Silicon and arbuscular mycorrhizal fungi improve water-use efficiency and drought tolerance in sweet corn

Arbuscular Mycorrhizal Fungi as Nature-Based Solutions to Improve Drought Adaptation in Maize

In the face of climate change, drought stress represents a critical challenge to the sustainability of maize (Zea mays L.) cultivation. This study explored the potential of Arbuscular Mycorrhizal Fungi (AMF) to enhance maize tolerance to drought. The experiment was conducted in a glass greenhouse of the Soil Fertilizer and Water Resources Central Research Institute, Ankara, employing a factorial design with five AMF treatments under three water stress levels (70%, 50%, and 30% of field capacity). Maize plants inoculated with AMF demonstrated notable improvements in growth parameters under drought conditions. At 70% field capacity, the AMF treatment with Rhizophagus intraradices (M3) significantly increased plant height (PH) by up to 104.2 cm and fresh weight (FW) by 35.7 g, compared to control values of 95.7 cm and 27.5 g, respectively. Similarly, at 50% field capacity, AMF treatments sustained higher stem diameter (SD) measurements, with a notable instance being Rhizophagus irregularis (M2) at 5.44 cm, against a control value of 4.74 cm. The resilience of AMF-treated plants was further underlined by the improved root dry weight (RDW) in the face of severe drought stress (30% field capacity), where Glomus iranicum (M5) treatments resulted in RDW of 1.20 g compared to 0.73 g in non-AMF-treated plants. These findings substantiate the hypothesis that mycorrhizal symbiosis can significantly mitigate the effects of drought stress on maize, suggesting a viable strategy to enhance crop resilience and productivity in water-limited environments.

Synergistic Effects of Vitreous Amendment and Mycorrhizal Fungi on Durum Wheat Water Stress Tolerance

Foliar silicon application enhances maize agronomic performance under drought stress

Drought stress poses a critical threat to maize productivity by impairing physiological processes and yield formation. Silicon (Si) has emerged as a stress-mitigating element due to its ability to improve plant water status, preserve membrane stability, and protect photosynthetic pigments under drought conditions. However, there is a further need to explore the effectiveness of foliar-applied Si in hybrid maize under different drought conditions, especially during the reproductive stage. This pot experiment was conducted during fall 2023 to evaluate the effectiveness of foliar-applied silicon (Si) in mitigating drought-induced damage in hybrid maize. The experiment was arranged in a completely randomized design using a factorial arrangement with three field capacity levels (100%, 80%, and 60% FC) and four silicon concentrations (0, 4, 6, and 8 mM). Drought stress at 60% FC reduced grain yield per plant by 32.7%, thousand-grain weight by 16.3%, relative water content by 23.9%, and chlorophyll a by 46.2% compared with the well-watered control. While foliar application of 8 mM Si alleviated drought effects by increasing grain yield by 30.7%, biological yield by 7.5%, and relative water content by 9.2% compared with untreated plants under 60% FC. Cell membrane injury was reduced by 12.9% with 8 mM Si under severe drought. Significant FC × Si interaction effects were observed for thousand-grain weight, grain yield per plant, biological yield, grain protein content, and grain rows per cob. These findings suggest that, among the tested treatments, foliar application of 8 mM Si was most effective in reducing drought-induced physiological damage and maintaining yield under severe reproductive-stage drought stress.

Arbuscular Mycorrhizal Fungi Can Increase Nitrogen Use Efficiency in Aerobically Grown Rice Under Water‐Limited Conditions

Rice is a vital staple crop for more than half of the global population, but water limitations threaten its production under flooded conditions. A transition to aerobic production of rice would ease water limitations but may increase nutrient management issues. Arbuscular mycorrhizal (AM) fungi could help by boosting nutrient and water uptake, but little is known about nitrogen (N) dynamics in these systems. We used a precision irrigation platform to apply watering treatments in combination with three soil N application treatments (160 kg urea ha −1 , 320 kg urea ha −1 or split applications of 160 kg urea ha −1 twice each) inoculation with AM fungi ( Rhizophagus irregularis ), and three commercial rice varieties: Reiziq, Topaz, and Viand. Water availability was a stronger determinant of grain biomass production than N application or AM fungal inoculation. Inoculation with AM fungi led to increased grain N concentration and N use efficiency in some varieties under water‐limiting conditions. Nitrogen availability determined how much water was used by the plants, and a mid‐development N application triggered increased plant water use, stomatal conductance and carbon assimilation, regardless of water availability. We conclude that AM fungal inoculation may support aerobic rice production, but that the benefits will likely be limited under low N availability.

