Application of arbuscular mycorrhizal fungi inocula in a soybean - brassicaceae - maize rotation

• Research unit: COST
• Project number: C07.0102

Key words (English)

P nutrition; soybean; mycorrhiza; seed coating; P depleted soils

Research programs (English)

COST-Action 870 - From production to application of arbuscular mycorrhizal fungi in agricultural systems: a multidisciplinary approach

Short description (English)

Symbiotic relationships between plants and arbuscular mycorrhizal fungi (AMF) play an important role in productivity and health of agricultural crops. In arable systems, the AMF symbiosis has to be re-established after each harvest due to crop removal and tillage operations. Moreover, the AMF are weakened by the cultivation of non-host plants of the families Brassicaceae (e.g. cabbage, rape) and the Chenopodiaceae (e.g. sugar beet, beet root). Recently it has been shown that although AMF species and strains are relatively unspecific in forming symbiosis with most agricultural crops, their capacity to stimulate plant growth and improve nutrient uptake depends on the crop and AMF genotype. The aim of the project is to establish AMF in the soil and improve nutrient uptake and plant growth performance of a soybean – Brassicaceae (cabbage) – maize rotation. We will first test the hypothesis that multiple strain inoculation of soybean is more effective than single strain inoculation, whereby all strains previously have been tested in the greenhouse for positive stimulation of soybean growth. Secondly, we will try to maintain a high AMF infection potential of soils in the cabbage non-host crop by cultivation of an AMF compatible green manure. Maize planted subsequently is serving as indicator plant to test after-effects of the AMF inoculation and the green manure management because of its high demand for phosphorus and nitrogen. The project will deliver meaningful data for further development of AMF application under practical farm conditions with a view to safeguard natural resources such as fertilizers.

Further information (English)

Full name of research-institution/enterprise: Forschungsinstitut für biologischen Landbau FiBL

Partners and International Organizations (English)

AT, BE, CH, CZ, DE, DK, ES, FI, FR, GR, HU, IE, IL, IT, NL, NO, PL, PT, RO, SI, SK, TR, UK

Abstract (English)

The presence of an arbuscular mycorrhizal fungi (AMF) non-host crop in a rotation may induce a significant reduction of the fungal network and of living fungal spores in the soil. This could cause negative effects for the subsequent crop, as it may take several months until a functional AMF network has re-established in the soil. So as to avoid such breakdowns of the AMF community in arable soils, AMF host plants may be undersown in the main crop to maintain living hyphae. A three-year field trial was established on a phosphorus-deficient site in Buus (Canton of Basle) in order to test the effect of undersown AMF host green manure species in a non-host fodder beet crop on maize performance in the subsequent year. In the first experimental year, soybean was inoculated with a consortium of several AMF strains, but no inoculation effects were observed on the AMF root colonisation and growth of soybean. During the second year we focussed on the maintenance of the indigenous AMF network in the AMF non-host fodder beet crop with AMF host green manure species. Six weeks after having planted the fodder beets, three AMF host green manure species were undersown: caraway (Carum carvi L.), marigold (Calendula officinalis L.) and white clover (Trifolium repens L.). In addition, false flax (Camelina sativa L.), scorpionweed (Phacelia tanacetifolia Benth), white lupine (Lupinus albus L.) and blue lupine (L. angustifolius L.) were sown as AMF non-host controls. The crop biomass of the beets and the undersown plants was measured three times in July, August and at harvest to assess potential competition between the main crop and the undersown plants. However biomass was not found to be reduced in the plots with undersown green manure plants compared to the control. Among the undersown green manure species, the AMF hosts showed the expected root colonization degree (28-32 %), while the AMF non-hosts were only marginally colonized. We therefore conclude that the establishment of a living AMF network in the plots undersown with AMF host plants was successful and that the undersown plants did not compete with the beets. An un-inoculated maize crop was established in the third year as an indicator to assess after-effects of the undersown plants from the previous cropping season. Despite the clear difference in the AMF root colonisation rate of AMF host and non-host green manure plant in the year before, no effects were observed on silage maize yield, plant height, SPAD values (an indicator of chlorophyll content) as well as nitrogen and phosphorus concentration in maize shoots. Regardless of the preceding fodder beet crop, maize roots were highly colonized with AMF (68-77 %) independently of the treatment applied in the previous year. This can be explained by the diverse crop rotation and the low fertilizer level applied at the experimental site.

References in databases (English)

Swiss Database: COST-DB of the State Secretariat for Education and Research Hallwylstrasse 4 CH-3003 Berne, Switzerland Tel. [phone] Swiss Project-Number: C07.0102