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Article

A Study of Growth and Yield of Four Peanut Varieties with Rhizobia Inoculation under Field Conditions

by
Bin Ding
1,
Mengshi Feng
1,
Rui Wang
1,
Lei Chang
1,
Ying Jiang
1,
Jixian Xie
1 and
Da Tian
2,*
1
Taizhou Institute of Agricultural Sciences, Jiangsu Academy of Agricultural Sciences, Taizhou 225300, China
2
Anhui Province Key Lab of Farmland Ecological Conservation and Nutrient Utilization, College of Resources and Environment, Anhui Agricultural University, Hefei 230036, China
*
Author to whom correspondence should be addressed.
Agronomy 2024, 14(7), 1410; https://doi.org/10.3390/agronomy14071410
Submission received: 8 June 2024 / Revised: 26 June 2024 / Accepted: 27 June 2024 / Published: 28 June 2024
(This article belongs to the Special Issue Environmental Ecological Remediation and Farming Sustainability—Volume II)
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Versions Notes

Abstract

:
The symbiotic nitrogen fixation between rhizobia and peanuts offers an advantage in reducing nitrogen fertilizer inputs, decreasing the incidence rate of peanuts, and enhancing soil fertility. Inoculating rhizobia agent is an effective pathway to improve both the quality and yield of peanuts, contributing to food security and promoting sustainable agricultural practices. This study conducted a one-year field experiment in a subtropical humid monsoon climate area in Southeast China to investigate the effects of rhizobia agents on the growth and crop yield of four peanut varieties (i.e., Taihua No.4, No.6, No.8, and No.10). Our research showed that inoculation with rhizobia agent can increase the plant height, lateral branch length, fresh root weight, and leaf area of the four peanut varieties. Meanwhile, inoculation with a rhizobia agent can significantly (p < 0.05) increase the ~50% number of root nodules. Especially for the early-maturing and drought-resistant variety, Taihua No.4 exhibited the highest number of nodules and peanut fruits per plant in the pod-setting stage after inoculation with rhizobia agent, i.e., 24.5 and 18.0, respectively. Under the conventional fertilization conditions (N-P2O5-K2O 15-15-15, 450 kg/hm2), Taihua No.4 and No.6 inoculated with rhizobia agent achieved higher yield increase rates of 11.0% and 11.6% compared to other peanut varieties. This study indicated that the Taihua No.4 and No.6 are the most suitable peanut varieties for rhizobia inoculation and promotion, with enormous potential for yield increase. Meanwhile, optimizing rhizobia inoculation techniques and evaluating soil health status, economic benefits of peanuts, and applicable regions should be explored in the future.

