Effects of soymilk root irrigation on the growth of flue-cured tobacco

and bacterial community in soilDai H.X.1; Yang J.J.2; Li L.3, Xi J.Q.1; Liang T.B.1; Wang J.W.1; Chen Y.C.2; Su X.H.*2; Zhang X.*3

1. Zhengzhou Tobacco Research Institute of CNTC, Zhengzhou 450001, China

2. Company of Sanmenxia City of Henan Provincial Tobacco Company, Sanmenxia 472000, China

3. Institute of Plant Nutrition, Resource and Environment, Henan Academy of Agricultural Sciences, Zhengzhou 450002, China.

Introduction

Soymilk root irrigation (SRI, traditional soymilk and fermented soymeal), a topdressing technology with local characteristics for soil conservation, has became a routine

agricultural technical measure in tobacco planting area of western Henan province for more than 20 years. To unravel the effects of SRI on the growth of flue-cured tobacco, pot

and field experiments were performed to analyze soil nutrient status, agronomic traits, root growth, soil bacteria counts and bacterial community structure. The results showed

that the contents of soil nutrients such as alkali-hydrolyzed N, available P and available K remained relatively high in the middle and late stages of SRI. The growth of tobacco

root and leaves were promoted after SRI. The abundance of dominant bacteria in soil varied significantly among different treatments at the early stage of SRI, however, similar

dominant bacteria abundance was observed in the middle and late stage of SRI. The bacteria number increased significantly, and the relative abundance of twenty-two soil

functional bacteria categorized mainly in nutrient cycling, secretion plant growth regulators, and inhibiting pathogens exhibited great increment in the early stage of SRI.

Therefore, SRI may improve the yield and quality of flue-cured tobacco by increasing soil nutrients contents, increasing the relative abundance of beneficial functional bacteria,

improving soil micro-ecological environment, and promoting the growth of root and leaf of flue-cured tobacco.

.

Main results

Conclusion➢The contents of soil protein and active carbon increased significantly in the early stage of SRI, and the contents of

alkali-hydrolyzed N, available P and available K remained relatively high in the middle and late stages of SRI.

➢The growth of tobacco root and leaves were promoted after SRI.

➢At the early stage of SRI, the number of bacteria increased rapidly, and the abundance of dominant bacteria in soil

varied significantly among different treatments.

➢At the early stage of SRI, the relative abundance of various soil functional bacteria involved in nutrient cycling,

secretion plant growth regulators, and inhibiting pathogens increased significantly.AcknowledgmentsThis study was financially supported by the Henan Tobacco Company Research Project (2018410000270036), the China Tobacco Henan

Industrial Co., Ltd. Project (2019410000340029), and the Sanmenxia company project of Henan Tobacco Company (201641120024056).

Tab. 1 The nutrient composition of traditional soymilk and fermented soymeal（g/kg）

DaysTreat

ment

Alkali-

hydrolyzed

N

Available

P

Available

K

Organic

matters

Available

Fe

Exchang

eable Ca

Exchangea

ble Mg

Active

carbon

Soil

protein

index

CK 286.3 a 31.4 a 256.6 a 17.7 a 21.2 a 3103.2 a 644.8 a 357.1 a 1.44 a

0 d T1 275.7 a 29.4 a 221.7 a 16.8 a 19.5 a 2912.6 a 653.6 a 356.3 a 1.30 a

T2 288.1 a 30.8 a 211.9 a 17.2 a 18.2 a 2921.4 a 632.4 a 364.9 a 1.39 a

CK 280.6 a 30.5 a 241.9 a 17.2 a 20.7 a 3058.7 a 686.1 a 365.2 b 1.72b

5 d T1 294.4 a 26.8 a 234.3 a 18.4 a 18.2 a 2824.6 a 661.1 a 401.7 a 2.56 a

T2 294.8 a 31.1 a 244.2 a 17.6 a 17.9 a 2873.9 a 602.6 a 408.9 a 2.60 a

CK 220.2 b 17.7 c 218.0 b 16.7 a 16.5 a 2540.7 b 514.2 b 325.3 a 1.64 b

20 d T1 268.2ab 24.4 b 235.5 b 17.9 a 16.9 a 2863.4 a 677.5ab 366.0 a 1.99 a

T2 300.3 a 30.0 a 307.2 a 17.1 a 19.0 a 3154.4 a 779.0 a 358.7 a 2.01 a

CK 245.6 a 20.1 b 289.4 a 17.6 a 21.2 a 2743.7 a 625.5 b 304.0 a 1.34b

35 d T1 287.9 a 26.1 b 279.6 a 17.4 a 20.3 a 2575.5 a 644.4 b 330.8 a 1.68 a

T2 282.3 a 32.7 a 299.4 a 18.2 a 21.3 a 3066.9 a 740.0 a 319.7 a 1.54ab

CK 127.0 b 15.5 b 209.0 a 16.6 a 18.6 a 2902.0 a 611.3 a 287.4 a 1.21 a

55 d T1 158.1 a 22.6 a 213.5 a 17.9 a 20.6 a 2806.9 a 662.5 a 319.3 a 1.24 a

T2 149.6 a 27.1 a 205.1 a 17.5 a 20.2 a 2732.7 a 612.0 a 322.5 a 1.20 a

CK 111.9 b 10.8 b 160.6 b 15.7 a 17.3 a 2823.8 a 552.6 a 223.4 a 1.05 a

75 d T1 163.3 a 18.3 a 191.7 a 16.2 a 18.8 a 2714.9 a 591.2 a 211.9 a 1.20 a

T2 168.9 b 20.8 a 187.9 a 16.9 a 20.4 a 2847.7 a 587.0 a 230.6 a 1.13 a

CK 112.9 b 5.0 b 146.8 b 9.9 a 18.6 a 2747.0 a 459.3 a 340.5 a 0.99 a

95 d T1 168.2 a 16.4 a 169.0 a 10.3 a 19.6 a 2530.1 a 402.4 a 361.6 a 1.21 a

T2 180.7 a 14.1 a 177.1 a 10.7 a 19.1 a 2733.2 a 401.1 a 353.2 a 1.23 a

Tab. 2 Effects of soymilk root irrigation on the soil nutrient contents in field（mg/kg）