Effects of Priestia aryabhattai Inoculation on Growth, Grain Production, and Oxidative Metabolism of Common Bean Under Contrasting Irrigation Regimes

Water deficit represents a major environmental constraint that severely limits the growth and yield of common bean (Phaseolus vulgaris L.). Although inoculation with plant growth-promoting rhizobacteria (PGPR) has emerged as a promising strategy to mitigate drought-induced stress, the efficacy of specific strains, such as Priestia aryabhattai CMAA 1363, remains to be fully elucidated. This study evaluated the morpho-agronomic and biochemical responses of common bean to seed inoculation with P. aryabhattai CMAA 1363 under two contrasting irrigation regimes: 100% (well-watered) and 40% (water-restricted) of available water capacity (AWC) under greenhouse conditions. Water restriction significantly compromised plant performance, reducing plant and pod length, root dry biomass, and yield components (pod and grain counts, and total grain mass). Conversely, bacterial inoculation enhanced vegetative traits, increasing plant length by approximately 15% and root dry biomass by approximately 25% compared to non-inoculated controls. Notably, under severe water deficit (40% AWC), inoculated plants achieved a 20% increase in total grain mass per plant relative to their non-inoculated counterparts. Biochemical profiling indicated that inoculation effectively attenuated oxidative stress, as evidenced by lower malondialdehyde (MDA) accumulation and modulated superoxide dismutase (SOD) activity, while water-stressed plants adapted by accumulating total soluble sugars and increasing peroxidase (POD) activity. Overall, P. aryabhattai CMAA 1363 promotes vegetative development, preserves grain production under drought, and orchestrates antioxidant defense mechanisms, highlighting its potential as a sustainable bioinput to improve common bean resilience in water-limited agricultural systems.

Growth and Physiological Responses of Petunia to Chitosan and Arbuscular Mycorrhizal Fungi Under Sustained Water Content Reduction

Reducing irrigation inputs is essential for sustainable container crop production; however, the ability of biostimulants to mitigate the effects of deficit irrigation on ornamental crop quality and postharvest often may be crop-specific, product-specific, and application-specific. Two independent experiments were conducted to evaluate whether chitosan applied as a substrate amendment or arbuscular mycorrhizal fungi (AMF) applied during germination could improve growth, physiology, and postharvest performance of petunia ( Petunia milliflora ‘Picobella TM Pink’) under sustained water content reduction. Plants were grown under three container capacity (CC) treatments (100%, 70%, and 40%) combined with chitosan application timing (no application, week 1, or week 3) or AMF application (with or without). After production, plants were exposed to postharvest environments at 30 °C or 40 °C for 2 weeks. The growth index and canopy area decreased by 10% to 40% relative to plants grown at 100% CC under 70% and 40% CC; however, flower coverage percentage remained unaffected during production. Water use reduced by 20% at 70% CC and by up to 50% at 40% CC, while irrigation water use efficiency (IWUE) was maintained with all CC treatments. In the AMF experiment, plants grown at 40% CC with AMF exhibited the highest IWUE and increased root colonization under severe deficit irrigation. Photosynthetic pigment concentrations were generally maintained under deficit irrigation, whereas malondialdehyde concentrations temporarily increased at week 4 under 40% CC, indicating increased oxidative stress. Neither chitosan nor AMF consistently enhanced plant growth or reduced biochemical stress indicators under the evaluated conditions. Chitosan application timing strongly influenced plant responses, with week 3 applications reducing growth and increasing oxidative stress across CC treatments. During the postharvest evaluation, temperature was the primary factor affecting plant performance, with plants maintained at 40 °C exhibiting lower flower coverage and canopy area compared with plants maintained at 30 °C. The combination of deficit irrigation and chitosan application showed limited potential to improve postharvest heat tolerance, whereas AMF application did not improve postharvest performance. Overall, petunia demonstrated substantial tolerance to sustained deficit irrigation, and 70% CC appeared to be a practical strategy for reducing irrigation inputs while maintaining marketable crop quality.