Effects of rhizosphere nitrogen-fixing, phosphate-solubilizing and potassium-solubilizing bacteria on leaf nutrients and physiological traits in different natural populations of Malus sieversii

doi:10.17521/cjpe.2022.0406

Abstract

Abstract:

Aims This study aimed to investigate how the colonization numbers of nitrogen-fixing, phosphate-solubilizing, and potassium-solubilizing bacteria affect the physiological traits of Malus sieversii and to ascertain the abundance of rhizosphere microorganisms conducive to their thriving in Xinjiang, China.
Methods In this study, we utilized the rhizosphere soil of M. sieversii sourced from eight distinct natural populations in Xinjiang as our primary experimental materials. Our objectives included the isolation and quantification of nitrogen-fixing bacteria (NFB), organic phosphate-solubilizing bacteria (oPSB), inorganic phosphate-solubilizing bacteria (iPSB), and potassium-solubilizing bacteria (KSB). Additionally, we assessed the physiological characteristics of M. sieversii leaves, as well as determined the nitrogen, phosphorus, and potassium content in both the leaves and the soil.
Important findings (1) A statistically significant difference was observed in the total count of four functional bacterial strains colonizing the rhizosphere across eight distinct populations of M. sieversii. The population in Wild Fruit Forest, Xinyuan County exhibited the highest cumulative count of oPSB, iPSB, NFB, and the four functional strains, while the population in Nazi Work Team, Gongliu County, displayed the highest count of KSB. (2) Both the cumulative count of the four functional bacterial strains and the count of PSB exhibited a positive correlation with changes in catalase activity within the leaves. Simultaneously, the count of KSB demonstrated a positive correlation with peroxidase activity. These findings support the existence of a correlation between the population of rhizosphere bacteria activating nitrogen, phosphorus, and potassium in M. sieversii and its resistance to external factors. (3) Regarding nutrient uptake, the counts of oPSB corresponded to phosphorus and nitrogen levels in the leaves, while iPSB counts aligned with soil phosphorus content. Additionally, both oPSB and NFB counts correlated with soil nitrogen content, while KSB counts reflected the potassium content in both leaves and soil. (4) Optimal nutritional growth of M. sieversii occurred with bacterial colonization counts of 7.08 × 10⁴ CFU·g^-1 (NFB), 2.7 × 10⁷ CFU·g^-1 (PSB), and 4.98 × 10⁵ CFU·g^-1 (KSB), respectively, resulting in higher nitrogen, phosphorus, and potassium levels in both leaves and soil.

Key words: nitrogen-fixing bacteria, phosphate solubilizing bacteria, potassium solubilizing bacteria, number of colonies, physiological traits, nitrogen content, phosphorus content, potassium content

JIAO Hui-Ying, LIU Li-Qiang, YANG Jia-Xin, QIN Wei, WANG Rui-Zhe. Effects of rhizosphere nitrogen-fixing, phosphate-solubilizing and potassium-solubilizing bacteria on leaf nutrients and physiological traits in different natural populations of Malus sieversii[J]. Chin J Plant Ecol, 2024, 48(7): 930-942.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2022.0406

https://www.plant-ecology.com/EN/Y2024/V48/I7/930

Figures/Tables 6

Table 1 Summary of rhizosphere soil sampling sites for Malus sieversii

采样地点 Sampling site	土壤类型 Soil type	经度 Longitude (E)	纬度 Latitude (N)	海拔 Altitude (m)
A1	黑钙土 Chernozem	80.79°	44.43°	1 121.95
A2		80.80°	44.43°	1 121.85
A3		80.80°	44.44°	1 121.92
B1	灰钙土 Sierozem	81.39°	43.93°	625.80
B2		81.39°	43.93°	625.44
B3		81.39°	43.93°	625.97
C1	黑钙土 Chernozem	83.61°	43.38°	1 445.31
C2		83.60°	43.37°	1 445.28
C3		83.61°	43.38°	1 445.32
D1	黑钙土 Chernozem	82.73°	43.20°	1 296.37
D2		82.73°	43.20°	1 296.29
D3		82.73°	43.20°	1 296.56
E1	棕钙土 Brown calcium soil	82.75°	43.22°	1 273.59
E2		82.75°	43.22°	1 273.28
E3		82.75°	43.22°	1 272.98
F1	黑钙土 Chernozem	82.86°	43.26°	1 289.57
F2		82.86°	43.26°	1 288.86
F3		82.86°	43.26°	1 289.31
G1	黑钙土 Chernozem	84.00°	46.37°	1 250.84
G2		84.00°	46.37°	1 250.67
G3		84.00°	46.37°	1 250.29
H1	黑钙土 Chernozem	83.53°	46.15°	900.26
H2		83.53°	46.15°	900.59
H3		83.53°	46.15°	900.76

