria in different treatment groups (Figure 3a,b) showed that there were no significant differences in the richness of rhizosphere microorganisms in rapeseed at different stages between flooding treatment, fertilization mode, and control treatment (p > 0.05).

3.4. Analysis of Rhizosphere Bacteria Bate in Rapeseed Seedling Stage under Different Fertilization Modes and Water Treatments

Beta diversity analysis measures the differences in microbial community composition under different soil environments, also known as diversity among samples or habitat diversity. To verify the differences and similarities in fungal communities between different samples, the ANOSIM showed that there were significant differences (r = 0.40, p < 0.05) in the rhizosphere bacterial community structure among the 12 treatment groups. Beta analysis was conducted on 36 groups of samples using PLS-DA. The results showed that under normal water supply after 14 days of continuous cultivation of rapeseed seedlings supplemented with microbial fertilizer, the bacterial community in the rhizosphere soil did not change significantly. On the second principal component, PC2 (with a differential explanatory rate of 10.73%), compared with no flooding treatment, flooding for 7 days caused the greatest difference in rhizosphere bacterial communities in rapeseed supplemented with microbial fertilizer, which was similar to the results of the other two fertilization methods (Figure 4a–c). Under the conventional fertilization model after 14 days of continuous cultivation without flooding treatment, the first principal component, PC1 (with a difference interpretation rate of 10.95%), the rhizosphere soil community of rapeseed showed the greatest difference, which was similar to the difference shown by the addition of organic fertilizer (Figure 4b,c).

3.5. Analysis of Rhizosphere Soil Community Composition of Rapeseed Seedlings under Different Fertilization Patterns and Water Treatments

Samples were taken from the rhizosphere soil of 12 groups of rapeseed treatments (Table 1). Three replicates were set up for each treatment group, resulting in a total of 36 soil samples. After sequencing these samples, a total of 53 phyla were detected in the 12 treatment groups, of which Proteobacteria, Acidobacteriota, Bacteroidota, Gemmatimonadota, and Chloroflexi were the dominant phyla. Their relative abundances were 30.6–38.8%, 14.0–20.4%, 10.4–20.7%, 2.8–10.8%, and 2.4–8.6% (Figure 5). The results of the differential analysis are shown in Figure 6a–d. After 7 days of flooding treatment, compared with conventional fertilization, the relative abundance of Verrucomicrobiota in the rapeseed rhizosphere soil supplemented with organic fertilizer was higher (p < 0.05). Under normal water supply, compared with conventional fertilization, the relative abundance of Bacteroidota in the rapeseed rhizosphere soil supplemented with organic fertilizer and microbial fertilizer was higher (p < 0.05). After 14 days of recovery from flooding treatment, compared with conventional fertilization, the relative abundance of Actinobacteriota in the rapeseed rhizosphere soil supplemented with microbial fertilizer was higher (p < 0.05). After 14 days of continuous cultivation without flooding treatment, compared with conventional fertilization, the relative abundance of Chloroflexi and Actinobacteriota in the rapeseed rhizosphere soil supplemented with organic fertilizer was higher (p < 0.05).
At the genus level, the top 10 dominant bacterial genera with relative abundance were: Flavobacterium, Gemmatimonas, uncultured, Bryobacter, Sphingomonas, Flavisolibacter, SC-I-84, WD2101_soil_group, Ellin6067, and Candidatus_Solibacter. After 7 days of flooding treatment, compared with the supplementary application of organic fertilizer, the relative abundance of Ellin6067 was higher in the rapeseed rhizosphere soil supplemented with microbial fertilizer (p < 0.05) compared with conventional fertilization. The relative abundance of SC-I-84 was higher in the rapeseed rhizosphere soil supplemented with microbial fertilizer (p < 0.05). Under normal water supply, compared with conventional fertilization, the relative abundance of Flavobacterium was higher in the rapeseed rhizosphere soil supplemented with organic and microbial bacterial fertilizer (p < 0.05). After 14 days of continuous cultivation without flooding, compared with the supplementary application of organic and microbial fertilizer, the relative abundance of the WD2101_soil_group was higher in the conventionally fertilized rapeseed rhizosphere soil (p < 0.05) (Figure 7a–d).
Based on the abundance distribution of taxa or the similarity between samples, clustering analysis was conducted on the top 20 genera in different samples. Compared with normal water supply, the relative abundance of Anaeromyxobacter, Citrifermentans, and Flavisolibacter was higher in flooded rapeseed rhizosphere soil, while the relative abundance of Edaphobaculum, Subgroup_7, SC−I−84, and Flavobacterium was lower (Figure 8).
The threshold value of the screening criteria was set to 3 using LEfSe to find biomarkers with statistical differences between different samples, and the relative contribution relationship of different treatments was examined. As shown in Figure 9, a total of 89 differentially expressed biomarker groups were found in 12 treatment groups. Among them, 44 differential groups were found in the rhizosphere soil supplemented with organic fertilizer; however, the number of differentially expressed taxa found in the supplementary application of microbial fertilizer and conventional fertilization was relatively small. The LEfSe analysis results showed that fertilization patterns can change the bacterial community structure of soil. The different groups found in the supplementary application of organic and microbial fertilizer may have a positive effect on improving the waterlogging tolerance of rapeseed and promote its growth during the seedling stage. However, further research is still needed to understand how these dominant bacteria respond to waterlogging in rapeseed.

