School of Biological Sciences, Universiti Sains Malaysia, 11800 USM, Pulau Pinang, Malaysia.
Department of Soil Science, The Islamia University of Bahawalpur, Bahawalpur, 63100, Pakistan.
Environ Monit Assess. 2020 Oct 12;192(11):697. doi: 10.1007/s10661-020-08655-x.
Environmental change is one of the primary issues faced by the farming community. Low rainfall and high temperature in arid and semiarid regions lead to the development of secondary salinisation, thus making the problem more severe. Under saline conditions, sodium is the most crucial cation that competes with potassium (K) and adversely affects plant metabolism by inhibiting plant enzymatic activities. Potassium-solubilising bacteria (KSB) play a vital role in solubilising fixed potassium and making it accessible to plants. In the current study, 42 KSB strains were isolated from paddy rhizosphere soil grown under salt-affected conditions. The plant-growth-promoting (PGP) properties of these rhizobacteria were also evaluated. Thirteen KSB strains, positive for all tested PGP traits, were evaluated for potassium solubilisation under sodium stress, namely, 0%, 3%, 5% and 7% NaCl stress. The five best strains (Acinetobacter pittii strain L1/4, A. pittii strain L3/3, Rhizobium pusense strain L3/4, Cupriavidus oxalaticus strain L4/12 and Ochrobactrum ciceri strain L5/1) based on the K-solubilising potential were identified by amplification, sequencing and bioinformatic analysis of the 16S rDNA sequences. The maximum potassium solubilisation was measured at 30 °C and pH 7 with glucose as carbon source. The application of these KSB strains significantly improved the shoot length, fresh weight, dry weight and chlorophyll contents of paddy plants grown under saline conditions. Hence, these strains could be halotolerant KSB bioinoculants that can be used to protect plants against salt stress.
环境变化是农业社区面临的主要问题之一。干旱和半干旱地区降雨量低、温度高，导致次生盐渍化的发展，使问题更加严重。在盐胁迫条件下，钠离子是与钾（K）竞争的最关键阳离子，通过抑制植物酶活性对植物代谢产生不利影响。解钾菌（KSB）在溶解固定钾并使其可被植物利用方面发挥着重要作用。在本研究中，从盐胁迫条件下生长的稻田根际土壤中分离出 42 株 KSB 菌株。还评估了这些根际细菌的植物促生（PGP）特性。对 13 株具有所有测试 PGP 特性的 KSB 菌株在钠胁迫下（即 0%、3%、5%和 7%NaCl 胁迫）进行了钾溶解能力评估。根据钾溶解能力，从 5 株最佳菌株（不动杆菌 L1/4 株、不动杆菌 L3/3 株、根瘤菌 L3/4 株、氧化醋酸杆菌 L4/12 株和食酸寇氏菌 L5/1 株）中鉴定出 16S rDNA 序列的扩增、测序和生物信息分析。在 30°C 和 pH 7 条件下，以葡萄糖为碳源时，钾的最大溶解量最高。在盐胁迫条件下，这些 KSB 菌株的应用显著提高了水稻植株的茎长、鲜重、干重和叶绿素含量。因此，这些菌株可以作为耐盐 KSB 生物菌剂，用于保护植物免受盐胁迫。
