Abiotic stresses hamper plant growth and productivity. Climate change and agricultural malpractices like excessive use of fertilizers and pesticides have aggravated the effects of abiotic stresses on crop productivity and degraded the ecosystem. There is an urgent need for environment-friendly management techniques such as the use of arbuscular mycorrhizal fungi (AMF) for enhancing crop productivity. AMF are commonly known as bio-fertilizers. Moreover, it is widely believed that the inoculation of AMF provides tolerance to host plants against various stressful situations like heat, salinity, drought, metals, and extreme temperatures. AMF may both assist host plants in the up-regulation of tolerance mechanisms and prevent the down-regulation of key metabolic pathways. AMF, being natural root symbionts, provide essential plant inorganic nutrients to host plants, thereby improving growth and yield under unstressed and stressed regimes. The role of AMF as a bio-fertilizer can potentially strengthen plants’ adaptability to changing environment. Thus, further research focusing on the AMF-mediated promotion of crop quality and productivity is needed. The present review provides a comprehensive up-to-date knowledge on AMF and their influence on host plants at various growth stages, their advantages and applications, and consequently the importance of the relationships of different plant nutrients with AMF.

The role of arbuscular mycorrhizal fungus (AMF, Glomus versiforme) in amelioration of drought-induced effects on growth and physio-biochemical attributes in maize (Zea mays L.) was studied. Maize plants were exposed to two drought regimes, i.e., moderate drought (MD) and severe drought (SD), with and without AMF inoculation. Drought at both levels reduced plant height, and chlorophyll and carotenoid content, thereby impeding photosynthesis. In addition, drought stress enhanced the generation of toxic reactive oxygen species (ROS), including H2O2, resulting in membrane damage reflected as increased electrolyte leakage and lipid peroxidation. Such negative effects were much more apparent under SD conditions that those of MD and the control, however, AMF inoculation significantly ameliorated the deleterious effects of drought-induced oxidative damage. Under control conditions, inoculation of AMF increased growth and photosynthesis by significantly improving chlorophyll content, mineral uptake and assimilation. AMF inoculation increased the content of compatible solutes, such as proline, sugars and free amino acids, assisting in maintaining the relative water content. Up-regulation of the antioxidant system was obvious in AMF-inoculated plants, thereby mediating quick alleviation of oxidative effects of drought through elimination of ROS. In addition, AMF mediated up-regulation of the antioxidant system contributed to maintenance of redox homeostasis, leading to protection of major metabolic pathways, including photosynthesis, as observed in the present study. Total phenols increased due to AMF inoculation under both MD and SD conditions. The present study advocates the beneficial role of G. versiforme inoculation in maize against drought stress.

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Light quality and gibberellins affect growth, development and morphogenesis of plants. In order to improve the quality of tobacco seedlings under greenhouse conditions, the influence of different light sources and their interaction with foliar-applied gibberellic acid (GA3) on key growth and metabolic parameters in tobacco were examined. Light sources included white, red and blue lights while GA3 was applied in three concentrations, i.e., 0, 50 and 100 mg L-1. The survival rate of the seedlings was observed after transplanting. Morphological parameters like plant height, stalk diameter, and length, width and number of leaves increased maximally with higher concentration of GA3 under all three light regimes, however, light sources did not show any visible difference. Further, root vitality, chlorophyll content and the activities amylase and nitrate reductase increased significantly due to GA3 application and achieved highest values with blue light + 100 mg L-1 GA3. Supplementation of red and blue light along with foliar application of GA3 significantly increased the growth parameters including seedling height, stem diameter, root-shoot ratio, leaf length and root vitality. The contents of carbon metabolites including starch, soluble sugars, and reducing sugars improved significantly in plants grown under red and blue lights in combination with foliar application of GA3. The results of the present study depict that growing tobacco under blue light and the application GA3 is beneficial in terms of achieving increased growth, root characteristics, carbon and nitrogen metabolism of tobacco seedlings.