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Table 2 Effect of N-fertilizer/application method and PGPM on root growth and rhizosphere pH, shoot nutrient content and dry matter (55 days after sowing)

From: Densely rooted rhizosphere hotspots induced around subsurface NH4 +-fertilizer depots: a home for soil PGPMs?

Source of variation

RLD 5 × 5 cm to seed (8 cm radius) (cm cm−3)

Rhizosphere pH 5 × 5 cm to seed (8 cm radius)

δ15 N (o/oo)15N/14N

N conc. (% DM)

N content (mg N plant−1)

P conc. (mg P g−1 DM)

P content (mg P plant−1)

Shoot DM (g plant−1)

 LS means N*BE

  14NO3 -mixed*NoBE

6.4

5.62

170

1.83

114.0

2.18

13.7

6.35

  14NO3 -mixed*Pro

6.2

5.89

148

2.22

130.1

2.32

13.6

5.91

  15NH4 +-depot*NoBE

10.5

4.41

25,260

2.47

137.1

2.93

16.2

5.60

  15NH4 +-depot*Pro

9.9

4.55

21,257

2.66

133.9

3.15

15.9

5.09

  Standard error

0.68

0.13

831

0.13

4.69

0.146

0.62

0.420

 Two-Way ANOVA

  N

0.001***

0.001***

< 0.001***

0.002 **

0.014*

< 0.001***

0.002**

NS

  14NO3

6.3

5.75

159

2.03 b

122.0 b

2.52 b

13.6 b

6.13

  15NH4 +

10.2

4.48

23,259

2.57 a

135.5 a

3.04 a

16.0 a

5.35

  BE

NS

NS

0.036

0.051

NS

NS

NS

NS

  NoBE

8.4

5.01

12,715

2.15

125.7

2.56

15.0

5.97

  Pro

8.0

5.22

10,702

2.44

132.0

2.73

14.7

5.50

  N*BE

NS

 

NS

NS

NS

NS

NS

NS

  1. P values are in italics; NS no significant difference, P ≥ 0.1; P < 0.1 is italic; *P < 0.5; **P < 0.01; ***P < 0.001; Means not sharing the same letters are significantly different from each other, Tukey test α = 0.05; Factors and interaction is italic; 14NO3 -mixed, non-isotopically labelled Ca(NO3)2 homogenously mixed in substrate; 15NH4 +-depot, 15N-labelled stabilized (NH4)2SO4 +DMPP placed in substrate as a depot; BE, bio-effector; NoBE, no bio-effector; Pro, Pseudomonas sp. DSMZ 13134. ANOVA on δ15N (o/oo) 15N/14N was performed on square root transformed data. RLD, root length density