Field response of garlic inoculated with arbuscular mycorrhizal fungi to phosphorus fertilization

Several studies have demonstrated improved growth of plants infected with arbuscular mycorrhizal fungi (AMF) compared to non-AMF plants. The growth responses of garlic (Allium sativum L.) to an AMF in soil fertilized with different levels of phosphorus (P) were studied under field conditions. Garlic cloves were planted in furrows after treatment with different P levels (0, 20, 40, and 60 Kg P ha(-1)), and with or without the AMF Glomus fascicilatum. Roots were sampled at three growth stages to quantify AMF. AMF colonization occurred at all samplings and the root colonization by AMF increased gradually with time, peaking at mid-bulb filling stage in the AMF-inoculated treatments. The AMF-inoculated plants had higher fresh bulb yield and mean bulb weight than uninoculated plants regardless of P level. This increase in yield and mean bulb weight was associated with a significant increase in the bulb P total accumulation of AMF inoculated plants. The enhancement in fresh bulb yield and mean bulb weight due to AMF-inoculation was highest in plots fertilized with 20 Kg P ha(-1), whereas the AMF inoculation had no significant effect on these characters at higher P levels (40 and 60 Kg P ha(-1)). The AMF inoculant had no effect on bulb P concentration in plots fertilized with 60 Kg P ha(-1), but increased the P total accumulation of garlic plants at all P levels. Results of this study indicate that garlic was dependent on mycorrhizae and responded to an AMF inoculant in soils containing intermediate levels of P Therefore, AMF inoculants should be introduced into soil to ensure satisfactory garlic yields and reduced P fertilization.