Performance of Arbuscular Mycorrhizal Fungi on the Growth of Maize Plants in An Acid Sulfate Soil Region of Thailand.

The pH of Acid sulfate soil (ASS) of Thailand is extremely low, and phosphate deficiency occurs quite often in various crops. Arbuscular mycorrhizal fungi (AMF) are soil fungi that colonize roots in most of plants, and they are functioning to make easy especially phosphate absorption through the roots into the host plant. Therefore, it could be hypothesized that the inoculation of AMF in the roots of crop would improve plant growth by activating immobile mineral nutrients like phosphate in the improved ASS with lime. The purpose of the present study is to elucidate the effectiveness of artificial AMF inoculation on the crop growth in ASS region of Thailand.
The experiment was made on the field of the Royal ASS Experimental Station at Banna, in Thailand in the consecutive years from 2005 to 2007. The experimental field was improved for pH by application of lime (Ca(OH)₂) at the rate of 1.8kg m^-2. The seeds of maize plants (Zea mays L., var Yumeno Corn 85) were sowed with 200g of AMF inoculum. In 2007, P-fertilizer (triple superphosphate) plot was additionally prepared to know if the inoculation effectiveness is changed or not with the different levels of phosphate in the soil.
The inoculated plants showed higher values than the non-inoculated plants in the parameters of the vegetative growth like plant length, dry matter weight and the number of leaves. In P-fertilizer additionally applied plot prepared, the vegetative growth was intermediate between the inoculated and non-inoculated plants. This suggested that the available phosphate was not sufficient in the ASS even if the pH was improved by liming. It could be concluded that the artificial AMF inoculation would be remarkably effective to promote the growth of maize plants in ASS conditions, as far as the pH was improved by liming.