1. Introduction

Nitrogen is an essential element for plant growth and development, playing a crucial role in various biochemical processes [1,2]. However, most atmospheric nitrogen is in the form of molecular nitrogen (N2), which plants cannot directly absorb [3]. In order to supply the demand for nitrogen and enhance crop yields, many agricultural practices rely on the use of chemical fertilizers [4,5]. However, nitrogen fertilizer utilization by crops during the growing season is less than 35%, and the production of chemical nitrogen fertilizers is energy-intensive, leading to increased agricultural costs and contributing to air pollution, etc. [6]. Additionally, long-term excessive use of nitrogen fertilizers can also cause soil acidification (decrease of 0.5 units in pH), alter soil quality, and pose a risk to the eutrophication of water bodies [7,8,9].
Biological nitrogen fixation by microorganisms (e.g., nitrogen-fixing bacteria) is an alternative pathway for nitrogen supply to plants [10,11]. It can reduce plants’ reliance on chemical fertilizers [12]. Meanwhile, this biological pathway can also maintain crop productivity and preserve soil health and environmental quality [13]. Rhizobia is a commonly nitrogen-fixing bacteria that lives in symbiosis with the roots of leguminous plants, where it form nodules and fixes atmospheric nitrogen, making it available to the plants [14,15]. According to statistics, rhizobia symbiotic nitrogen fixation can provide 40 million tons of nitrogen annually worldwide [12]. This symbiotic relationship is essential for the nitrogen nutrition of these plants.
The application of rhizobia inoculants not only increases the yield of leguminous crops but also improves their quality [16]. For example, the use of rhizobia (Bradyrhizobium) inoculates can increase peanut growth and yields [17]. In addition, the use of rhizobia inoculants can also reduce the need for synthetic nitrogen fertilizers, which can have negative environmental impacts [18]. It maintains soil fertility and promotes biodiversity in the agricultural ecosystem [19]. Therefore, the use of rhizobia inoculants is a sustainable agricultural practice, especially for reducing nitrogen input.
Peanuts (Arachis hypogaea L.) are indeed a significant oil crop globally and play a crucial role in providing protein and oil for human consumption and various industrial uses [20,21]. In China, the annual production of peanuts exceeds 16 million tons, accounting for 45% of the total production in the world [12]. The symbiotic relationship between peanuts and rhizobia is an essential aspect of their cultivation, as it allows the plants to fix atmospheric nitrogen, reducing the need for nitrogen fertilizers [20]. Peanuts can form nodules in symbiosis with rhizobia, fixing approximately 55% of their required nitrogen from the atmosphere [22]. This process significantly contributes to global biological nitrogen fixation, which is estimated to be around 175 million tons per year, compared to the 100 million tons fixed through industrial methods [23]. Hence, inoculating rhizobia agents are an effective pathway to reduce nitrogen fertilizer input in peanut cultivation.
Inoculating peanuts with rhizobia can also improve their ability to resist diseases to a certain extent [24]. Due to continuous cultivation and soil limits, peanut growth, dry matter accumulation, and so on are affected by sitting disorders [25]. Currently, no practical and feasible measures exist to overcome the obstacles of continuous peanut cultivation [26]. Inoculating with rhizobia can make peanuts grow vigorously and resist the occurrence of diseases [27]. However, the inoculation effect of rhizobia is different in various peanut varieties [28]. Therefore, it is necessary to further confirm the interaction effect of peanut varieties screened and cultivated on rhizobia.
This study primarily aims to investigate the effect of rhizobia agents on the traits of different peanut varieties, including plant height, lateral branch length, leaf age, number of branches, fresh leaf weight, stem and branch weight, fresh root weight, leaf area, number of nodules, etc. In addition, the effects of the rhizobia agent on the yield of different peanut varieties are also investigated to provide technical guidance for the high-yield promotion of peanuts.

2. Materials and Methods

2.1. Peanut Varieties

The Taixing Agricultural Science Research Institute selected four peanut varieties (Taihua No.4, Taihua No.6, Taihua No.8, and Taihua No.10) with new variety identification and the registration numbers GPD peanut (2020) 320120, GPD peanut (2018) 320307, CNA009228E, and GPD peanut (2018) 320325 for each variety, respectively. Taihua No.4 was an early-maturing variety that could be used for oil and food. It had moderate drought resistance and strong moisture resistance. Taihua No.6 belonged to the pearl bean type and had a high protein variety. The protein content in the seeds was 30.23%, highly resistant to bacterial wilt, lodging, drought, and strong seed dormancy. Taihua No.8 was an early-maturing variety with strong stress resistance and moderate disease resistance. Taihua No.10 had moderate lodging resistance, drought resistance, strong moisture resistance, moderate resistance to leaf spot disease, and strong resistance to rust disease.

2.2. Peanut Rhizobia Agent

The peanut commercial rhizobia agent ( with a trade name of Yigengjing) was purchased from Leading Bio Agriculture Co., Ltd. (Beijing, China), with an effective viable bacterial (Bradyrhizobium) count of ≥20 × 108 CFU/mL (Figure S2). The dosage of the rhizobia agent mixed with peanut seeds was 150 mL of agent with 20–25 kg of peanut seeds (Figure S2). Before the sowing, spray the liquid agent evenly on the surface of the peanut seeds and mix evenly (Figure S2). Then, the treated peanuts seeds will be sown after drying in the shade at room temperature (Figure S2).