4. Discussion

Winter rapeseed grown in southern China often suffers from waterlogging damage. When rapeseed is affected by waterlogging, the roots are the first to be affected. The aerobic respiration of the rapeseed roots under waterlogging stress is weakened, nutrient transport is blocked, and toxic substances accumulate, which affects the normal growth of rapeseed during the seedling stage. This experiment obtained similar results, that is, waterlogging seriously affected the growth of rapeseed, and plant height, stem diameter, plant dry weight, and plant fresh weight decreased (Table 2). The plant root activity decreased and it was difficult for this to recover to a normal level in a short period of time (Figure 1). These similar phenomena have also appeared in previous reports [27,28,29].
An important role of organic and microbial fertilizers in the application process is to improve soil structure and increase nutrients in the soil [12,15,30]. The experimental results showed that under normal water conditions, there was no significant difference in dry matter accumulation between rapeseed seedlings supplemented with organic fertilizer and microbial fertilizer (Table 2). When rapeseed seedlings were subjected to waterlogging stress, compared with the rapeseed seedlings treated with conventional fertilization, the seedlings treated with additional microbial and organic fertilizer showed significant differences in growth and more dry matter accumulation. Although there are few reports on the ability of microbial and organic fertilizers to promote rape resistance to waterlogging, Zhang and Zhao believe that microbial and organic fertilizers enhance the ability of crops to resist stress and disease [28,31]. This may be related to the increase in nutrients in the soil, the change in soil structure, and the impact on the community relationship of soil microorganisms. Another experimental result showed that after 7 days of flooding stress, compared with conventional fertilization, the root system was more vigorous, and during the later recovery process, supplementing organic fertilizer and microbial fertilizer restored rapeseed root vigor faster. This may promote the metabolism of the root of rapeseed after suffering from waterlogging, thereby better allowing the rapeseed seedlings to accumulate dry matter. It is worth noting that the effect of supplementing organic fertilizer on improving the root activity of rapeseed under waterlogging stress is better than that of supplementing microbial fertilizer.
As the most dominant microbial group in soil, bacteria account for about 80% of the total microbial biomass in soil. They can effectively promote the decomposition of organic matter and the release of nutrients in the soil, and bacteria in the rhizosphere soil are of great significance for plant growth [31,32,33]. Changes in soil moisture conditions can affect the changes in rhizosphere microbial communities. According to existing reports, microbial and organic fertilizers can affect the community changes in rhizosphere microorganisms [13,15]. This study aimed to reveal the effects of waterlogging stress and fertilization patterns on the rhizosphere bacteria of rapeseed.
Based on OUT clustering analysis and alpha analysis, among the 12 groups of treated rhizosphere soils, there were no significant differences in bacterial relative abundance or diversity. Prior to this, the results of Azarbad et al. [34] showed that waterlogging reduced the abundance of bacteria in the rhizosphere of wheat. However, other studies have also found that waterlogging increases the number of bacteria in the rhizosphere of maize [35]. Obviously, the results of the two studies are contradictory, which may be related to the type of crop.
ANOSIM and PLS-DA showed that the flooding treatment and fertilization mode significantly changed the bacterial community structure in the rhizosphere of rapeseed. According to previous studies, when waterlogging occurs, due to differences in the intensity of root respiration, environmentally sensitive microorganisms undergo changes [34,36,37,38]. In addition, after 7 days of flooding treatment, the differences in the bacterial community structure of the root system between the supplementary application of microbial and organic fertilizer were relatively small. The rhizosphere bacterial community structure of the two treatments and the conventional fertilization treatment showed significant differences, similar to the differences in the growth of rapeseed seedlings under different fertilization patterns.
Based on the gate level analysis, the dominant bacterial phyla in all soil samples were Proteobacteria, Acidobacteriota, Bacteroidota, Gemmatimonadota, and Chloroflexi. According to previous studies, Proteobacteria, Acidobacteriota, Gemmatimonadota, and Bacteroidota are the dominant bacterial phyla in the rhizosphere of crops. This study is consistent with previous research [38,39,40,41]. The Proteobacteria phylum is the most abundant bacterial group in rhizospheric soil, mainly due to its ability to utilize a variety of plant root exudates and its rapid growth [42]. A large number of studies have shown that Acidobacteriota mainly degrades plant residue polymers [43] and participates in iron cycling [44,45]. In addition, Acidobacteriota is a stable component of the bacterial ecosystem and has good adaptability to the environment [46,47]. Bacteroidota is now believed to be significantly associated with the oxidation and reduction of nitrates [48,49]. Under normal water supply, compared with conventional fertilization, the relative abundance of Bacteroidetes in the rhizosphere soil was higher under the application of organic and microbial fertilizer. This may be related to the promotion of seedling growth by applying organic fertilizer and topdressing with microbial fertilizer. Gemmatimonadota can generally convert various sugar molecules into vitamins [50]. Relevant studies have shown that appropriately increasing the vitamin content in the roots can promote the growth of wheat [51]. After 7 days of flooding treatment, compared to the supplement of microbial fertilizer, the conventional fertilization method resulted in higher Gemmatimonadota levels in the rhizosphere soil. After 14 days without flooding treatment, the conventional fertilization method had higher Gemmatimonadota levels in the rhizosphere soil compared to the supplementary organic fertilization method. This may be related to the secretion of more sugar substances by the root system under conventional fertilization. Zhao et al. found that Chloroflexi prefer to live in nutrient-rich environments, and adequate nutrients are more conducive to the growth and reproduction of Chloroflexi [52]. After 14 days without flooding treatment, compared with conventional fertilization and supplementary microbial fertilizer, Chloroflexi were higher in the rhizosphere soil. This indicates that the application of organic fertilizer increases the nutrients in the soil.
In addition, the experimental results also showed that during the recovery period after the end of flooding, the supplementary application of microbial and organic fertilizer better enriched Actinobacteriota. According to previous reports, Actinobacteriota can decompose cellulose and lignin, and abundant actinomycetes are beneficial to the decomposition of plant residues in soil [53]. The supplementary application of microbial and organic fertilizer during the experiment can help rapeseed recover faster from flooding stress, which may be related to the enrichment of Actinobacteriota in the rhizosphere soil of rapeseed by the supplementary application of microbial and organic fertilizer. Orellana [54] believed that the Verrucomicrobiota was related to the degradation of polysaccharides. Through the degradation of polysaccharides, the polysaccharides in the soil are converted into small-molecule sugars that can be absorbed by plant roots. Our results also showed that after 7 days of flooding treatment, the supplementary application of organic fertilizer enriched the Verrucomicrobiota, which may be related to promoting the growth of rapeseed under flooding stress.
At the genus level, differential analysis was conducted on the top 10 bacterial groups with relatively high richness. The four genera of Flavisolibacter, SC-I-84, Ellin6067, and WD2101_soil_group showed significant differences in different water treatments and different fertilization patterns. According to Yoon’s [55] research, Flavisolibacter can increase carbon-related functional groups, further increasing carbon sequestration, which may be related to promoting plant growth. In the control group treated with flooding for 7 days, compared to conventional fertilization, the Flavisolibacter content in the rapeseed rhizosphere soil supplemented with organic and microbial fertilizer was higher. This may be one of the reasons why the application of organic and microbial fertilizer can promote the growth of rapeseed seedlings. Ellin6067 is an ammonia-oxidizing bacterium that can oxidize ammonia to nitrite [56]. This indicates that Ellin6067 can promote the absorption of nitrogen by plants. In the control group that was treated with flooding for 7 days, compared to the application of organic fertilizer, the addition of microbial fertilizer to rapeseed rhizosphere soil resulted in higher Ellin6067 levels. This may be the reason why the application of microbial fertilizer can promote the growth of rapeseed when suffering from waterlogging. Existing research has shown that WD2101_soil_group can participate in the decomposition of polysaccharides [57]. The experimental results showed that under conventional fertilization conditions, after the rape was subjected to flooding treatment, the relative abundance of WD2101_soil_group was low. After 14 days of recovery, the relative abundance of WD2101_soil_group increased significantly. This may be related to the normal growth of rapeseed after the flooding is lifted. SC-I-84 is known as anaerobic ammonia oxidation bacterium [58]. This is also beneficial for the absorption of nitrogen by plant roots: after 7 days of flooding treatment, the microbial fertilizer enriched SC-I-84. This may also be related to the promotion of rapeseed growth.

