International Master Program of Agriculture, National Chung-Hsing University.
Department of Soil and Environmental Science, National Chung-Hsing University.
Microbes Environ. 2020;35(2). doi: 10.1264/jsme2.ME19147.
Plant growth-promoting bacteria (PGPB) are beneficial microbes that increase plant growth and yield. However, limited information is currently available on PGPB in onion (Allium cepa Linn.). The aims of the present study were to isolate and identify PGPB in onion and examine the effects of isolated PGPB on germination and growth during the vegetative stage in onion, pak choy (Brassica chinensis), and sweet pepper (Capsicum annuum). Twenty-three strains of PGPB were isolated from the roots, bulbs, and rhizosphere soil of onion. All isolated bacterial strains showed one or more PGP traits, including indole acetic acid production, phosphate solubilization ability, and 1-aminocyclopropane-1-carboxylate deaminase and nitrogenase activities; most of these traits were derived from Bacillus sp., Microbacterium sp., and Pseudomonas sp. Eight bacteria that exhibited strong abilities to produce indole acetic acid were selected for a Petri dish trial, soil pot test, and vermiculate pot test. The Petri dish trial showed that strains ORE8 and ORTB2 simultaneously increased radicle and hypocotyl lengths in onion, but inhibited growth in sweet pepper after 7 d. The soil pot experiment on onion revealed that strains ORE5, ORE8, and ORTB2 strongly promoted growth during the vegetative stage with only a half dose of chemical fertilizer. The present results indicate that ORE8 (Bacillus megaterium) and ORTB2 (Pantoea sp.) are the most promising biofertilizers of onion and may simultaneously inhibit the seedling growth of other plants.
植物促生菌（PGPB）是一类有益微生物，能够促进植物生长和产量。然而，目前关于洋葱（Allium cepa Linn.）中 PGPB 的信息有限。本研究的目的是从洋葱的根、鳞茎和根际土壤中分离和鉴定 PGPB，并研究分离的 PGPB 对洋葱、白菜（Brassica chinensis）和甜椒（Capsicum annuum）营养生长阶段发芽和生长的影响。从洋葱的根、鳞茎和根际土壤中分离出 23 株 PGPB。所有分离的细菌菌株均表现出一种或多种 PGP 特性，包括吲哚乙酸的产生、磷酸盐的溶解能力以及 1-氨基环丙烷-1-羧酸脱氨酶和固氮酶的活性；这些特性主要来自芽孢杆菌属、微杆菌属和假单胞菌属。选择了 8 株具有较强产生吲哚乙酸能力的细菌进行了培养皿试验、土壤盆栽试验和蛭石盆栽试验。培养皿试验表明，ORE8 和 ORTB2 菌株同时增加了洋葱的胚根和下胚轴长度，但在 7 天后抑制了甜椒的生长。洋葱的土壤盆栽试验表明，ORE5、ORE8 和 ORTB2 菌株在半剂量化肥条件下强烈促进了营养生长阶段的生长。本研究结果表明，ORE8（巨大芽孢杆菌）和 ORTB2（泛菌属）是最有前途的洋葱生物肥料，可能同时抑制其他植物的幼苗生长。
