Effects of PGPR Co-fermented Broth Nursery Substrate on the Pepper Seedling

doi:10.13560/j.cnki.biotech.bull.1985.2025-1077

Abstract

Abstract:

Objective To investigate the effects and underlying mechanisms of a bio-nursery substrate prepared from PGPR co-fermented broth on the growth of pepper seedlings under tray-based seedling cultivation conditions, which may provide a basis for the research and development of biological nursery substrate. Method Co-fermented strains were selected through compatibility analysis of four PGPR strains, IAA (indoleacetic acid) content determination of different strain combination's culture, and pepper seed soaking experiments. The optimal strain combination was determined by analyzing the effects of co-fermented broth on pepper seed germination and seedling growth using tray seedling cultivation. The optimal addition ratio was determined by assessing the effects of different proportions co-fermented broth on the seedlings growth during the seedling tray stage. The seedling growth-promoting mechanism was elucidated by analyzing the effects of co-fermented liquids on nutrient content and microbial diversity in the nursery substrate. Result The co-fermented broth of Burkholderia pyrrocinia P10 and Bacillus flexus HGD12 contained 60.84 mg/L IAA, significantly higher than the single-strain culture, which significantly promoted seed germination and seedling growth of peppers under both soaked-seed and tray-seedling cultivation conditions. Adding 15% co-fermented broth to the seedling substrate provided optimal growth promotion for seedlings in the seedling tray stage, significantly increasing pepper seedling height, stem diameter, fresh weight, dry weight, number of leaves, leaf area, and chlorophyll SPAD value by 29.17%, 17.67%, 64.68%, 94.44%, 22.30%, 49.45%, and 17.83%, respectively. The organic matter, alkali-hydrolyzed nitrogen, and available phosphorus content of the substrate increased by 11.31%, 20.39%, and 14.14%, respectively. Moreover, the co-fermented broth significantly increased bacterial species richness while reducing fungal community diversity in the substrate. The abundance of Bacteroidota, Gemmatimonadota, Chloroflexi, Halobacterota, Rozellomycota, and Basidiomycota, had significantly positively correlation with substrate nutrient content, all increased; whereas the abundance of Proteobacteria, Ascomycota, and Glomeromycota demonstrated a negative correlation with nutrient content, showing a decline. Conclusion Co-fermented broth from P10 and HGD12 strains added to seedling substrates increased nutrient content and altered microbial community structure, thereby significantly promoting pepper seed germination and seedling growth during the tray stage.

Key words: plant growth-promoting rhizobacteria, Burkholderia pyrrocinia, Bacillus flexus, co-fermented broth, bio-nursery substrate, pepper, substrate nutrients, bacterial and fungal communities

KONG Bing-bing, WANG Qing, JIANG Biao, HAN Li-zhen. Effects of PGPR Co-fermented Broth Nursery Substrate on the Pepper Seedling[J]. Biotechnology Bulletin, 2026, 42(6): 326-339.