2.3. Experimental Design

The experiment was conducted in Taixing City, Jiangsu Province (E 119°59′32″, N 32°32′57″). This region was a primary peanut planting area in China and features a subtropical, humid monsoon climate. This climate was characterized by warm temperatures and high humidity, which were conducive to the growth of peanuts and the symbiotic relationship between peanut plants and rhizobia bacteria. The altitude of this area is 5 m. In this area, the long-term experimental field has planted peanuts for four consecutive years (2018–2021). During this period, no other crops were planted. After the winter fallow period, peanuts are planted in the second year. The experiment field had sandy loam soil, flat terrain, good drainage and irrigation, and moderate to even fertility. The soil pH is 7.8, with 5.3 g/kg organic matter, 71.0 mg/kg available nitrogen, 52.9 mg/kg available phosphorus, and 151.0 mg/kg available potassium (Table S1). In the experimental field, the average temperature during the growing season is 23.8 °C, the average rainfall is 229.7 mm, and the average sunshine time is 221.8 h.
Eight treatments were performed, i.e., Taihua No.4 (T4), Taihua No.4+rhizobia agent (T4R), Taihua No.6 (T6), Taihua No.6+rhizobia agent (T6R), Taihua No.8 (T8), Taihua No.8+rhizobia agent (T8R), Taihua No.10 (T10), and Taihua No.10+rhizobia agent (T10R). The experiment adopted a field randomized block design, with three replicates for each treatment, and each community had an area of 14.4 m2. Before the sowing, a rotary cultivator plowed and leveled the field. Then, using ridge forming and fertilizing machine, peanut seeds were sown with a compound fertilizer (N-P2O5-K2O 15-15-15) of 450 kg/hm2 (i.e, input 4.5 kg N, P2O5, and K2O, respectively, in 0.667 hectares) in April 2022. The ridges were mechanically ridged with a bottom width of 75 cm, a top width of 45 cm, and a height of 15 cm. Two rows were sown on each top ridge, with a hole spacing of 18–20 cm. The arrangement was random and repeated three times. Each plot had four ridges, with a width of 3.2 m and a length of 4.5 m (14.4 m2), spaced 50 cm apart, and protective rows were set around. On 30th May 2022, the sowing of different peanut seeds was finished. All other cultivation and management were carried out in accordance with high-yield requirements.

2.4. Sampling Collection and Analysis

The entire growth period of the four peanut varieties is about 115 days. The plants were collected from each treatment during the seedling stage (4 July 2022), flower-pegging stage (28 July 2022), pod-setting stage (16 August 2022), and maturation stage (22 September 2022). In each sample collection, ten peanuts’ plants were randomly collected in each community. After sample collection, the plant height, lateral branch length, leaf age, number of branches, fresh leaf weight, stem and branch weight, fresh root weight, leaf area, number of nodules, etc., were evaluated. The plant height (cm) and lateral branch length (cm) were measured by a meter ruler. The leaf age was measured by counting the number of leaves that had already been born on the main stem, except for two pairs of lateral branches. The leaf area was measured by the disc method [29]. Before the test, the third compound leaf below the top of the main stem was removed from the sampled plant. After washing, a circular punch was used to punch holes in the middle of the leaf. Then, the collected samples were dried at 75 °C to a constant weight. Meanwhile, the remaining leaves were also dried and weighed, and then the leaf area of the sampled plant was converted. The number of branches only measured the branches above 5 cm in the entire plant. In addition, the fresh leaf weight, stem and branch weight, fresh root weight, and peanut fruit were measured by electric balance. The number of nodules was tallied by counting the total number of nodules on the main and lateral roots. During harvest, all plants will be harvested by a peanut combine harvester for yield testing.

2.5. Statistical Analysis

Statistical analyses were performed using SPSS 26.0 software (IBM SPSS 26.0, SPSS Inc., Chicago, IL, USA) and the graphs were plotted with Origin Ro 8.5 (OriginLab, Northampton, MA, USA). The significant differences in fresh peanut weight, number of nodules, and peanut fruit among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA.

3. Results

3.1. Peanut Plant Height, Lateral Branch, Leaf Age, and Branch Number

The peanut plant height, lateral branch, leaf age, and branch number showed an increasing trend from the seedling stage to the maturation stage in each treatment (Figure 1). In the T4, T6, T8, and T10 treatments, the peanut plant height was increased from ~6.5 to ~32.7 cm during the growth period (Figure 1A). Meanwhile, the plant height had a higher value in the T4R, T6R, T8R, and T10R (inoculate with rhizobia agent) treatments, increased from ~7.6 to ~34.7 cm during the growth period (Figure 1A). Similarly to plant height, the lateral branch, leaf age, and branch number had the same increase trend in the T4, T6, T8, and T10 treatments (Figure 1B–D). The inoculation of the rhizobia agent also improved the peanut lateral branch, leaf age, and branch number in the T4R, T6R, T8R, and T10R treatments (Figure 1B–D).

