Effect of endophytic Bacillus and arbuscular mycorrhiza fungi (AMF) against Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici

Background Fusarium wilt of tomato caused by Fusarium oxysporum f. sp. lycopersici (FOL) is a serious disease that causes significant economic losses in tomato production. Seventeen endophytic Bacillus isolates from tomato roots of Meghalaya were tested for antagonistic and plant growth promotion activities. Dominating arbuscular mycorrhiza fungi (AMF) spores were isolated from the rhizosphere soils of tomato grown in Meghalaya. The effect of different combinations of AMF and endophytic Bacillus on Fusarium wilt severity and growth of tomato plant under pot and field conditions was studied. Results The endophytic Bacillus isolates ERBS51 and ERBS10 showed a maximum inhibition against FOL, with 58.43 and 55.68%, respectively, in a dual culture experiment. ERBS51 and ERBS10 were identified as Bacillus velezensis and Bacillus sp., respectively, based on 16s rRNA sequencing. Both isolates were found positive for iturin A, surfactin, bacillomycin D, protease, cellulase, pectinase, alpha-amylase, siderophore, ammonia production and ZnCO3 solubilization. Funneliformis mosseae and Glomus fasciculatum were the dominating AMF species in tomato rhizosphere of Meghalaya. The result of pot and field experiments revealed that out of all the treatments, combination of Funneliformis mosseae + Glomus fasciculatum + Bacillus velezensis + Bacillus sp. was shown to be the best in reducing the severity of Fusarium wilt to 77.44 and 66.74%, respectively. F. mosseae + G. fasciculatum + B. velezensis + Bacillus sp. also recorded the highest in most growth attributes and yield. Conclusions Endophytic Bacillus (B. velezensis and Bacillus sp.) and AMF (F. mosseae and G. fasciculatum) were safe and effective biocontrol agents against Fusarium wilt of tomato.

Spatial variability and environmental drivers of cassava—arbuscular mycorrhiza fungi (AMF) associations across Southern Nigeria

Cassava, forming starch-rich, tuberous roots, is an important staple crop in smallholder farming systems in sub-Saharan Africa. Its relatively good tolerance to drought and nutrient-poor soils may be partly attributed to the crop’s association with arbuscular mycorrhiza fungi (AMF). Yet insights into AMF-community composition and richness of cassava, and knowledge of its environmental drivers are still limited. Here, we sampled 60 cassava fields across three major cassava-growing agro-ecological zones in Nigeria and used a DNA meta-barcoding approach to quantify large-scale spatial variation and evaluate the effects of soil characteristics and common agricultural practices on AMF community composition, richness and Shannon diversity. We identified 515 AMF operational taxonomic units (OTUs), dominated by Glomus, with large variation across agro-ecological zones, and with soil pH explaining most of the variation in AMF community composition. High levels of soil available phosphorus reduced OTU richness without affecting Shannon diversity. Long fallow periods (> 5 years) reduced AMF richness compared with short fallows, whereas both zero tillage and tractor tillage reduced AMF diversity compared with hoe tillage. This study reveals that the symbiotic relationship between cassava and AMF is strongly influenced by soil characteristics and agricultural management and that it is possible to adjust cassava cultivation practices to modify AMF diversity and community structure. Graphical abstract

Effects of Indigenous and Non-Indigenous Arbuscular Mycorrhizal Fungi on Growth and Plant Nutrient Uptake by Terung Asam (Solanum lasiocarpum Dunal)

Terung asam (Solanum lasiocarpum Dunal) is a native fruit vegetable that is gaining interest as a commercial crop in Sarawak and Malaysia. Malaysia is covered by soils that are highly weathered, acidic, and low in fertility and depend on chemical fertilisers to promote good plant growth. Alternative means to reduce dependency on chemical fertiliser, for example arbuscular mycorrhiza fungi (AMF), must be sourced. Very few research on terung asam has been documented particularly on nutrients uptake. The objectives of this research were to investigate the effect of indigenous and non-indigenous AMF on nutrient uptake by terung asam. A greenhouse experiment was conducted consisting of three treatments namely control (T1), indigenous AMF (T2), non-indigenous AMF (T3). The treatments were arranged in a complete randomised design with four subsamples and four replicates. Thirty-day-old seedlings were transplanted and measured for their heights and stem diameters for 90 days. Fresh and dry shoot and root weights were taken during harvesting. Plant nutrient analyses were conducted using Kjeldahl method for total N, single ashing for P and single ashing and double acid for K, Ca and Mg. The results revealed the addition of AMF spores at 200 spores per pot, increased plant height by 13 to 33% and stem diameter by 5 to 25% and more leaves were retained by T3 plants at harvesting. T3 recorded higher fresh shoot (11.27%) and dry shoot (14.98%) as well as fresh root (23.67%) and dry root (22.77%) weights than T1 plants. Addition of AMF in treatments T2 and T3 promoted better nutrient uptake by aboveground and belowground biomasses particularly for K, Ca and Mg. T3 was superior in terms of the nutrient uptake for most nutrients. AMF used in T3 showed better results as the AMF spores were proven effective in promoting plant growth while AMF used in T2 were obtained from the field and untested. The findings of this study showed the potential of indigenous and non-indigenous AMF in promoting growth and nutrient uptake by terung asam plants.

