Enhancement of sorghum grain yield and nutrition: A role for arbuscular mycorrhizal fungi regardless of soil phosphorus availability

Abstract

Societal Impact StatementSorghum is an important cereal crop that provides calories and nutrients for much of the world's population, and it is often grown with low fertiliser input. Optimising the yield, nutritive content and bioavailability of sorghum grain with minimal input is of importance for human nutrition, and arbuscular mycorrhizal (AM) fungi have previously shown potential to assist in this. Across sorghum genetic diversity, AM fungi improved the yield, nutrition and zinc and iron bioavailability of grain in a low phosphorus soil. Thus, food production systems that effectively manage AM fungi may improve consumer outcomes.Summary Sorghum is a C4 cereal crop that is an important source of calories and nutrition across the world, predominantly cultivated and consumed in low‐ and middle‐income countries. Sorghum can be highly colonised by arbuscular mycorrhizal (AM) fungi, and the plant‐fungal association can lead to improvements in biomass and nutrient uptake. High‐throughput phenotyping allows us to non‐destructively interrogate the ‘hidden’ effects of AM fungi on sorghum growth and phenology. Eight genetically diverse sorghum genotypes were grown in a soil amended with 2 or 20 mg P kg−1 and inoculated with an AM fungal culture of Rhizophagus irregularis. High‐throughput phenotyping uncovered the ‘hidden’ effects of AM fungi on growth and phenology, while grain biomass, nutrition, Zn and Fe bioavailability and root AM colonisation was determined after destructive harvest. Sorghum plants colonised by AM fungi generally performed better than non‐AM control plants, with greater yield, harvest indices, and grain P, Zn and Fe contents. During the early growth stages, AM colonisation led to temporary growth depressions. There were also AM fungal and P fertilisation effects on sorghum time‐of‐flowering. The sorghum genotype with the highest AM colonisation could barely produce grain when non‐inoculated. The two genotypes that failed to mature had very low AM colonisation. Generally, the genetically diverse sorghum genotypes were highly responsive to AM colonisation and produced more grain of greater nutritive quality when colonised, without adverse consequences for micronutrient bioavailability.

Host filtering, not competitive exclusion, may be the main driver of arbuscular mycorrhizal fungal community assembly under high phosphorus

“…These treatments resulted in plant available (Colwell) P concentrations of 5.11 mg kg −1 (±1.1), 16 mg P kg −1 (±0.92) and 29 mg P kg −1 (±3.2), in the low, medium and high P treatments respectively. Thus the low P treatment was below the critical P values for sorghum (15–22 mg P kg −1 ), while the medium P treatment fell within these values and the high P treatment resulted in P availability that was above these values (Peverill et al, 1999; Watts‐Williams et al, 2021). All plants were grown in the glasshouse, watered ad libitum with tap water for 12 weeks with 11 h day length and day/night temperatures of 28°C/18°C, while average daylight in the glasshouse for this period was 750 μmol m −2 s −1 .…”

Increased Carbon Partitioning to Secondary Metabolites Under Phosphorus Deficiency in Glycyrrhiza uralensis Fisch. Is Modulated by Plant Growth Stage and Arbuscular Mycorrhizal Symbiosis

“…Our previous study demonstrated that well-established AM symbiosis could substantially improve licorice growth and facilitate glycyrrhizin and liquiritin accumulation under P limitation ( Xie et al, 2018 ), mainly attributed to improved plant P nutrition by AM symbiosis ( Xie et al, 2019 ). In this study, we investigated mycorrhizal effects on plant growth under P deficiency at two growth stages, representing the less developed AM symbiosis but high plant P demand stage ( Li et al, 2006 ; Watts-Williams et al, 2022 ) and AM symbiosis well-established stage, respectively. We hypothesized that plants would suffer P deficiency even with AM symbiosis especially in the early growth stage, thus resulting in increase in internal P recycling by modulating C allocation and partitioning.…”

Combined Effect of Biochar and Mycorrhizal Fungi on Wheat (Triticum aestivum L.) Growth and Performance in Calcareous Soil

“…Arbuscular mycorrhizal fungus availability affects wheat growth (Watts-Williams et al, 2022). These organisms work in harmony with plant roots to increase plant resilience to stress and nutrient availability (Zhang et al 2019).…”