3.2. Peanut Fresh Leaf, Stem, Fresh Root, and Fresh Fruit Weight

The peanut fresh leaf, stem, and root weight per plant showed an increasing trend in each treatment with the growth of plant (Figure 2). In the T4, T6, T8, T10, T4R, T6R, T8R, and T10R treatments, the fresh leaf weight in the seedling stage ranged from 5.53 to 9.08 g per plant and increased to a range of 27.4 to 48.0 g per plant in the maturation stage (Figure 2A). Meanwhile, the change of fresh stem and root weight in all treatments had a similar trend, i.e., with fresh leaf weight increased from 33.6 to 69.3 and 4.7 to 9.0 g per plant, respectively (Figure 2B,C). The fresh fruit weight in the T6 and T8 treatments had the lowest values at 54.1 and 51.9 g (Figure 2D). In the T4, T4R, T6R, T8R, and T10 treatments, the fresh fruit weight had no significant difference, ranging from 56.0 to 62.9 g (Figure 2D). However, the fruit weight in the T10R treatment reached the maximum value of 85.8 g, significantly higher than in other treatments (Figure 2D).

3.3. Leaf Area

The overall trend of leaf area in each treatment was increased from the seedling stage to the pod-setting stage and decreased from the pod-setting stage to the maturation stage (Figure 3). In the T4, T6, T8, and T10 treatments, the leaf area increased from 0.60~0.88 to 2.20~5.15 cm2 from the seedling to pod-setting stage. Meanwhile, the leaf area in the T4R, T6R, T8R, and T10R treatments had a similar trend and higher values, i.e., increased from 0.65~0.99 to 3.29~5.90 cm2 (Figure 3). In the pod-setting and maturation stage, T4R had the highest leaf area of 5.90 and 4.76 cm2, and T8 had the lowest leaf area of 3.20 and 2.71 cm2 (Figure 3).

3.4. Number of Root Nodules

In the flower-pegging stage and pod-setting stage, the number of root nodules was 5.0, 3.2, 3.5, 4.8 and 12.9, 6.60, 8.6, 8.5 in the T4, T6, T8, and T10 treatments, respectively (Figure 4). After inoculating with a rhizobia agent, the number of root nodules in T4R, T6R, T8R, and T10R showed a significantly (p < 0.05) increasing trend (Figure 4). Compared with the T4, T6, T8, and T10 treatments, the number of nodules in the flower-pegging stage and pod-setting stage significantly (p < 0.05) increased, to 6.1, 7.4, 7.4, 7.1 and 24.5, 11.9, 14.6, 17.8, respectively (Figure 4). In the T4R treatment, the number of nodules had the highest value of 24.5 in the pod-setting stage (Figure 4).

3.5. Number of Peanut Fruit

The total number of peanut fruits per plant in the T4 and T6 treatments was 15.4 and 16.4 (Figure 5A). In the T4R and T6R treatments, the number of peanut fruits had the highest value of 18.0 and 18.1, significantly (p < 0.05) higher than in the T8, T8R, T10, and T10R treatments (14.0, 14.1, 9.6, and 11.6, respectively) (Figure 5A). In addition, the full peanut fruit number in T4, T6, T6R, T8, T8R, T10, and T10R ranged from 4.3 to 8.0, significantly (p < 0.05) lower than the fruit number of 9.5 in the T4R treatment (Figure 5A). In the T6R treatment, the number of withered peanuts had the highest value of 8.0, significantly (p < 0.05) higher than in other treatments (Figure 5A). The ratio of full/withered peanut fruit between the T4, T6, T8, T10 and 4R, T6R, T8R, T10R treatments were 1.1, 1.4, 1.3, 1.2 and 2.1, 1.3, 1.5, 1.9, respectively (Figure 5B).

