Physiological and Morphological Responses of Okra (Abelmoschus esculentus L.) to Rhizoglomus irregulare Inoculation under Ample Water and Drought Stress Conditions Are Cultivar Dependent

Okra is an important crop species for smallholder farmers in many tropical and subtropical regions of the world. Its interaction with mycorrhiza has been rarely studied, and little is known about its mycorrhizal dependency, especially under drought stress. In a glasshouse experiment, we investigated the effect of Arbuscular Mycorrhiza Fungi (AMF) inoculation on growth, evapotranspiration, mineral nutrition and root morphology of five okra cultivars under ample water and drought stress conditions. ‘Khartoumia’, ‘HSD6719’, ‘HSD7058’, ‘Sarah’ and ‘Clemson Spineless’-cultivars commonly used by farmers in Sudan were chosen for their geographical, morphological and breeding background variations. The plants were either inoculated with R. irregulare or mock-inoculated. Seven weeks after seeding, the soil–water content was either maintained at 20% w/w or reduced to 10% w/w to impose drought stress. Drought stress resulted in plant P deficiency and decreased shoot dry biomass (DB), especially in HSD7058 and Clemson Spineless (69% and 56% decrease in shoot DB, in the respective cultivars). Plant inoculation with AMF greatly enhanced the shoot total content of P and the total DB in all treatments. The mycorrhizal dependency (MD) -the degree of total plant DB change associated with AM colonization- differed among the cultivars, irrespective of the irrigation treatment. Key determinants of MD were the root phenotype traits. Khartoumia (with the highest MD) had the lowest root DB, root-to-shoot ratio, and specific root length (SRL). Meanwhile, HSD6719 (with the lowest MD) had the highest respective root traits. Moreover, our data suggest a relationship between breeding background and MD. The improved cultivar Khartoumia showed the highest MD compared with the wild-type Sarah and the HSD7058 and HSD6719 landraces (higher MD by 46%, 17% and 32%, respectively). Interestingly, the drought-affected HSD7058 and Clemson Spineless exhibited higher MD (by 27% and 15%, respectively) under water-deficiency compared to ample water conditions. In conclusion, the mediation of drought stress in the okra plant species by AMF inoculation is cultivar dependent. The presence of AMF propagules in the field soil might be important for increasing yield production of high MD and drought susceptible cultivars, especially under drought/low P environments.

Effect of arbuscular mycorrhizal fungi and planting media on seedlings growth of Helicteres isora L. in the nursery

A screw tree (Helicteres isora L.) is a small/large shrub species that grows and spreads in many Asian countries, including Indonesia (NTT and Maluku). It is a medicinal plant commonly used to treat many diseases, such as bleeding and constipation. This study aimed to determine the effect of Arbuscular Mycorrhizal (AM) fungi and planting media on the growth of screw tree seedlings in a nursery. This research was conducted at Bogor Forest Research and Development Center’s nursery, Indonesia. This study consisted of two factors: AM fungi with three levels, namely control, Glomus aggregatum and Glomus clarum and growth media with two levels, namely mixed media of soil: rice husk charcoal (2:1) and mixed soil of media: rice husk charcoal: cocopeat (2:1:1). The results showed that treatment of G. aggregatum and soil mixed of media: rice husk charcoal: cocopeat (2:1:1) was significantly different from other treatments except for G. clarum and soil mixture of media: rice husk charcoal: cocopeat (2:1:1) that significantly increased height, diameter and dry weight of seedlings and the values were 97, 56, 126 and 46, 37, 127% compared to the control. Mycorrhizal dependency of screw tree was very high (126 and 127%). Generally, interaction treatment of G. clarum and mixed media of soil: rice husk charcoal: cocopeat (2:1:1) increased the growth of 11-month-old screw tree in the nursery.

The influence of compost and arbuscular mycorrhizal fungi on sugarcane growth and nutrient uptake

Compost and Arbuscular mycorrhizal fungi are environmentally sustainable and low-cost materials that can benefit tropical soils with high phosphorus fixation and low organic matter content. This study investigated the effects of Arbuscular mycorrhizal fungi (AMF) and compost on the growth and nutrient uptake efficiency of sugarcane (Saccharum officinarum) seedlings. The experimental design was a completely randomized factorial design, where factor A (n = 5) was the compost doses (0, 15, 30, 60 and 120 t ha-1) and B (n = 3) the AMF inoculum (Rhizophagus clarus, Gigaspora margarita, and non-inoculated). At 30 and 90 d, seedlings’ diameter and height were measured. Mycorrhizal colonization rate, biomass production, nutrient uptake (P and N), and mycorrhizal dependency were assessed at the end of the experiment. The AMF and compost doses affected the colonization rate, initial growth, biomass production, and nutrient uptake of sugarcane seedlings. Overall, the AMF benefited plant growth at lower doses of compost. R. clarus had a higher impact on the shoot diameter of sugarcane seedlings. Mycorrhizal colonization increased with compost addition only in seedlings inoculated with G. margarita. There was no clear trend among AMF treatments for nutrient uptake. In general, sugarcane seedlings dependency on mycorrhizal condition to produce growth was higher at lower compost doses.

