Seasonal fluctuations in Vitis vinifera root respiration in the field

Abstract

We studied the seasonal fluctuation of soil respiration (RS), and its root-dependent (RR) and basal (RB) components, in a Vitis vinifera (Chardonnay) vineyard. The RS components were estimated through independent field methods (y-intercept and trenching) and modeled on the basis of a Q10 response to soil temperature, and fine and coarse root respiration coefficients. The effect of assimilate availability on RR was assessed through a trunk girdling treatment. The apparent Q10 for RR was twice that of RB (3.5 vs 1.6) and increased linearly with increasing vine root biomass. The fastest RR of fine roots was during rapid fruit growth and the fastest RR of coarse roots was immediately following fruit development. RS was estimated at 32.6kgha-1d-1 (69% as a result of RR) for the hottest month and at 7.6kgha-1d-1 (18% as a result of RR) during winter dormancy. Annual RS was low compared with other natural and cultivated ecosystems: 5.4Mgha-1 (46% as a result of RR). Our estimates of annual vineyard RS are the first for any horticultural crop and suggest that the assumption that they are similar to those of annual crops or forest trees might lead to an overestimation. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.