Arbuscular mycorrhizal fungi contribute to phosphorus uptake by wheat grown in a phosphorus-fixing soil even in the absence of positive growth responses
Author for correspondence: Huiying Li Tel: +61 (8) 83036787 Fax: +61 (8) 83036511 Email: email@example.com
- • We used 32P to quantify the contribution of an arbuscular mycorrhizal (AM) fungus (Glomus intraradices) to phosphorus (P) uptake by wheat (Triticum aestivum), grown in compartmented pots. The soil was from a major cereal-growing area, the Eyre Peninsula, South Australia; it was highly calcareous and P-fixing. Fertilizer P was added to soil at 20 mg kg−1, as solid or liquid. Two extraction methods were used to estimate plant-available P.
- • Fungal colonization was well established at harvest (36 d). Application of P decreased both colonization and hyphal length density in soil, with small differences between different P fertilizers.
- • Plants showed large positive responses in terms of growth or total P uptake to all P additions, and showed no positive (or even negative) responses to AM colonization, regardless of P application.
- • 32P was detected only in AM plants, and we calculated that over 50% of P uptake by plants was absorbed via AM fungi, even when P was added. The results add to the growing body of knowledge that ‘nonresponsive’ AM plants have a functional AM pathway for P transfer to the plant; it should not be ignored in breeding plants for root traits designed to improve P uptake.