Figures/Tables 14

References 51

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不同处理 Different treatment	添加比例 Addition ratio （%）	株高 Plant height （cm）	茎粗 Stem diameter （mm）	鲜重 Plant weight （g）	干重 Dry weight （g）	叶片数 Leaf number	叶面积 Leaf area （cm²）	叶绿素SPADC hlorophyll （SPAD）
CK		12.48±0.85fg	2.49±0.12gh	2.01±0.25ghi	0.18±0.02h	7.67±0.98fg	23.48±3.59f	31.12±1.33k
LB	5	12.44±1.30fg	2.64±0.27defh	2.25±0.13fg	0.20±0.03gh	7.75±1.22defg	28.35±2.45de	32.74±1.70j
	10	12.22±1.11fg	2.35±0.19hi	1.91±0.35ghij	0.18±0.04h	7.25±0.87gh	22.54±3.17f	33.19±1.71ij
	15	12.36±0.65fg	2.32±0.17i	1.75±0.15ij	0.17±0.03h	6.88±0.60h	22.07±2.88f	34.99±2.20fgh
	20	10.79±0.78h	2.56±0.24g	1.89±0.34hij	0.16±0.03h	7.71±0.84efg	21.20±1.75f	35.43±1.32defgh
	25	8.22±1.42i	2.34±0.15hi	1.62±0.33j	0.16±0.04h	7.38±0.69gh	21.95±3.94f	34.49±2.03ghi
P10	5	16.42±0.28b	2.73±0.05cdef	2.78±0.08cd	0.26±0.01def	8.58±0.34bcd	28.88±0.68cde	34.48±0.33ghi
	10	14.76±0.22de	2.62±0.02efg	2.60±0.07de	0.25±0.01def	8.42±0.19cdef	33.35±1.06ab	34.05±0.36hi
	15	14.89±0.32de	2.80±0.05bcd	2.88±0.13cd	0.29±0.01cde	8.92±0.23abc	33.26±1.16ab	35.11±0.3efgh
	20	14.88±0.71de	2.85±0.08bc	2.74±0.14cde	0.30±0.02bcd	8.58±0.26bcd	35.48±1.59a	35.74±0.32cdefg
	25	14.56±0.32e	2.60±0.04fg	2.80±0.16cd	0.27±0.02def	8.50±0.26cde	34.14±1.04ab	35.86±0.36cdefg
HGD12	5	14.68±0.47de	2.77±0.06bcdef	2.79±0.11cd	0.27±0.01def	8.92±0.23abc	32.52±1.27abc	34.58±0.26gh
	10	15.5±0.33bcde	2.76±0.04bcdef	2.95±0.15cd	0.28±0.02def	8.75±0.28abc	32.33±1.43abcd	36.89±0.73abc
	15	15.23±0.38cde	2.78±0.04bcde	2.87±0.17cd	0.26±0.01def	8.25±0.25cdef	31.76±1.21abcd	35.89±0.62cdefg
	20	13.21±0.30f	2.77±0.06bcdef	2.40±0.10ef	0.24±0.01fg	8.42±0.29cdef	27.84±1.26e	36.39±0.37cdef
	25	11.75±0.36gh	2.61±0.05efg	2.17±0.09fgh	0.24±0.01ef	8.50±0.29cde	27.40±0.88e	36.48±0.37bcde
P10+HGD12	5	17.88±2.35a	3.02±0.20a	3.11±0.62bc	0.34±0.09ab	9.50±1.24a	32.08±6.49abcd	36.55±1.20bcd
	10	17.79±1.46a	3.03±0.28a	3.52±0.38a	0.36±0.04a	9.46±0.66a	35.32±4.27a	36.35±1.53cdef
	15	16.12±1.22bc	3.05±0.21ab	3.31±0.45ab	0.35±0.04a	9.38±0.51ab	35.09±5.49a	36.67±1.59bcd
	20	15.78±1.10bcd	2.88±0.16abc	2.82±0.12cd	0.32±0.07abc	8.58±0.90bcd	30.98±5.26bcde	37.82±1.01ab
	25	12.64±0.79fg	2.81±0.13bcd	2.65±0.39de	0.27±0.04def	8.75±0.75abc	30.68±6.12bcde	38.01±1.14a