5. Conclusions

To sum up, after being subjected to flooding stress, rapeseed will affect the seedling height, stem diameter, dry matter accumulation, root activity, and other aspects. Supplementing microorganisms and organic fertilizers can make rapeseed grow better under flooding conditions, reduce the impact of flood stress on rapeseed seedlings, and enable rapeseed to recover faster after suffering flood stress during the seedling stage. Through the beta analysis of bacterial communities in the rhizosphere of rapeseed, it was found that different water treatments and fertilization patterns can change the community structure of bacteria in the rhizosphere soil. Through the analysis of the differences between different treatment groups at the phylum level, it was found that under normal water supply, the application of organic fertilizer enriched the rhizosphere soil of rapeseed with P_Bacteroidota, P_Actinobacteriota, P_Chloroflexi, and G_Flavisolibacter, and the application of microbial fertilizer enriched the rhizosphere soil of rapeseed with P_Bacteroidota and G_Flavisolibacter. After flooding treatment, the application of organic fertilizer enriched the rhizosphere soil of rapeseed with P_Verrucomicrobiota, and the application of microbial fertilizer enriched the rhizosphere soil of rapeseed with P_Actinobacteriota, G_SC-I-84, and G_Ellin6067. The enrichment of these bacterial groups may be related to the growth promotion and waterlogging tolerance of rapeseed, but the specific functions of these bacterial groups remain to be further verified.

Author Contributions

Conceptualization, M.G.; methodology, X.W. and B.H.; software, J.W., D.Z. and B.Z.; investigation, X.W.; writing—original draft preparation, X.W.; writing—review and editing, M.G.; visualization, X.W.; supervision, M.G. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by the National Rapeseed Industrial Technology System (CARS-12) and the Hunan Agriculture Research System of DARA (Xiangnongfa (2022)).

