Abstract

Broad manipulation of halotolerant plant growth promoting bacteria (PGPB) is very important in agriculture. In the present research, survival and adaptability of PGPB was determined under saline conditions. From the rhizospheric soil of Justicia adhatoda, Chenopodium murale and Cenchrus ciliaris, growing in Khewra salt mine, 20 bacterial strains were isolated. Out of these, six strains were found to be highly salt tolerant and they were characterized on the basis of their morphology, biochemical traits and sequence analysis of 16S-rRNA gene. These strains were identified as Bacillus megaterium, Bacillus tequilensis, Bacillus xiamenensis, Pseudomonas putida, Pseudomonas aeruginosa and Staphylococcus pasteuri. On the basis of plant growth promoting activities and extracellular enzyme secretions, B. megaterium, B. tequilensis and P. putida were selected and used for further analyses. All selected PGPRs showed antibiotics tolerance and the maximum tolerance was exhibited by B. tequilensis. Moreover, all the selected bacterial strains produced various phytohormones including indole-3-acetic acid (IAA), gibberellic acid (GA3) and abscisic acid (ABA). These strains enhanced root length, shoot length and leaf area of wheat seedlings by increasing the uptake of macronutrients (nitrogen, phosphorus and potassium). On the basis of these findings, these PGPRs can be considered as potential bio-inoculants to mitigate salt tolerance.

摘要

对耐盐植物生长促进细菌 (PGPB) 的广泛操作在农业中非常重要。在目前的研究中，PGPB 的存活率和适应性是在盐水条件下确定的。从生长在Khewra盐矿的Justicia adhatoda、Chenopodium murale和Cenchrus ciliaris的根际土壤中分离出20株细菌。其中，发现6株具有高度耐盐性，并根据其形态、生化性状和16S-rRNA基因序列分析对其进行表征。这些菌株被鉴定为巨大芽孢杆菌、龙舌兰芽孢杆菌、厦门芽孢杆菌、恶臭 假单胞菌、铜绿假单胞菌和巴氏葡萄球菌. 根据植物生长促进活性和胞外酶分泌，选择巨大芽孢杆菌、龙舌兰芽孢杆菌和恶臭假单胞菌进行进一步分析。所有选定的 PGPR 均表现出抗生素耐受性，最大耐受性由龙舌兰酒表现出。此外，所有选定的细菌菌株都产生了各种植物激素，包括吲哚-3-乙酸 (IAA)、赤霉酸 (GA3) 和脱落酸 (ABA)。这些菌株通过增加常量营养素（氮、磷和钾）的吸收来增加小麦幼苗的根长、芽长和叶面积。基于这些发现，这些 PGPR 可以被认为是减轻耐盐性的潜在生物接种剂。