Effect of Mycorrhizas on Young Grapevine Performance
Meyer, A H
Louw, P J E
To determine the contribution of vesicular-arbuscular mycorrhizas (VAM) to young grapevine performance regarding growth improvement, nutrition and water relations, a field trial was carried out at Groenland, a commercial farm just outside Stellenbosch. Merlot grafted onto 101-14 Mgt and 110 R (on a Westleigh soil form), and 99 R (on a Fernwood soil form), was planted and VAM inoculation applied during planting in December 1998.
VAM populations were already well-established in the soil. This was evident from high infections in the control and VAM treated plants. Infection occurred at a level ranging between 40% and 85% during the 1998 and 1999 season and increased slightly after two seasons. Little or no differences were observed in growth, nutrition and water relations because the presence of naturally occurring VAM probably masked the potential effect, if any, of inoculation. High spore counts provided further support that the soil from Groenland contains an already well-established indigenous VAM population.
Throughout the trial soil phosphorus (P) concentrations were relatively high, up to 89 mg. kg-1 P. Despite this, percentage root infection was high. Less than 1% dieback was recorded after three seasons, which can partially be ascribed to the indigenous VAM, which probably facilitated the survival of the young vines by overcoming transplant shock. Given the importance of phosphate fertilisation as a common practice, further investigations should be carried out regarding the effects of phosphorous concentrations on percentage root infection. Quantitative and qualitative investigations into indigenous VAM in vineyard soils are also regarded as of paramount importance and may result in the establishment of inoculation guidelines for farmers.
Meyer, A H, Valentine, A J, Botha, A, Archer, E, Louw, P J E. 2004. Young grapevine response and root colonisation following inoculation with arbuscular mycorrhizal fungi, South African Journal of Enology and Viticulture, v. 25 (1) (p. 26-32)