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data are contained within the article.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Li, C.-J. A statistical analysis of the storm flood disasters in China. J. Catastrophol. 1996, 11, 59–63, (In Chinese with English Abstract). [Google Scholar]
  2. Liu, H.-L. Practical Cultivation of Rapeseed; Shanghai Scientific and Technical Publishers: Shanghai, China, 1987. (In Chinese) [Google Scholar]
  3. Tian, X.; Li, Z.; Liu, Y.; Li, W. Role of tillage measures in mitigating waterlogging damage in rapeseed. BMC Plant Biol. 2023, 23, 1–11. [Google Scholar] [CrossRef]
  4. Hu, Q.; Hua, W.; Yin, Y.; Zhang, X.; Liu, L.; Shi, J.; Wang, H. Rapeseed research and production in China. Crop J. 2017, 5, 127–135. [Google Scholar] [CrossRef]
  5. Barnawal, D.; Bharti, N.; Maji, D.; Chanotiya, C.S.; Kalra, A. 1-Aminocyclopropane-1-carboxylic acid (ACC) deaminase-containing rhizobacteria protect Ocimum sanctum plants during waterlogging stress via reduced ethylene generation. Plant Physiol. Biochem. 2012, 58, 227–235. [Google Scholar] [CrossRef] [PubMed]
  6. Grichko, V.P.; Glick, B.R. Flooding tolerance of transgenic tomato plants expressing the bacterial enzyme ACC deaminase controlledby the 35S, rolD or PRB-1b promoter. Plant Physiol. Biochem. 2001, 39, 19–25. [Google Scholar] [CrossRef]
  7. Canarini, A.; Dijkstra, F.A. Dry-rewetting cycles regulate wheat carbon rhizodeposition, stabilization and nitrogen cycling. Soil Biol. Biochem. 2015, 81, 195–203. [Google Scholar] [CrossRef]
  8. Castrillo, G.; Teixeira, P.J.P.L.; Paredes, S.H.; Law, T.F.; De Lorenzo, L.; Feltcher, M.E.; Dangl, J.L. Root microbiota drive direct integration of phosphate stress and immunity. Nature 2017, 543, 513–518. [Google Scholar] [CrossRef]
  9. Grayston, S.J.; Wang, S.; Campbell, C.D.; Edwards, A.C. Selective influence of plant species on microbial diversity in the rhizosphere. Soil Biol. Biochem. 1998, 30, 369–378. [Google Scholar] [CrossRef]
  10. Tang, Z.C.; Kozlowski, T.T. Water relations, ethylene production, and morphological adaptation of Fraxinus pennsylvanica seedlings to flooding. Plant Soil 1984, 77, 183–192. [Google Scholar] [CrossRef]
  11. Nabti, E.; Jha, B.; Hartmann, A. Impact of seaweeds on agricultural crop production as biofertilizer. Int. J. Environ. Sci. Technol. 2017, 14, 1119–1134. [Google Scholar] [CrossRef]
  12. Ning, C.; Gao, P.; Wang, B.; Lin, W.P.; Jiang, N.H.; Cai, K.Z. Impacts of chemical fertilizer reduction and organic amendments supplementation on soil nutrient, enzyme activity and heavy metal content. J. Integr. Agric. 2017, 16, 1819–1831. [Google Scholar] [CrossRef]
  13. Meng, X.; Liu, B.; Xi, C.; Luo, X.; Yuan, X.; Wang, X.; Zhu, W.; Wang, H.; Cui, Z. Effect of pig manure on the chemical composition and microbial diversity during co-composting with spent mushroom substrate and rice husks. Bioresour. Technol. 2018, 251, 22–30. [Google Scholar] [CrossRef] [PubMed]
  14. Kaje, V.V.; Sharma, D.K.; Shivay, Y.S.; Jat, S.L.; Bhatia, A.; Purakayastha, T.J.; Bhattacharyya, R. Long-term impact of organic and conventional farming on soil physical properties under rice (Oryza sativa)-wheat (Triticum aestivum) crop system in north-western Indo-Gangetic plains. Indian J. Agric. Sci. 2018, 88, 107–113. [Google Scholar] [CrossRef]
  15. Zheng, M.; Li, H.; Zhao, J.; Liu, H.; Xie, B. Current situation and developmental trend of microbial fertilizer researches. Acta Agric. Jiangxi 2018, 30, 52–56. [Google Scholar]
  16. Deng, W.; Qing, X.G.; Yang, Y. Effects of applying organic fertilizer on rice lodging resistance and yield. Agric. Sci. Technol. Hunan 2010, 11, 98–101. [Google Scholar]
  17. Xu, H.L. Effects of a microbial inoculant, organic fertilizer and chemical fertilizer on water stress resistance of sweet corn. J. Crop Prod. 2001, 3, 223–233. [Google Scholar] [CrossRef]
  18. Li, L.; Li, Q.; Davis, K.E.; Patterson, C.; Oo, S.; Liu, W.; Zhang, B. Response of root growth and development to nitrogen and potassium deficiency as well as microRNA-mediated mechanism in peanut (Arachis hypogaea L.). Front. Plant Sci. 2021, 12, 695234. [Google Scholar] [CrossRef]
  19. Zhang, J.; Kobert, K.; Flouri, T.; Stamatakis, A. PEAR: A fast and accurate Illumina Paired-End reAd mergeR. Bioinformatics 2014, 30, 614–620. [Google Scholar] [CrossRef]
  20. Rognes, T.; Flouri, T.; Nichols, B.; Quince, C.; Mahé, F. VSEARCH: A versatile open source tool for metagenomics. PeerJ 2016, 4, e2584. [Google Scholar] [CrossRef]
  21. Edgar, R.C.; Haas, B.J.; Clemente, J.C.; Quince, C.; Knight, R. UCHIME improves sensitivity and speed of chimera detection. Bioinformatics 2011, 27, 2194–2200. [Google Scholar] [CrossRef]
  22. Edgar, R.C. UPARSE: Highly accurate OTU sequences from microbial amplicon reads. Nat. Methods 2013, 10, 996–998. [Google Scholar] [CrossRef]
