Field Evaluation

Mycorrhizal associations have evolved in complex and relatively stable natural environments which support mixed assemblages of plant species, but today man seeks to manage the symbiosis in simplified systems often involving monocultures of agricultural, horticultural or forest crops. Research on mycorrhizal functions has been carried out largely under standardized laboratory or glasshouse conditions specifically designed to exclude the complexities associated with natural soil as well as interspecific interactions between 'hosts' and fungal symbionts. This explains partly why we are able to manipulate the mycorrhiza of single fungal and 'host' species under sterile conditions, or in those soils lacking indigenous inocula, however, attempts to introduce or manage fungal symbionts in natural conditions have often failed in the past. In the 1990s, several reports in the area of plant propagation presented positive results demonstrating the value of AM fungi in the field (Table 2).

Before end users actually make use of AM fungi, the technology must be tested. The following issues need to be critically evaluated during the assessment of technology in the field:

1. Performance of plant species inoculated with AM fungi with respect to growth parameters, yield benefits, nutrient uptake and cost-economic feasibilities.

2. Nutrient budgeting, which tests the efficiency of AM fungi in improving the availability of nutrients to the plant.

3. Savings in costs on fertilizer purchase.

4. Improvement of soil conditions.

AM fungal inocula raised monoxenically at TERI, India, were tested in the field in different regions of the country with a variety of crop hosts, in fields

Table 2. Successful reports on field application of arbuscular mycorrhizal (AM) fungi on different crops (continued on next page)

Crops

AMF used for inoculation

Reference

Agricultural crops

Acacia nilotica

Glomus intraradices

Sharma et al. (1996)

Allium cepa

Indigenous AMF

Gaur and Adholeya (2000)

Allium sativum

Indigenous AMF

Kochet al. (1997)

Glomus etunicatum,

Matsubara et al. (1994)

Glomus intraradices

Apium graveolens

Glomus etunicatum,

Matsubara et al. (1994)

Glomus intraradices

Cajanus cajan

Glomus sp.

Ianson and Linderman (1993)

Calpogonium

Nine AMF species

Ikram et al. (1992)

caeruleum

Capsicum annuum

Glomus intraradices,

Douds and Reider (2003)

Glomus mosseae,

Glomus etunicatum,

Gigaspora rosea

Coriandrum sativum

Glomus intraradices

Gaur et al. (2000)

Cucumis sativus

Glomus spp.

Rosendahl and Rosendahl (1991)

Daucus carota

Glomus intraradices

Gaur et al. (2000)

Eleusine coracana

AMF species

Isobe andTsuboki (1998)

Ervum lens

Glomus clarum

Xavier and Germida (2002)

Glycine max

AMF species

Isobe and Tsuboki (1998)

Hordeum vulgare

Glomus etunicatum

Mendoza and Bori (1998)

Linum-usitatissimum

Native AMF

Thompson (1994)

Manihot

Glomus clarum

Fagbola et al. (1998)

Oryza sativa

AMF species

Isobe and Tsuboki (1998)

Phaseolus vulgaris

AMF species

Isobe and Tsuboki (1998)

Pisum sativum

Glomus etunicatum,

Matsubara et al. (1994)

Glomus intraradices

Solanum tuberosum

Indigenous AMF

Gaur and Adholeya (2000)

Sorghum bicolor

Glomus sp.

Isobe and Tsuboki (1998)

Trifolium repens

AMF species

Isobe and Tsuboki (1998)

Trigonella

Glomus intraradices

Gaur et al. (2000)

foenum-graecum

Triticum aestivum

Glomus sp.

Ryan and Angus (2003)

Vigna spp.

AMF species

Isobe and Tsuboki (1998)

Zea mays

Glomus mosseae,

Bi et al. (2003)

G. versiforme

where their potential was evaluated. The tested crop species included wheat, potato, mungbean, black gram, soybean, chickpea, chilli and sugarcane, all of which exhibited an average increase in yield of 0.4 t/ha (tonnes/hectare) and a decrease of approximately 25-50% in the expenditure on phosphate

Table 2. (continued) Trees

Coffea arabica

Gymnacranthera farquhariana

Knema attenuata

Liquidamber styraciflua Myristica fatua

Poinsettia Sporobolus wrightii Zephyranthes

Fruit crops

Asparagus officinalis

Bromus inermis Citrullus lanatus Citrus unshiu

Fragaria Olea europia

Rubus

Gigaspora margarita, Acaulospora laevis Acaulospora laevis, Gigaspora gigantea, Glomus fasciculatum, G. geosporum, G. macrocarpum Acaulospora laevis, Gigaspora gigantea, Glomus fasciculatum, G. geosporum, G. macrocarpum Glomus etunicatum

Acaulospora laevis, Gigaspora gigantea, Glomus fasciculatum, G. geosporum, G. macrocarpum Gigaspora margarita AMF species Glomus intraradices

Bhattacharya and Bagyaraj (1998) Bhat and Kaveriappa (1998)

Bhat and Kaveriappa (1998)

Brown et al. (1981) Bhat and Kaveriappa (2000)

Barrows and Roncadori (1977) Richter and Stutz (2002) Scagel (2004)

Gigaspora margarita, Glomus fasciculatum, G. mosseae Glomus fasciculatum Glomus clarum Glomus ambisporum, G. fasciculatum, G. mosseae,

Gigaspora ramisporophora Glomus intraradices Glomus intraradices, G. mosseae Glomus clarum, G. etunicatum, G. intraradices, Gigaspora rosea, Gi. gigantea, Gi. margarita, Scutellospora calospora, S. heterogama, S. persica

Matsubara et al. (2000)

Bildusas et al. (1986) Kaya et al. (2003) Shrestha et al. (1996)

Taylor and Harrier (2000)

fertilizers. The use of such inocula allowed reclamation of several stressed systems such as fly ash overburdens, alkali chlorine sludge and distillery effluent loaded sites. AM fungal technology in India has evolved as a low-cost way to ensure an enhanced phosphorus supply, thereby ensuring an increased yield in an environmentally safe manner.

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