Arbuscular mycorrhizae (AM) are benefi cial symbionts for plant growth. They are associated with higher plants by a symbiotic association, and benefi t plants in uptake of phosphorus nutrients, production of growth hormones, increase of proteins, lipids and sugars levels, helps in heavy metal binding, salinity tolerance, disease resistance, and even in the uptake of radionuclides. Mycorrhizal genes also applicable in improvement of crop plants, due to their delivery in to plants, by a process called, particle bombardment. The comibined association of mycorrhizal fungi and Rhizobium, with legume plants, as a symbiotic association, increased the beneficial aspects comparatively more than their single associations with the host plants. This review focuses on all beneficial aspects of AM fungi, regarding plant growth.

/pdf/arbuscular-mycorrhizae-a-diverse-personality-2kplq8p5al.pdf

Arbuscular mycorrhizae: a diverse personality

Plant growth, mycorrhizal development and vesicular arbuscular spore production were examined in five tropical crop host species inoculated with Glomus clarum and grown in a glasshouse. In one of the two experiments, sequential harvests of maize, sorghum and chickpea were made in order to study spore production in relation to plant growth and mycorrhizal development. Spore numbers in each of these hosts increased at a fairly constant rate until maximum plant dry weight, when spore production ceased. Sorghum and maize produced considerably more spores than chickpea, with spore numbers being closely correlated with mycorrhizal root length. In the second experiment, Glomus clarum was cultured on each of maize, millet, sorghum, groundnut and chickpea for three consecutive generations before cross-inoculation of the spores from each host onto all five hosts. Sporulation with respect to host size was generally greatest when the inoculum used to infect a host had been produced on that host. The growth-promoting effects of the fungus were not influenced by the source of the inoculum. More spores were produced on the cereals than the legumes. Differences in spore numbers amongst hosts and plant generations were apparently influenced mainly by infected root length and by the growth period.

Spore production and mycorrhizal development in various tropical crop hosts infected with Glomus clarum.

Potato (Solanum tuberosum L.) is a widely planted crop. The primary obstacles for potato production are the high demands of fertilizers and the occurrence of widespread diseases. Traditional intensively managed agroecosystems depend on fertilizers and biocides, which could induce soil degradation and environmental problems. This review emphasizes the effects of inoculating crops with plant growth-promoting bacteria, endophytes, especially arbuscular mycorrhizal fungi (AMF), as well as the potential application of these microbes in the establishment of a sustainable potatoes cultivation system. We concluded that it is worth to isolate the most efficient microbial strains during the process of microbial diversity investigations. And it is also worth to apply flavonoids and other stimulators to promoter beneficial microbes growth since emerging evidence implies that these compounds can stimulate native mycorrhizal activity and subsequent potato yield. In summary, more practical application of bio-fertilizers and bio-control methods should be encouraged to facilitate potato production.

	 

	Key words: Arbuscular mycorrhizal fungi, beneficial microbes, disease resistance, potato production, sustainable agriculture.

/pdf/prospect-of-beneficial-microorganisms-applied-in-potato-35s47qbitt.pdf

Prospect of beneficial microorganisms applied in potato cultivation for sustainable agriculture

Five crops inoculated with Glomus mosseae were grown for 10 weeks and the development of mycorrhizal infection and sporulation were assessed. Infected roots from pot cultures of different ages were used to examine the host effect on the development of mycorrhizae. The effectiveness of each host was assessed by measuring spore numbers. For all hosts, the percentage of root length infected increased rapidly up to 10 weeks after sowing. Infectivity of root inocula increased with increasing percentage of root length infected with the inoculum for all crops, except where large numbers of mature spores (1755) had been produced on barley. The highest spore numbers were achieved in the rhizosphere of barley plants, followed by chickpea and beans. The lowest spore numbers were found in the rhizosphere of corn and okra plants. The type of the crop as well as the harvest date greatly influenced the size of the spore population and the extent of root colonization of G. mosseae.

Mass production of Glomus mosseae spores

Arbuscular mycorrhizal fungi (AMF) have obligatory symbiotic relationship with more than 80% of terrestrial plant species. AMF symbiosis acclimatizes plants for their better survival, enhanced growth and development in biotic as well abiotic environment, thereby promoting sustainable growth and development of plants. Being highly competitive and better suited, plants with AMF association with ease tolerate environmental stress to face plethora of various biotic as well as abiotic changes. These fungal symbionts offer an eco-friendly biological sound substitute to chemical fertilizers and pesticides for managing both plant quality and quantity in agriculture, horticulture and forestry. AMF are now regarded as the cornerstone of sustainable agriculture; as such, there is a necessity to accelerate their integration in agricultural production systems. It becomes important now that soil scientists and agriculturalists pay due attention to the management of AMF in the formal way to increase, restore or maintain soil fertility which indirectly influences the growth and development of plant. Present review emphasizes the mycorrhizal symbiosis as a keystone to plant productivity and diversity because of their influence on almost all metabolic processes of plants and maintains and, in many cases, stimulates plant growth and development due to their diverse functionality/benefits to host plant, consolidated here.

Arbuscular Mycorrhizal Fungi for Sustainable Agriculture

Cassava tuber skin contained VAM fungal spores, mycelial bits which embedded in between the layers and the cassava root system are non-specific to native or non-indigenous mycorrhizal fungus. Hence, an efficient strain of a VAM fungus can be multiplied in cassava and the cassava skin can be used for propagating VA-mycorrhizae in the field for crop production.

Cassava as an alternate host for multiplication of VAM fungi

Tubers of Coleus parviflorus were inoculated with spores of the vesicular arbuscular mycorrhizal fungus Glomus microcarpum. The spores had been suspended in a lignite slurry and stored in a refrigerator for 1–6 months periods. Inoculation took place by soaking the tubers in the slurry for 3 h followed by drying in the shade, subsequent planting of such tubers gave rise to nearly 100% infection even after 6 months of storage.

V. P. Potty

Papers

Cassava as an alternate host for multiplication of VAM fungi

Use of lignite slurry as inoculating medium for vesicular arbuscular mycorrhiza in Chinese potato (Coleus parviflorus).