3.6. Peanut Weight and Crop Yield

The peanut weight per plant in T10R showed the highest value of 85.8 g, significantly (p < 0.05) higher than in the T4, T6, T8, T10, T4R, T6R, and T8R treatments, i.e., 62.9, 65.6, 54.1, 62.7, 51.9, 56.0, and 59.3 g (Figure 6A). The yield of peanuts in the T4, T6, T8, T10, T4R, T6R, T8R, and T10R treatments were 289.1, 321.0, 301.5, 336.4, 344.7, 367.3, 330.3, and 355.97 kg per mu (667 m2), respectively (Figure 6B). Compared with T4, T6, T8 and T10, the peanut yield increase rate in the T4R, T6R, T8R and T10R treatments were 11.0% (T4R/T4), 11.6% (T6R/T6), 6.6% (T8R/T8), and 7.8% (T10R/T10), respectively (Figure 6B).

4. Discussion

Biological nitrogen fixation is the predominant pathway through which peanuts assimilate nitrogen throughout their growth cycle, accounting for approximately 60% of the total absorbed and fixed nitrogen [30]. This process significantly enhances the efficiency of nitrogen fertilizer utilization in peanut cultivation, thereby increasing yield and contributing to environmental stewardship [31]. In addition, peanut plants exhibit a progressive increase in nitrogen demand throughout their development, with the highest requirement occurring during the reproductive phase [32]. Concurrently, the nitrogen-fixing capacity of root nodules sees continuous enhancement, which is essential for supporting the transition from vegetative to reproductive growth [33]. Our research indicated that rhizobia inoculation treatment not only improved the nutritional structure of four peanut varieties (such as plant height, fresh weight, lateral branch length, leaf area, etc.) but also increased the yield of the four peanut varieties (Figure 1, Figure 2, and Figure S1). This result is similar to previous research, confirming that inoculation with rhizobia is an effective way to improve the quality and yield of peanuts [20,34]. However, it is worth noting that the ability of rhizobia agents to improve on diverse peanut varieties is different, especially in response to different growth stages.
Enhancing the absorption and utilization of nitrogen by crops can significantly foster the growth and development of various organs within peanut plants and amplify the accumulation of dry matter [20,34]. Inoculating rhizobia can promote peanut nitrogen fixation and increase plant height and lateral branch growth [35]. In this study, notable variations were observed in the response of different peanut varieties to rhizobia agent treatments (Figure S1). Varieties treated with rhizobia agent exhibited an early-onset advantage, displaying a marked increase in plant height and lateral branch growth rate post the flower-pegging stage (Figure 1). Mishra et al. also confirmed that the inoculation of peanut seeds with rhizobia can also obtain a greater plant height than without inoculation [36]. Meanwhile, the inoculation of rhizobia with polythene would further increase the plant height, which is beneficial for increasing community leaf area and photosynthetic area [20]. After inoculation with a rhizobia agent, T4, T6, T6, and T8 rapidly increased leaf age in the early stages of growth, which is conducive to the early onset and rapid growth of plants (Figure 1). Sustaining maximum leaf age throughout the latter stages of growth is instrumental in augmenting the photosynthetic area, thereby facilitating organic matter accumulation [37].
The leaf area (LA) serves as an effective indicator of the intensity of photosynthesis within a plant canopy [38]. Generally, a larger LA correlates with more robust photosynthetic activity and a greater accumulation of organic matter [39]. Compared with no rhizobia inoculation, the inoculation of seeds with rhizobia can significantly increase the peanut LA in harvest [20]. In this study, the inoculation with rhizobia also increased the LA for all four peanut varieties (Figure 3). However, the LA follows a pattern of initial increase followed by a decrease throughout the entire growth period (Figure 3). The rate of increase in LA during the seedling stage is relatively slow. Then, as the plants grow and develop, LA has a marked acceleration after reaching the flowering and needle stage, culminating in the maximum LA during the pod-setting stage (Figure 3). In particular, Taihua No.4 has the highest LA value of 5.90 cm2 after inoculation with rhizobia (Figure 3). The larger LA would contribute to peanuts’ high dry matter accumulation due to the higher solar radiation interception [20]. After this stage, as the lower leaves begin to senesce and turn yellow, there is a corresponding decline in the LA (Figure 3).
The number and size of root nodules serve as crucial indicators of a plant’s nitrogen fixation capabilities, significantly influencing the absorption, utilization, and overall growth of symbiotic plants [40,41]. Compared with no rhizobia treatment, inoculation with rhizobia has been shown to stimulate the formation of nodules in peanut seedlings earlier and in greater quantities, thereby providing a substantial basis for nitrogen fixation and fostering plant growth and development (Figure 4). However, there is a notable variation in the number of nodules formed among different peanut varieties following rhizobia inoculation. After rhizobia inoculation, T4R has the highest number of nodules in the pod-setting stage, significantly higher than T6R, T8R, and T10R, i.e., 24.5 vs. 11.9, 14.5, and 17.8 (Figure 4B). However, compared with other rhizobia agents, the number of nodules in the T4 peanut varieties also has a lower value. The inoculation with agents USDA 4438 and USDA 3180 can produce ~80 nodules in peanuts [35]. Significantly, the use of these above agents did not increase the yield of peanuts. In this research, Taihua No.4 variety inoculation with agent increased yield by 11.6%. This could be related to peanut varieties, strain of rhizobia, and sowing conditions. Therefore, Taihua No.4 variety inoculated with rhizobia agent has a great potential for yield increase, especially in the future spread of cultivation.
The effective number of peanuts, full fruit number, and withered fruit number of peanuts can significantly affect the yield that occurs [42,43]. From the perspective of the maturation stage, inoculation with a rhizobia agent can reduce the number of peanut withered fruits in the T4, T8, and T10 treatments and increase the full fruit number (Figure 5A). However, the ratio of full fruit to withered fruit in the T6R treatment showed a decreasing trend after inoculation with rhizobia, with the lowest value of 1.26 (Figure 5B). In contrast, the proportion of full/withered fruits in the T4 variety after inoculation with rhizobia reached the maximum value of 2.12 (Figure 5B). This result indicates that inoculation with rhizobia has the best effect on the fullness and maturity of Taihua No.4 variety fruits, which can improve the quality of peanut fruits.
Among all four peanut varieties, the inoculation with rhizobia agent increased the crop yield, with an increasing rate ranging from 6.57% to 11.60% (Figure 6). Although varieties Taihua No.8 and Taihua No.10 had a higher peanut yield than Taihua No.4 and Taihua No.6, the efficiency of yield increase by rhizobia agent was lower than Taihua No.4 and Taihua No.6, i.e., 6.57% and 7.79% vs. 11.03% and 11.6% (Figure 6). Therefore, from the perspective of yield-increasing efficiency, T4 and T6 are more suitable peanut varieties for rhizobia inoculation than T8 and T10. However, the high proportion of withered fruits in the podding stage of T6 peanuts significantly affects both yield and quality. Consequently, despite the relatively lower yield of Taihua No.4 peanuts, it can be considered the best choice for rhizobia agent inoculation.

