acid soil stress in cowpea with a local population of
arbuscular mycorrhizal fungi
Ayut Kongpun1*, Bernard
Dell2 and Benjavan Rerkasem1
of Agronomy, Department of Plant Science and Natural
Resources, Faculty of Agriculture, Chiang Mai University,
Chiang Mai, 50200, Thailand.
Ecosystems Research Institute, Murdoch University, Perth,
Western Australia, Australia.
*Corresponding author. E-mail:
Tel: 66897579334. Fax: 66 53 210000.
Phosphorus; AMF, arbuscular mycorrhizal fungi;
YFEL, youngest full expanded leaves; LSD, least
significant difference; P1, P2 and
applying phosphorus 50, 104 and 141 mg P pot-1,
arbuscular mycorrhizal fungi;
AM0, un-inoculated treatment;
DW, dry weight; N, nitrogen.
Accepted 13 July, 2011
In Huai Teecha village in Northern Thailand, local cowpeas
were grown on acidic low phosphorus soil without stress
symptoms. Arbuscular mycorrhizal fungi from this system have
been found to promote growth of many crops but there is no
information about their benefit in cowpea. In a field
experiment, three improved cowpea lines (ITD - 1131, Ubon
Ratchathani and IT90K – 227 - 2) and a local line (Teecha 1)
were grown in 3 farmer’s fields on acid low P soils. Roots
of the cowpea lines were all heavily colonized by the fungi
and their leaf P was within the sufficient range. In a pot
experiment, the cowpea line Ubon Ratchathani was grown in
acidic and non acidic (pH 5 and 6.7, respectively) soil with
three rates of phosphorus (50, 104 and 141 mg phosphorus pot-1)
with and without arbuscular mycorrhizal fungi inoculation.
Total dry weight of inoculated cowpea was not affected by
soil acidity while it was depressed in un-inoculated plants.
The fungi increased total dry weight at 50 and 104 mg
phosphorus ha-1 but had no effect at 141 mg
phosphorus pot-1. Therefore, the fungi had been
shown to enhance P uptake by cowpea roots, which resulted in
direct benefit to cowpea growth in acidic low P soil.
Mycorrhiza, cowpea, acid soil.