Re-examination and meta-analysis of previous research as a tool to evaluate the suitability of rootstocks in adaptation to global change. A study case from Spanish viticulture

Introduction

Meta-analysis (MA) is a method that allows statistical synthesis of the results of several similar individual studies (Figure 1). This term was introduced by Glass in 1976 as a useful tool for the scientific community to pool and summarise the enormous amount of information collected in the literature (Glass, 1976).  However, the MA is not only used to quantify the results obtained from different trials, but also allows to Identify characteristics of the different trials where the variability of the results lies, Identify possible areas for future research focus and, present new hypotheses in response to conflicting results

Agronomy, like any other science, has the same need to compile the enormous amount of data and information collected in research work. For this reason, the MA is a methodology of great interest for this science, and researchers are making increasing use of it. If we analyse the use of this tool by consulting the Scopus database on the number of articles in the field of agronomy that use this word (“meta-analysis”) in their title or abstract, we can see how, over the years, there has been an exponential increase in their use, nearly no records in the 1990s, around 50 articles per year in the early 2000s, raising up to 250 articles per year in the early 2010s, and currently reaching  750 articles per year. In the case of viticulture, there are already some relevant meta-analysis have also been performed (Payen et al., 2021; Santesteban et al., 2019; Winter et al., 2018), and their informativeness is undeniable.

In a context where viticulture is facing emerging challenges, not only due to the effect of climate change on grape yield and composition, but also due to the social demand for environmental-friendly agricultural management, rootstocks have been already identified as key players to face these challenges (Marín et al., 2020). Therefore, there is a need to re-examine previous works to anticipate which can be the behaviour expected for each rootstock in this changing environment, particularly considering that rootstock performance can only be evaluated after time and space consuming experiments, and that any decision made when establishing a vineyard will condition grape and wine characteristics throughout its entire lifetime. The statistical analysis of the results of previous scientific studies (i.e., a meta-analysis) can be a complementary tool to new field experiments to evaluate rootstock suitability to new conditions.