不同处理 Different treatment	添加比例 Addition ratio （%）	株高 Plant height （cm）	茎粗 Stem diameter （mm）	鲜重 Plant weight （g）	干重 Dry weight （g）	叶片数 Leaf number	叶面积 Leaf area （cm²）	叶绿素SPADC hlorophyll （SPAD）
CK		12.48±0.85fg	2.49±0.12gh	2.01±0.25ghi	0.18±0.02h	7.67±0.98fg	23.48±3.59f	31.12±1.33k
LB	5	12.44±1.30fg	2.64±0.27defh	2.25±0.13fg	0.20±0.03gh	7.75±1.22defg	28.35±2.45de	32.74±1.70j
	10	12.22±1.11fg	2.35±0.19hi	1.91±0.35ghij	0.18±0.04h	7.25±0.87gh	22.54±3.17f	33.19±1.71ij
	15	12.36±0.65fg	2.32±0.17i	1.75±0.15ij	0.17±0.03h	6.88±0.60h	22.07±2.88f	34.99±2.20fgh
	20	10.79±0.78h	2.56±0.24g	1.89±0.34hij	0.16±0.03h	7.71±0.84efg	21.20±1.75f	35.43±1.32defgh
	25	8.22±1.42i	2.34±0.15hi	1.62±0.33j	0.16±0.04h	7.38±0.69gh	21.95±3.94f	34.49±2.03ghi
P10	5	16.42±0.28b	2.73±0.05cdef	2.78±0.08cd	0.26±0.01def	8.58±0.34bcd	28.88±0.68cde	34.48±0.33ghi
	10	14.76±0.22de	2.62±0.02efg	2.60±0.07de	0.25±0.01def	8.42±0.19cdef	33.35±1.06ab	34.05±0.36hi
	15	14.89±0.32de	2.80±0.05bcd	2.88±0.13cd	0.29±0.01cde	8.92±0.23abc	33.26±1.16ab	35.11±0.3efgh
	20	14.88±0.71de	2.85±0.08bc	2.74±0.14cde	0.30±0.02bcd	8.58±0.26bcd	35.48±1.59a	35.74±0.32cdefg
	25	14.56±0.32e	2.60±0.04fg	2.80±0.16cd	0.27±0.02def	8.50±0.26cde	34.14±1.04ab	35.86±0.36cdefg
HGD12	5	14.68±0.47de	2.77±0.06bcdef	2.79±0.11cd	0.27±0.01def	8.92±0.23abc	32.52±1.27abc	34.58±0.26gh
	10	15.5±0.33bcde	2.76±0.04bcdef	2.95±0.15cd	0.28±0.02def	8.75±0.28abc	32.33±1.43abcd	36.89±0.73abc
	15	15.23±0.38cde	2.78±0.04bcde	2.87±0.17cd	0.26±0.01def	8.25±0.25cdef	31.76±1.21abcd	35.89±0.62cdefg
	20	13.21±0.30f	2.77±0.06bcdef	2.40±0.10ef	0.24±0.01fg	8.42±0.29cdef	27.84±1.26e	36.39±0.37cdef
	25	11.75±0.36gh	2.61±0.05efg	2.17±0.09fgh	0.24±0.01ef	8.50±0.29cde	27.40±0.88e	36.48±0.37bcde
P10+HGD12	5	17.88±2.35a	3.02±0.20a	3.11±0.62bc	0.34±0.09ab	9.50±1.24a	32.08±6.49abcd	36.55±1.20bcd
	10	17.79±1.46a	3.03±0.28a	3.52±0.38a	0.36±0.04a	9.46±0.66a	35.32±4.27a	36.35±1.53cdef
	15	16.12±1.22bc	3.05±0.21ab	3.31±0.45ab	0.35±0.04a	9.38±0.51ab	35.09±5.49a	36.67±1.59bcd
	20	15.78±1.10bcd	2.88±0.16abc	2.82±0.12cd	0.32±0.07abc	8.58±0.90bcd	30.98±5.26bcde	37.82±1.01ab
	25	12.64±0.79fg	2.81±0.13bcd	2.65±0.39de	0.27±0.04def	8.75±0.75abc	30.68±6.12bcde	38.01±1.14a

多样性指数 Diversity index	Observed OTUs	Chao1	Pielou	Shannon	Simpson	Coverage （%）
CK	1 390.33±38.07a	1 395.60±37.93a	0.84±0.01a	8.77±0.04a	0.99±0.00a	99.99
P10	1 280.67±74.19bc	1 283.94±75.44bc	0.84±0.01a	8.64±0.20a	0.99±0.00a	100.00
HGD12	1 234.33±27.39c	1 238.43±28.19c	0.82±0.02a	8.47±0.15a	0.99±0.00a	99.99
P10+HGD12	1 377.00±37.40ab	1 384.05±44.98ab	0.83±0.01a	8.63±0.17a	0.99±0.00a	99.99

多样性指数 Diversity index	Observed OTUs	Chao1	Pielou	Shannon	Simpson	Coverage （%）
CK	1 390.33±38.07a	1 395.60±37.93a	0.84±0.01a	8.77±0.04a	0.99±0.00a	99.99
P10	1 280.67±74.19bc	1 283.94±75.44bc	0.84±0.01a	8.64±0.20a	0.99±0.00a	100.00
HGD12	1 234.33±27.39c	1 238.43±28.19c	0.82±0.02a	8.47±0.15a	0.99±0.00a	99.99
P10+HGD12	1 377.00±37.40ab	1 384.05±44.98ab	0.83±0.01a	8.63±0.17a	0.99±0.00a	99.99

多样性指数 Diversity index	Observed OTUs	Chao1	Pielou	Shannon	Simpson	Coverage （%）
CK	385.33±23.46a	387.64±22.99a	0.63±0.01a	5.41±0.15a	0.94±0.01a	100
P10	355.33±70.15a	355.84±70.82a	0.59±0.03a	5.03±0.25a	0.92±0.01ab	100
HGD12	374.67±84.63a	374.94±84.84a	0.58±0.03a	4.94±0.25a	0.88±0.01b	100
P10+HGD12	373.67±22.81a	373.90±22.68a	0.59±0.04a	5.03±0.18a	0.9±0.01b	100