  23. Ye, J.; McGinnis, S.; Madden, T.L. BLAST: Improvements for better sequence analysis. Nucleic Acids Res. 2006, 34, W6–W9. [Google Scholar] [CrossRef]
  24. Pruesse, E.; Quast, C.; Knittel, K.; Fuchs, B.M.; Ludwig, W.; Peplies, J.; Glöckner, F.O. SILVA: A comprehensive online resource for quality checked and aligned ribosomal RNA sequence data compatible with ARB. Nucleic Acids Res. 2007, 35, 7188–7196. [Google Scholar] [CrossRef]
  25. R Core Team. R: A Language and Environment for Statistical Computing; R Foundation for Statistical Computing: Vienna, Austria, 2021. [Google Scholar]
  26. Segata, N.; Izard, J.; Waldron, L.; Gevers, D.; Miropolsky, L.; Garrett, W.S.; Huttenhower, C. Metagenomic biomarker discovery and explanation. Genome Biol. 2011, 12, 1–18. [Google Scholar] [CrossRef]
  27. Zhang, H.-P.; Zhang, P.-P.; Li, B.; Li, D.; Liu, W.-B.; Feng, N.-J.; Zheng, D.-F. Effects of uniconazole on alleviation of waterlogging stress in soybean. Chin. J. Oil Crop Sci. 2017, 39, 655. [Google Scholar]
  28. Zhang, Z.Y.; Qin, B.T.; Xiong, S.P.; Wang, H.Z.; Xu, S.J.; Tian, W.Z.; Wang, X.C.; Ma, X.M. Effects of irrigation at flowering stage on soil nutrient and root distribution in wheat field. Ying Yong Sheng Tai Xue Bao = J. Appl. Ecol. 2022, 33, 3328–3336. [Google Scholar]
  29. Wang, X.; Shangguan, Z. Effect of nitrogen on root vigor and growth in different genotypes of wheat under drought stress. J. Triticeae Crops 2017, 37, 820–827. [Google Scholar]
  30. Lu, W.; Jia, Z.; Zhang, P.; Cai, T.; Li, R.; Hou, X.; Li, Y. Effects of organic fertilization on winter wheat photosynthetic characteristics and water use efficiency in semi-arid areas of southern Ningxia. Plant Nutr. Fertil. Sci. 2011, 17, 1066–1074. [Google Scholar]
  31. Zhao, J.; Ni, T.; Li, J.; Lu, Q.; Fang, Z.; Huang, Q.; Shen, Q. Effects of organic–inorganic compound fertilizer with reduced chemical fertilizer application on crop yields, soil biological activity and bacterial community structure in a rice–wheat cropping system. Appl. Soil Ecol. 2016, 99, 1–12. [Google Scholar] [CrossRef]
  32. Shang, Q.; Yang, G.; Wang, Y.; Wu, X.; Zhao, X.; Hao, H.; Wang, R. Illumina-based analysis of the rhizosphere microbial communities associated with healthy and wilted Lanzhou lily (Lilium davidii var. unicolor) plants grown in the field. World J. Microbiol. Biotechnol. 2016, 32, 1–15. [Google Scholar] [CrossRef]
  33. Fan, M.; Li, J.; Yan, W.; Shi, H.; Shangguan, Z. Shifts in the structure and function of wheat root-associated bacterial communities in response to long-term nitrogen addition in an agricultural ecosystem. Appl. Soil Ecol. 2021, 159, 103852. [Google Scholar] [CrossRef]
  34. Azarbad, H.; Constant, P.; Giard-Laliberté, C.; Bainard, L.D.; Yergeau, E. Water stress history and wheat genotype modulate rhizosphere microbial response to drought. Soil Biol. Biochem. 2018, 126, 228–236. [Google Scholar] [CrossRef]
  35. Guo, T.Z.; Yuan, L.Z.; Zhao, Y.Q.; Liu, J.Y.; Gu, C. Effects of waterlogging on maize yield and the rhizosphere soil microorganism. Hubei Agric. Sci. 2014, 53, 505–507, (In Chinese with English Abstract). [Google Scholar]
  36. Evans, S.E.; Wallenstein, M.D. Soil microbial community response to drying and rewetting stress: Does historical precipitation regime matter? Biogeochemistry 2012, 109, 101–116. [Google Scholar] [CrossRef]
  37. Unger, I.M.; Kennedy, A.C.; Muzika, R.M. Flooding effects on soil microbial communities. Appl. Soil Ecol. 2009, 42, 1–8. [Google Scholar] [CrossRef]
  38. Meisner, A.; Leizeaga, A.; Rousk, J.; Bååth, E. Partial drying accelerates bacterial growth recovery to rewetting. Soil Biol. Biochem. 2017, 112, 269–276. [Google Scholar] [CrossRef]
  39. Hu, R.; Zheng, L.; Liu, H.; Huang, J.B. Effects of straw returning on microbial diversity in rice rhizosphere and occurrence of rice sheath blight. Acta Phytophyl. Sin. 2020, 47, 1261. [Google Scholar]
  40. Fierer, N.; Bradford, M.A.; Jackson, R.B. Toward an ecological classification of soil bacteria. Ecology 2007, 88, 1354–1364. [Google Scholar] [CrossRef]
  41. Wang, G.P.; Ayiguli TH, T.; Wang, R.; Zhu, C.Q. Study on the diversity and community structure of salt tolerant bacteria in saline alkali soil in Wuerhe, Xinjiang. J. Microbiol. 2021, 41, 17–26, (In Chinese with English Abstract). [Google Scholar]
  42. Ai, C.; Sun, J.W.; Wang, X.B.; Liang, G.Q.; He, P.; Zhou, W. Advances in the study of the relationship between plant rhizodeposition and soil microorganism. J. Plant Nutr. Fertil. 2015, 21, 1343–1351. [Google Scholar]
  43. Pankratov, T.A.; Ivanova, A.O.; Dedysh, S.N.; Liesack, W. Bacterial populations and environmental factors controlling cellulose degradation in an acidic Sphagnum peat. Environ. Microbiol. 2011, 13, 1800–1814. [Google Scholar] [CrossRef]
  44. Lu, S.; Gischkat, S.; Reiche, M.; Akob, D.M.; Hallberg, K.B.; Küsel, K. Ecophysiology of Fe-cycling bacteria in acidic sediments. Appl. Environ. Microbiol. 2010, 76, 8174–8183. [Google Scholar] [CrossRef]