Tab.3 Effects of soybean milk root irrigation on the agronomic characters of flue-cured tobacco in field

0

2

4

6

8

10

12

14

0 5 20 35 55 75 95

CK

T1

T2

Bac

teri

alam

ou

nts

（1

08

cfu

·g-1）

Fig. 1 Effects

of soymilk root

irrigation on

the number of

soil bacteria

Fig. 3 Comparison of Chao and Shannon indices of soil bacteria at 5 d (A, D), 35 d

(B, E) and 95 d (C, F) after soymilk root irrigation

Functions Bacteria CK T1 T2

Streptomyces 2.78 b 1.59 c 6.23 a

Rhodanobacter 0.92 b 2.03 a 1.61 a

Mizugakiibacter 0.68 b 0.23 c 1.32 a

Nitrospira 1.05 a 0.57 b 0.12 c

Massilia 0.45 b 1.65 a 1.20 a

Soil nutrient cycling

Gemmatimonas 1.07 a 0.45 b 0.33 b

Sphingomonas 0.33 b 1.39 a 0.20 b

Sphingobacterium 0.00 c 0.13 b 4.51 a

Chitinophaga 0.10 c 1.30 a 0.92 b

Klebsiella 0.01 b 0.04 b 3.53 a

Devosia 0.25 b 0.45 a 0.37 ab

Dongia 0.02 b 0.04 a 0.04 a

Rhodocytophaga 0.01 b 0.03 a 0.03 a

Cellvibrio 0.03 b 0.05 a 0.05 a

Secretion of plant

growth regulators

Bacillus 0.23 c 0.35 b 0.60 a

Pseudomonas 0.11 c 5.97 a 3.05 b

Pseudoduganella 0.05 c 1.77 a 1.04 b

Luteibacter 0.03 c 0.18 b 3.72 a

Inhibition of pathogenic

bacteria

Lysobacter 2.77 c 3.92 b 12.20 a

Pseudoxanthomonas 0.05 c 1.29 a 0.69 b

Mycobacterium 0.08 b 0.17 a 0.19 a

Bdellovibrio 0.01 b 0.03 b 0.05 a

Tab.5 Changes in abundance of soil bacteria at the early stage (5 d) of soymilk root irrigation(%）

Traditional soymilk Fermented soymeal Soymilk root irrigation

Items Organic

matters

Crude

fat

Crude

protein

Soluble

protein

Carbohy

drate

P Fe Ca K Small peptides and

amino acids

Traditional

soymilk

674.3 497.4 605.2 398.7 350.7 14.6 0.17 3.10 14.12 2.52

Fermented

soymeal

705.6 32.9 537.1 350.3 386.2 8.24 0.16 2.93 13.91 1.71

TreatmentHeight/

cm

Pitch/

cm

Laimosphere/

cm

Numbers of

leaves

Length of maximum

middle leaf/cm

Width of maximum

middle leaf /cm

Length of maximum

top leaf/cm

Width of maximum

top leaf/cm

CK 102.4 a3.68 a 8.15 a 21.4 a 62.3 b 23.5 a 50.4 a 19.8 b

T1 105.6 a3.73 a 8.24 a 22.0 a 64.2 a 24.6 a 50.6 a 21.4 a

T2 104.8 a3.75 a 8.27 a 21.9 a 64.4 a 24.8 a 51.2 a 21.5 a

TreatmentTotal root

length/cm

Surface

area/cm2

Average

diameter/mm

Length of per

volume root/(cm∙m-3)

Root

volume/cm3

Root dry

weight/g

CK 14067.12 b 2986.57 b 1.76 b 14088.76 b 52.55 b 7.81 b

T1 16861.83 a 3786.08 a 2.07 a 16943.51 a 72.68 a 9.37 a

T2 16137.72 a 3989.45 a 2.13 a 16217.14 a 74.55 a 9.48 a

Chao

index

Shan

non i

ndex

aCB

aE F

CK T1 T2 CK T1 T2 CK T1 T2

a

a

b

A

b

a

a

a

a

aD

a

aa

aa

aa

After 28 days of transplanting, tobacco seedlings were treated with water(CK), soybean milk (T1) and traditional soymilk in field (T2).

Means with the same letter are not significantly different at P = 0.05 among the 3 treatments at each of the 6 time points.

Tab. 4 Effect of soymilk root irrigation on the root growth characters of flue-cured tobacco in pot

b

a

ba a a

a b a a a a a

a

ba

b b ab b b b a a a ab

a

aba

b c b ca c a a b b

0102030405060 CK T1 T2

a a

a aa a a a a a a a a

a

aa

a a aa a a a a a a

a a

a a a aa a a a a a a

01020304050

a

aa

aa a

aa a a a a a

a

aa a a a

a a a a a a a

a

aa

a a aa

a a a a a a0

10

20

30

40

50

Ab

un

da

nce

(%

)

Fig.2 Abundances of bacterial communities at phylum level in tobacco-planting soils at 5

d (A,), 35 d (B) and 95 d (C) after soymilk root irrigation

A

B

C

2020

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