Contribution of Mycorrhizae to Early Growth and Phosphorus Uptake by a Neotropical Palm

Arbuscular mycorrhizal fungi (AMF) can act as an extension of the root system of their host plants. In Desmoncus orthacanthos Martius (Arecaceae), which has thick and unbranched roots (i.e., magnolioid roots) and low densities of root hairs, this association may be essential to reach a maximum growth with minimum fertilizers. This is important because of the potential in the south of Mexico to use D. orthacanthos' shoots as a raw material to build handcrafts. To evaluate the effect of arbuscular mycorrhizae on phosphorus (P) uptake and initial growth of D. orthacanthos seedlings, a 160-day bi-factorial experiment was carried out in which plants were subject to one of two levels of mycorrhizal colonization (with or without) and one of three levels of P substrate addition (4, 12, and 24 ppm). Our results show that total dry weight (DW) and leaf area (LA) responded significantly to P addition but not to mycorrhizal colonization. Phosphorus concentration in plant tissues (Pt) was increased by both factors (mycorrhizae and P addition). Mycorrhizae increased relative growth rate (RGR) at low P level. Our results indicate that AMF play an important role in early growth and P uptake by D.orthacanthos seedlings; therefore, the AMF must be considered in plantations of this potentially economically important palm.