5. Conclusions

Inoculating rhizobia agents are an effective pathway to improve peanut nitrogen fixation ability, increase crop yield, and reduce the input of chemical fertilizers. This study investigated the effects of inoculation with rhizobia on four peanut varieties’ growth, development, and crop yield (Taihua No.4, No.6, No.8, and No.10). Inoculating rhizobia can increase the yield of peanuts by increasing their fresh weight, leaf area, and number of nodules. Meanwhile, inoculation with rhizobia can also reduce the number of withered fruits in peanuts and increase their yield. Compared with the high-yield peanut varieties (Taihua No.8 and Taihua No.10), the rhizobia agent has a more significant promoting effect on peanut varieties with lower yields, i.e., Taihua No.4 and Taihua No.6. Therefore, the cultivation and promotion of low-yield peanut varieties (Taihua No.4 and Taihua No.6) would be best served by inoculation with rhizobia agent, especially in the interest of a sustainable agricultural development.

Supplementary Materials

The following supporting information can be downloaded at: https://www.mdpi.com/article/10.3390/agronomy14071410/s1, Table S1: The basic physicochemical properties of soil in field experiments. Figure S1: The image of different peanut varieties after inoculation with rhizobia agent in the maturation stage. Figure S2: The image of peanut commercial rhizobia agent in this research.

Author Contributions

Conceptualization, B.D. and D.T.; methodology, B.D., M.F. and R.W.; software, R.W. and L.C.; validation, B.D., Y.J. and J.X.; formal analysis, L.C.; investigation, Y.J. and J.X.; resources, B.D.; data curation, B.D.; writing—original draft preparation, B.D. and D.T.; writing—review and editing, B.D. and D.T.; visualization, B.D., R.W., L.C. and D.T.; funding acquisition, B.D. All authors have read and agreed to the published version of the manuscript.

