Soil available phosphorus status determines indigenous mycorrhizal colonization of field and glasshouse-grown spring wheat from Argentina

• Published in: Applied soil ecology : a section of Agriculture, ecosystems & environment Vol. 35; no. 1; pp. 1 - 9
• Main Authors: Covacevich, Fernanda, Echeverría, Hernán E., Aguirrezabal, Luis A.N.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 2007
• Subjects: Arbuscular mycorrhizal colonization; dry matter accumulation; fertilizer application; field experimentation; greenhouses; nutrient availability; phosphorus fertilizers; Shoot P concentration; shoots; Soil available phosphorus; soil nutrients; spring wheat; Triticum aestivum; vesicular arbuscular mycorrhizae; Wheat; Argentina; Shoot P concentration; Soil available phosphorus; Wheat; Arbuscular mycorrhizal colonization
• ISSN: 0929-1393; 1873-0272
• DOI: 10.1016/j.apsoil.2006.06.001

Wheat production ( Triticum aestivum L.) has increased across the world during last century with the intensification of agriculture. Phosphorus (P) fertilization is a common practice to improve wheat growth in Argentina. We investigate whether indigenous arbuscular mycorrhizal colonization (AMC) of hard red spring wheat is controlled by shoot P content (SPc) or by available soil P in an agricultural soil from the southeastern Argentine Pampas. In the field, AMC was monitored four times during two growing seasons of a conventional wheat crop. Treatments were: without P supply, annual supply of 11 and 22 kg P ha −1 during the last 5 years, and 164 kg P ha −1 applied once 5 years before the experiment. In the glasshouse, AMC was assessed three times in wheat growing in pots filled with the soil from unfertilized plots; treatments were: P (0 and 20 mg P pot −1), and nitrogen (N) fertilization (0 and 150 mg N pot −1). A range of soil P between 6 and 60 mg P kg −1 was obtained and the AMC ranged from 1% to 67% of root length colonized under both field and glasshouse conditions. P supplied annually increased growth and SPc but decreased AMC. N fertilization did not affect growth or AMC. Variations in SPc did not account for AMC. Variability in AMC was best accounted for local current soil available P content ( r 2 = 0.59). A linear-plateau relationship between soil P and indigenous AMC was established in wheat plants growing under contrasting environmental and experimental (field and glasshouse) conditions. Indigenous AMC was depressed by available soil P in the range 0–27 mg P kg −1 (a decrease of 2.8% mg P −1 kg −1). Above 27 mg P kg soil −1, AMC was stabilized at about 10%. Grain yield increased with fertilization and the highest relative shoot dry matter in field was obtained at 15.5 mg P kg soil −1. The soil P range that ensures high wheat production without deterring indigenous AMC is discussed.