Soil respiration and root production under low water availability conditions

Abstract

Belowground processes play an important role in water and carbon balances. Roots play a major role in controlling these balances by colonizing the soil, providing anchorage, absorbing water and nutrients, but also contributing to carbon storage and producing exudates. In vineyards these roles are very often performed by rootstocks. Soil respiration has a root component and a soil biota component, which are inseparable because they are interdependent. The objective of this work was to establish the dynamics of soil respiration in relation to belowground growth, depending on rootstock and variety under different water availability conditions. In March 2012, 1 year old grapevines (Vitis vinifera) ‘Grenache’ grafted onto 110-R and 140Ru, and ‘Marselan’ grafted onto 110-R, were placed in a rhizotron consisting in a set of boxes of 60 cm x 50 cm surface and 110 cm height each, filled with a sandy soil and with a glass front to non-invasively observe root development. Two drip irrigation treatments were established: low dose (1) and very low dose (2). Root growth was monitored from first appearance in August 2012. From June 2013 to April 2014, coinciding with root growth monitoring, soil respiration was monitored using a SRS1000 (ADC). Soil respiration had variable dependence on temperature, depending on the time of the year. Low soil water availability was much more limiting during the summer than temperature. Also during summer, very low root production rates were observed, whereas in the fall, especially after harvest, rates of root production and soil respiration were at their peak. Plant material did not show significant differences in root growth or soil respiration. Environmental conditions were very restrictive, probably masking possible differences due to plant material.