The use of soil biostructures created by soil fauna ecosystem engineers fed with different organic matterials as inoculum source of arbuscular mycorrhiza fungi on cocoa seedling

<p><span lang="IN">Soil fauna as ecosystem engineers </span><span>have the ability to </span><span lang="IN">creat</span><span>e </span><span lang="IN">soil biostructure</span><span>s, with the capacity to </span><span lang="IN">sav</span><span>e</span><span lang="IN"> arbuscular mycorrhizal fungi (AMF) spores. </span><span>This study therefore aims to </span><span lang="IN">investigate the </span><span>AMF </span><span lang="IN">spore density in the biostructures created by cooperation between earthworms and ants with a different organic matter composition</span><span>,</span><span lang="IN"> and to analyze the </span><span>biostructures’ </span><span lang="IN">potential as a source of </span><span>AMF </span><span lang="IN">inoculum on cocoa seedlings. </span><span>In the first experiment, a </span><span lang="IN">combination of earthworms and ants composition</span><span>, as well as a </span><span lang="IN">mixture of <em>G. sepium</em> leaf (GLP), cocoa shell bean (CSB), and sago dregs (SD)</span><span>,</span><span lang="IN"> was tested</span><span>. Meanwhile, </span><span lang="IN">in the </span><span>second</span><span lang="IN"> experiment</span><span>, t</span><span lang="IN">he</span><span> effect of</span><span lang="IN"> biostructures on cocoa seedlings grown </span><span>i</span><span lang="IN">n unsterile soil</span><span>,was </span><span lang="IN">examined</span><span>. According to the results, the highest</span><span lang="IN"> AMF spore </span><span>density was obtained using </span><span lang="IN">20 earthworms+10 ants with 50%GLP+50%CSB + 0%SD treatment</span><span>. Furthermore, the t</span><span lang="IN">otal AMF spores </span><span>were </span><span lang="IN">positively correlated</span><span> with the total P value, but negatively correlated </span><span lang="IN">with </span><span>the </span><span lang="IN">C/N ratio</span><span>. Therefore, bi</span><span lang="IN">ostructure application increased AMF spores number in rhizosphere and </span><span>the cocoa seedling’s </span><span lang="IN">root infection</span><span>. Furthermore, </span><span lang="IN">biostructure</span><span>s</span><span lang="IN"> resulting from the collaborative activity </span><span>between</span><span lang="IN"> different soil fauna ecosystem engineers </span><span>were able to transmit </span><span lang="IN">AMF spore</span><span>s </span><span lang="IN">to </span><span>infected </span><span lang="IN">plant root</span><span>s</span><span lang="IN"> growing </span><span>i</span><span lang="IN">n non-sterile soil.</span></p>

Mycorrhiza stimulates Rhizobium infection in Paraserianthes falcataria (L.) I.C. Nielson under Hg contamination

Symbiosis of and AMF increase soybean production, but the information on the association between these microbes in Paraserianthes falcataria (L.) I.C. Nielson or ‘sengon’ under Hg contamination is limited. We observed P. falcataria inoculated with arbuscular mycorrhiza fungi (Glomus sp.) stimulate nodule formation under Hg contamination. The study was set up in a pot experiment in the growth chamber a the Hg concentration was adjusted to 50 ppm in soil medium. Inoculation of AMF stimulates nodule formation and increases P. falcataria tolerance to Hg. We isolated several bacteria from the rhizosphere belonging to Rhizobium group and others. Understanding the ecology of soil bacteria is important for Hg bioremediation using P. falcataria.

The distribution and presence of versicular-arbuscular mycorrhiza fungi in rhizosphere soil of Da Xanh pummelo in Ba Ria Vung Tau province

The study was carried out to determine the distribution and presence of versicular-arbuscular mycorrhiza (VAM) fungi in rhizosphere soil and roots of Da Xanh pummelo in Phu My town, Ba Ria Vung Tau province. The rhizosphere soil and root samples were collected from 6 - 7 years old pummelo of two main soil types, on two soil layers at depths of 0 - 20 cm and 20 - 40 cm, at 2/3 and the edge of canopy. The results showed that the presence of VAM spore density was higher in red basaltic soil (ferralsols) than black soil (luvisols), and common exist on the topsoil layer (0 - 20 cm) as well as the edge of canopy. Glomus and Acaulospora were two most abundant genera in survey areas, and the proportion of mycorrhizal spores ranged from 53.18 ± 2.59% to 58.54 ± 0.46 and from 23.68 ± 2.96% to 29.33 ± 0.64%, respectively. Increasing the soil depth negatively affected on spore density of VAM fungi. The VAM fungi composition aslo changed with soil depth. The percentage of root colonization by VAM fungi ranged from 56.20 ± 3.11% to 62.00 ± 3.37%, and the highest percentage of root colonization by VAM fungi was detected in red basaltic soil.

Improvement yield of sweet corn (Zea mays Saccharata (Sturt.) bailey using arbuscular mycorrhiza fungi (AMF) and cow manure fertilizer (CMF) on ultisol

This study aims to determine the effectiveness of arbuscular mycorrhiza fungi and cow manure to yield of sweet corn on Ultisol. This research was conducted using a randomized block design (RCBD) in a factorial pattern. The first factor is arbuscular mycorrhizal fungi (AMF) which consists of four levels, namely without AMF (A0), AMF 5 g/planting hole (A1), AMF 10 g/planting hole (A2), AMF 15 g/planting hole (A3). The second factor is cow manure fertilizer (CMF) consisting of three levels, namely without CMF (B0), CMF 5 tons ha-1 (B1), CMF 10 tons ha-1 (B2). The treatment applied consisted of 12 treatment combinations which were repeated in 3 replications, so that there were 36 experimental units. The observed variables were: weight of cob with cob, weight of cob without cob, cob length, ear diameter, number of rows of seeds and crop production (ton ha-1). The results showed that the highest average weight cob with husk was obtained in a combination treatment of AMF 10 g/planting hole and without CMF (A2B0) as 289.2 g. The highest average corn crop productivity was obtained in the combination of treatment without AMF and CMF 5 tons ha-1 (A0B1) as 8.52 tons ha-1.