Abstract

Wheat (Triticum aestivum L.) yields higher than the national average are achieved in southern Chile. However, these yields are only possible through application of high doses of P fertilizer and around of 80% of P is accumulated in soil as residual P. Arbuscular mycorrhizal (AM) symbiosis is known to improve P acquisition under low P availability, however some cereals - especially wheat - are believed to not respond significantly to colonization. The present study aimed to evaluate the response on plant growth and root development of two wheat cultivars with contrasting P acquisition efficiency colonized by two mycorrhizal species. Seeds of ´Crac` (P efficient cv) and ´Tukan` (P no efficient cv, according to previous screening) were pre-germinated for 3 days and then transferred to plastic pots with a mixture of sand and vermiculite (1:1). Mycorrhizal inoculum of Claroideoglomus claroideum and Rhizoglomus intraradices were mixed with the substrate before planting (20% v/v). Plants were grown for 33 days and watered every day to field conditions with Taylor and Foy nutrient solution with low P (10 µM). At harvest, soil samples were taken to measure organic acid and acid phosphatase exudation. Roots and shoot were excised and samples were cutted to measure AM colonization. The remaining roots were analyzed with winRHIZO software and then dried at 65º C. Mycorrhizal colonization by C. claroideum significantly reduced root growth, length, area and number of forks in ´Tukan, while R. intraradices increased the same parameters. Both AM inoculum improved shoot growth in ´Tukan´, being CC. the most effective. Our preliminary results suggest that mycorrhizal symbiosis can contribute to P acquisition and to enhance growth in less efficient cultivars. The efficiency attributed to ´Crac´ may not be related to mycorrhizal symbiosis, as it did not significantly affect development. This data also supports the idea of functional diversity, however P, organic acid and phosphatase concentration, need to be measured to support our findings.