  45. Coates, J.D.; Ellis, D.J.; Gaw, C.V.; Lovley, D.R. Geothrix fermentans gen. nov., sp. nov., a novel Fe (III)-reducing bacterium from a hydrocarbon-contaminated aquifer. Int. J. Syst. Evol. Microbiol. 1999, 49, 1615–1622. [Google Scholar] [CrossRef] [PubMed]
  46. Kielak, A.; Pijl, A.S.; Van Veen, J.A.; Kowalchuk, G.A. Differences in vegetation composition and plant species identity lead to only minor changes in soil-borne microbial communities in a former arable field. FEMS Microbiol. Ecol. 2008, 63, 372–382. [Google Scholar] [CrossRef] [PubMed]
  47. Zhang, Y.; Cong, J.; Lu, H.; Li, G.; Qu, Y.; Su, X.; Li, D. Community structure and elevational diversity patterns of soil Acidobacteria. J. Environ. Sci. 2014, 26, 1717–1724. [Google Scholar] [CrossRef] [PubMed]
  48. García-López, M.; Meier-Kolthoff, J.P.; Tindall, B.J.; Gronow, S.; Woyke, T.; Kyrpides, N.C.; Göker, M. Analysis of 1,000 type-strain genomes improves taxonomic classification of Bacteroidetes. Front. Microbiol. 2019, 10, 2083. [Google Scholar] [CrossRef] [PubMed]
  49. Feng, D.; Wu, Z.; Xu, S. Nitrification of human urine for its stabilization and nutrient recycling. Bioresour. Technol. 2008, 99, 6299–6304. [Google Scholar] [CrossRef] [PubMed]
  50. Xu, J.-Y.; Zhou, J.R.; Wu, J.; Wang, Y.; Cheng, L.Y.; Zhao, G. Medium-and long-term effects of the veterinary antibiotic sulfadiazine on soil microorganisms in a rice field. J. Agro-Environ. Sci. 2020, 39, 1757–1766. [Google Scholar]
  51. Wang, K.; Yang, Y.A.; Yuan, K.N. Effects of three vitamins on the growth and physiological properties in wheat. Bull. Sci. Technol. 1995, 11, 301–305, (In Chinese with English Abstract). [Google Scholar]
  52. Zhao, L.J.; Liu, Y.G.; Wang, Y.; Zhao, R.; Ren, W.; Xu, M.Z. Bacterial community structure and diversity of sediments in a typical plateau lakeshore. Microbiol. China 2020, 47, 401–410. [Google Scholar]
  53. Kanokratana, P.; Uengwetwanit, T.; Rattanachomsri, U.; Bunterngsook, B.; Nimchua, T.; Tangphatsornruang, S.; Eurwilaichitr, L. Insights into the phylogeny and metabolic potential of a primary tropical peat swamp forest microbial community by metagenomic analysis. Microb. Ecol. 2011, 61, 518–528. [Google Scholar] [CrossRef]
  54. Orellana, L.H.; Francis, T.B.; Ferraro, M.; Hehemann, J.H.; Fuchs, B.M.; Amann, R.I. Verrucomicrobiota are specialist consumers of sulfated methyl pentoses during diatom blooms. ISME J. 2022, 16, 630–641. [Google Scholar] [CrossRef]
  55. Yoon, M.H.; Im, W.T. Flavisolibacter ginsengiterrae gen. nov., sp. nov. and Flavisolibacter ginsengisoli sp. nov., isolated from ginseng cultivating soil. Int. J. Syst. Evol. Microbiol. 2007, 57, 1834–1839. [Google Scholar] [CrossRef]
  56. Wei, W.; Guan, D.; Ma, M.; Jiang, X.; Fan, F.; Meng, F.; Li, J. Long-term fertilization coupled with rhizobium inoculation promotes soybean yield and alters soil bacterial community composition. Front. Microbiol. 2023, 14, 1161983. [Google Scholar] [CrossRef] [PubMed]
  57. Kovaleva, O.L.; Merkel, A.Y.; Novikov, A.A.; Baslerov, R.V.; Toshchakov, S.V.; Bonch-Osmolovskaya, E.A. Tepidisphaera mucosa gen. nov., sp. nov., a moderately thermophilic member of the class Phycisphaerae in the phylum Planctomycetes, and proposal of a new family, Tepidisphaeraceae fam. nov., and a new order, Tepidisphaerales ord. nov. Int. J. Syst. Evol. Microbiol. 2015, 65, 549–555. [Google Scholar] [CrossRef] [PubMed]
  58. Jiang, Z.; Huang, X.; Wang, S.; Xiong, J.; Xie, C.; Chen, Y. Divalent manganese stimulates the removal of nitrate by anaerobic sludge. RSC Adv. 2024, 14, 2447–2452. [Google Scholar] [CrossRef] [PubMed]
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Figure 1. Effect of different fertilization patterns and different water treatments on the root vigor of rapeseed seedlings. (a): The root activity of rapeseed under different fertilization treatments with and non-flooding for seven days, (b): The root activity of rapeseed under different fertilization treatments after 14 days of flooding recovery and 14 days of continuous cultivation non-flooding. The data are from three biological replicates, and the error bars represent the standard error. Different lowercase letters indicate significant differences at the 0.05 level between different treatments. Treatments the same as Table 1.
Figure 1. Effect of different fertilization patterns and different water treatments on the root vigor of rapeseed seedlings. (a): The root activity of rapeseed under different fertilization treatments with and non-flooding for seven days, (b): The root activity of rapeseed under different fertilization treatments after 14 days of flooding recovery and 14 days of continuous cultivation non-flooding. The data are from three biological replicates, and the error bars represent the standard error. Different lowercase letters indicate significant differences at the 0.05 level between different treatments. Treatments the same as Table 1.