Funding

This research was funded by Jiangsu Agricultural Science and Technology Independent Innovation Funding (No. CX (22)3086), Jiangsu Modern Agricultural Industrial Technology System (No. JATS (2023) 271), and Jiangsu Provincial Key Research and Development Project (Modern Agriculture) (No. BE2022411).

Data Availability Statement

Data is contained within the article or supplementary material.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. The plant height (A), length of plant lateral branch (B), leaf age (C), and plant branch number (D) of peanut in each treatment during the growth stage. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
Figure 1. The plant height (A), length of plant lateral branch (B), leaf age (C), and plant branch number (D) of peanut in each treatment during the growth stage. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
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Figure 2. The plant fresh leaf weight (A), plant stem weight (B), plant fresh root weight (C), and plant fresh fruit weight (D) of peanuts in each treatment during the growth period. The different lower-case letters indicate a significant difference between the treatments (p < 0.05). The significant differences among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
Figure 2. The plant fresh leaf weight (A), plant stem weight (B), plant fresh root weight (C), and plant fresh fruit weight (D) of peanuts in each treatment during the growth period. The different lower-case letters indicate a significant difference between the treatments (p < 0.05). The significant differences among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
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Figure 3. The leaf area (cm2) of peanut in each treatment during the growth stage. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
Figure 3. The leaf area (cm2) of peanut in each treatment during the growth stage. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
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Figure 4. The number of nodules in each treatment during the flower-pegging and pod-setting stage. The different lower-case letters indicate a significant difference between the treatments (p < 0.05). The significant differences among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
Figure 4. The number of nodules in each treatment during the flower-pegging and pod-setting stage. The different lower-case letters indicate a significant difference between the treatments (p < 0.05). The significant differences among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
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Figure 5. The number of peanut fruit (A) and full/withered peanut fruit ratio (B) in each treatment at the maturation stage. The different lower-case letters indicate a significant difference between the treatments (p < 0.05). The significant differences among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
Figure 5. The number of peanut fruit (A) and full/withered peanut fruit ratio (B) in each treatment at the maturation stage. The different lower-case letters indicate a significant difference between the treatments (p < 0.05). The significant differences among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
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Figure 6. The peanut fruit weight (A), peanut yield and yield increase rate (B) in each treatment at the maturation stage. The different lower-case letters indicate a significant difference between the treatments (p < 0.05). The significant differences among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
Figure 6. The peanut fruit weight (A), peanut yield and yield increase rate (B) in each treatment at the maturation stage. The different lower-case letters indicate a significant difference between the treatments (p < 0.05). The significant differences among the treatments were identified by Tukey’s honestly significant difference test (p < 0.05) via one-way ANOVA. T4, T6, T8, T10 and T4R, T6R, T8R, T10R represent the treatments of Taihua No.4, Taihua No.6, Taihua No.8, Taihua No.10 and Taihua No.4+rhizobia agent, Taihua No.6+rhizobia agent, Taihua No.8+rhizobia agent, Taihua No.10+rhizobia agent, respectively.
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Ding, B.; Feng, M.; Wang, R.; Chang, L.; Jiang, Y.; Xie, J.; Tian, D. A Study of Growth and Yield of Four Peanut Varieties with Rhizobia Inoculation under Field Conditions. Agronomy 2024, 14, 1410. https://doi.org/10.3390/agronomy14071410

AMA Style

Ding B, Feng M, Wang R, Chang L, Jiang Y, Xie J, Tian D. A Study of Growth and Yield of Four Peanut Varieties with Rhizobia Inoculation under Field Conditions. Agronomy. 2024; 14(7):1410. https://doi.org/10.3390/agronomy14071410

Chicago/Turabian Style

Ding, Bin, Mengshi Feng, Rui Wang, Lei Chang, Ying Jiang, Jixian Xie, and Da Tian. 2024. "A Study of Growth and Yield of Four Peanut Varieties with Rhizobia Inoculation under Field Conditions" Agronomy 14, no. 7: 1410. https://doi.org/10.3390/agronomy14071410

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