Table 2 Number of rhizosphere functional strains in different populations of Malus sieversii

种群 Population	有机解磷菌 oPSB (CFU·g^-1)	无机解磷菌 iPSB (CFU·g^-1)	固氮菌 NFB (CFU·g^-1)	解钾菌 KSB (CFU·g^-1)	4种功能菌株总数 Total number of 4 functional bacterias (CFU·g^-1)
A	7.12 × 10^6Cc	7.05 × 10^4Ef	7.08 × 10^4Bb	1.12 × 10^3Ccd	7.27 × 10^6Cc
B	1.30 × 10^6Ff	3.85 × 10^5Cc	3.82 × 10^2Gg	1.29 × 10^4Bb	1.69 × 10^6Ff
C	2.48 × 10^7Aa	2.47 × 10^6Aa	8.30 × 10^4Aa	5.27 × 10^3Cc	2.75 × 10^7Aa
D	3.68 × 10^6Dd	3.62 × 10^5Cd	1.63 × 10^3Ff	1.22 × 10^4Bb	4.05 × 10^6Dd
E	8.27 × 10^6Bb	8.15 × 10^5Bb	8.21 × 10^2FGg	5.15 × 10^2Cd	9.09 × 10^6Bb
F	2.32 × 10^6Ee	5.00 × 10^4Ef	5.00 × 10^4Cc	4.98 × 10^5Aa	2.92 × 10^6Ee
G	7.60 × 10^5Gg	1.18 × 10^5De	3.54 × 10^4Dd	1.19 × 10^2Cd	9.13 × 10^5Gg
H	1.65 × 10^4Hh	3.72 × 10^3Fg	1.23 × 10^4Ee	7.94 × 10^2Ccd	3.34 × 10^4Hh

Fig. 1 Changes in leaf physiological characteristics (column) of different populations of Malus sieversii and their total number (polyline) of four functional strains of rhizosphere bacteria (mean ± SE). Car, carotenoid content; CAT, catalase activity; Chl a, chlorophyll a content; Chl b, chlorophyll b content; MDA, malondialdehyde content; POD, peroxidase activity; Pro, proline content; SOD, superoxide dismutase activity. Distinct lowercase letters denote significant differences at the 0.05 significance level, while differing uppercase letters signify significant distinctions at the 0.01 significance level among populations. Site see Table 1.

Fig. 2 Redundancy analysis of nitrogen, phosphorus and potassium content (mean ± SE) in leaves of Malus sierversii of different populations and the number of NFB, PSB, and KSB. iPSB, inorganic phosphate-solubilizing bacteria; KSB, potassium-solubilizing bacteria; NFB, nitrogen-fixing bacteria; oPSB, organic phosphate-solubilizing bacteria; TN, total number of four functional strains. LN, leaf nitrogen content; LK, leaf potassium content; LP, leaf phosphorus content. Distinct lowercase letters denote significant differences at the 0.05 significance level, while differing uppercase letters signify significant distinctions at the 0.01 significance level among populations. Site see Table 1.

Fig. 3 Redundanly analysis analysis of nitrogen, phosphorus and potassium content (mean ± SD) in soil of different populations and their relationship with the number of NFB, PSB, and KSB in the rhizosphere of Malus sieversii in Xinjiang. iPSB, inorganic phosphate-solubilizing bacteria; KSB, potassium-solubilizing bacteria; NFB, nitrogen-fixing bacteria; oPSB, organic phosphate-solubilizing bacteria; TN, total number of four functional strains. SN, soil nitrogen content; SK, soil potassium content; SP, soil phosphorus content. Distinct lowercase letters denote significant differences at the 0.05 significance level, while differing uppercase letters signify significant distinctions at the 0.01 significance level among populations. Site see Table 1.

Fig. 4 Correlation between the population of rhizosphere functional bacteria and various physiological characteristics, as well as the nitrogen, phosphorus, and potassium content of Malus sieversii. Car, carotenoid content; CAT, catalase activity; Chl a, chlorophyll a content; Chl b, chlorophyll b content; LN, leaf nitrogen content; LK, leaf potassium content; LP, leaf phosphorus content; MDA, malondialdehyde content; POD, peroxidase activity; Pro, proline content; SK, soil potassium content; SN, soil nitrogen content; SOD, superoxide dismutase activity; SP, soil phosphorus content; Spr, soluble protein content; SS, soluble sugar content. iPSB, inorganic phosphate-solubilizing bacteria; KSB, potassium-solubilizing bacteria; NFB, nitrogen-fixing bacteria; oPSB, organic phosphate-solubilizing bacteria. *, p ≤ 0.05; **, p ≤ 0.01.

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