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Figure 2. Venn diagram of the number of OTUs in different fertilization patterns. (a) Venn diagram of the number of OTU under different treatments with supplementary microbial fertilizer. (b) Venn diagram of OTU numbers under different treatments under conventional fertilization conditions. (c) Venn diagram of the number of OTU under different treatments with supplementary organic fertilizer. Treatments the same as Table 1.
Figure 2. Venn diagram of the number of OTUs in different fertilization patterns. (a) Venn diagram of the number of OTU under different treatments with supplementary microbial fertilizer. (b) Venn diagram of OTU numbers under different treatments under conventional fertilization conditions. (c) Venn diagram of the number of OTU under different treatments with supplementary organic fertilizer. Treatments the same as Table 1.
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Figure 3. Effect of fertilization pattern and water treatment on abundance based on Chao1 (a) and Shannon (b) indices. Different letters indicate significant differences between the two treatments, and the treatments are the same as Table 1.
Figure 3. Effect of fertilization pattern and water treatment on abundance based on Chao1 (a) and Shannon (b) indices. Different letters indicate significant differences between the two treatments, and the treatments are the same as Table 1.
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Figure 4. PLS−DA analysis of bacterial communities in rhizosphere soils under different treatments. (a) PLS-DA analysis of different water treatments and periods under the condition of supplementary microbial fertilizer, (b) PLS-DA analysis of different water treatments and periods under the condition of conventional fertilization, (c) PLS-DA analysis of different water treatments and periods under the condition of supplementary organic fertilizer. Treatments the same as Table 1.
Figure 4. PLS−DA analysis of bacterial communities in rhizosphere soils under different treatments. (a) PLS-DA analysis of different water treatments and periods under the condition of supplementary microbial fertilizer, (b) PLS-DA analysis of different water treatments and periods under the condition of conventional fertilization, (c) PLS-DA analysis of different water treatments and periods under the condition of supplementary organic fertilizer. Treatments the same as Table 1.
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Figure 5. Relative richness of samples under different treatments. Treatments the same as Table 1.
Figure 5. Relative richness of samples under different treatments. Treatments the same as Table 1.
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Figure 6. Changes in relative abundance of bacterial phyla in the rhizosphere of rapeseed in different treatment groups. (a) The differences in relative abundance of rhizosphere bacteria at the phylum level in rape under different fertilization patterns after 7 days of flooding treatment. (b) The differences in relative abundance of rhizosphere bacteria at the phylum level in rape under different fertilization patterns after 7 days of non-flooding treatment. (c) The differences in relative abundance of rhizosphere bacteria at the phylum level in rape under different fertilization patterns after 14 days of flooding recovery. (d) The differences in relative abundance of rhizosphere bacteria at the phylum level in rape under different fertilization patterns after 14 days of non-flooding recovery. with treatments as in Table 1; *: p < 0.05.
Figure 6. Changes in relative abundance of bacterial phyla in the rhizosphere of rapeseed in different treatment groups. (a) The differences in relative abundance of rhizosphere bacteria at the phylum level in rape under different fertilization patterns after 7 days of flooding treatment. (b) The differences in relative abundance of rhizosphere bacteria at the phylum level in rape under different fertilization patterns after 7 days of non-flooding treatment. (c) The differences in relative abundance of rhizosphere bacteria at the phylum level in rape under different fertilization patterns after 14 days of flooding recovery. (d) The differences in relative abundance of rhizosphere bacteria at the phylum level in rape under different fertilization patterns after 14 days of non-flooding recovery. with treatments as in Table 1; *: p < 0.05.