Ecophysiology, quality, and mycorrhizal dependency in Musa spp. (cv. Grand naine) seedlings

The use of alternative technologies involving biological processes, with economic and ecological gains, is desirable for both the expansion of Musa spp. farming and the renovation of areas with low yields. Arbuscular mycorrhizal fungi (AMF) can stimulate plant growth, especially by increasing the absorption of phosphorus (P) and other nutrients. This study analyzes the influence of AMF on the growth and physiology of micropropagated Musaspp. plants submitted to doses of P. The experimental design was randomized blocks, in a 5 x 5 factorial arrangement, in which the factors were inoculation with AMF (Glomus clarum, Gigaspora margarita, , Gigaspora albida,Clareoideoglomus etunicatum, and the control without AMF) and five doses of P (0, 50, 100, 200, and 400 mg kg-1), with four replicates. The application of P doses increased growth in micropropagated Musaspp. seedlings, regardless of mycorrhizal inoculation. The highest rates of mycorrhizal colonization occurred at the lowest P doses, and the dose of 50 mg kg-1 P provided better conditions for mycorrhizal formation in all AMF species under study. The symbioses with AMF, as well as the use of P, increased photosynthesis rate, thus favoring the growth, development, and quality of Musa spp. seedlings. Species G. clarum, C. etunicatum, and G. margarita were the most promising for plant growth.

Mycorrhizae Applications in Sustainable Forestry

Arbuscular mycorrhizal (AM) association is the most common symbiotic association of plants with microbes. AM fungi occur in the majority of natural habitats and they provide a range of important biological services, in particular by improving plant nutrition, abiotic resistance, and soil structure and fertility. AM fungi also interact with most crop varieties and forest plants. The possible benefit of AM fungi in forestry can be achieved through a combination of inoculum methods. The mycorrhizal inoculum levels in the soil and their colonization in different forest plant roots which leads to reduce the fertilizers, pathogen effects and fungicides and to protect topsoil, soil erosion, and water-logging. Currently, several reports were suggested that AM symbiosis can improve the potential for different plant species. Two steps could be used to produce high yielding of different plant biomass that would be both mycorrhizal dependency and suitability for sowing into the field with high inoculum levels Therefore, the wide-scale inoculation of AM fungi on forest trees will become economically important. The successful research is required in the area of mass production of AM fungal inoculum and AM fungi associated with roots which will contribute to sustainable forestry.

Arbuscular mycorrhizal colonization outcompetes root hairs in maize under low phosphorus availability

Background and Aims An increase in root hair length and density and the development of arbuscular mycorrhiza symbiosis are two alternative strategies of most plants to increase the root–soil surface area under phosphorus (P) deficiency. Across many plant species, root hair length and mycorrhization density are inversely correlated. Root architecture, rooting density and physiology also differ between species. This study aims to understand the relationship among root hairs, arbuscular mycorrhizal fungi (AMF) colonization, plant growth, P acquisition and mycorrhizal-specific Pi transporter gene expression in maize. Methods Using nearly isogenic maize lines, the B73 wild type and the rth3 root hairless mutant, we quantified the effect of root hairs and AMF infection in a calcareous soil under P deficiency through a combined analysis of morphological, physiological and molecular factors. Key Results Wild-type root hairs extended the rhizosphere for acid phosphatase activity by 0.5 mm compared with the rth3 hairless mutant, as measured by in situ zymography. Total root length of the wild type was longer than that of rth3 under P deficiency. Higher AMF colonization and mycorrhiza-induced phosphate transporter gene expression were identified in the mutant under P deficiency, but plant growth and P acquisition were similar between mutant and the wild type. The mycorrhizal dependency of maize was 33 % higher than the root hair dependency. Conclusions The results identified larger mycorrhizal dependency than root hair dependency under P deficiency in maize. Root hairs and AMF inoculation are two alternative ways to increase Pi acquisition under P deficiency, but these two strategies compete with each other.

The Role of MycoSilvi, Lime and Compost on The Growth of Balsa (Ochroma bicolor Rowlee.) Seedling in Post Silica Sand Mine Media

Problems arising from silica sand mining are decreasing soil fertility, as well as the presence of high heavy metals such as Fe and Al, which inhibits the growth of revegetation plants. The purpose of this study was to analyze the response of the growth of balsa seedlings (Ochroma bicolor Rowlee.) on silica sand post-mining media treated with MycoSilvi, compost, and lime and determine the most optimal combination of MycoSilvi, compost, and lime treatment. This study uses a completely randomized design (CRD) with a split-plot design with 3 treatment factors, namely the addition of MycoSilvi, compost, and lime. Each treatment consisted of five replications. The results showed that the planting media that were not treated (control) was not able to support the growth of balsa seedlings. The interaction of MycoSilvi, compost, and lime significantly affected the height, diameter, biomass, and percentage of mycorrhizal colonization parameters, and significantly affected the plant chlorophyll content. The combination of MycoSilvi type 1 treatment, namely Glomus mosseae and lime (C0K1M1) type, resulted in the highest total growth rate, diameter, biomass, and colonization percentage compared to other treatments. The addition of lime and compost to the growth medium can reduce the degree of mycorrhizal dependency of balsa seedling.