Ashwin Revanna, Bagyaraj Davis Joseph, Mohan Raju Basavaiah
Centre for Natural Biological Resources and Community Development (CNBRCD), 41 RBI Colony, Anand Nagar, Bangalore, Karnataka, 560024, India.
Centre for Research and Development (CRD), PRIST University, Vallam, Thanjavur, Tamil Nadu, 613403, India.
Fungal Biol Biotechnol. 2023 May 3;10(1):10. doi: 10.1186/s40694-023-00157-y.
Drought stress is currently the primary abiotic stress factor for crop loss worldwide. Although drought stress reduces the crop yield significantly, species and genotypes differ in their stress response; some tolerate the stress effect while others not. In several systems, it has been shown that, some of the beneficial soil microbes ameliorate the stress effect and thereby, minimizing yield losses under stress conditions. Realizing the importance of beneficial soil microbes, a field experiment was conducted to study the effect of selected microbial inoculants namely, N-fixing bacteria, Bradyrhizobium liaoningense and P-supplying arbuscular mycorrhizal fungus, Ambispora leptoticha on growth and performance of a drought susceptible and high yielding soybean cultivar, MAUS 2 under drought condition.
Drought stress imposed during flowering and pod filling stages showed that, dual inoculation consisting of B. liaoningense and A. leptoticha improved the physiological and biometric characteristics including nutrient uptake and yield under drought conditions. Inoculated plants showed an increased number of pods and pod weight per plant by 19% and 34% respectively, while the number of seeds and seed weight per plant increased by 17% and 32% respectively over un-inoculated plants under drought stress condition. Further, the inoculated plants showed higher chlorophyll and osmolyte content, higher detoxifying enzyme activity, and higher cell viability because of less membrane damage compared to un-inoculated plants under stress condition. In addition, they also showed higher water use efficiency coupled with more nutrients accumulation besides exhibiting higher load of beneficial microbes.
Dual inoculation of soybean plants with beneficial microbes would alleviate the drought stress effects, thereby allowing normal plants' growth under stress condition. The study therefore, infers that AM fungal and rhizobia inoculation seems to be necessary when soybean is to be cultivated under drought or water limiting conditions.
干旱胁迫是当前全球范围内导致作物减产的主要非生物胁迫因素。尽管干旱胁迫会显著降低作物产量，但不同物种和基因型对胁迫的反应存在差异；一些能够耐受胁迫影响，而另一些则不能。在多个系统中，已经表明一些有益土壤微生物可以减轻胁迫影响，从而在胁迫条件下将产量损失降至最低。认识到有益土壤微生物的重要性，开展了一项田间试验，以研究选定的微生物接种剂，即固氮细菌辽宁慢生根瘤菌和提供磷的丛枝菌根真菌细弱无梗囊霉，对干旱敏感且高产的大豆品种MAUS 2在干旱条件下生长和性能的影响。
在开花期和结荚期施加干旱胁迫表明，由辽宁慢生根瘤菌和细弱无梗囊霉组成的双重接种提高了干旱条件下的生理和生物特征，包括养分吸收和产量。与干旱胁迫条件下未接种的植株相比，接种的植株单株荚数和荚重分别增加了19%和34%，而单株种子数和种子重量分别增加了17%和32%。此外，与胁迫条件下未接种的植株相比，接种的植株由于膜损伤较小，表现出更高的叶绿素和渗透溶质含量、更高的解毒酶活性以及更高的细胞活力。此外，它们还表现出更高的水分利用效率，除了积累更多养分外，还表现出更高的有益微生物负载量。
用有益微生物对大豆植株进行双重接种可减轻干旱胁迫影响，从而使植株在胁迫条件下正常生长。因此，该研究推断，在干旱或水分受限条件下种植大豆时，接种丛枝菌根真菌和根瘤菌似乎是必要的。