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Figure 7. Changes in relative abundance of bacterial genera in the rhizosphere of rapeseed in different treatment groups, (a) The differences in relative abundance of rhizosphere bacteria at the genus level in rape under different fertilization patterns after 7 days of flooding treatment. (b) The differences in relative abundance of rhizosphere bacteria at the genus level in rape under different fertilization patterns after 7 days of non-flooding treatment. (c) The differences in relative abundance of rhizosphere bacteria at the genus level in rape under different fertilization patterns after 14 days of flooding recovery (d) The differences in relative abundance of rhizosphere bacteria at the genus level in rape under different fertilization patterns after 14 days of non-flooding recovery. with treatments as in Table 1; *: p < 0.05.
Figure 7. Changes in relative abundance of bacterial genera in the rhizosphere of rapeseed in different treatment groups, (a) The differences in relative abundance of rhizosphere bacteria at the genus level in rape under different fertilization patterns after 7 days of flooding treatment. (b) The differences in relative abundance of rhizosphere bacteria at the genus level in rape under different fertilization patterns after 7 days of non-flooding treatment. (c) The differences in relative abundance of rhizosphere bacteria at the genus level in rape under different fertilization patterns after 14 days of flooding recovery (d) The differences in relative abundance of rhizosphere bacteria at the genus level in rape under different fertilization patterns after 14 days of non-flooding recovery. with treatments as in Table 1; *: p < 0.05.
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Figure 8. Heat map and cluster analysis of the composition of the integrated population, as per Table 1.
Figure 8. Heat map and cluster analysis of the composition of the integrated population, as per Table 1.
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Figure 9. Analysis of species differences between different groups. Treatments the same as Table 1.
Figure 9. Analysis of species differences between different groups. Treatments the same as Table 1.
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Table 1. Fertilization patterns for each treatment and water supply methods at different stages.
Table 1. Fertilization patterns for each treatment and water supply methods at different stages.
Treatment CordFertilization ModeWater TreatmentPeriod
YZ-7Supplement organic fertilizerWaterlogging stressFlooded for 7 days
CZ-7Conventional fertilization
WZ-7Supplement microbial fertilizer
YW-7Supplement organic fertilizer Normal water supplyControl
CW-7Conventional fertilization
WW-7Supplement microbial fertilizer
YZ-14Supplement organic fertilizerWaterlogging stressEnd flooding and restore 14 days
CZ-14Conventional fertilization
WZ-14Supplement microbial fertilizer
YW-14Supplement organic fertilizerNormal water supplyControl
CW-14Conventional fertilization
WW-14Supplement microbial fertilizer
Table 2. The effect of different fertilization patterns and water treatments on physical indicators of rapeseed seedlings at different stages.
Table 2. The effect of different fertilization patterns and water treatments on physical indicators of rapeseed seedlings at different stages.
TreatmentPlant HeightStem DiameterAboveground Part/gRoot/gTotal Weight/g
(cm)(cm)Fresh WeightDry WeightFresh WeightDry WeightTotal Fresh WeightTotal Dry Weight
YZ-739.03 g0.94 f77.89 h7.72 h7.55 g1.61 f85.44 h9.33 h
CZ-737.90 g0.80 e67.08 i6.34 i5.99 h1.22 f73.07 i7.57 i
WZ-740.43 fg1.09 d75.98 h7.76 h7.59 g1.49 f83.57 h9.25 h
YW-745.00 de1.24 c94.80 f11.55 g10.99 e2.30 de105.79 f13.85 g
CW-743.33 ef1.09 d86.37 g11.06 g9.51 f2.09 e95.88 g13.15 g
WW-746.50 cde1.22 cd89.65 fg11.12 g11.42 e2.35 de101.07 fg13.46 g
YZ-1447.67 cd1.47 b152.40 d19.08 d14.97 c3.33 c167.37 d22.41 d
CZ-1445.03 de1.26 c137.47 e15.13 f12.85 d2.71 d150.32 e17.84 f
WZ-1445.77 de1.40 b147.10 d17.02 e14.98 c3.26 c162.08 d20.27 e
YW-1456.13 a1.92 a196.66 a28.37 a20.27 a4.67 a216.93 a33.04 a
CW-1450.20 bc1.85 a175.22 c25.59 c18.08 b4.13 b193.30 c29.72 c
WW-1451.90 b1.92 a188.89 b27.09 b20.54 a4.68 a209.43 b31.77 b
Treatments the same as Table 1. Different lowercase letters indicate significant differences at the 0.05 level between different treatments for the same indicator.
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Wu, X.; Wu, J.; Zhou, B.; Hong, B.; Zhao, D.; Guan, M. Effects of Fertilization Patterns on the Growth of Rapeseed Seedlings and Rhizosphere Microorganisms under Flooding Stress. Agronomy 2024, 14, 525. https://doi.org/10.3390/agronomy14030525

AMA Style

Wu X, Wu J, Zhou B, Hong B, Zhao D, Guan M. Effects of Fertilization Patterns on the Growth of Rapeseed Seedlings and Rhizosphere Microorganisms under Flooding Stress. Agronomy. 2024; 14(3):525. https://doi.org/10.3390/agronomy14030525

Chicago/Turabian Style

Wu, Xuepeng, Junjie Wu, Bingqian Zhou, Bo Hong, Dongfang Zhao, and Mei Guan. 2024. "Effects of Fertilization Patterns on the Growth of Rapeseed Seedlings and Rhizosphere Microorganisms under Flooding Stress" Agronomy 14, no. 3: 525. https://doi.org/10.3390/agronomy14030525

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